become permanent armamentaria in surgery. This report describes methods already in use at the Texas Heart Institute, along With techniques proposed for the ...
ABLATIVE TECHNIQUES FOR SURGICAL TREATMENT OF PAROXYSMAL TACHYCARDIA DENTON A. COOLEY, M.D., DAV'ID A. O1TT. M.D., PAUL C. GILLETTE, M.D., AND ART1 HUR GARSONJ.|R. M.D. In this report, the collaborative efforts of cardiologists and surgeons to provide optimal treatment of patients with rhythm disturbances are discussed, along with definitive advances in new surgical techniques to relieve supraventricular tachycardia and paroxysmal ventricular tachycardia. Some of the techniques described are destined to find a permanent place in the surgeon's armamentarium.
Surgical manipulation of the cardiac conduction system can relieve supraventricular and ventricular tachycardia; thus, greater emphasis has been focused upon the anatomic and functional aberrations of the cardiac conduction pathways as they apply to possible surgical interruption. 18 Noteworthy contributions include those regarding supraventricular tachycardia from Sealy and associates at Duke University,91 and those concerning recurrent ventricular tachycardia from Guiraudon, Fontaine, and colleagues of France.14 Development of diagnostic and surgical techniques for these purposes has proceeded rapidly, and although changes will obviously occur in the near future, some of the present techniques will become permanent armamentaria in surgery. This report describes methods already in use at the Texas Heart Institute, along With techniques proposed for the future. TECHNICAL CONSIDERATIONS
Patient selection for operation is based upon accurate, complex electrophysiologic data in addition to standard electrocardiographic and physical findings; therefore, a precise diagnosis of the cause of rhythm disturbance must be made. 15 Evaluation begins in a cardiac catheterization laboratory equipped to monitor electrical activity simultaneously in four to six intracardiac positions, with the use of electrode catheters to localize the dysrhythmia. Patients usually arrive in the operating room with pre-
From the Divisions of Surgery and Cardiology of the Texas Heart Institute and Texas
Children's Hospital, Houston, Texas. Address for reprints: Denton A. Cooley, M.D., Texas Heart Institute, P. 0. Box 20345, Houston, Texas 77025. 400
Cardiovascular Diseases, Bulletin of the Texas Heart Institute Volume 6
Number 4
December 1979
cise physiologic data that delineates the nature and location of the aberriation that causes the dysrhythmia. Facilities must be available in the operating room for temporary cardliopulmonary bypass. Intraoperative use of specializedimonitorinig equipment is also necessary to provide external and ofteni internal imlappinig of the ventricles and conduction mechanisml, because the tissue causiln the dysrhythmia frequently is not visible to the surgeon. Thus, a cardliologist skilled in such techniques frequently joins the surgical teamii at tlle opei-ating table to assist in acquiring electrophysiologic data. WAe have used special stimulating electrodes, which are sutured to the atria, andl also a special finger electrode of our own design to move around the epicardial sui-face of the ventricle (Fig. 1 A and B). Recordings are made, and the points of early atrial and ventricular excitation are identified. With this informiation, the surgeon may proceed with the appropriate ablative technique. Supraventricular Tachycardia (Sealy Procedure) Bundles of Kent and the Wolf-Parkinson-White Syndrome (WPW)
For these cases, monitoring and imiapping techniiquLes Imutist ai(l i (ldetermining whether the anomalous condluction pliathwalx (bundle of Keint) presents on the external circuimfer-ence or- free wall of thie riglht ventricle or on the free wall of the left ventricle. Less freqUently, the allomnalotus bundle extends between the atrial and( ventricUlar septuLm, eithlel anlteriorly or posteriorlv. Moreover, the anomlalous mIIUscle l)Un(lles rarelI arie multiple, and even with extended mapping, it mav' be im1possible to identify all of them. After initiation of total cardiopulmonary bypass and completion of both external and internal intraoperative mapping, the surgeon proceeds to eliminate the anomalous connection between the atria and ventricles. For Kent bundles, the connections are divided by sharp and bluint dissection. Cardioplegia is obtained by cross-clamping the ascending aorta ancd injecting cold cardioplegic solution.* When cardiac arrest has been achieved and blood has been aspirated from the cardiac chamabers, circumnfer-ential incisions are made around the tricuspid or IlmitIral valve, depending upion the location of the Kent bundle (Fig. 2). For division on the r-ight ventricle, we recommend an extensive internal incision around three-fourths of the circumference of the tricuspid valve. Because division of the His bundlle should be strictly avoided, the portion of the supraannular region overlying the bundle of His on the anterior and medial portion is not included.
