ON-PUMP VERSUS OFF-PUMP IN PATIENTS WITH LOW EJECTION FRACTION

Transcription

1 ON-PUMP VERSUS OFF-PUMP IN PATIENTS WITH LOW EJECTION FRACTION Thesis Submitted in Partial Fulfillment of The Doctorate Degree (M.D) in Cardiothoracic Surgery By Alaa Mohammed Omar (M.B.; B.Ch., M.Sc., Cairo University) Under supervision of Prof. Dr. El-Sayed Kamel Akl Professor of Cardiothoracic Surgery, Faculty of Medicine, Cairo University Dr. Ashraf Ahmed Esmat Assistant Professor of Cardiothoracic Surgery, Faculty of Medicine, Cairo University Dr. Ahmed Salah El-Din Fouad Lecturer of Cardiothoracic Surgery, Faculty of Medicine, Cairo University Faculty of Medicine, Cairo University 2012

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4 ACKNOWLEDGEMENT I would like to start this humble work by expressing my deepest gratitude to all the team that helped me in achieving it. I wish to thank our Professor Dr. El-Sayed Kamel Akl, Professor of Cardiothoracic Surgery, Faculty of Medicine, Cairo University; who honored me by carrying out the burden of meticulously revising my script and guiding my thoughts. I am also profoundly grateful to Dr. Ashraf Ahmed Esmat, Assistant Professor of Cardiothoracic Surgery, Faculty of Medicine, Cairo University, for his brotherly guidance and enormous support that was a great help to me. I am deeply indebted to Dr. Ahmed Salah El-Din Fouad, Lecturer of Cardiothoracic Surgery, Faculty of Medicine, Cairo University, whose kindness was more than encouraging. I am also profoundly grateful to Dr. Karim Said, Assistant Professor of Cardiology, Faculty of Medicine, Cairo University, for his effort, brotherly guidance and enormous support. And last and not least, I would like to express my deepest gratitude to our expert of statistics Professor Dr. Magdi Ibrahim, Professor of Obstetrics and Gynecology, Faculty of Medicine, Cairo University, who added too much to this work by sharing with us his great experience in data analysis. iii

5 To the Memory of my Father To the Memory of my Son Mohammed To the Memory of my Brother Emad To my Mother To my Brother Amr To my Beloved Wife I DEDICATE THIS WORK iv

6 Contents CONTENTS Page Introduction... 1 Review of Literature.. 4 o Historical Background 4 o Ischaemic Myocardial Injury... 9 o Extracorporeal Circulation and Organs Changes. 17 o American College of Cardiology (ACC) American Heart Association (AHA) Guidelines. 25 o Myocardial Viability Assessment in Patients With LV Dysfunction.. 34 o Surgical Strategies for Off-Pump CABG 40 o Contraindications to OP CABG Surgery 49 o Hemodynamic Instability and Acute Conversion. 51 o Cardiac Function Measures.. 53 Patients and Methods 61 Results.. 70 Discussion Summary. 104 References Arabic Summary 116 v

7 List of Figures LIST OF FIGURES No. Title Page 1 Vineberg s free internal thoracic artery implant. Reprinted 5 with permission from the American Association for Thoracic Surgery Vladimir P. Demikhov, a Russian surgeon pioneered in 7 heart-lung transplantation and coronary artery surgery. Reprinted with permission from the Society of Thoracic Surgery, Consequences of coronary arterial atherosclerosis Morphologic effects of reperfusion following severe 14 myocardial ischemia. 5 Relation between cerebral oxygen consumption and 18 nasopharyngeal temperature during CPB at 2 L/min/m 2. 6 Effect of age by decade on neuropsychologic outcome 21 after coronary artery bypass graft surgery 7 Small capillary and arterial dilatations in cerebral vessels 22 in a patient who expired 48 hours after coronary artery bypass graft surgery using cardiopulmonary bypass 8 The single stitch approach to exposing the LAD artery 41 9 Schematic showing the potentially deleterious effect of 42 outflow tract compression of the left ventricle (LV) during stabilization of the diagonal artery (DA) compared to the LAD artery where compression occurs mainly on the septum. RV: right ventricle 10 View of the inferior wall during grafting of the mid-pda. 43 See text for explanation. 11 Silicone loop snaring. Distally, a single loop is used to 45 decrease potential intimal injury 12 Intracoronary shunts of various sizes Soft-padded aortic side-clamp Use of sequential anastomoses Mechanical ventilation time Hospital stay Preoperative, immediate postoperative and 3 months later 90 end diastolic dimension 18 Preoperative, immediate postoperative and 3-months later ejection fraction for both groups 92 vi

8 List of Tables LIST OF TABLES No. Title Page 1 Approximate time of onset and recognition of key 12 features of ischemic myocardial injury 2 Major sources of Microemboli 19 3 Preoperative data in both groups 75 4 Distribution of number of grafts in patients in each 76 group 5 Aortic cross clamp time in relation to number of 78 grafts 6 Postoperative ECG months postoperative NYHA functional class 86 8 Chest pain analysis 87 vii

