Atrial Fibrillation

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stratification in patients with atrial fibrillation has been almost exclusively restricted to ..... (3) Pectinate muscles should not be confused with pathology.
Tanta University Faculty of Medicine Cardiology Department

THE ROLE OF ECHOCARDIOGRAPHY IN ASSESSMENT OF THROMBOEMBOLIC RISK IN PATIENTS WITH NONVALVULAR ATRIAL FIBRILLATION Thesis Submitted to Faculty of Medicine Tanta University in Partial Fulfillment for the Requirement of Master Degree In Cardiovascular Medicine

By Reham Selmy Abo El Magd Rasheed (M.B.B.Ch.)

Supervisors Prof. Dr. Seham

Fahmy Badr

Professor of Cardiology Faculty of Medicine Tanta University

Prof. Dr. Mohammed

El Sayd El Setiha

Professor of Cardiology Faculty of Medicine Tanta University

Dr. Suzan

Bayomi El Hefnawy

Assist. Prof. of Cardiology Faculty of Medicine Tanta University 2016

Introduction

INTRODUCTION Nonvalvular atrial fibrillation is a powerful risk factor for ischemic stroke , Left atrial appendage thrombus is the predominant mechanism.The velocity of blood flowing from the left atrial appendage into the left atrial cavity is reduced in atrial fibillation , corresponding to loss of synchronous contraction and dilatation of the appendage . Retarded left atrial appendage flow velocity is consistently associated with thrombus formation and fundemental to the pathogenesis of thromboembolism.(1) Echocardiography is a widely used and versatile technique that can provide comprehensive information concerning thromboembolic risk in patients with atrial fibrillation. The main focus of transthoracic echocardiography derived measures as predictors of stroke or risk stratification in patients with atrial fibrillation has been almost exclusively restricted to depressed left ventricular ejection fraction. Nevertheless, other parameters as echocardiography

left atrial diameter measured on M-mode

has already shown some evidence of accuracy,

suggesting a possible role in risk stratification. Some attempts have been made to examine and acquire indexes of left atrial appendage using two dimensional transthoracic echocardiography.Imaging of left atrial appendage using 2D transthoracic echocardiography is operator dependent.(1) Two-dimensional transesophageal echocardiography provides excellent characterization of the left atrial appendage and left atrial environment because of the anatomic relationship of these structures to 2

Introduction

the esophagus. The left atrial appendage thrombi can be very accurately identified using two dimensional transesophageal echocardiography (2DTEE), with values of sensitivity and specifity approaching 99%(2) A

disadvantage

of

both

two

dimensional

transthoracic

echocardiography(2D TTE) and two dimensional transesophageal echocardiography (2D TEE) is that they provide only a thin slice or section of cardiac structures at any given time limiting their utility in comprehensively assessing the left atrial appendage (LAA) for thrombus. On the other hand, three dimensional transthoracic echocardiography (3DTTE) overcomes this limitation of both 2D TTE and 2D TEE because of its ability to encompass whole of the left atrial appendage in three dimensions in the acquired data set, which can then be cropped and sectioned systematically at any desired angulation to more definitively look for clot. 3D TTE is also useful in differentiating a clot from pectinate muscles in the LAA, which can mimic a thrombus resulting in patient mismanagement.(3,4)

3

Aim of the work

AIM OF THE WORK Aim of the work The aim of this work was to evaluate the role of echocardiography in the assessment of thromboembolic risk in patients with nonvalvular atrial fibrillation.

4

Review of literature

Chapter 1

Atrial Fibrillation Atrial fibrillation (AF or A-fib) is an abnormal heart rhythm characterized by rapid and irregular beating. Often it starts as brief periods of abnormal beating which become longer and possibly constant over time. Most episodes have no symptoms. Occasionally there may be heart palpitations, fainting, shortness of breath, or chest pain. The disease increases the risk of heart failure, dementia, and stroke. It is a type of supraventricular tachycardia. (5) Nonvalvular AF is restricted to cases in which the rhythm disturbance occurs in the absence of rheumatic mitral stenosis or a prosthetic heart valve. (5)

Pathophysiology In AF, the normal regular electrical impulses generated by the sinoatrial node in the right atrium of the heart (figure1, 2) are overwhelmed by disorganized electrical impulses usually originating in the roots of the pulmonary veins. This leads to irregular conduction of ventricular impulses that generate the heartbeat. (6) The primary pathologic change seen in atrial fibrillation is the progressive fibrosis of the atria; however, genetic causes and inflammation may be factors in some individuals. Any inflammatory state that affects the heart can cause fibrosis of the

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Chapter 1

atria. May also be due to autoimmune disorders that create autoantibodies against myosin heavy chains. (7) AF can be distinguished from atrial flutter (AFL), which appears as an organized electrical circuit usually in the right atrium. AFL produces characteristic saw-toothed waves of constant amplitude and frequency on an ECG whereas AF does not. (7) Although the electrical impulses of AF occur at a high rate, most of them do not result in a heart beat. A heart beat results when an electrical impulse from the atria passes through the atrioventricular node (AVN) to the ventricles and causes them to contract. During AF, if all of the impulses from the atria passed through the AV node, there would be severe ventricular tachycardia, resulting in severe reduction of cardiac output. This dangerous situation is prevented by the AV node since its limited conduction velocity reduces the rate at which impulses reach the ventricles during AF. (8) Thus, the atria and ventricles no longer beat in a coordinated way. This creates a fast and irregular heart rhythm. In AF, blood isn't pumped into the ventricles as well as it should be. Also, the amount of blood pumped out of the ventricles to the body is based on the random atrial beats. (8)

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Chapter 1

Figure (1) : normal sinus rhythm, After Mischke,etal 2013 (6)

Figure (2):intrinsic conduction system of the heart,After Mischke,etal 2013 (6)

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Chapter 1

Etiology Atrial fibrillation (AF) is strongly associated with the following risk factors:(9) 

Hemodynamic stress



Atrial ischemia



Inflammation



Noncardiovascular respiratory causes



Alcohol and drug use



Endocrine disorders



Neurologic disorders



Genetic factors

Hemodynamic stress Increased intra-atrial pressure results in atrial electrical and structural remodeling and predisposes to AF. The most common causes of increased atrial pressure are mitral or tricuspid valve disease and left ventricular dysfunction. Systemic or pulmonary hypertension also commonly predisposes to atrial pressure overload, and intracardiac tumors or thrombi are rare causes. (9,10)

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Chapter 1

Atrial ischemia Coronary artery disease infrequently leads directly to atrial ischemia and AF. More commonly, severe ventricular ischemia leads to increased intra-atrial pressure and AF.(10) Inflammation Myocarditis and pericarditis may be idiopathic or may occur in association with collagen vascular diseases; viral or bacterial infections; or cardiac, esophageal, or thoracic surgery.(10) Noncardiovascular respiratory causes Pulmonary embolism, pneumonia, lung cancer, and hypothermia have been associated with AF. (10) Drug and alcohol use Stimulants, alcohol, and cocaine can trigger AF. Acute or chronic alcohol use (ie, holiday or Saturday night heart, also known as alcohol-related cardiomyopathy) and illicit drug use (ie, stimulants, methamphetamines, cocaine) have been specifically found to be related to AF. (10) Endocrine disorders Hyperthyroidism, diabetes, and pheochromocytoma have been associated with AF. (10)

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Chapter 1

Neurologic disorders Intracranial processes such as subarachnoid hemorrhage or stroke can precipitate AF. (10) Genetics A family history of AF may increase the risk of AF. A study of more than 2,200 people found an increased risk factor for AF of 1.85 for those that had at least one parent with AF. Various genetic mutations may be responsible. (11) Three types of genetic disorder are associated with atrial fibrillation: 

Familial AF as a monogenic disease



Familial AF presenting in the setting of another

inherited cardiac disease (hypertrophic cardiomyopathy , dilated cardiomyopathy, familial amyloidosis) 

Inherited arrhythmic syndromes (congenital long

QT syndrome, short QT syndrome, Brugada syndrome).(12)

Classification: Classification of atrial fibrillation (AF) begins with distinguishing a first detectable episode, irrespective of whether it is symptomatic or self-limited. Published guidelines from an American

College

of

Cardiology (ACC)/American

Heart

Association (AHA)/ European Society of Cardiology (ESC) committee of experts on the treatment of patients with atrial 10

Review of literature

Chapter 1

fibrillation recommend classification of AF into the following 3 patterns (figure3) : (13) 

Paroxysmal AF – Episodes of AF that terminate

spontaneously within 7 days (most episodes last less than 24 hours) 

Persistent AF - Episodes of AF that last more than 7 days

and may require either pharmacologic or electrical intervention to terminate 

Permanent AF - AF that has persisted for more than 1

year, either because cardioversion has failed or because cardioversion has not been attempted

Figure(3) :Classification scheme for patients with atrial fibrillation, After Levy S 2000. (13)

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Chapter 1

Paroxysmal AF Atrial fibrillation is considered to be recurrent when a patient has two or more episodes. If recurrent AF terminates spontaneously, it is designated as paroxysmal.(13) Some patients with paroxysmal AF, typically younger patients, have been found to have distinct electrically active foci within their pulmonary veins. These patients generally have many atrial premature beats noted on Holter monitoring. Isolation or elimination of these foci can lead to elimination of the trigger for paroxysms of AF.(13) Paroxysmal AF may progress to permanent AF, and aggressive attempts to restore and maintain sinus rhythm may prevent comorbidities associated with AF. (13) Persistent AF If recurrent AF is sustained, it is considered persistent, irrespective of whether the arrhythmia is terminated by either pharmacologic therapy or electrical cardioversion.(13) Persistent AF may be either the first presentation of AF or the result of recurrent episodes of paroxysmal AF. Patients with persistent AF also include those with longstanding AF in whom cardioversion has not been indicated or attempted, often leading to permanent AF. (13)

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Chapter 1

Patients can also have AF as an arrhythmia secondary to cardiac disease that affects the atria (eg, congestive heart failure, hypertensive heart disease, rheumatic heart disease, coronary artery disease). These patients tend to be older, and AF is more likely to be persistent. (13) Persistent AF with an uncontrolled, rapid ventricular heart rate response can cause a dilated cardiomyopathy and can lead to electrical remodeling in the atria (atrial cardiomyopathy). Therapy, such as drugs or atrioventricular nodal ablation and permanent pacemaker implantation, to control the ventricular rate can improve left ventricular function and improve quality of life scores. (13) Permanent AF Permanent AF is recognized as the accepted rhythm, and the main treatment goals are rate control and anticoagulation. While it is possible to reverse the progression from paroxysmal to persistent and to permanent, this task can be challenging. (13) Lone atrial fibrillation In addition to the above schema, the term "lone atrial fibrillation" has been used to identify AF in younger patients without structural heart disease, who are at a lower risk for thromboembolism.

The

definition

of

lone

AF

remains

controversial, but it generally refers to paroxysmal, persistent, or

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Chapter 1

permanent AF in younger patients (< 60 y) who have normal echocardiographic findings. (14)

Diagnosis History and physical examination The history of the individual's atrial fibrillation episodes is probably the most important part of the evaluation. Distinctions should be made between those who are entirely asymptomatic when they are in AF (in which case the AF is found as an incidental finding on an ECG or physical examination) and those who have gross and obvious symptoms due to AF may experience one or more of the following symptoms:(15) 

General fatigue



Rapid and irregular heartbeat



Fluttering or “thumping” in the chest



Dizziness



Shortness of breath and anxiety



Weakness and Sweating



Faintness or confusion



Fatigue when exercising



Chest pain or pressure.

