Does preoperative computed tomography reduce the risks ... - CiteSeerX

ARTICLE IN PRESS New Ideas

doi:10.1510/icvts.2008.189506

www.icvts.org

Best evidence topic - Cardiac general

Department of Cardiothoracic Surgery, University Hospital of South Manchester NHS Foundation Trust, Southmoor Road, Manchester, M23 9LT, UK

Summary

Historical Pages Negative Results Follow-up Paper

A best evidence topic was written according to the structured protocol. The question addressed was whether preoperative computed tomography (CT) scan reduces the risk associated with re-do cardiac surgery. A Medline search revealed 412 papers, of which seven were deemed relevant to the topic. We conclude that preoperative CT angiography using ECG-gated multi-detector scan enables excellent anatomical details of heart, aorta and previous grafts, and highlights high-risk cases due to adherent grafts or ventricle or aortic atherosclerosis. This allows for better risk stratification and change of surgical strategy to reduce the potential risk in patients coming for re-do cardiac surgery. According to published reports, high-risk CT-scan findings in these patients caused clinicians to cancel surgery in up to 13% of cases, while preventive surgical strategies including non-midline approach, peripheral vascular exposure or establishing cardiopulmonary bypass prior to re-sternotomy have been reported in over two-thirds of patients with significant reduction in the operative risk. The risk of damage to vital structures, including previous grafts, heart or larger vessels is generally reported fewer than 10%, with evidence of significantly lower incidence of intra-operative injuries in patients who had prior CT-scans compared to those who did not. Hence, adequate preoperative imaging using ECG-gated multi-slice CT is essential for optimum planning of re-do cardiac surgery. 䊚 2009 Published by European Association for Cardio-Thoracic Surgery. All rights reserved.

ESCVS Article

Received 29 July 2008; received in revised form 2 February 2009; accepted 25 February 2009

Institutional Report

Nouman U. Khan*, Nizar Yonan

Protocol

Does preoperative computed tomography reduce the risks associated with re-do cardiac surgery?

Case Report

Interactive CardioVascular and Thoracic Surgery 9 (2009) 119–123

Keywords: Re-do cardiac surgery; Re-sternotomy; CT-scan

1. Introduction

3. Three-part question

A best evidence topic was constructed according to a structured protocol. This is fully described in the ICVTS w1x.

In (patients undergoing repeat sternotomy) does (a CTscan) reduce the chances of (serious complications on resternotomy)?

2. Clinical scenario

Four hundred and twelve papers were found from Medline using the current search strategy. Seven were considered relevant and are documented in Table 1. 6. Comments Recent decades have seen a steady increase in the number of cases referred for re-do cardiac surgery, which are associated with increased risk of morbidity and mortality

Nomenclature

䊚 2009 Published by European Association for Cardio-Thoracic Surgery

5. Search outcome

Brief Communication

*Corresponding author: Tel.: q44 161 291 2092; Fax: q44 161 291 2091. E-mail address: [email protected] (N.U. Khan).

Medline search 1950 – January 2009 was performed using OVID interface. (Re-do cardiac surgery OR re-do coronary artery bypass grafting OR re-do CABG OR re-do off-pump CABG OR re-do valve surgery OR re-do aortic valve surgery OR re-do mitral valve surgery OR resternotomy OR repeat cardiac surgery OR re-operative heart surgery OR repeat CABG OR repeat coronary artery bypass grafting OR repeat valve surgery.mp).

Best Evidence Topic

You are about to see a 74-year-old man who has been referred for re-do coronary artery bypass grafting. His firsttime coronary artery surgery was performed over 10 years ago, with left internal mammary artery (LIMA) anastomosed to left anterior descending artery, a saphenous vein graft to the circumflex and another vein graft to the posterior descending branch of the right coronary artery. He has angina on exertion, and also has evidence of peripheral vascular disease. The coronary angiogram revealed a patent LIMA but the two vein grafts are occluded. There are suitable target vessels for surgical revascularization. However, you are concerned about the position of the patent LIMA graft, and want to know the risk of injury to LIMA during re-sternotomy. You also want to know if the aorta has significant atherosclerosis. You wonder if performing a multi-slice CT-scan will help to define the mediastinal anatomy, including route and adhesion of the LIMA graft, ventricle and the aortic atherosclerosis.