9 Abbreviations ABBREVIATIONS ACC : American College of Cardiology ACS : Acute coronary syndrome AHA : American Heart Association ATP : Adenosine triphosphate BAL : Bronchoalveolar lavage BSA : Body surface area CHF : Congestive heart failure CI : Cardiac index CO : Cardiac output CPB : Cardiopulmonary bypass EACTS : European Association of Cardiothoracic Surgery ES : End-systole ESC : European Society of Cardiology FDG : Fluorodeoxy glucose HR : Heart rate IAB : Intra-aortic balloon ITA : Internal thoracic artery IVC : Inferior vena cava LAD : Left anterior descending LCX : Circumflex artery LIPV : Left inferior pulmonary vein LM : Left main trunk LSPV : Left superior pulmonary vein NYHA : New York Heart Association OPCAB : Off-pump coronary artery bypass PCI : Percutaneous coronary intervention PDA : Posterior descending artery PET : Positron emission tomography POCD : Postoperative cognitive deficit RCT : Randomized clinical trial ROOBY : Randomized on/off bypass trial SCADS : Small capillary and arteriolar dilatations SPECT : Single photon emission computed tomography STICH : Surgical treatment of ischemic heart failure SVR : Surgical ventricular reconstruction WMSI : Wall motion score index viii

10 Abstract ABSTRACT Background: The number of patients with severe left ventricular dysfunction referred for coronary artery bypass grafting (CABG) is increasing. Large number of studies showed that surgical intervention in this category of high risk patients had higher survival benefits and excellent outcome compared to medical therapy. Aim of work: Is to evaluate our experience with coronary artery bypass surgery in patients with EF 35% either to perform operation using off-pump technique or using cardiopulmonary bypass technique and try to reach conclusion about which technique may be safer regarding cardiac function and associated morbidities in this high risk group of patients. Patients and Methods: The prospective observational patient cohort study included 40 consecutive patients divided into 2 groups each of 20 patients selected according to surgeons experience in each technique. Results: Improvement of EF was encountered in our study; the mean 3-months postoperative EF increased for both groups increased nearly equal (36% versus 37%) for off -pump and on-pump groups respectively. There was no significant statistical difference in data collected for both groups ( p-value>0.05) regarding all points of comparison. Renal dysfunction was slightly higher in the on-pump group but without reaching a significant difference (p-value>0.05). Conclusion: CABG in this high risk group has acceptable results with on-pump and off-pump techniques with nearly comparable results in our study in early 3-months postoperative period. Offpump CABG seems to be valuable in this high risk group of patients with additional co-morbidities like renal dysfunction (p-value>0.05). However, larger studies are needed to confirm this point. Use of intra-aortic balloon in this high risk group of patients found to be beneficial when indicated. Inspite of lack of statistical significance ( p-value >0.05, 3 patients developed renal dysfunction in on-pump group). Our study may suggest that off-pump technique may be safer for patients with renal dysfunction. Our study was designed for early (3 months) postoperative period and we did not include graft patency in our study. We recommend a longer follow-up period including follow-up of graft patency and postoperative viability study to reach more valuable data. Keywords: Coronary revascularization Ventricular dysfunction ix

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12 Introduction INTRODUCTION Despite improvement in medical therapies and surgical techniques, the management of patients with coronary artery disease and low ejection fraction is still challenging. Current treatment options for this cohort include intensive medical therapy, surgical revascularization, ventricular remodeling and heart transplantation. Medical treatment alone is problematic because of limited long-term survival, heart-transplantation offers excellent results with 65.6%. 5-year survival rate, however, the scarcity of donor organs makes this option impractical for a majority of patients (Dicarli et al., 1998). Coronary artery bypass grafting (CABG) has shown to be superior to medical therapy alone for patients with low EF, demonstrating significant clinical improvement and long-term survival for this population with left ventricular dysfunction. There are major risk factors for postoperative complications and late death after CABG. However, recent studies have shown that early postoperative survival after CABG has improved as a result of advances in surgical techniques, myocardial protection strategies, mechanical anesthesia, support. postoperative Although pharmacological peri-operative and surgical management has lowered operative mortality rates after CABG in 1

13 Introduction patients with severe left ventricular dysfunction, a major concern remains as to whether coronary revascularization improves ventricular function and provides long-term survival (Yamaguchi et al., 1998). The greatest survival benefit after CABG is seen in patients with three vessels or left main coronary artery disease and depressed left ventricular function (Eagle et al., 1999). CABG often leads to improvement of left ventricular function indices of 0.05 (5%) to 0.12 (12%) in patients with depressed left ventricular function because of presence of stunned or hibernating myocardium. In patients with severe congestive heart failure symptoms preoperatively, an expected mean gain of at least one New York Heart Association (NYHA) class should persist for at least 4 years postoperatively on average (Corr et al., 2002). Cardiac surgeons are increasingly faced with the challenge of evaluating patients with ischemic cardiomyopathy and severe left ventricular (LV) dysfunction for surgical revascularization. There is growing evidence that CABG in this population of patients offers a survival benefit over medical therapy (Elefteriades et al. 1997). Long-term survival following CABG in this subgroup of patients with depressed LV function may be comparable to that seen with cardiac transplantation (Housmann 2