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Chapter 1

Atrial fibrillation may present for the first time with an embolic complication most commonly ischemic stroke & transient ischemic attacks. (16) Atrial fibrillation is diagnosed on an electrocardiogram (ECG), an investigation performed routinely whenever an irregular heartbeat is suspected. Characteristic findings are the absence of P waves, with disorganized electrical activity in their place, and irregular R-R intervals due to irregular conduction of impulses to the ventricles (figure4). At very fast heart rates atrial fibrillation may look more regular, which may make it more difficult to separate from SVT or ventricular tachycardia.

(17)

Figure(4) :ECG of atrial fibrillation (top) and normal sinus rhythm (bottom). The purple arrow indicates a P wave, which is lost in atrial fibrillation,Gutierrez C,etal 2011(17)

QRS complexes should be narrow, signifying that they are initiated by normal conduction of atrial electrical activity through

the intraventricular

conduction

system.Wide

QRS

complexes are worrisome for ventricular tachycardia, although in cases where there is disease of the conduction system, wide 15

Review of literature

Chapter 1

complexes may be present in A-Fib with rapid ventricular response.(17) If paroxysmal AF is suspected but an ECG during an office visit shows only a regular rhythm, AF episodes may be detected and documented with the use of ambulatory Holter monitoring (e.g., for a day). (17) Routine blood work While many cases of AF have no definite cause, it may be the result of various other problems. Hence, kidney function and electrolytes are routinely determined, as well as thyroid stimulating hormone (commonly suppressed in hyperthyroidism ) and a blood count.(18) In acute-onset AF associated with chest pain, cardiac troponins or other markers of damage to the heart muscle may be ordered. Coagulation studies

(INR/aPTT)

are

usually

performed.(18)

Atrial Fibrillation Complications AF has two major complications can be occurred, they are stroke, and heart failure. (19) (I) Stroke In atrial fibrillation, the lack of an organized atrial contraction can result in some stagnant blood in the left atrium (LA) or left atrial appendage (LAA). This lack of movement of 16

Review of literature

Chapter 1

blood can lead to thrombus formation then it can break causing embolus proceeds to the brain may result in an ischemic stroke or a transient ischemic attack (TIA).(19,20) Determining the risk of an embolism causing a stroke is important for guiding the use of anticoagulants. The most accurate clinical prediction rules are: (21) 

CHADS2



CHA2DS2-VASc

the CHADS2 (Congestive heart failure, Hypertension, Age≥75 years, Diabetes mellitus, previous Stroke/transient ischaemic attack.The 2006 AHA/ESC guideline listed potential additional risk factors including female sex, age 65-74 years, coronary artery disease, and thyrotoxicosis. Since 2006, stronger evidence has accumulated that these additional risk factors (with the exception of thyrotoxicosis) should be considered in assessing thromboembolic risk and would be of value in identifying those patients at truly low risk.The additional risk factors have been expressed in the CHA2DS2-VASc (Congestive heart failure, Hypertension, Age≥75

years, Diabetes mellitus, previous

Stroke/transient ischaemic attack, Vascular disease, Age 65-74 years, Sex category. (21) Both the CHADS2 and the CHA2DS2-VASc score predict future stroke risk in people with AF with CHA2DS2-VASc being more accurate. Some that had a CHADS2 score of 0 had a

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Chapter 1

CHA2DS2-VASc score of 3, with a 3.2% annual risk of stroke. Thus a CHA2DS2-VASc score of 0 is considered very low risk. (21) The European Society of Cardiology (ESC) and National Institute for Health and Care Excellence (NICE)

guidelines

recommend that if the patient has a CHA2DS2-VASc score of 2 and above, oral anticoagulation therapy (OAC) with a Vitamin K Antagonist (VKA, e.g. warfarin with target INR of 2-3) or one of the non-VKA oral anticoagulant drugs (NOACs, e.g. dabigatran, rivaroxaban, edoxaban, or apixaban) is recommended.MIf the patient is 'low risk' using the CHA2DS2-VASc score (that is, 0 in males or 1 in females), no anticoagulant therapy is recommended. In males with 1 risk factor (that is, a CHA2DS2-VASc score=1), antithrombotic therapy with OAC should be considered. (21) More than 90% of cases of thrombi associated with nonvalvular atrial fibrillation evolve in the left atrial appendage. However, the LAA lies in close relation to the free wall of the left ventricle and thus the LAA's emptying and filling, which determines its degree of blood stagnation, may be helped by the motion of the wall of the left ventricle, if there is good ventricular function. (20) (II) Heart Failure Heart failure occurs if the heart can't pump enough blood to meet the body's needs. AF can lead to heart failure because the ventricles are beating very fast and can't completely fill with

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Chapter 1

blood. Thus, they may not be able to pump enough blood to the lungs and body. (15) Fatigue and shortness of breath are common symptoms of heart failure. A buildup of fluid in the lungs causes these symptoms. Fluid also can build up in the feet, ankles, and legs, causing weight gain. (15)

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Chapter 2

Left atrial appendage The left atrial appendage (LAA) is the main location of thrombus formation, predominantly in patients with nonvalvular AF.Thus, it is now clinically important to understand LAA anatomy and the optimal imaging techniques to identify or exclude LAA thrombi.(22)

Anatomy of the left atrial appendage (LAA): The LAA is a remnant of the original embryonic left atrium formed during the third week of gestation. The left atrial appendage LAA is a long, hook-like true diverticulum of the left atrium (LA).While parallel running pectinate muscles are contained within the LAA , the body of the LA is a smoothwalled structure.(22,23) The LAA lies within the pericardium next to the superior lateral aspect of the main pulmonary artery, and superior to the left ventricular free wall and it’s often multilobed (figure 5,6). (22) An autopsy study of 220 cases , the LAA found a range of volumes from 0.7 to19.2 ml, minimum diameter from 5 to 27 mm, maximum diameter from 10 to 40 mm, and a variation in length from 16 to 51 mm. In 70% of the cases, the long axis was significantly “bent “or spiral shaped. (24)

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Review of literature

Chapter 2

Figure(5):.Picture of a gross specimen of the heart with the pericardium. The position of the appendage between the left ventricle and pulmonary artery and in close relation to the pericardium can be appreciated. After Al-Saady NM, etal 1999 .(22)

Figure.(6):Acoronal section of the heart showing: trabeculated appendages incontrast to the smooth walled atrial bodies. After AlSaady NM, etal 1999 .(22) 21

Review of literature

Chapter 2

LAA structure varies significantly. Another autopsy study (n = 500) showed that most had two lobes (54%), followed by three lobes (23%), one lobe (20%), and four lobes (3%) and noted there were no significant age or sex related differences in LAA morphologies. An increased number of lobes was associated with the presence of a thrombus. In a recent study using multidetector computed tomography (MDCT) and cardiac magnetic resonance (CMR),the shapes of the LAA were classified into 4 morphological types with “chicken wing” being the most common (48%) has a dominant lobe that presents with an obvious bend in its proximal or middle part, folding back on itself at some distance from the orifice, and it may have secondary lobes, followed by “cactus” (30%), has a dominant central lobe and secondary lobes arise from it superiorly and inferiorly then “windsock” (19%), has a dominant lobe as the primary structure and there are variations in the location and number of secondary or even tertiary lobes and “cauliflower” (3%) , characterized by a short overall length, more complex internal characteristics, a variable number of lobes with lack of a dominant lobe, and a more irregular shape of the orifice . (25,26) (Figure 7)

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Chapter 2

Figure(7):Showing the Different LAA Intraluminal Morphologies (A) Chickenwing. (B) Windsock. (C) Cauliflower. (D) Cactus. A, B and C, D are pairs of the same casts but viewed from different perspectives showing the overlap that exists regarding LAA morphology, After,KoplayM,etal,2012. ( 26)

Ultrastructure and anatomical relations of LAA: The endocardium. The myocardium: The cardiac muscle cell structure of the appendages is similar to that of myocardium elsewhere. (27)  The epicardium and pericardium: The epicardium on the surface of the atria is thicker than over the ventricles.(27)

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Chapter 2

Blood supply: provided by the left circumflex and right coronary arteries from their course in the left and right atrioventricular sulci. (28)  Innervation: The atria are innervated by both sympathetic

and

parasympathetic

fibers.

Myelinated

or

unmyelinated afferent nerve fibers pass either in the vagus nerves to the brain stem or through sympathetic afferents to the spinal cord. (29) The summarizing points about LAA anatomy include: (25,26,27) (1) The left atrial appendage (LAA) is the main location of thrombus formation

(2) The LAA is a 3D structure, most often having two or more lobes. (3) Pectinate muscles should not be confused with pathology. (4) Evaluation of the LAA should include multiple planes so as to evaluate each lobe.

Function of the LAA: The LAA has several important physiological functions (22,30) (1) As it is more distensible than the left atrium itself it can act as a decompression chamber when left atrial pressure is high. Animal experiments have shown that eliminating access to the LAA results in an increase in the size and mean pressure in the left atrium.(22,30)

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Chapter 2

(2) The LAA is known to mediate thirst (at least in animals).Thus people without a LAA might have a greater tendency to become dehydrated.(22,30) (3) Removal of the LAA has been shown to reduce stroke volume and cardiac output and may thus promote heart failure. Its removal could be particularly detrimental in patients with existing heart failure as it would further reduce their cardiac output and perhaps promote pulmonary congestion.(22,30) (4) The LAA is a major endocrine organ and is the main producer of ANP (atrial natriuretic peptide) in the human heart. The ANP concentration is 40 times higher in the LAA walls than in the rest of the atrial free wall. A study of patients having undergone the maze procedure and associated LAA removal found a significantly lower ANP secretion and a commensurate increase in salt and water retention. Whether this could eventually lead to hypertension is not known.(22,30)

Role of LAA in thromboembolism: The LAA is the site most commonly associated with thrombus formation, particularly in patients with non-valvular atrial fibrillation. The pathogenesis of LAA thrombus has not been fully elucidated, but the predilection for its formation in the LAA is likely to result from stagnation within the long, blind ended trabeculated pouch.(31) Transoesophageal echocardiography on 233 patients with atrial fibrillation of more than 48 hours duration who were 25

Review of literature

Chapter 2

not on chronic anticoagulation revealed that 15% had evidence of left atrial thrombus, and in all but one case this was located in the appendage. (32) In another series of 272 patients with non-rheumatic atrial fibrillation, the prevalence of thrombi detected at transoesophageal echocardiography was 8% and all were in the appendage. less commonly, intra-atrial thrombi also form in patients with atrial flutter and were detected at transoesophageal echocardiography in five of 24 patients with atrial flutter and again, all thrombi were located in the LAA. (32) Spontaneous echo contrast (SEC) arises in conditions of stasis, has been attributed to rouleaux formation, and is strongly associated with LAA thrombus formation.(33) Left atrial size is larger in patients with spontaneous echo contrast and thrombosis in the LAA than in those without these features. LAA area has been shown to be larger in patients who have evidence of LAA thrombus, whether they are in atrial fibrillation or in sinus rhythm.(33) In patients with recent onset atrial fibrillation, LAA thrombus is associated with a large LAA area33 and in chronic atrial fibrillation it has also been shown, that LAA area is significantly larger in patients with thrombus than in those without.(34)