*THI Cardioplegic Solution: 500 ml 5%Potassium Chloride 20 mM (20 mEq) Magnesium Chloride 7.5mM (15 mEq) Sodium Bicarboniate 2.5 mM (2.5 mEq) 1.0 mM (2.0 mEq) Calcium Chloride
Dextrose anid 0.45%
NaCl containling:
[ 1492.() m;g]; [1527.03 mg]: [2 10.0 mg]; [ 147.14 mng]. 401
s@ s
I
E
A
B Fig. I Electrodes used during intraoperative scanning or mapping of the ventricles for demonstration of early excitation. (A) Small metal wire loops are sutured to the atria or ventricles for stimulation or recording. (B) A special finger ring bipolar electrode is placed on the surgeon's index finger and moved around the epicardial surface of the ventricles.
402
Right Coronary Artery
N Incision around
Incision around mitral valve
tricuspid valve
Coronary Sinus *A.V. Node Fig. 2 Location of incisions in the supra-annular tissues of the right and left atria for division of Kent bundles. On the right, the encircling incision is interrupted over the area close to the bundle of His. On the left, the incision is interrupted at the fibrous trigone above the anterior mitral leaflet. The posterior extent of the incision should be made cautiously because of the proximity of underlying left bundle branch or fascicles of the bundle of Kent.
For anomalous atrioventricular muscle bundles involving the left ventricle, the incision includes two-thirds of the annular circumference; it does not include the fibrous trigone of the mitral valve, which is adjacent to the anterior leaflet of the valve at its confluence with the aortic valve annulus. No anatomic connection of the atrial musculature with the ventricular myocardium occurs in this zone. Posteriorly, some danger exists that deep incision could divide the left proximal bundle branches. If these zones are avoided, the anomalous atrioventricular bundles of Kent may be divided without disturbing normal atrioventricular conduction mechanisnms. In light of the foregoing objectives and limitations, the method of division is essentially the same for both the right and left anomalous bunidles. The incision is made through the endocardium and the atrial muscular wall and into the underlying fat pad (Fig. 3 A). The adjacent coronary artery should be exposed. Sharp and blunt dissection with the use of a small nerve hook ensures that all connections, however small, will be divided. We believe that the surgeon should wear magnifying optical loupes (four power magnification) and a headlamp with a fiberoptic light source to provide optimal visualization. After the atria have been detached from the 403
ventricles (and we have not found it necessary to incise the epicardium externally), the incision is closed with a continuous 6-0 monofilament polypropylene suture (Fig. 3 B). For lesions on the left side, the incision is extended to the level of the circumflex coronary artery and the adjacent and superiorly located coronary sinus and great cardiac vein. The left-sided incision is similarly closed with a 6-0 polypropylene suture. Anterior and posterior septal Kent bundles are the most difficult to divide surgically because of the danger of injuring the adjacent bundle of His.16 The anteriorly placed septal bundles are usually divided by the right-sided incision described, which includes that general area (Fig. 2). The posterior septal Kent bundles are the inost difficult to divide without complications. They may require cautious dissection from either the left atrial or right atrial approach. In the event that the bundle of His is injured, a permanently implanted electronic pacemaker may be required. Re-entry Pathways to the Bundle of His (Atrio-His Pathways) In these patients, abnormal pathways and excitation impulses enter the bundle of His distal to the node of His-Tawara. Thus, the normal protection of the AV node is bypassed and the patient may suffer rapid ventricular response to supraventricular tachycardia. 1 7 This problem may be controlled by destroying or ablating the bundle of His and implanting a permanent electronic pacemaker.18 The choice of pacemaker depends upon several considerations. For older patients, a standard demand pacemaker is usually sufficient; for younger patients, however, a sequentially-con-