4. Search strategy

ARTICLE IN PRESS 120

N.U. Khan, N. Yonan / Interactive CardioVascular and Thoracic Surgery 9 (2009) 119–123

Table 1 Best evidence papers Author, date and country, Study type (level of evidence)

Patient group

Outcome

Key results

Comments

Cremer et al., (1998), J Thorac Cardiovasc Surg, Germany, w23x

99 adult patients who had re-operative coronary artery surgery with preoperative spiral CT without contrast angiography

Relationship of heart, grafts and aorta to the sternum

Right ventricle adherent to sternum in 44.5%. Only grafts patent on angiography were evaluated

Safe re-entry according to CT findings

Obtained in 97 patients (98%)

Retrospective, descriptive study. No control group Cases other than isolated coronary surgery not described. Multi-detector CT-scan not used. No 3-D reconstructions

Other than routine cannulation for cardiopulmonary bypass

None

Damage to vital structures

2%

Alternate surgical strategy

14% in CT group, 19% in no-CT group had femoral cannulation

Injuryyhemorrhage during sternotomy

3% in CT group vs. 19% in no-CT group (Ps0.02)

Mortality

6% in CT group vs. 23% in no-CT group (Ps0.03)

Accuracy of CT-scan to demonstrate cardiac and graft anatomy (adhesion described as distance from 0 to 3 mm)

CT-scan accurately demonstrated cardiac and graft anatomy, adhesions and graft occlusion, and aortic calcifications

Change of surgical strategy

Operation cancelled in 2 cases (13%); surgical strategy altered in 8 out of 13 cases (61.5%)

Alteration of surgical strategy. Surgical outcome

Operation deferred in 2 cases (6%) surgical strategy altered in 7 patients (21%); Operative injury to the right ventricle in 1 case, to vein graft in 1 case, no injury to mammary artery; mortality 5 (17%)

Comparison between CXR, coronary angiography and CT angiography

CT-scan provides more accurate topographical anatomy of the mediastinum than CXR and coronary angiography

Morphological features on CT-scan predisposing to adhesions between sternum and large vessels

20 patients (30%) had sternum to large vessel adhesions; presence of extracardiac conduit, ratio of aortic diameter to distance between sternum and vertebra (AoyD) -0.5, and ratio of pulmonary artery diameter to distance between sternum and vertebra (PAyD) -0.25 predispose to adhesions

Change of surgical strategy

10 patients (14.9%) had femoral vessels exposed before re-sternotomy, CPB commenced in three patients

Retrospective cohort study (level 3b)

Morishita et al., (2003), Ann Thorac Surg, Japan, w22x Retrospective cohort study (level 2b)

Aviram et al., (2005), Ann Thorac Surg, Israel, w14x Retrospective cohort study (level 3b)

Gasparovic et al., (2005), Eur J Cardiothorac Surg, USA, w16x Retrospective cohort study (level 3b)

Yamauchi et al., (2006), Surg Today, Japan, w24x Retrospective cohort study (level 3b)

90 patients undergoing third or fourth re-sternotomy for valve operations from 1981–2001. Outcome of patients with preoperative CTscan (ns64) compared against historical cohort (ns26) 15 adult patients with prior CABG undergoing re-do cardiac surgery, Impact of ECG-gated contrast enhanced CTscan with 2-D and 3-D reconstructions

33 adult patients undergoing re-operative cardiac surgery with preoperative contrast enhanced CT-scan

67 patients who had resternotomy for cardiac surgery with preoperative chest CT-scan

Retrospective study, small population over prolonged duration, CT group compared with historical cohort

Retrospective study. No control group. Outcome data not mentioned. Nine out of 24 patients who underwent re-do cardiac surgery during the same period did not have MDCT, but were not included in the outcome analysis Retrospective review, heterogeneous population of patients, no control group

Retrospective study on heterogeneous group of patients, variable surgical techniques

(Continued on next page)


Table 1 (Continued) Patient group

Outcome

Key results

Comments Case Report

Author, date and country, Study type (level of evidence)

Alteration of surgical strategy according to MDCT

86% in patients with highrisk MDCT findings vs. 28% in patients without high-riskMDCT (P-0.001), including non-midline incisions (9%), deep hypothermic circulatory arrest (4%), CPB before incision (11%) and extra-thoracic vessel exposure (52%)