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Chapter 2

Left atrial appendage flow patterns: Doppler transoesophageal echocardiography has been used extensively to determine the velocity and pattern of blood flow at the orifice of the appendage (figure 8). (22)

Figure (8): Left atrial appendage flow during atrial fibrillation, as determined by pulsed Doppler during transoesophageal echocardiography. Both the velocity and the pattern of flow have been related to the formation of thrombi and to the development of subsequent thromboembolic events. In this example, a well defined flow pattern is present and the maximum inflow velocity is approaching 0.4 m/s, a relatively high velocity. Thus the risk of thrombus formation in this patient would be relatively low,afterAlSaady NM,etal1999(22)

Reduced or absent LAA inflow and outflow velocities and low LAA ejection fractions are associated with LAA spontaneous echo contrast (SEC) and thrombus formation in patientsin sinus rhythm and in those in A.F(32,35,37) and low peak LAA filling and emptying velocities have been found to be related to a history of systemic embolism.(38)

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Chapter 2

LAA flow patterns have been classified into three types according to the appearance on Doppler transoesophageal echocardiography. (36) 1. Type I: patients in sinus rhythm with a regular pattern of filling and emptying. 2. Type II: patients in atrial fibrillation with an active “saw tooth” pattern. 3. Type III: patients in atrial fibrillation with no identifiable flow waves. Patients with the type III pattern have a significantly higher incidence of LAA spontaneous echo contrast and thrombus than those with the type II or I pattern. (39) The size and mobility of the thrombus are also determinants of thromboembolic risk. Thrombus dimensions of more than 1.5 cm and thrombi that are pedunculated and mobile are associated with increased risk of thromboembolism. (40) Patients with atrial fibrillation who are successfully cardioverted with drugs or DC shock show depressed left atrial mechanical function for a variable period following restoration of sinus rhythm. Similar findings have been reported in studies on LAA function. LAA spontaneous echo contrast develops de novo, and inflow and outflow velocities in the appendage decrease after successful cardioversion of atrial fibrillation. (41,42) These findings are important, as depressed LAA function may result in thrombus formation. The finding of 28

Review of literature

Chapter 2

decreased atrial mechanical function after cardioversion is sometimes referred to as “stunning”; however, this term is a misnomer as it implies that the DC shock itself results in damage to the atrium and appendage with consequent depressed function and stasis. This is unlikely to be the case as studies on patients have

shown

that

pharmacological fibrillation,

(44)

(43)

the

phenomenon

occurs

after

both

and spontaneous cardioversion of atrial

and shocks have not been shown to cause atrial

mechanical dysfunction in patients cardioverted for ventricular tachycardia.(45) Decreased

atrial

mechanical

function

after

cardioversion may occur as a result of an atrial fibrillation induced atrial and appendageal myopathy as the depression of function is related to the duration of the previous atrial fibrillation. (31)

Haematological and endocardial correlates of LAA thrombus: Thrombi are not fixed structures but are continuously forming and resolving. Hence left atrial thrombus is associated with raised peripheral blood concentrations of fibrinopeptide A, reflecting thrombin mediated fibrin formation, and D dimer, a degradation product of fibrinogen. The observation that warfarin treatment results in disappearance of LAA thrombi when patients are re-examined with transoesophageal echocardiography after four weeks of therapy further suggests that the presence of 29

Review of literature

Chapter 2

thrombus is the result of a dynamic process of clot formation and lysis. The relative role of platelets and endothelium in the pathophysiology of LAA thrombus formation is not known. (46)

Obliteration of LAA as aprophylaxis of thromboembolism: A significant proportion of patients with AF do not receive

anticoagulation

due

to

relative

or

absolute

contraindications or patients reluctance. Mechanical alternatives have been based on the assumption that the left atrial appendage (LAA) is the locus for virtually all clots in nonvalvular AF. Several methods have been developed to achieve this by percutaneous or surgical approaches (figure9), the primary aim being to exclude blood flow into and out of the LAA(47). Percutaneous LAA occlusion

(48)

has the advantage of being a

minimally invasive treatment for patients in whom long-term anticoagulation treatment is seemed unsuitable and may be equivalent to treatment with oral anticoagulant agents in those individuals

considered

at

moderate

thromboembolism .(49)

30

to

high

risk

of

Review of literature

Chapter 2

Figure (9): Devices for percutaneous transcatheter LAA closure. (a)The PLAATO (ev3 Endovascular, Inc., North Plymouth,MN, USA) device was the first transcatheter LAA occlusion device implanted percutaneously in patients with atrial fibrillation. (b)TheWATCHMAN(Atritech Inc.) LAA occlusion system consists of a parachute-shaped device with a self-expanding nitinol frame structure with a permeable polyester membrane over the atrial side and mid-perimeter fixation barbs to secure it in the LAA. (c) The Amplatzer cardiac plug (AGA Medical Corporation, Golden Valley,MN, USA) device consists of two bodies: a distal anchoring lobe and a proximal sealing disc linked via a flexible central wais, after S.R. Gangireddy,etal 2012.(49)

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Chapter 3

Echocardiography An echocardiogram is a type of ultrasound test that uses high-pitched sound waves that are sent through a device called a transducer. The device picks up echoes of the sound waves as they bounce off the different parts of the heart. These echoes are turned into moving pictures of the heart that can be seen on a video screen. (50) Echocardiographic techniques are including: Transthoracic (2D –TTE and 3D-TTE) echocardiography. Transoesophageal (2D-TEE and 3D-TEE) echocardiography. I-Transthoracic Echocardiography: 1-Two dimensional transthoracic echocardiography(2DTTE) The main focus of transthoracic echocardiographyderived measures as predictors of stroke or risk stratification in patients with atrial fibrillation has been almost exclusively restricted to

depressed left

ventricular ejection fraction.

Nevertheless, other parameters as left atrial diameter measured on M-mode echocardiography has already shown some evidence of accuracy, suggesting a possible role in risk stratification. Some attempts have been made to examine and acquire indexes of left atrial

appendage

using

two 32

dimensional

transthoracic

Review of literature

Chapter 3

echocardiography. Imaging of left atrial appendage using 2D transthoracic echocardiography is operator dependent.(51) (figure 10)

Figure(10) : Imaging of left atrial appendage using 2D transthoracic echocardiography apical 2 chamber view,After Ayirala,etal 2011 (51)

Various established parameters for assessment of LA size are available.(52) The LA anteroposterior diameter as assessed with M mode is most commonly used. However, it is not sufficient to determine true LA size, since M mode represents only one dimension of the LA.(52)In particular in LA enlargement, which may result in an asymmetrical geometry of the LA, M mode echocardiography may underestimate LA size. Therefore, optimal assessment of LA size should include LA volume measurements. (52)

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Chapter 3

Various methods for the assessment of LA volume with two dimensional echocardiography are available, including the cubical method, area–length method, ellipsoid method and modified Simpson's rule ( table 1)(53). In a prospective study it was demonstrated that the biplane area length method and the biplane Simpson's method compared closely (mean LA volume 39±14 ml/m2 and 38±13 ml/m2, correlation coefficient 0.98), whereas the ellipsoid method systematically underestimated LA volume (mean LA volume 32±14 ml/m2). (54) (figure11)(52)

Figure(11): Measurement of left atrial (LA) volume from biplane method of disks (modified Simpson’s rule) using apical 4chamber ( A4C ) and apical 2-chamber ( A2C ) views at ventricular end systole (maximum LA size,After Lang RM,etal,2005.(52)

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Chapter 3

(Table-1) . Methods for left atrial volume quantification with Two-dimensional echocardiography. METHOD

PARAMETER

VIEW

EQUATION

Cube

APD

PSLAX

4/3π (APD/2)3

Ellipsod

-APD

PSLAX

-LA transversal diameter (D1). -LA length (L).

Area Length

-LA area

4CH

4/3π(APD/2)(D1/2)(L/2)

Simpson’s

ellipsoid geometry

4CH

2CH

LA has an 8/3π [(A4C)(A2C)/L]

-LA area

Modified

LA has a spherical shape LA has an

planimetry (A2C).

planimetry (A4C).

ASSUMPTION

ellipsoid geometry

4CH

-LA length (L).

2CH or 4CH

LA planimetry

2CH or

Summation of discs

4CH

Total volume can be calculated from sum of

Rule

smaller volumes

APD=anterior–posterior diameter; L =left atrium; PSLAX = parasternal long axis; A4 C= four-chamber view ; A2C = apical two chamber view; 2CH = two chamber view; 4CH = fourchamber view. After Laurens, FT et al.(53) 35

Review of literature

Chapter 3

2-Three Dimensional Transthoracic Echocardiography (3D-TTE): The interpretation of echocardiographic images requires a complex mental integration of multiple image planes for a true understanding of

anatomic

and

pathologic

structures.The

presentation of images in a three dimensional format more closely resembles

reality

and

could

therefore

enhance

image

interpretation. In addition, 3-dimensional imaging allows direct calculation of volumes and is, thus, more accurate than current models relying on geometric assumptions.(55) First attempts to incorporate multiple views to form a three dimensional image were made in the seventies. But, because of technical limitations (e.g. lack of processing power, relatively poor image quality, difficulties in image plane alignment) this technique was limited to an experimental setting. The advent of transesophageal echocardiography together with newer imaging probes and enhanced image processing capabilities have now led to a remarkable progress in the field of three dimensional imaging.(55) Numerous

applications

of

three

dimensional

echocardiography (3Decho) have been proposed. For example, improvements in image interpretation with 3D-echo could be of value in the decision making and planning of cardiac surgery, and in the diagnosis of complex cardiac lesions

(56).