trolled atrial-to-ventricular pacemaker that provides synchronous atrial and ventricular contractions may produce more physiologic conditions. Destruction or ablation of the bundle of His may not be as simple as the cardiac surgeon expects after having the misfortune of inadvertently injuring the bundle during surgical repair of congenital septal defects. In contrast to the exposed or superficial location of the bundle of His in the presence of septal defects, the bundle in other instances is somewhat protected from injury by overlying tissue. Sealy has discussed dissection of tissues overlying the bundle to assist in ablation; 14 this may not be necessary in most instances. Precise location of the bundle by use of physiologic mapping techniques also inay be helpful. Because the bundle is small and is usually located within a relatively confined and identifiable anatomic position, the experienced surgeon should be able to destroy it by an appropriate technique. The methods of bundle destruction that we have used include strangulation with a heavy suture, electrocauterization, and, more recently, cryosurgery. We believe that cryosurgery offers the best means of destroying the bun(dle (Fig. 4). TFle tip of thie crvosUirgical probe produces an ice ball approxinmately 1 5 Imm in diaimeter at -650C(. After the probe has been placed in the desired position, the unit is activated and quickly reaches the desired subfreezing temperature. The probe should be held in place for no more than 120 seconds, and, to avoid tissue adherence, the temperature should be raised to above freezing before the probe is withdrawn. Healing of tissue after freezing is more favorable than heal404
A.V. Node
Fig. 3 The Sealy procedure shows the position of the supraannular incisions above the tricuspid valve. (A) The incision is extended to a depth that enters the fat pad and exposes the underlying right coronary artery. The epicardium need not be incised. (B) After the incision is completed, it is repaired with a continuous suture. 405
-Tricuspid valve
Coronary sinus
Fig. 4 The anatomic relationships of the bundle of His are shown. After the bundle or node is located by electrophysiologic means, the cryosurgical probe is applied for 90 to 120 seconds at -600 C.
ing after electrocauterization, which causes extensive injury to collagenous and other soft tissues. The bundle of His does not regenerate even when the surrounding tissues are heated. A strangulating suture may not encompass the entire bundle and may not interrupt all of the impulses passing through the tissue included in the suture. The bundle of His is usually approached through the right atrium (Fig. 4). The bundle is located close to the posterior rim of the interventricular membranous septum at the commissure between the anterior and mural (posterior) leaflets of the tricuspid valve. The cryosurgical probe is placed at this point for the prescribed period of freezing. In the event that atrioventricular block is not produced, the probe may be moved to another point nearby, although repeated or excessive freezing in this area could lead to injury of the underlying coronary artery. In one patient operated upon before the cryosurgery unit was available, in whom we failed to interrupt conduction through the bundle of His by placement of strangulating sutures and the electrocautery, we approached the bundle through the left ventricle by opening the aortic root (Fig. 5). In that case, a suture passed below the membranous septum pro406
duced immediate AV block. This approach mav become standard in the future, particularly with the use of the cryosurgical unit, because experience with aortic valve replacement has made surgeons aware of the vulnerabilitv to interruption of impulses through the bundle of His at this location.
Finally, an approach suggested by Sealy may be used, wvhereby the surgeon would incise vertically the atrial septum posteriorly at the junction with the membranous ventricular septum and repair the resulting septal defect with sutures.2( Although we have not had occasion to use this method, it should be definitive. Ventricular Tachycardia
Cases of ventricular tachycardia are of a different nature than those involving supraventricular tachycardia in that the area of abnormal excitation occurs in a site located in the ventricular myocardium, which disrupts the normal pattern of transmission. Chronic recurrent ventricular tachycardia or ventricular fibrillation with (leath mav resulIt. The r-espolnsibilities of the cardiologist in these cases max be to ilentify the location of the area with abnormal automaticity of the reentry circuit. Two groups of pa-
Orif ices of
Aortic valve
coronary a.a.