Intra-operative severe bleeding

7 cases (4.4%), no difference between high- or low-risk groups

Injury to vital structures

8 cases (5%), no difference between high- or low-risk groups 2.5%

30-day mortality Luciani et al., (2008), J Thorac Cardiovasc Surg, w25x Retrospective cohort study (level 2b)

Impact of establishing CPB via peripheral cannulation before resternotomy on the incidence of re-entry injuries and outcome

Retrospective study on inhomogeneous population, several indications for using CPB before re-sternotomy, more patients having CPB before re-sternotomy towards the later part of the study

Nomenclature

operations described the incidence of injury to previous grafts in 2.5%, injury to the heart in 2%, and injury to great vessels in 1.5% of patients. Approximately two-thirds of the injuries occurred during sternal re-entry and early dissection, resulting in significantly increased risk of death (12% vs. 4% in those with no intra-operative injuries, P-0.0001). Ellman et al. have reported 9.1% incidence of re-entry injuries; nearly half of them to the previous grafts. However, they found no difference in mortality between injured vs. non-injured group w9x. Some other centres have also reported an equal early mortality between first-time and re-do cardiac operations w10, 11x. To reduce the risk of repeat cardiac operations, meticulous surgical planning for entry, cannulation and myocardial preservation is pivotal w12x. Using alternate surgical strategies, D’Ancona et al. reported perioperative MI in 3.9%

Brief Communication

compared to the first-time operations w2, 3x. Apart from older age and comorbidities, the presence of adhesions from previous surgery provides technical challenges for the surgeon, particularly to achieve safe re-entry, to prevent injury to previous grafts or adherent structures, and to obtain satisfactory myocardial preservation w4, 5x. One study showed the risk of catastrophic haemorrhage during sternal re-entry at approximately 1%, with an associated mortality of 21% w6x. Most studies have reported a higher risk (between 3–7%) of perioperative myocardial infarction (MI) in re-do cardiac operations w3, 7x. In a review of 655 patients undergoing re-do coronary artery bypass grafting (CABG) at Cleveland clinic, the prevalence of injury to patent LIMA graft was 5.3%, resulting in perioperative MI in 40% of these patients, and a higher mortality (8.6%) w8x. A recent study from the same centre looking at 1847 re-

Use of CPB before resternotomy associated with less re-entry injuries (Ps0.046), reduced operative time (Ps0.012), less postoperative bleeding (Ps0.001), less need for prolonged inotropes and shorter ICU stay (P-0.05). However, no difference in operative mortality, MI or stroke

Best Evidence Topic

610 patients for re-do cardiac surgery between 2000–2006; 158 patients (25.9%) had cardiopulmonary bypass before resternotomy due to CT evidence of dense retrosternal adhesions, depressed ejection fraction, tricuspid regurgitation, or previous mediastinitis

Retrospective study without control group Patency of the grafts not described. Difference in mortality between high- and low-risk MDCT groups not described

Negative Results

49% of the patients had 1 or more of the high-risk MDCT findings. Seven cases (4%) were cancelled due to the very high risk determined by CT-scan

Historical Pages

Prevalence of high-risk MDCT findings (-1 cm distance between the chest wallysternum and right ventricleyaortay grafts)

ESCVS Article

Retrospective cohort study (level 2b)

167 adult patients with prior CABG undergoing re-do cardiac surgery with preoperative contrast enhanced multi-detector CT angiography

Institutional Report

Kamdar et al., (2008), Ann Thorac Surg, USA, w15x

Aortic injury in two patients (2.9%), one death

Protocol

before re-sternotomy, and thoracotomy in three patients before resternotomy Damage to vital structures