In addition, 3-

dimensional imaging allows quantitative parameters such as valve

36

Review of literature

Chapter 3

areas, the size of defects (atrial septal defect, ventricular septal defect) or volumes to be obtained.(57,58) With new developments that allow system integration of 3D scanning, rapid or even near real time 3D-reconstruction and measurements, 3D-echo is now on the verge of becoming an integral part of an echo examination .(55) Three-dimensional

transthoracic

imaging

can

be

performed with mechanical steering devices, which are attached to standard transducers. These devices steer the transducer motion causing incremental changes in the scan plane either by rotating, shifting or fanning the probe. In addition, various locating systems (i.e. acoustic or electromagnetic) have been used effectively. The advantage of this technique is that freely definable image planes can be chosen allowing for more flexibility. (59) Volumetric real-time echocardiography is a recently developed technique based on the design of an ultrasound transducer with a matrix array that instantaneously acquires the image contained in a pyramidal volume. Volumetric real-time echocardiography is a novel imaging concept, which holds promise as a break through technology for 3D-echo. Employing a matrix array echo probe this technique allows instant (real-time) acquisition of a complete 3 dimensional data set without complex post-processing. Several studies have already demonstrated the

37

Review of literature

Chapter 3

validity of real-time volumetric echocardiography for the calculation of cardiac volumes.(60) The potential applications of 3D-echo can be categorized into 3 major areas: (61,55) (1) Interpretation of morphology and pathology. (2) Quantification of volumes and function. (3) 3D echocardiography as a teaching tool. 1-Interpretation of Morphology and Pathology The clinical potential of 3D-echocardiography has been thoroughly explored. It was clearly demonstrated that the anatomy (Figure 12) and pathology of the heart and the great vessels can often be displayed in a more comprehensive format.(61,62) Even fairly small structures such as coronary arteries, a paravalvular leak or small masses and vegetations can be visualized. (61,63) Findings also show that this technique can be applied in numerous settings. For example, in valvular heart disease , to determine the size of infectious vegetations, to determine the mitral valve area in mitral stenosis , for complex congenital malformations, or aortic dissection . Furthermore, it has also been shown that jets can be reconstructed from color Doppler information to assist in the quantification of valvular lesions.(64)

38

Review of literature

Chapter 3

Figure (12): Three-dimensional reconstruction of the mitral valve (left) as seen from the left atrium. An anatomical specimen for comparison is shown on the right. After Binder T. (55) 2- Quantification of volumes and function: 3D-echo has been applied to derive quantitative measurements of volume, mass and dimensions of the left and right ventricles and also other cardiac lesions, such as atrial and ventricular septal defects.(65) (figure 13) While quantification of ventricular volumes with twodimensional

imaging

requires

geometric

assumptions,

measurement obtained with 3Decho represents true volumes. Several studies have shown 3D-echo to be superior to 2Dechocardiography for both left and right ventricular volumes. The process requires acquisition of a 3-dimensional data set and manual

endocardial

contour

tracing.

39

Several

calculations

Review of literature

Chapter 3

including volumes (throughout the cardiac cycle), global and regional ejection fractions can be computed.(66) The endocardial surface of the ventricular cavity can be displayed from multiple angles in a dynamic mode. Since the process of manual endocardial border tracing is still time consuming, semi-automated contour detection algorithms are now being developed. In addition, there is experimental evidence that contrast opacification of the left ventricle could further enhance the applicability of 3D-volume computation.(67) The advent of real time volumetric scanning will certainly enhance the applicability of 3Dvolume computation.(68)

Figure(13): 3D acqusition of left ventricle from parasternal window .,After, Hubka M ,etal, 2002. (65)

3- 3D-Echocardiography as Teaching and Research Tool: Spatial representation of cardiac structures greatly enhances the understanding of cardiac function and pathology. 40

Review of literature

Chapter 3

Thus, three dimensional images could assist in the teaching of echocardiography where a significant amount of spatial understanding is required. An example of such an application is a system which couples 3D-echo with a virtual reality heart model. The system allows standardized echocardiographic views to be selected on the virtual heart and displayed from the 3D-dataset to provide a correlation between anatomy of the heart and echocardiographic image planes.(69) Role of 3D transthoracic echocardiography in detection of left atrial thrombi: The left atrium (LA) is the most important location for the formation of thrombi in many cardiovascular conditions. Most of these clots occur in the left atrial appendage LAA, which is a small finger-like out-pouching of the left atrium. The shape and location of LAA allow for stasis of blood in atrial fibrillation, mitral stenosis, and other conditions with low cardiac output, particularly states with poor LV function, or enlargement of the left atrium.(70) The LAA, a multilobulated structure (figure 14). The LAA may have anywhere between 1 and 4 lobes in 80% of the general population, with about 54% having 2 lobe.(71) It is internally lined by pectinate muscles which are arranged in a parallel fashion, giving it a web-like appearance. (71)

41

Review of literature

Chapter 3

Figure(14): 3DTTE image of LAA. Arrowheads point to individual lobes as visualized by cropping a 3D data set of LAA. After Karakus, G et al.(72) Traditionally, it has been difficult to visualize by twodimensional transthoracic echocardiography (2DTTE), and in most cases two-dimensional transoesophageal echocardiography (2DTEE) has been considered to evaluate its morphology and for any abnormality such as the presence of a thrombus. It has long been believed that the LAA is not well visualized on 2DTTE. However; 2DTEE has been shown to obtain superior images of the LAA because of its close proximity to the esophagus permitting use of a higher frequency transducer. (22) The LAA is usually a multilobed structure. Thus, the LAA

should

be

scanned

meticulously

in

multiple

echocardiographic planes, most precisely by multiplane TEE, and the number of lobes determined. A detailed examination of all 42

Review of literature

Chapter 3

lobes is necessary for exclusion of LAA thrombi. Owing to this complex structural feature of the LAA, the diagnosis of LAA thrombi by TEE is prone to misdiagnosis, over diagnosis(false interpretation of prominent pectinate muscles) (71,73) Under diagnosis (occult thrombi in multilobed appendages).(74) Although the visualization of this structure is much clearer in 2D-TEE with a sensitivity of 100% and a specificity of 99%, TEE is semi invasive, uncomfortable to the patient and not without risks. More recently, it has been increasingly possible to visualize the LAA by 2D-TTE due to improved technology such as improved harmonics, as well as increasing awareness, diligence and experience. The LAA can be visualized not only in parasternal short-axis views but also from the apical approach.(70) The LAA is larger in patients with atrial fibrillation, mitral stenosis, and in patients with a LAA thrombus making it easier to visualize on 2DTTE.(70) But both 2DTEE and 2DTTE are only slice techniques, visualizing only one plane at any given time, preventing comprehensive examination of the LAA and making it difficult to differentiate a clot from pectinate muscles in some patients. (71,75,76)

43

Review of literature

Chapter 3

This limitation may be overcome by obtaining a 3D transthoracic image of the LAA (figure 15). Once the LAA can be visualized from transthoracic images, it is possible to obtain a live/real time 3D image of the LAA. After a good quality image is acquired, it can be sectioned in any plane with any desired angulation, thereby increasing the confidence in accurately identifying the presence or absence of a thrombus and differentiating it from pectinate muscles especially if they are prominent or hypertrophied.(72)

Figure(15):Three dimensional transthoracic echocardiogram The thrombus (arrowhead). There was no evidence of lysis within the thrombus. AV = aortic valve, LA = left atrium, LAA = left atrial appendage, MPA = main pulmonary artery, RVO = right ventricular outflow tract. After Karakus, G et al.(72)

44

Review of literature

Chapter 3

3D imaging planes and orientation of the heart: The standard anatomical position is the starting point for 3D echocardiography orientation. Anatomic orientation assumes the body is standing upright, facing the observer. The feet are flat on the floor. The arms are hanging at the sides of the body. The palms face forward and the thumbs are pointed away from the body. (77,78) All images are displayed as if the observer is facing the patient. The standard acquisition windows for echocardiography will remain the same: left parasternal, right parasternal, apical, subcostal, suprasternal.(77,78) Most 3D echo images are displayed in two different acquisition formats. The Live 3D Echo format displays a volumetric sector. Full volume datasets are used to image a larger portion of the cardiac structures. A full volume dataset is comprised of multiple sectors that are obtained during consecutive heartbeats without moving the transducer.(77,78) The sectors are integrated to provide a pyramid-shaped dataset of 90◦ by 90◦. In pediatric echocardiography, the realtime volumetric sector can often visualize the entire heart .(77,78)

45

Review of literature

Chapter 3

Image orientation As in the study of anatomy, echocardiography images may be dissected or sectioned in planes. For the purposes of this discussion, the planes described are relative to the heart itself and not to the heart’s orientation to the body. In dissection, the most frequently used planes are the sagittal, coronal, and transverse planes. These planes lie at right angles to each other. (77.78) 1. A sagittal plane (long axis or longitudinal) is a vertical plane that divides an organ into right and left portions. 2. A coronal plane (frontal) is also a vertical plane that divides an organ into anterior and posterior portions. A four chamber view represents an oblique coronal plane of the heart. 3. A transverse plane (short axis) runs parallel to the ground, and divides the organ into superior and inferior portions. These planes can be used to reveal the structures of the heart in both anatomic specimens and echocardiography images. The use of anatomical planes to describe real-time 3D echocardiography images results in six possible views for the valves, atria, and ventricles. Each structure of the heart can be assessed from these anatomic perspectives or views 16).

46

(77,78)

(figure

Review of literature

Chapter 3

Figure(16): The heart may be described using two descriptive terms, the plane and the viewing perspective. After Nanda, CN et al.(77) Recommended 3D echocardiography basic sections: The concept of using sections to identify structures in the heart is based on viewing perspectives. For example, the heart is sectioned and the sections are displayed like opening a book and viewing the pages. To use this viewing method, the heart is displayed with the apex down. Some users may prefer to view the heart with the apex up to correspond to 2D images. Learning curve with the proposed method may be faster if the heart is viewed with the apex down .(77,78) (figures 17,18,19) 1. Sagittal section—viewed from left-hand side or right- hand side. 2. Coronal section—viewed from above and below. 47

Review of literature

Chapter 3

3. Transverse section—viewed from base or apex. 4. Oblique plane—sections performed as necessary to visualize structures outside of the basic imaging views, but may be related to nearest basic sections, for example, an oblique sagittal plane.

Figure(17): Oblique coronal (frontal) section—viewed from above and below.After Nanda, CN et al (77)

48

Review of literature

Chapter 3

Figure(18): Sagittal (long axis or longitudinal) section-viewed from left side or right side. After Nanda, CN et al (77)

Figure (19): Transverse (short axis) section—viewed from base or apex. After Nanda, CN et al (77) 49

Review of literature

Chapter 3

II-Transoesophageal echocardiography: 1-Two Dimesional Transesophageal Echocardiography (2DTEE): Transthoracic echocardiography sometimes produces poor images, especially if the patient is overweight or has obstructive airways disease. Some structures are difficult to visualise in transthoracic views, such as the left atrial appendage, pulmonary

veins,

thoracic

aorta

and

interatrial

septum.