(NON-CORONARY CUSP)
2 3 ';'
Membranous septum Mitral valve
Fig. 5 An alternate approach for ablation of the bundle of His in which the root of the aorta is incised transversely to expose the aortic valve and left ventricular outflow region. Application of the cryosurgical probe is at the junction of the membranous portion of the interventricular septum, where it is contiguous with the mitral leaflet. 407
tients have been identified, namely those with myocardial damage caused by ischemia or infarction and those without a history of ischemia. Foci Without Associated Ischemia
For these lesions, intraoperative epicardial mapping is essential to obtain a satisfactory surgical result. At operation, the cardiac physiologist must identify the zone of early or premature excitation of the ventricle, which may be located at any place on the surface of the right or left ventricle-or may involve the septum. Once the focus is identified, the surgeon makes an incision into the ventricular cavity at that position. Excision of tissue may not be practical, but application of the cryosurgical probe may enhance the technique. The ventriculotomy is closed in the same manner as is used after excision of a ventricular aneurysm, namely, with mattress sutures over a polyester felt strip reinforced with interrupted or continuous sutures (Fig. 6). Foci with Associated lschemia
Patients with myocardial damage and scarring after infarction may experience cardiac rhythm disturbances with impulses arising in the border zone between normal myocardium and scar tissue. Simple removal of the cicatricial tissue or ventricular aneurysm may not eliminate the arrhythmic problem. The basic purpose of ventricular aneurysmectomy is to restore a more normal geometric configuration of the left ventricle and prevent overfilling of the chamber. In some instances, relieving the strain on the overfilled chamber will control the production of excitation stimuli that causes arrhythmias. The two surgical objectives which exist when a ventricular scar or aneurysm produces arrhythmia can best be met by making an encircling endocardiomyotomy proximal to the scarred area. 14 As depicted in Figure 7, an incision in the endocardium and intracavitary myocardium should interrupt these abnormal pathways in their progress outward to stimulate the conduction mechanism in a pathological manner. The encircling endomyocardial incision is made to a depth of a few millimeters below the epicardial surface or through the interventricular septum. The incision is closed with a continuous suture of 3-0 polypropylene before the ventricular aneurysm is excised. Subsequently, the ventricular cavity is reshaped, and the ventriculotomy is repaired in the usual manner. DISCUSSION
In the past, management of cardiac tachyarrhythmias has been largely a problem assigned to the cardiologist, who has used mostly pharmacologic substances to reduce the irritability of cardiac tissues or to retard electrical conduction through the normal specialized pathways. More recently, however, physical methods have become available. For example, supraventricular tachycardia, atrial flutter and fibrillation, and other arrhythmias have been shown to respond to electrical countershock, consisting of a high-energy direct current discharge over the precordium. The use of 408
R. Ventricle L. Ventricle
Felt strip --,
Coronary sinus Inferior vena cava Fig. 6 Ablation of an aberrant zone of ventricular excitation by making a full thickness incision into the myocardium at the involved area and performing a ventriculorrhaphy over polyester felt strips.
countershock for cardiac resuscitation during acute ventricular fibrillation has become standard practice and has saved countless lives. Other electrical adjuncts such as implanted pacemakers to "overdrive" the heart that is subject to tachyarrhythmia have also been used successfully. Experiments are progressing toward development of an implantable electrical defibrillator which, on signal, functions by radiofrequency transmission to 409
Anterior wallK l aneurysm area ) *
!
Fig. 7 Technique of encircling endomyocardial incision to interrupt abnormal impulses passing upward into the more proximal conduction system and causing ventricular ectopy and paroxysmal tachycardia.