14 Introduction et al., 1997). A satisfactory outcome hinges on the quality of target vessels, the presence of viable myocardium in the territory of bypassed vessels and the absence of significant associated comorbidities. Off-pump beating heart surgery has emerged as yet another option in the revascularization of the severely depressed left ventricle (Puskas et al., 2003). Recent evidence indicates that some of the associated morbidities encountered with the on-pump arrested heart technique may be reduced with beating heart surgery (Sabik et al., 2002). 3

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16 Review of Literature HISTORICAL BACKGROUND Alexis Carrel remarked in 1910 (Carrel, 1910) "I attempted to perform an indirect anastomosis between descending aorta and left coronary artery. It was for many reasons a difficult operation. On account of continuous motion of the heart, it was not easy to dissect and to suture the artery, in one case, I implanted one end of along carotid artery preserved in a cold storage, on the descending aorta. The other end was passed through the pericardium and anastomosed to the pericardial end of the coronary near the pulmonary artery unfortunately the operation was too slow. Three minutes after the interruption of the circulation fibrillary contractions appeared, but the anastomosis took five minutes. By message of the heart, the dog was kept alive, but he died less than two hours after operation. It shows that the anastomosis must be done in less than three minutes". After performing his technique on animals Claude Beck performed anastomosis between pedicle graft of pectoralis muscle to the left ventricular wall in 1930, the patient made an uneventual recovery and was angina-free after the operation. Beck subsequently performed his operation with modifications on 16 patients, postmortem examination showed that anastomotic vessels did develop between tissues and myocardium. 4

17 Review of Literature Fig. (1): Vineberg s free internal thoracic artery implant. Reprinted with permission from the American Association for Thoracic Surgery Arthur Vineberg in 1946 reported implanting the internal mammary artery through a tunnel in the myocardium, but he did not actually anastomose the left internal mammary artery to a coronary artery. Mason Sones validated Vineberg's concept by demonstrating communications between the graft in the myocardium and the coronary system by angiography in two patients operated on 5 and 6 years earlier. In the middle 1960, the Vineberg operation with many variations was performed at many institutions in the United States and Canada (Vineberg, 1975). 5

18 Review of Literature Longmire and colleagues were the first to report endarterectomy of the coronary arteries for the treatment of ischemic coronary disease. Selective coronary angiography was developed by Sones and Shirey at the Cleveland Clinic and reported in their classic paper entitled, Cine coronary arteriography (Sones et al., 1962). Dr. Robert H. Goetz performed what appears to be the first clearly documented coronary artery bypass operation in a human, which was successful. The surgery took place at Van Etten Hospital in New York City on May 2, He operated an 38 year old man who was severely symptomatic and used a nonsuture technique to connect the right internal mammary artery and right coronary artery. It took him 17 seconds to join the 2 arteries using a hollow metal tube. It was confirmed patent by angiography performed 14th postoperative day Patient remained a symptomatic for a year then developed recurrent angina and died of myocardial infarction (Konstantinov, 2000). A case of autogenous saphenous vein bypass grafting performed 1964 by Garret, Dennis and De Bakey by suturing saphenous vein graft proximally to aorta and distally to left anterior descending artery in 1973 patient was alive and angiogram showed that the graft was patent. 6

19 Review of Literature Shaumaker Credits Longmire with the first internal mammary coronary artery anastomosis in early Demikhov, a soviet surgeon was anastomosing the internal mammary artery to left coronary artery in dogs. Fig. (2): Vladimir P. Demikhov, a Russian surgeon pioneered in heart-lung transplantation and coronary artery surgery. Reprinted with permission from the Society of Thoracic Surgery, In 1967 a soviet surgeon Kolessov reported his experience with mammary artery coronary artery anastomosis for the treatment of angina pectoris in six patients in an American Surgical Journal (Kolessov VI, 1967). 7

20 Review of Literature Rene Favalaro from Cleveland Clinic used saphenous vein for bypassing coronary obstructions. Favalaro's 1968 article focused on 15 patients, where interpositional graft of saphenous vein was sutured from aorta to right coronary artery to be sutured end to end after dividing right coronary artery after site of obstruction. The contributions by Favalaro, Kolessov, Green, Bailey and Hirose all were important, but arguably, the official start of coronary bypass surgery as we know today happened in 1969 when Dr. Dudley Johnson and Co-workers reported their series of 301 patients who had undergone various operations for coronary artery disease since February of 1967 (Johnson et al., 1969). Dr. Johnson stated: Our experience indicates that five factors are important to direct surgery. One: Do not limit graft to proximal portions of large arteries, Two: Do not work with diseased arteries, Three: Always do end-to-side anastomosis, Four: Always work on a dry, quiet field, Five: Do not allow the hematocrit to fall below 35. Owing to the persistence of Drs. Green, Loop, Grondin and Others, internal mammary artery grafts eventually became the conduit of choice when their superior long-term patency became known (Loop et al., 1986). 8