Transoesophageal echocardiography (TOE) uses an endoscopelike ultrasound probe which is passed into the oesophagus under light sedation and positioned behind the LA (figure20). This produces high-resolution images, which makes the technique particularly valuable for investigating patients with prosthetic valve dysfunction, congenital abnormalities (e.g. Atrial septal defect), aortic dissection, infective endocarditis (vegetations that are too small to be detected by transthoracic echocardiography) and systemic embolism (intracardiac thrombus or masses). (79) The left atrial appendage is routinely analized during transesophageal echocardiography (TEE) looking for: Clots, Spontaneous echo contrast (SEC) and Abnormalities in emptying flow velocities, especially in patients with a cerebrovascular thromboembolic events. It has been demonstrated that >15% of strokes originate from the heart, and from the LAA in particular.(80,81)

50

Review of literature

Chapter 3

Figure(20) : Transoesophageal echocardiography (TOE) uses an endoscope-like ultrasound probe which is passed into the oesophagus under light sedation,After Bashir M,etal2001. (79) TEE provides an access to this small structure, enabling cardioversion in patients with atrial fibrillation (AF) without 4 weeks of prior anticoagulation. (82) The encouraging results of radiofrequency ablation therapy increase the need for good left atrial (LA) and LAA assessment by TEE.(83,84) In addition; Doppler echocardiographic studies provide us with a better understanding of the determinants of LAA function. 51

Review of literature

Chapter 3

When investigating the LAA by Transoesophageal TwoDimensional Echocardiography, it is important to keep in mind that he LAA is a threedimensional (3D) multilobed structure. Therefore; a multiplane probe revolving around the cavity (0 to180°) will improve the assessment of its frequently complex structure. Meticulous LAA cavity evaluations should be sufficient to exclude an abnormal intraluminal echo-density signal. (85) Nevertheless, exclusion of clot might be difficult, and even experts postpone electrical cardioversion because of inability to exclude clot formation. Clots may remain hidden because of the three-dimensional complexity of the LAA, and a false-positive diagnosis of thrombus may stem from false interpretation of a prominent pectinate muscle. Therefore; evaluation should include imaging in multiple planes, in order to image the entire 3D complex structure. Pectinate muscles should not be confused with thrombus. (86) (figure 21,22) Two-dimensional (2-D) images of the appendage can help to diagnose a thrombus and spontaneous echo contrast (SEC). When blood flow velocities are reduced in cardiac chambers and especially in the LAA, “smoke-like” echoes in the cavity may be seen(86)(table2)

52

Review of literature

Chapter 3

Figure (21): TEE in the horizontal plane (0◦) demonstrates a normal LAA with prominently noted pectinate muscles (arrows). Located between the ascending aorta (Ao), pulmonary artery (Pa), and the LAA is the transverse sinus (∗) ; Transoesophageal echocardiography showing prominent pectinate muscles. LA=left atrium; LV=left ventricle; arrows indicate pectinate muscles,AfterErwan D,etal,2005. (86)

Figure (22): Transesophageal echocardiogram image of a thrombus in the left atrial appendage (dotted line), AfterErwan D,etal,2005. (86)

53

Review of literature

Chapter 3

TABLE(2):Qualitative definition of the SEC: Score

Attributes

0

Absence of echogenicity.

1

Mild : Minimal echogenicity. Only transiently detectable with optimal gain settings during the cardiac cycle

2

Mild to moderate : Transient SEC without increased gain settings and more dense pattern than 1

3

Moderate : Dense swirling pattern throughout the cardiac cycle.

4

Severe : Intense echo density. very slow swirling patterns in the LA appendage, usually with similar density in the main cavity

From Fatkin et al .(87)

54

Review of literature

Chapter 3

Although it remains an “eye-ball” judgment, dependent on echo gain control. (88,89) With respect to imaging LAA, few studies by magnetic resonance imaging MRI and spiral CT scan have been reported on detection of LAA thrombus and SEC.(90) Although TEE is considered the “gold standard “for excluding LAA thrombi, in some patients dense SEC and artifacts may hamper the identification or exclusion of thrombi. Injection of contrast agent may also enhance detection of the complex borders of the LAA. (95,96) Atrial septum (bicaval) view This is a unique transoesophageal view with no equivalent transthoracic image It is perfect for studying both atria and the septum. Finding the view.(91,92) (figure23) • From the long axis views rotate the sector to around 110 °. • Turn the probe clockwise away from the left ventricle. You will see the septum come into view as a line across the screen. (91,92) • Withdraw, advance and turn the probe. Focus on a clear view of the septum, with the ‘dip’ of the fossa ovalis in the centre. (91,92)

55

Review of literature

Chapter 3

• The optimal view includes inferior and superior vena cavae on either side with the right atrial appendage visible on the right. (91,92) Use this view to assess • Drainage of superior and inferior vena cava. • Assessment for atrial septal defect and patent foramen ovale. • Drainage of right upper pulmonary vein. • Eustachian valve. (91,92) Use this view to measure • The tricuspid regurgitation jet may be aligned for Doppler measures. • A slightly adjusted view can be used to look at the right upper pulmonary vein flow. Key features of view • Left and right atria: the left atrium is nearest the probe. • Interatrial septum: this is the most prominent feature and can be qualitatively assessed for thickness and atrial septal defects. Colour flow mapping and contrast provide more detailed information on interatrial shunts. (93)

56

Review of literature

Chapter 3

• Inferior vena cava and Eustachian valve: these lie on the left of the image and flow can be mapped with colour flow. The Eustachian valve is seen as a mobile strand originating from the orifice of the inferior vena cava. (94) • Superior vena cava and christa terminalis: these lie on the right of the image with the christa terminalis usually seen as a bright bar below the superior vena cava separating it from the right atrial appendage. (94) • Right atrial appendage: this is a wide-mouthed, shallow, trabeculated appendage lying on the right of the image below the superior vena cava. Atrial pacing wires may be seen hooking into the appendage. (95) • Tricuspid valve: the tricuspid valve may be seen in the far field. To optimize the valve image advance the probe. Colour flow can assess regurgitation and the valve is often aligned for Doppler measures.(95) • Right upper pulmonary vein: to see the vein the probe needs to be turned anticlockwise slightly to focus on the superior vena cava. The right upper pulmonary vein lies parallel to the superior vena cava. The vein is often aligned for Doppler measures. This view is used to look for abnormal pulmonary venous drainage. (96)

57

Review of literature

Chapter 3

Figure(23): TEE bicaval view perfect for studying both atria and the septum. Finding the view,After Jaber WA,etal,2004.(91) Two chamber (atrial appendage) view This view is important for several features of the left heart: mitral valve, left ventricular function and left atrial appendage .The view is equivalent to the transthoracic apical 2chamber view. (figure24). 58

Review of literature

Chapter 3

Finding the view • Rotate back from the bicaval view to see mitral valve and left ventricle. • Change the sector to around 75 °. (97) • Withdraw and advance the probe to focus on a clear view of the mitral valve and left ventricle. Turn the probe to obtain the longest view of the left ventricle. (98) • To see the left atrial appendage clearly you may need to adjust the sector angle between 90 ° and 50 ° (98) • The optimal view includes mitral valve, left atrial appendage, and left ventricle. The left ventricle and left atrial appendage may not be visible in the same view and in this case separate images should be stored for each feature. (99) Use this view to assess • Global and regional left ventricle function, wall thickness. • Mitral valve morphology (orifice, prolapse). • Left atrial appendage. • Left upper pulmonary vein.

59

Review of literature

Chapter 3

Use this view to measure • Left ventricle diastolic and systolic dimensions. • Ejection fraction. (100)

Figure (24): TEE 2-chamber view cutting across mitral valve commissure, After Jaber WA,etal,2004. (91) 60

Review of literature

Chapter 3

Complications of transesophageal echocardiography: 1. Gastrointestinal Complications: I. Injuries of Gastrointestinal Tract: Dental

trauma,

sub-mucosal

hematoma

and

jaw

subluxation may occur during probe insertion. Esophageal perforations mostly occur in the abdominal followed by intrathoracic and cervical portions. They are caused by anatomic variations, poor cooperation and inadequate skill. Perforation if goes

unnoticed;

ultimately

results

in

mediastinitis

and

sepsis.(101,102) II. Gastroesophageal Lesions and Anatomic Variations; Neoplasm, diverticulum,

(101,103)

achalasia, Barrett’s

esophagus, esophagitis, scleroderma and tumors are risk factors. Esophageal intubations most often fail at the level of cricopharynx. Esophageal varices due to portal hypertension can cause bleeding. (104) III. Unsuccessful Esophageal Intubation: Due to incooperation, inexperience and anatomic abnormalities. (102) IV. Injury to Other Solid Organs & Oral Injuries: Splenic laceration can occur due to deep insertion of the probe into the stomach for transgastric imaging. 61

(105)

Dysphagia

Review of literature

Chapter 3

can occur due to local compression from probe insertion which affects pharyngoesophageal tissue especially in female and pediatric patients.(106) 2. Respiratory Complications: Incidence

of

increases with obesity awake

patients;

oxygen (107)

desaturation

and

aspiration

and during emergency procedures. In

bronchospasm,

laryngospasm,

posterior

pharyngeal wall hematoma, supraglottic hematoma may occur. (108,109,110)

3. Cardiovascular Complications: Intubation can induce vagal and sympathetic reflexes such as hypertension or hypotension or even myocardial infarction.(111,112,113) Arrhythmias are manifested as non-sustained ventricular tachycardia, SVT, AF and third degree heart block.(114) Pulmonary embolization from right atrial mass

(115,116)

mitral

vegetation and left intracardiac thrombus(117) can occur resulting in stroke.(118) 4. Infections: Such as endocarditis by staph aureus and staph epidermidis.(119,120) 5. Medication Related Complications: Sedation: Benzodiazepines and propofol may cause respiratory 62

Review of literature

Chapter 3

depression, hypotension and allergy. (110) Local Anaesthetic Medication: Congenital absence of

methemoglobin

reductase

enzyme

and

topical

local

anaesthetics like lidocaine and benzocaine can lead to methemoglobinemia. (121,122) 2-Three Dimesional Transesophageal Echocardiography (3DTEE): Transesophageal echocardiography (TEE) is an essential diagnostic

tool

in

patients

with

poor

transthoracic

echocardiographic windows or when de tailed im aging of struc tures dis tant from the chest wall is necessary. A real-time 3D TEE probe has been fabricated in order to increase the amount of information available during a transesophageal procedure. The latest 3D TEE technology utilizes fully sampled matrix array transducers, acquire data in a 3D pyramidal fashion, with the ability to focus in on a small region of interest.(figure25,26) (123)

Figure (25):3D TEE probe scanning a pyramidal volume,After Freeman(123)

63

Review of literature

Chapter 3

Figure (26): Three-dimensional transesophageal echocardiography 80° section shows small immobile linear formations in the lateral appendage wall (arrows) as pectinate muscles. LA = Left atrium, LAA = Left atrial appendage, LUPV = Left upper pulmonary vein,After Freeman(123) .

64

Patients and methods

PATIENT AND METHODS Study Population: Fifty patients, age range from 42 to 65 years, of both sex admitted at Cardiology Department, Tanta University Hospital or came for follow up or referred for cardiac consultation and for transthoracic

and

transesophageal

echocardiography

were

included in the study. Place of the study: Cardiology Department, Tanta University Hospital. The study was approved by the ethics committee of faculty of Medicine, Tanta University. Duration of the study: From June 2015 to November 2015 Inclusions criteria: Patients presenting with: 1 – Palpitation and their ECG showed atrial fibrillation and echocardiography showed atrial fibrillation not due to valvular lesion. (Nonvalvular AF is restricted to cases in which the rhythm disturbance occurs in the absence of rheumatic mitral stenosis or a prosthetic heart valve). (5) 2 – History of atrial fibrillation or thromboembolic complications commonly as transient ischemic attacks (TIA) or ischemic stroke. 65

Patients and methods

Exclusion criteria: 1 – Patients with atrial fibrillation due to valvular lesion. 2 – Patients with history of mechanical valve replacement. 3 – Patients in the acute phase of cardiovascular disease or infection. Procedures: An informed consent was taken from all prticipitants. All patients was subjected to the following : 1 – Full history taking. 2 – Clinical examination. 3 – Electrocardiography (ECG). 4 – Two dimensional transthoracic echocardiography (2DTTE) •

All patients were assessed

to exclude cases of atrial

fibrillation due to valvular lesion , assessment of ejection fraction, left atrial diameter, assessment of LAA, presense of intracardiac thrombi and atherosclerosis in aorta. • Transthoracic studies were done by a standard technique using GE Vivid 7(figure 27) with M4S probe. LA diameter was taken in the parasternal long axis view in M-mode at end systole. • To maximize the transthoracic visualization of LA thrombus, the LA was examined in standard parasternal long axis, apical, subcostal and parasternal short axis views