New Ideas




and a mortality of just under 5% in patients undergoing re-do coronary artery bypass grafting w7x. The crux of surgical planning is an accurate demonstration of mediastinal anatomy through preoperative imaging. The introduction of multi-slice CT-scan using ECG-gated technology and reconstruction techniques has allowed for high spatial and temporal resolution of the mediastinal anatomy w12, 13x. It has therefore gained popularity amongst cardiac surgeons allowing for better risk stratification, alteration of operative strategy and avoidance of potentially catastrophic injuries w14–16x. Reports from various centres reveal that CT-scan findings caused clinicians to cancel surgery in 4– 13% of patients, while surgical approach is altered in up to 80% of cases with high-risk CT findings w14, 15x. The significance of chest imaging is highlighted in the report by Roselli et al. who mentioned that incomplete imaging was the prime cause of lapse in preventive strategy leading to inadvertent intra-operative injuries w17x. Despite preoperative CT imaging, intra-operative recognition of vital structures is often difficult. To overcome this issue, surgeons in Munich have reported the use of stereolithography, a rapid prototype technique to create a threedimensional model of patient’s anatomy using CT-scan data. This helped to clearly understand the relationship between various mediastinal structures, and prevent intra-operative injury w18x. Apart from topographical information, multislice CT-scan also demonstrates other vascular pathologies, such as aortic atherosclerosis and aneurysms w13x. Aortic atherosclerosis is recognized as the single most important determinant of postoperative stroke w19x. Based on the CT findings, surgeons can employ alternate strategies, including no-touch technique, axillary artery cannulation or avoidance of CPB with significant reduction in the risk of stroke w7, 20, 21x. 7. Clinical bottom line Re-do cardiac surgery is associated with an increased risk of morbidity and mortality, mostly related to the intraoperative injuries w17x. CT angiography provides optimum demonstration of mediastinal anatomy in patients coming for re-do cardiac surgery, however, its real advantage on circumventing procedure-related risks are debated. The available evidence shows that high-risk CT-scan findings led to cancellation of surgery in 4–13% of cases, whilst alternate surgical strategies were adopted in up to 80% of cases with significant reduction in the risk of re-entry injuries and mortality w14, 15, 22x. One study looking at intraoperative adverse events in 1847 re-do cardiac surgical patients revealed that most of the lapses in preventive strategy were due to incomplete preoperative imaging w17x. Hence, CT-scan forms an important tool for risk stratification in these patients. References w1x Dunning J, Prendergast B, Mackway-Jones K. Towards evidence-based medicine in cardiothoracic surgery: best BETS. Interact CardioVasc Thorac Surg 2003;2:405–409. w2x Schmuziger M, Christenson JT, Maurice J, Mosimann E, Simonet F, Velebit V. Reoperative myocardial revascularization: an analysis of 458 reoperations and 2645 single operations. Cardiovasc Surg 1994;2:623– 629.