impart the defibrillating electrical charge. 1) Raidiofrequencv tr-anismiiission ofl impulses to the atrium mav also be usedl to eliminate SupravenitriCUlar tach vcardia. Revascularization of the ischemnic myocardium bv means of saphenous vein bypass has been successful in some patients, and, in a fewN, dramatic instances, this method has been employed on an emnergenicy basis. Surgical treatment of the so-called mitral "click" syndrome (Barlow's svndro me) has proved of interest, particularly in those patients who have arrhvthmias as the basic symptom. Although experience at this time is limited, surgical relief of posterior leaflet prolapse appears to improve, if not eliminate cardiac rhythm disturbances in some patients.21,22 The techniques described in this report documlent ajoint effort bv cardiologists and cardiac surgeons to provide definitive treatmnent of a different type of cardiac disease, which has not been attempted previously. REFERENCES 1. Burchell HB, Frve RL, Anderson NIMW7, McGoon DC: Atri-oventriCUlar and ventricular excitation in Wolff-Parkinson-WN"hite syndrome (Type B). Cir-culation 36:663,1967
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2. GallagherJJ, KasellJ, Sealy WC, Pritchett ELC, Wallace AG: Epicardial m11apping in the Wolff-Parkinson-White syndrome. Circulatioin 57(5):854, 1978 3. Wittig JH, Boineau JP: Surgical treatment of ventricular arrhythmias using epicardial transmural and endocardial mapping. Ann Thorac Surg 20(2):117, 1975 4. Gallagher JJ, Sealy WC, Anderson RW, Kasell J, Pritchett EL, Wallace AG, Harrison L: The surgical treatment of arrhythmias. In Re-entrant Arrh1t1h111niaA. (edited by Kulbertus HE). University Park Press, Baltimore, 1977 WG 330 R 327, 1976 5. Gillette PC: Concealed anomalous cardiac conduction pathways: A frequent cause of supraventricular tachycardia. AmJ Cardiol 40:848, 1977 6. Gillette PC, Gallagher JJ, Sealy WC: Concealed anomalous cardiac conduction pathway: An operable cause of supraventricular tachycardia. J Pediatr 90:427, 1977 7. Durrer D: Medical and surgical treatment of the Wolff-Parkinson-White syndrome. Annu Rev Med 27:63, 1976 8. Wellens HJJ, Janse MJ, van Dam RT, van Capelle FJL, Meijne NG, Mellink HM, Durrer D: Epicardial mapping and surgical treatment in Wolff-Parkinson-White syndrome type A. Am HeartJ 88(1):69, 1974 9. Cobb FR, Blumenschein SD, Sealy WC, Boineau JD, Wagner GS, Wallace AG: Successful surgical interruption of the bundle of Kent in a patient with Wolff-Parkinson-White syndrome. Circulation 38:1018, 1968 10. Sealy WC, Wallace AG, Ramming KP, Gallagher Jj, Svenson RH: Anl un11proved operation for the definitive treatment of the Wolff-Parkinson-Whbite syndrome. Ann Thorac Surg 17:107, 1974 11. Sealy WC, Boineau JP, Wallace AG: The identification and division of the bundle of Kent for premature ventricular excitation and supraventricular tachycardia. Surgery 68(6): 1009, 1970 12. Sealy WC, Gallagher, JJ, Wallace AG: The surgical treatment of the WolffParkinson-White syndrome: Evaluation of the improved methods of identification and interruption of the Kent bundle. Ann Thorac Surg 22:443, 1976 13. Sealy WC: Surgical treatment of Supraventricular tachyarrhythmias associated with the Wolff-Parkinson-White syndrome. In Davis-Chlristophler\' Textbook of Sur,gery (edited by Sabiston DC). WB Saunders, Philadelphia, 1977 14. Guiraudon G, Fontaine G, Frank R, Escande G. Etievent P, Cabrol C: Encircling endocardial ventriculotomy: A new surgical treatment for lifethreatening ventricular tachycardias resistant to medical treatment following myocardial infarction. Ann Thorac Surg 26(5):438, 1978 15. Wellens HJJ, Bar FW, Gorgels AP, FarreJ: Electrical maniagemiieilt of arrhythmias with emphasis on the tachycardias. Amii j Cardiol 4 1:1025. 1978 16. Gallagher JJ, Sealy WC, Anderson RW, Kasell J, Mellar R, Campbell RWF, Harrison L, Pritchett ELC, Wallace AG: Cryosurgical ablation of accessory atrioventricular connections. Circulation 55(3):47 1, 1977 17. Pritchett ELC, Anderson RW, Benditt DG, Kasell j, Harrison L, Wallace AG, Sealy WC, Gallagher JJ: Reentry within the atrioventricular node: Surgical cure with preservation of atrioventricular conduction. Circulation 60:2, 1979 411
18. Harrison L, GallagherJJ, KasellJ, Anderson RH, Mikat E, Hackel DB, Wallace AG: Cryosurgical ablation of the AV node-His bundle. Circulation 55(3):463, 1977 19. Sealy WC, Gallagher Jj, Wallace AG: TI he surgical treatment of WolffParkinson-White syndrome: Evolution of improved methods for identification and interruption of the Kent bundle. Ann T horac Surg 22(5):443, 1976 20. Sealy WC: Personal communication. 21. Cooley DA, Al-Bassam MS, Wukasch DC: Mitral click syndrome: Further observations on surgical treatment. Cardiovascular Diseases, Bulletin of the Texas Heart Institute 5(3):2 16, 1978 22. Al-Bassam MS, Cooley DA: Arrhythnmia with mitral valve prolapse: Results of annuloplasty in two patients. Cardiovascular Diseases, Bulletin of the Texas Heart Institute 5(4):397, 1978
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