66

Patients and methods

with angulation of transducer to enhance the imaging of LA appendage. The Machine:GE Vivid 7® Pro Color Ultrasound System

Figure (27) : GE Vivid 7® Pro Color Ultrasound System

5 -Two dimensional transesophageal echocardiography(2DTEE) TEE was performed after TTE. GE vivid 7 with 6T TEE Probe (6T Multiplane Transesophageal Transducer (2.9 - 6.7 MHz)) was used. All patients were given local pharyngeal anaesthesia (1% Lidocaine spray) and intravenous diazepam 3mg. 67

Patients and methods

During the study: heart rate, blood pressure, ECG and pulse oximetry were monitored. TEE probe was introduced with the patient lying supine in left lateral position. The LA was scanned in short axis view and bicaval view. With a counter clockwise rotation of the probe at the level of aortic valve, the LA appendage was visualized and flow velocity assessed. LAA thrombus was diagnosed by the presence of well defined echogenic intracavity mass with an echo texture different from that of underlying endocardium and not due to pectinate muscle. LA spontaneous echo contrast was diagnosed by the presence of dynamic smoke like echoes in the LA cavity and LA appendage with swirling motion distinct from white noise artifact after adjusting the gain setting properly. Searching for other intracardiac thrombi & atherosclerosis in aorta. After completion of TEE, patients were observed in the ward for 2 hours prior to discharge. Measures to prevent TEE Complications (111,114) Careful medical history : allergy - bleeding disorder - dysphagia - esophageal varices – GIT bleeding - esophageal and neck surgeries - use of antacid, 68

Patients and methods

salicylates, anticoagulants and antiplatelet agents. Physical Examination. a. Oral and dental hygiene and loose teeth. b. Assessment of neck mobility, stability and arthritic changes. c. Assessment of airway. Endocarditis prophylaxis for high risk patients. Fasting for 6 hours before the procedure. Surveillance and monitoring of vital signs at baseline and throughout the procedure. Supplementation and venous access are established. Suction device and resuscitation equipments are kept ready. Dentures were removed and bite guard were placed. TEE probe is lubricated and kept in unlocked control-wheel position. Awake patient is asked to swallow. Insertion of probe only up to 40-50 cm from incisors is advocated. Patients were monitored until fully awake and eating and drinking is allowed once the effect of local anesthetic is dissipated. 6 – Three dimensional transthoracic echocardiography (3DTTE) Three dimensional images were obtained using a GE vivid 7 with 3V Probe / Vector Array: 3V Cardiac Vector Array Probe (1.5- 3.6 MHz).

69

Patients and methods

The instrument acquires full volume pyramidal images. Images were acquired from parasternal and apical windows and displayed in parasternal long-axis, short-axis, apical four- and five chamber views. LAA was sectioned; focus was placed on the presence or absence of a clot and differentiating it from pectinate muscles and LAA flow velocity assessed. The image was rotated 180◦ to display the LAA in an orientation similar to the display from mid-esophageal TEE acquisition. For the purposes of LAA visualization, 3D and 2D image quality was classified as suboptimal (LAA walls were not clearly identifiable) or diagnostic quality (all the walls and cavity of LAA seen clearly). Other intracardiac thrombi were searched for & detection of presence of atherosclerosis in aorta or not. 7 – Laboratory data including : a-INR b-Serum creatinine level. c-Serum TSH. d-Rondom blood sugar. e-sodium & potassium level f-Complete blood count.

70

Patients and methods

STATISTICAL ANALYSIS.

Statistical analysis of the data Data were fed to the computer and analyzed using IBM SPSS software package version 20.0. Qualitative data were described using number and percent. Quantitative data were described using range (minimum and maximum), mean, standard deviation and median. Significance of the obtained results was judged at the 5% level. The used tests were 1 - McNemar-Bowker Used to analyse the significance between the different stages 2 - Marginal Homogeneity Used to analyse the significance between the different stages 1.

Kotz S, Balakrishnan N, Read CB, Vidakovic B. Encyclopedia of statistical sciences. 2nd ed. Hoboken, N.J.: Wiley-Interscience; 2006.

2.

Kirkpatrick LA, Feeney BC. A simple guide to IBM SPSS statistics for version 20.0. Student ed. Belmont, Calif.: Wadsworth, Cengage Learning; 2013.

71

Results

RESULTS OF THE STUDY CLINICAL DATA (tables3,4) 











 

The present study included 50 adult patients: 30 males (60%), 20 females (40%); age range 42-65 years; mean age 53.26 years ± 6.54. (figure 28). They were admitted at Cardiology Department, Tanta University Hospital or came for followup or referred for cardiac consultation & for transthoracic and transesophageal echocardiography examination. Eight patients (16%) were asymptomatic and the other 42 patients (84%) were symptomatic & complaining of palpitation, fluttering, dyspnea, chest pain or presented with thromboembolic complication as ischemic stroke, 15 patients (30%) were in stroke (figure30) & 35 patients (70%) were not in stroke. The duration of atrial fibrillation from the date of discovery of AFib was observed that the longer the duration of the atrial fibrillation the more risk of thrombembolic complications. Thirty seven patients (74%) were in NYHA class III followed by 10 patients (20%) in NYHA class II and 3 patients (6%) in NYHA class IV.(figure29) Only one patient (2%) had CHADS2VASC2 score zero & 5 patients (10%) had score 1 & 44 paients (88%) had score equal or more than 2.(figure31) Two patients there thyroid profile show hyperthyroidism. On follow up 6 patients came in stroke so at end of study (after 6 months) there were 21 patients (42%) complicated with stroke.

72

Results

Table (3): Distribution of the studied cases according to clinical data (n=50) No.

%

Male

30

60.0

Female

20

40.0

Sex

Age Min. – Max.

42.0 – 65.0

Mean ± SD.

53.26 ± 6.54

Median

53.5

Date of discovery of AFIB (years) Min. – Max.

0.0 – 60.0

Mean ± SD.

7.73 ± 11.41

Median

4.0 No.

%

Yes

15

30.0

No

35

70.0

II

10

20.0

III

37

74.0

IV

3

6.0

0

1

2.0

1

5

10.0

>2

44

88.0

In stroke

NYHA

CHADS2VASC2

73

Results

Table (4): Relation between incindence of stroke and duration of AFIB (from date of discovery) Incidence of stroke No (n = 29)

Yes (n = 21)

Min. – Max.

0.0 – 60.0

0.0 – 36.0

Mean ± SD.

5.32 ± 11.43

11.05 ± 10.77

2.0

6.0

Z

p

2.792*

0.005*

Duration of AFIB (years)

Median

Z: Z for Mann Whitney test *: Statistically significant at p ≤ 0.05

In patients who complicated with stroke have longer duration of atrial fibrillation, so the longer the duration the more risk of thromboembolic complication.

Sex Female 40%

Male 60%

Figure (28): Distribution of the studied cases according to sex

74

Results

IV 6%

NYHA

II 20%

III 74%

Figure (29): Distribution of the studied cases according to NYHA

In stroke

Yes 30%

NO 70%

Figure (30): Distribution of the studied cases if they presented with stroke or not Zero 2%

CHADS2VASC2

One 10%

Equal or more than two 88%

Figure (31): Distribution of the studied cases according to CHADS2VASC2 score 75

Results

ECHOCARDIOGRAPHIC DATA. Two Dimensional Echocardiographic Examination (tables5,6): 2D-TTE was done for all 50 patients & there diagnosis were - 35 patients (70%) had dilated cardiomyopathy (DCM). - 7 patients (14%) had ischaemic heart disease (IHD). - 5 patients (10%) had hypertensive heart disease (HHD). -2 patients (4%) had no significant abnormal echo data (NSA). -1 patient (2%) had restrictive cardiomyopathy (RCM)(figure32) For the purposes of LAA visualization, the image quality was classified as sub-optimal (LAA walls were not clearly identifiable) or diagnostic (all walls and cavity of LAA seen clearly). Left atrial appendage was seen in 35 patients with good quality in 20 patients (58%) and sub-optimal quality in 15 patients (42%). There were decreased left atrial appedage flow velocity in 23 patients (46%), (figure34), all patients who had left atrial appendage thromus had decreased LAA flow velocity. By 2D-TTE; 16 patients (32% of total population of the study) had thrombus in their LAA. Of them: -15 patients (94%) had dilated left atrium > 4cm. - 7 patients (44%) had impaired left ventricular i.e. EF < 40%. - 11 patients (69%) and dilated left ventricle i.e. LVED > 6cm There were intracardiac thrombi other than left atrial appendage thrombi in 6 patients (12%) one of them whose diagnosis was restrictive cardiomyopathy had a large echo density within the right atrium, consistent with a thrombus and the other 5 patients had apical left ventricular thrombus . (figure33) 76

Results

There were 10 patients (20%) had atherosclerosis in aorta, 8 0f them had stroke. (figure 35) Table (5): Distribution of the studied cases according to 2DTTE data 2D-TTE Data

No.

%

Diagnosis (n=50) DCM IHD HHD NSA RCM

35 7 5 2 1

70.0 14.0 10.0 4.0 2.0

Left atrial Diameter (n=50) Min. – Max. Mean ± SD. Median

3.70 – 5.90 4.85 ± 0.53 5.0

Ejection Fraction% (n=50) Min. – Max. Mean ± SD. Median

27.0 – 70.0 44.3 ± 12.21 40.0

LAA flow velocity (n=35) Decreased Normal

23 12

66% 34%

Atherosclerosis in aorta (n=50) Yes No

10 40

20% 80%

Non LAA Trombi (n=50) Yes No

6 44

12.0% 88.0%

77

Results

Tabl(6) 2D Transthoracic Echocardiography Data

pparameter LA diameter 6cm LAA visualization

Number of patients

LAA not seen

With LAA thrombus

With No LAA thrombus No %

NO

%

NO

%

47

15

32%

15

32%

17

36%

23

7

30%

7

30%

9

40%

35

12

34%

11

32%

12

34%

16

46%

19

54%

35

Figure (32): Distribution of the studied cases according to diagnosis 78

Results

Non LAA Thrombi Yes 12%

No 88%

Figure (33): Distribution of the studied cases according to presence of intracardiac thrombus other than LAA thrombus

Left atrial appedage flow velocity Normal 34% Decreased 66%

Figure (34): Distribution of the studied cases according to left atrial appendage flow velocity decreased or not

Atherosclerosis of aorta Yes 20%

NO 80%

Figure (35): Distribution of the studied cases according topresence of atherosclerosis in aorta or not

79

Results

Transosophageal Echocardiographic Examination (Table 7 ): 2D-TEE was done only for 40 patients (23 male and 17 female) of the total 50 patients. The other 10 patients were excluded from TEE examination because either TEE was refused or contraindicated (dysphagia, stricture,varices, and unconscious patients). Those 10 patients had only 2DTTE and 3DTTE examination. Left atrial appendage was seen in the all 40 patients (100%) with good quality in all 40 patients (100 %). Thrombus was seen in 22 cases (55%) while the other 18 patients (45%) had no thrombi. One patient had spontaneous echo contrast grade 1 in her left atrial appendage. Left atrial appendage flow velocity was decreased in 30 patients (75%) ,and was normal in 10 patients (25%) ,(figure36) all patients with LAA thrombus & the patient with spontaneous echo contrast had decreased flow velocity. There were other cardiac thrombi other than left atrial appendage thrombi in 4 patients (10%) one patient whose diagnosis was restrictive cardiomyopathy had a thrombus within the right atrium and the other 3 patients had apical left ventricular thrombus (figure37) Atheroslerosis of aorta presented in 11 patients (27%), 9 of them had stroke & aterosclerosis not present in other 29 patients (73%) (figure38) 80

Results

Table(7) : TEE Data CHARACTER

NO

%

40

100

Male

23

58%

Female

17

42%

< 4.0 cm

3

7%

> 4.0 cm

37

93%

LAA Visualization

40

100%

- Good LAA quality.