w3x Kron IL, Cope JT, Baker LD Jr, Spotnitz HM. The risks of reoperative coronary artery bypass in chronic ischemic cardiomyopathy: results of the CABG patch trial. Circulation 1997;96(9 Suppl):II-21–II-25. w4x Christenson JT, Schmuziger M, Simonet F. Reoperative coronary artery bypass procedures: risk factors for early mortality and late survival. Eur J Cardiothorac Surg 1997;11:129–133. w5x Yau TM, Borger MA, Weisel RD, Ivanov J. The changing pattern of reoperative coronary surgery. J Thorac Cardiovasc Surg 2000;120:156– 163. w6x Follis FM, Pett SB, Miller KB, Wong RS, Temes RT, Wernly JA. Catastrophic hemorrhage on sternal re-entry: still a dreaded complication? Ann Thorac Surg 1999;68:2215–2219. w7x D’Ancona G, Karamanoukian H, Ricci M, Salerno T, Lajos T, Bergsland J. Reoperative coronary artery bypass grafting with and without cardiopulmonary bypass: determinants of perioperative morbidity and mortality. Heart Surg Forum 2001;4:152–158; discussion 158–159. w8x Gillinov AM, Casselman FP, Lytle BW, Blackstone EH, Parsons EM, Loop FD, Cosgrove DM III. Injury to a patent left internal thoracic artery graft at coronary reoperation. Ann Thorac Surg 1999;67:382–386. w9x Ellman PI, Smith RL, Girotti ME, Thompson PW, Peeler BB, Kern JA, Kron IL. Cardiac injury during resternotomy does not affect perioperative mortality. J Am Coll Surg 2008;206:993–997. w10x Davierwala PM, Borger MA, David TE, Rao V, Maganti M, Yau TM. Reoperation is not an independent predictor of mortality during aortic valve surgery. J Thorac Cardiovasc Surg 2006;131:329–335. w11x Potter DD, Sundt Iii TM, Zehr KJ, Dearani JA, Daly RC, Mullany CJ, McGregor CGA, Puga FJ, Schaff HV, Orszulak TA. Operative risk of reoperative aortic valve replacement. J Thorac Cardiovasc Surg 2005; 129:94–103. w12x Flohr T, Prokop M, Becker C, Schoepf UJ, Kopp AF, White RD, Schaller S, Ohnesorge B. A retrospectively ECG-gated multislice spiral CT-scan and reconstruction technique with suppression of heart pulsation artifacts for cardio-thoracic imaging with extended volume coverage. Eur Radiol 2002;12:1497–1503. w13x Gilkeson RC, Markowitz AH, Ciancibello L. Multisection CT evaluation of the reoperative cardiac surgery patient. Radiographics 2003;23 Spec No: S3–17. w14x Aviram G, Sharony R, Kramer A, Nesher N, Loberman D, Ben-Gal Y, Graif M, Uretzky G, Mohr R. Modification of surgical planning based on cardiac multidetector computed tomography in reoperative heart surgery. Ann Thorac Surg 2005;79:589–595. w15x Kamdar AR, Meadows TA, Roselli EE, Gorodeski EZ, Curtin RJ, Sabik JF, Schoenhagen P, White RD, Lytle BW, Flamm SD, Desai MY. Multidetector computed tomographic angiography in planning of reoperative cardiothoracic surgery. Ann Thorac Surg 2008;85:1239–1245. w16x Gasparovic H, Rybicki FJ, Millstine J, Unic D, Byrne JG, Yucel K, Mihaljevic T. Three dimensional computed tomographic imaging in planning the surgical approach for redo cardiac surgery after coronary revascularization. Eur J Cardio-Thorac Surg 2005;28:244–249. w17x Roselli EE, Pettersson GB, Blackstone EH, Brizzio ME, Houghtaling PL, Hauck R, Burke JM, Lytle BW. Adverse events during reoperative cardiac surgery: frequency, characterization, and rescue. J Thorac Cardiovasc Surg 2008;135:316–323.e316. w18x Sodian R, Schmauss D, Markert M, Weber S, Nikolaou K, Haeberle S, Vogt F, Vicol C, Lueth T, Reichart B, Schmitz C. Three-dimensional printing creates models for surgical planning of aortic valve replacement after previous coronary bypass grafting. Ann Thorac Surg 2008; 85:2105–2108. w19x van der Linden J, Hadjinikolaou L, Bergman P, Lindblom D. Postoperative stroke in cardiac surgery is related to the location and extent of atherosclerotic disease in the ascending aorta. J Am Coll Cardiol 2001; 38:131–135. w20x Morino Y, Hara K, Tanabe K, Kuroda Y, Ayabe S, Kozuma K, Kigawa I, Fukuda S, Wanibuchi Y, Tamura T. Retrospective analysis of cerebral complications after coronary artery bypass grafting in elderly patients. Jpn Circ J 2000;64:46–50. w21x Hirose H, Gill IS, Lytle BW. Redo-aortic valve replacement after previous bilateral internal thoracic artery bypass grafting. Ann Thorac Surg 2004;78:782–785. w22x Morishita K, Kawaharada N, Fukada J, Yamada A, Masaru T, Kuwaki K, Abe T. Three or more median sternotomies for patients with valve

ARTICLE IN PRESS

sternum adhesion after cardiac surgery; a risk-factor analysis. Surg Today 2006;36:596–601. w25x Luciani N, Anselmi A, De Geest R, Martinelli L, Perisano M, Possati G. Extracorporeal circulation by peripheral cannulation before redo sternotomy: Indications and results. J Thorac Cardiovasc Surg 2008;136: 572–577.

Case Report

disease: role of computed tomography. Ann Thorac Surg 2003;75:1476– 1480. w23x Cremer J, Teebken OE, Simon A, Hutzelmann A, Heller M, Haverich A. Thoracic computed tomography prior to redo coronary surgery. Eur J Cardio-Thorac Surg 1998;13:650–654. w24x Yamauchi T, Miyamoto Y, Ichikawa H, Takano H, Sawa Y. Large vessel-

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New Ideas


Protocol Institutional Report ESCVS Article Historical Pages Negative Results Best Evidence Topic Brief Communication Nomenclature