40

100%

- Sub-optimal quality.

0

0%

- With LAA thrombus

22

55%

- Without LAA thrombus

18

45%

- Decreased LAA flow velocity

30

75%

- Normal LAA flow velocity

10

25%

Yes

4

10%

No

36

90%

Yes

11

27%

No

29

73%

Patient examined Gender

LA Diameter

Non LAA thrombi

Atherosclerosis in aorta

TEE not

LAA Thrombus by 3D-TTE

1

done in 10

No LAA Thrombus by 3D-TTE

9

patients

81

Results

Left atrial appendage flow velocity Normal 25% Decreased 75%

Figure (36): Distribution of the studied cases according to left atrial appendage flow velocity decreased or not.

Non LAA thrombi

Yes 10%

No 90%

Figure (37): Distribution of the studied cases according to presence of cardiac thrombi other than LAA thrombi.

Atherosclerosis in aorta Yes 27% No 73%

Figure (38): Distribution of the studied cases according to presence of atherosclerosis in aorta

82

Results

Three Dimensional Transthoracic Echocardiography (Table 8) It was done for all 50 patients. The left atrial appendage was seen in 100% of patients: 92% with good quality and 8% with sub-optimal quality. Thrombus was seen in 24 patients (48%) of while the remaining 26 patients (52%) had none. Left atrial appendage flow velocity was decreased in 33 patients (66%) & was normal in 17 patients (34%), (figure39) all patients with left atrial appendage thrombus showed decreased left atrial appendage flow velocity. There were intracardiac thrombi other than left atrial appendage thrombi in 6 patients (12%) (figure 41) one of them whose diagnosis was restrictive cardiomyopathy had a large echo density within the right atrium, consistent with a thrombus and the other 5 patients had apical left ventricular thrombus. There were aortic atherosclerosis in 12 patients (24%), 9 0f them had stroke and atherosclerosis not present in other 38 patients (76%). (figure 40) In the 10 patients in whom 2D-TEE was not performed; combined 2D-TTE and 3D-TTE examination showed LAA thrombus in 1 patients while the remaining 9 patients showed none.

83

Results

Table (8): 3D Echocardiographic data

3D-TTE data No.

%

No

0

0.0

Yes

50

100.0

Diagnostic

46

92.0

Sub-optimal

4

8.0

Absent

26

52.0

Thrombus

24

48.0

Decreased

33

66.0

Normal

17

34.0

Yes

6

12.0

No

44

88.0

Yes

12

24.0

No

38

76.0

LAA visualize

Quality

Content

LAA flow velocity

Non LAA thrombi

Atherosclerosis in aorta

84

Results

Left atrial appendage flow velocity Normal 34% Decreased 66%

Figure (39): Distribution of the studied cases according to left atrial appendage flow velocity decreased or not.

Atherosclerosis in aorta Yes 24% No 76%

Figure (40): Distribution of the studied cases according to presence of atherosclerosis in aorta

Non left atrial appendage thrombi

Yes 12%

No 88%

Figure (41): Distribution of the studied cases according to presence of cardiac thrombi other than LAA thrombi. 85

Results

Comparison between 2D-TTE, 2DTEE & 3D-TTE and in LAA visualization (table 9; figure 42,43,44) : 2DTTE  Left atrial appendage could be adequately visualized by 2DTTE in 35 patients (70% of the total group of patients). With diagnostic image quality in 20 patients (58%) and with suboptimal image quality in 15 patients (42%). Thrombus was seen in 16 patients (45%) & no thrombus seen in19 patients (54%) by 2D-TTE 2DTEE  In the 40 patients who underwent TEE examination; LAA was seen in all of them with good quality in all 40 patients (100%). 22 patients (55%) had thrombus in their LAA; while 18 patients (45%) had no thrombus. 3DTTE  By 3D-TTE examination LAA was visualized in 50 patients (100%) with good diagnostic image quality in 46 of them (92%) and sub- optimal in 4 patients. Thrombus was present in 24 cases (48%), while 26 patients (52%) had no thrombus.

86

Results

Table (9): Comparison between 2D-TTE, 2DTEE & 3D-TTE in LAA visualization, quality &content 2D-TTE Data

TEE data

3D-TTE data

No.

%

No.

%

No.

%

No

15

30.0

0

0.0

0

0.0

Yes

35

70.0

40

100

50

100.0

LAA visualize

p1= 0.001*, p24.0 cm in parasternal longaxis by 2D) and enlarged LAA by TEE. Left atrial appendage flow velocity was decreased in 33 patients (66%) & was normal in 17 patients (34%), all patients with left atrial appendage thrombus showed decreased left atrial appendage flow velocity. There were intracardiac thrombi other than left atrial appendage thrombi in 6 patients (12%) one of them whose diagnosis was restrictive cardiomyopathy had a large echo density within the right atrium, consistent with a thrombus and the other 5 patients had apical left ventricular thrombus. There were aortic atherosclerosis in 12 patients 105

Summary and Conclusion

(24%) , and not present in other 38 patients (76%). In the 10 patients in whom 2D-TEE was not performed; combined 2D-TTE and 3DTTE examination showed LAA thrombus in 1 patients while the remaining 9 patients showed none.

106

Summary and Conclusion

CONCLUSION AND RECOMMENDATIONS The present study concluded that presence of cardiac thrombi, decreased left atrial appendage flow velocity, or presence of atheromatous plaque in aorta are important echocardiographic predictors of increased risk of thromboembolic comlications commonly stroke. Transesophageal echocardiography is the gold standered method

for

detection

of

predictors

of

increased

risk

of

thromboembolism, but it is semi-invasive technique needs adequate preparation & adequate sedation. 3D echocardiography showed so close results as Transesophageal echocardiography, its advantage is that it is noninvasive techniqueand the studies can be easily and quickly performed at the point of care, but it depends on echogenicity of patient, patients with technically difficult 2D transthoracic echocardiography (body habitus, chronic lung disease) will be technically difficult in 3D transthoracic echocardiography as well.

In patients with good acoustic windows and good quality transthoracic images, 3D-TTE may be used as a screening tool in assessment

of

thromboembolic

risk

especially

in

patients

contraindicated to TEE e.g. unconscious patients.

For patients scheduled for 2D-TEE for the evaluation of LAA thrombus, a combined 2D-TTE and 3D-TTE should be attempted first. If the LAA is well visualized by both 2D-TTE and 107

Summary and Conclusion

3D-TTE, then in this group of patients it may not be necessary to perform a 2D-TEE. However, if the LA is not well visualized from the transthoracic approach, then a 2D-TEE would be warranted.

This study suggests that combined 2DTTE and 3DTTE has comparable accuracy to TEE in evaluating the LA and LAA for a thrombus. Further studies in larger number of patients are needed to establish the clinical diagnostic role of 3D-TTE in evaluation of LAA thrombus and to determine the exact role of combined 2DTTE and 3DTTE in evaluating the LAA for thrombi.

In the next few years, the role of echocardiography in thromboembolic risk assessment of patients with nonvalvular AF may undergo dramatic changes. Many parameters are currently being tested (namely, those related to myocardial deformation) that hold promise and may change the way we assess and treat patients.

108

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124

‫الملخص العربي‬ ‫يعد وجود جلطات بالقلب‪ ،‬وانخفاض تدفق طرف األذين األيسر‪ ،‬أو وجود‬ ‫تصلب في الشريان األورطي عوامل هامة للتبؤ باحتمالية حدوث انسداد تجلطي واشهرها‬ ‫جلطة بالمخ‪.‬‬ ‫الموجات الفوق الصوتية على القلب ثنائية األبعاد عبر المرئ تعد األسلوب‬ ‫األفضل للتنبؤ بزيادة خطر االنسداد التجلطي‪ ،‬وإنما هو شبه غازي و يحتاج للتحضير‬ ‫المناسب‪ ،‬والتخدير المناسب‪ .‬أظهر الموجات الفوق الصوتية ثالثية األبعاد على القلب عبر‬ ‫الصدر نتائج قريبة من الموجات الفوق الصوتية على القلب ثنائية األبعاد عبر المرئ ‪،‬‬ ‫ميزته هو أن يمكن القيام بها بسهولة وبسرعة ‪ ،‬ولكن ذلك يعتمد على المريض (خلقة الجسم‬ ‫وأمراض الرئة المزمنة) سوف يكون من الصعب من الناحية الفنية‪.‬‬ ‫االستنتاج والنوصيات‪:‬‬ ‫يعد وجود جلطات بالقلب‪ ،‬وانخفاض تدفق طرف األذين األيسر‪ ،‬أو وجود‬ ‫تصلب في الشريان األورطي عوامل هامة للتبؤ باحتمالية حدوث انسداد تجلطي‪.‬‬ ‫في السنوات القليلة المقبلة‪ ،‬دور الموجات الفوق الصوتية على القلب في تقييم‬ ‫خطر االنسداد التجلطي المرضى الذين يعانون من رفة اذينية غير ناتجة عن اعتالل‬ ‫بالصمامات قد تخضع لتغييرات دراماتيكية‪ .‬ويجري حاليا اختبار العديد من المعايير التي‬ ‫يمكن أن تغير الطريقة تقييم وعالج المرضى‪.‬‬

‫‪125‬‬

‫الملخص العربي‬ ‫األيسر‪ .‬وكان أحد المرضى وجد األذين األيسر‪ .‬وقد انخفض سرعة تدفق الدم من طرف‬ ‫األذين األيسر أ في ‪ 30‬مريضا (‪ ،)75٪‬وكان طبيعيا في ‪ 10‬مريضا (‪ ،)25٪‬وكان جميع‬ ‫المرضى الذين يعانون من جلطة في طرف األذين األيسر والمريض الذي كان يعاني من‬ ‫تباين بصدى الموجات الفوق صوتية في طرف األذين األيسر‪ ،‬انخفضت سرعة التدفق من‬ ‫طرف األذين األيسر عندهم‪ .‬و كانت هناك جلطة داخل القلب في أماكن أخرى غير طرف‬ ‫األذين األيسر في ‪ 4‬مرضى (‪ )10٪‬واحد منهم يعاني من اعتالل عضلة القلب المقيد لديه‬ ‫جلطة في األذين األيمن‪ ،‬و‪ 3‬مرضى وجد جلطة بالبطين األيسر الخاص بهم‪ .‬و كان هناك‬ ‫‪ 11‬مرضى (‪ )27٪‬كان يعانون من تصلب في الشريان األورطي‪.‬‬ ‫وتم عمل موجات فوق صوتية ثالثية األبعاد على القلب عبر الصدر وكان ذلك‬ ‫لجميع المرضى وتم رؤية طرف األذين األيسر في ‪ ٪92‬من المرضى بجودة جيدة و ‪٪8‬‬ ‫من المرضى بجودة أقل‪ .‬كان يوجد جلطة في طرف األذين األيسر في ‪ 24‬مريضا (‪)48٪‬‬ ‫في حين أن ‪ 26‬مريضا المتبقين (‪ )52٪‬ال شيء‪ .‬وقد انخفض سرعة التدفق من طرف‬ ‫األذين األيسر الخاص بهم في ‪ 33‬مريضا (‪ )66٪‬وكانت السرعة طبيعية في ‪ 17‬مريضا‬ ‫(‪ ،)٪34‬وأظهر جميع المرضى الذين يعانون من جلطة في طرف األذين األيسر انخفاض‬ ‫سرعة التدفق بها‪ .‬كانت هناك جلطة داخل القلب في أماكن أخرى غير طرف األذين األيسر‬ ‫في ‪ 6‬مرضى (‪ )12٪‬واحد منهم يعاني من اعتالل عضلة القلب المقيد لديه جلطة في األذين‬ ‫األيمن‪ ،‬و ‪ 5‬مرضى وجد جلطة بالبطين األيسر الخاص بهم‪ .‬كان هناك تصلب بالشريان‬ ‫األورطي في ‪ 12‬مريضا (‪ ،)24٪‬وغير موجود في ‪ 38‬مريضا (‪.)76٪‬‬ ‫ان التوافق بين الموجات الفوق الصوتية ثالثية األبعاد على القلب عبر الصدر و‬ ‫الموجات الفوق الصوتية على القلب ثنائية األبعاد عبر المرئ يعد توافقا كبيرا‬ ‫يعد وجود جلطات بالقلب‪ ،‬وانخفاض تدفق طرف األذين األيسر‪ ،‬أو وجود‬ ‫تصلب في الشريان األورطي عوامل هامة للتبؤ باحتمالية حدوث انسداد تجلطي واشهرها‬ ‫جلطة بالمخ‪.‬‬ ‫ان التوافق بين الموجات الفوق الصوتية ثالثية األبعاد على القلب عبر الصدر و‬ ‫الموجات الفوق الصوتية على القلب ثنائية األبعاد عبر المرئ يعد توافقا كبيرا‪.‬‬ ‫‪126‬‬

‫الملخص العربي‬ ‫االنسداد التجلطي واشهرها جلطة بالشرايين المغذية للمخ وكان سبعة وثالثون مريضا‬ ‫(‪ )٪74‬في الفئة ‪ NYHA‬الثالث تليها ‪ 10‬مريضا (‪ )20٪‬في الفئة ‪ NYHA‬الثاني و ‪3‬‬ ‫مرضى (‪ )6٪‬في ‪ NYHA‬الدرجة الرابعة‪ .‬ولوحظ ان مريضا واحدا فقط (‪)2٪‬‬ ‫‪ CHADS2VASC2‬الخاص به يساوي الصفر و ‪ 5‬مرضى (‪ )10٪‬لديهم درجة ‪ 1‬و ‪44‬‬ ‫مريضا ( ‪ )٪88‬وكان النتيجة مساوية أو أكثر من ‪.2‬وكان اثنان من المرضى اظهر تحليل‬ ‫وظائف الغدة الدرقية فرط نشاطها‪ .‬ومع متابعة المرضى جاء ‪ 6‬منهم يعانون من السكتة‬ ‫الدماغية وبذلك في نهاية الدراسة (بعد ‪ 6‬أشهر) كان هناك ‪ 21‬مريضا (‪ )42٪‬قد حدث لهم‬ ‫مضاعفات االنسداد التجلطي في صورة سكتة دماغية‪.‬‬ ‫وقد تم عمل موجات فوق صوتية على القلب ثنائية األبعاد عبر الصدر لجميع‬ ‫المرضى و كان التشخيص ضعف بعضلة القلب ‪ 35‬مريضا (‪ )70٪‬و ‪ 7‬مرضى (‪)14٪‬‬ ‫يعانون من قصور بالشريان التاجي و ‪ 5‬مرضى (‪ )10٪‬من تضخم البطين األيسر للقلب‬ ‫نتيجة ارتفاع ضغط الدم وكان اثنين من المرضى (‪ )4٪‬اليعانون من اعتالل بالقلب‬ ‫ومريض واحد (‪ )2٪‬يعاني من اعتالل عضلة القلب المقيد‪ .‬وقد تمت رؤية زائدة األذين‬ ‫األيسر ‪ 35‬مريضا مع جودة جيدة في ‪ 20‬مريضا (‪ )58٪‬وجودة أقل في ‪ 15‬مريضا‬ ‫(‪ .)٪42‬وقد انخفضت سرعة تدفق الدم من زائدة األذين األيسر في ‪ 23‬مريضا (‪،)46٪‬‬ ‫وكان جميع المرضى الذين وجد جلطة في زائدة األذين األيسر الخاصة بهم ايضا انخفضت‬ ‫سرعة تدفق الدم منها ‪.‬و كانت هناك جلطة داخل القلب في أماكن أخرى غير طرف األذين‬ ‫األيسر في ‪ 6‬مرضى (‪ )12٪‬واحد منهم يعاني من اعتالل عضلة القلب المقيد لديه جلطة‬ ‫في األذين األيمن‪ ،‬و‪ 5‬مرضى وجد جلطة بالبطين األيسر الخاص بهم‪ .‬و كان هناك ‪10‬‬ ‫مرضى (‪ )20٪‬كان يعانون من تصلب في الشريان األورطي‪.‬‬ ‫وقد تم عمل موجات فوق صوتية على القلب ثنائية األبعاد عبر المرئ ألربعون‬ ‫مريضا (‪ 23‬من الذكور و ‪ 17‬من اإلناث) من إجمالي ‪ 50‬مريضا‪ .‬تم استبعاد ‪ 10‬مرضى‬ ‫من الفحص لرفض عملها أو أن حالة المريض ال تسمح (عسر البلع‪ ،‬تصلب المرئ‪ ،‬دوالي‬ ‫المرئ‪ ،‬والمرضى الغائبين عن الوعي)‪ .‬وكان هؤالء ‪ 10‬مرضى فقط‪ .‬تم قحص طرف‬ ‫الذين األيسر في جميع المرضى بجودة جيدة ‪.‬وجدت جلطة بطرف األذين األيسر في ‪22‬‬ ‫مريضا (‪ ،)55٪‬في حين كان ‪ 18‬مريض األخرين (‪ )45٪‬ال يوجد جلطة في طرف األذين‬ ‫‪127‬‬

‫الملخص العربي‬ ‫‪-2‬وجود تاريخ مرضي بأن سبق حدوث رجفان أذيني أو أحد األعراض الجانبية بسبب‬ ‫االنسداد التجلطي مثل السكتة الدماغية أو نوبات نقص دم دماغية عابرة‪.‬‬ ‫معايير االستبعاد‪:‬‬ ‫‪-1‬المرضى الذين يعانون من الرجفان األذيني نتيجة العتالل بصمامات القلب‪.‬‬ ‫‪-2‬المرضى ذوي تاريخ مرضي بأن سبق لهم الخضوع لعملية استبدال لصمام بالقلب‬ ‫بصمام ميكانيكي‪.‬‬ ‫‪-3‬المرضى في المرحلة الحادة من أمراض القلب‪.‬‬ ‫ولجميع الحاالت تم عمل‪:‬‬ ‫‪-1‬أخذ التاريخ المرضي للحالة‪.‬‬ ‫‪-2‬رسم قلب كامل‪.‬‬ ‫‪-3‬موجات فوق صوتية على القلب ثنائية األبعاد عبر الصدر‪.‬‬ ‫‪ -4‬موجات فوق صوتية على القلب ثنائية األبعاد عبر المرئ‪.‬‬ ‫‪-5‬موجات فوق صوتية على القلب ثالثية األبعادعبر الصدر‪.‬‬ ‫‪-6‬تحليل نسبة السيولة والهرمون المحفز للغدة الدرقية‪.‬‬ ‫‪-7‬متابعة المرضى لمدة ستة أشهرمنذ تلقي العالج‬

‫النتائج‪:‬‬ ‫تم تسجيل مدة الرجفان األذيني لجميع الحاالت (من تاريخ اكتشاف الرفة‬ ‫األذينية) ولوحظ ان كلما زادت مدة الرجفان األذيني كلما زادت احتمالية حدوث مضاعفات‬

‫‪128‬‬

‫الملخص العربي‬

‫الملخص العربي‬ ‫يعد الرجفان األذيني الغير ناتج عن اعتالل بالصمامات هو عامل خطر قوي‬ ‫لالصابة بالسكتة الدماغية ‪ ،‬واآللية الرئيسية لحدوث ذلك هي وجود تجلطات دموية في‬ ‫طرف األذين األيسرحيث يقل تدفق الدم من طرف األذين األيسر الى تجويف األذين األيسر‬ ‫نتيجة فقدان االنقباض واالنبساط المنتظم المتزامن في طرف األذين األيسر‪.‬‬ ‫وتعتبر الموجات الفوق صوتية على القلب هي األسلوب المستخدم على نطاق‬ ‫واسع ومتعدد االستعماالت وقد تبين أن الموجات الفوق صوتية على القلب بانواعها سواء‬ ‫ثنائية أو ثالثية األبعاد عبر الصدر أو ثنائية األبعاد عبر المرئ لها دور أساسي في تقييم‬ ‫مخاطر حدوث االنسداد التجلطي وذلك عن طريق عوامل كثيرة منها حجم األذين األيسر ‪،‬‬ ‫كفاءة عضلة القلب اللذان يمكن تقييمهما باستخدام الموجات الفوق صوتية ثنائية األبعاد عبر‬ ‫الصدر‪ ،‬و وجود تجلطات في األذين األيسر أو طرف األذين األيسر‪ ،‬واللتي يمكن رؤيتها‬ ‫باستخدام الموجات الفوق صوتية ثنائية األبعاد عبر المرئ أو الموجات الفوق صوتية ثالثية‬ ‫األبعاد وبالتالي لها دور أساسي في الوقاية من حدوث هذا االنسداد التجلطي‪.‬‬ ‫الهدف من الدراسة‪:‬‬ ‫دور الموجات الفوق صوتية على القلب في تقييم خطر االنسداد التجلطي في‬ ‫المرضى الذين يعانون من الرجفان األذيني الغير ناتج عن اعتالل بصمامات القلب‪.‬‬ ‫مدة الدراسة‪:‬‬ ‫من يونيه ‪ 2015‬حتى نوفمبر ‪2015‬‬ ‫معايير االشتمال‪:‬‬ ‫المرضى الذين يعانون من‪:‬‬ ‫‪-1‬خفقان ويظهر التخطيط الكهربائي للقلب الخاص بهم رجفان أذيني وتبين الموجات الفوق‬ ‫صوتية على القلب أن هذا الرجفان غير ناتج عن اعتالل بصمامات القلب‪.‬‬

‫‪129‬‬

‫الملخص العربي‬

‫‪130‬‬