- Email: [email protected]
Aortic root cardioplegia: An adequate method for myocardial protection in complete occlusion of the left main coronary artery
Aortic Root Cardioplegia: An Adequate Method For Myocardial Protection In Complete Occlusion Of The Left Main Coronary Artery Eugene K. W. Sim, FRCS,Chuen Neng Lee,
F’RCS,
Chee Siong Soo,
MRCP,
Lieng Hsi Ling,
MRCP
Division of Cardiothoracic Surgery and Cardiology Cardiac Department, National University Hospital, Singapore
T
hree cases of coronary artery bypass grafting for complete occlusion of the left main coronary artery are described. Delivery of cardioplegia through the aortic root was used in all 3 cases with no evidence of perioperative myocardial infarction. Despite its theoretical disadvantages, aortic root cardioplegic delivery is an adequate technique of myocardial preservation in the presence of sufilcient collateral vessels. (Asia Pacific J Thorac Cardiovasc Surg 1994;3(1):36-37)
Introduction
Case 3
Patients with complete occlusion of the left main coronary artery (LMCA) seldom present for surgery presumably because most would have died from the disease before they could be investigated. For survivors undergoing angiography, early coronary artery bypass graft (CABG) surgery is recommended. In patients with occlusion of the LMCA, the surgeon’s main concern is in obtaining adequate cardioplegic distribution beyond the obstruction. No previous reports of total occlusion of the LMCA have dealt specifically with the techniques of myocardial preservation in such patients. We report 3 patients with LMCA occlusion who underwent successful CABG surgery and on whom aortic root antegrade cardioplegia was used.
A 60-year-old Malay male with a prior myocardial infarction presented with a l-month history of progressive angina and exertional dyspnea. The echocardiogram revealed a dilated left ventricle, global hypokinesia, an akinetic septum, and mild mitral and tricuspid regurgitation. Coronary angiography showed total occlusion of the LMCA. The right coronary artery had a 75% stenosis in its distal portion and supplied collaterals to the left anterior descending and circumflex arteries. Ventriculography showed an ejection fraction of 24%.
Surgery and Myocardial Protection All 3 patients underwent CABG with saphenous vein grafts. Antegrade cardioplegia using St Thomas’s (II) solution at 4°C was delivered through the root of the aorta after applying the aortic cross clamp. Induction of cardioplegia was 5 min, and subsequent maintenance doses were delivered for 2 min at the completion of each distal anastomosis. Systemic cooling to 25°C was used, and topical cooling was applied with ice-saline. The cross clamp time was 54 min in patient 1 and 39 min in patients 2 and 3. The cardiopulmonary bypass times in patients 1,2 and 3 were 117,76 and 88 min, respectively. One patient developed ventricular fibrillation during surgery while on cardiopulmonary bypass and was cardioverted with a DC shock. None of the patients had perioperative infarction on enzymic or ECG criteria. The 3 patients were taken off inotropic support and extubated within 48 hours of operation. Except for patient 2, who had a bleeding duodenal ulcer, the postoperative courses of the 3 patients were uneventful.
case1 A 64-year-old Chinese male with a 1Zyear history of stable angina pectoris had a strongly positive exercise stress test. Coronary angiography revealed complete occlusion of the LMCA with the right coronary artery supplying extensive collateral vessels to the left anterior descending and circumflex arteries. Left ventriculography showed moderate anterolateral and apical septal hypokinesia.
Case 2 A 60-year-old Chinese male with progressively worsening angina pectoris had ST depression, as shown by the inferior leads of his resting electrocardiogram, and a strongly positive exercise stress test. Coronary angiography showed total occlusion of the LMCA, and a 95% stenosis of the mid-right coronary artery supplying collateral vessels to the left coronary arterial tree. Left ventricular function was preserved.
All 3 patients were discharged by the seventh postoperative day. All patients are well with minimal or no symptoms 1 year after operation.
36
AsiaPacificJ ThoracCardiovascSurg199+3(l)
Sim,Lee, Soo,Ling Aortic
Discusdon Perioperative myocardial damage remains the most common cause of mortality and death following technically successful cardiac operations l. The quest for better techniques of myocardial protection continues to engender much interest and research. In patients with complete occlusion of the LMCA, one of the main concerns is to obtain adequate distribution of the cardioplegic solution beyond the obstructed coronary vessels 2. In cases of LMCA occlusion there is a compelling argument for, and theoretical advantage to, the use of retrograde coronary sinus cardioplegic techniques 3 or antegrade cardioplegic delivery through the vein grafts after completion of the distal anastomosis of each graft. Experimental studies on animals have shown: inadequate distribution of cardioplegia following acute occlusion of coronary arteries; and retrograde perfusion improves delivery and distribution of the cardioplegic solution 4. However, there are significant differences between animals and humans with respect to the microvascular distribution of solutions delivered by the retrograde route 5. Furthermore, the distribution of cardioplegia on experimental models with acute occlusion is very different from that of patients with long-standing coronary artery disease where extensive collateral vessels exist. Consequently, findings in experimental animals should be interpreted cautiously. While being theoretically advantageous, antegrade delivery of cardioplegia through completed grafts may not prove to be superior in practice because the infusion of hyperkalemic cardioplegic solution through vein grafts may damage the endothelium of the vein grafts. Recent studies have provided evidence that myocardial protection is better in experimental models with combined antegrade and retrograde cardioplegia delivery systems 6. There have also been encouraging clinical reports of the superiority of retrograde cardio-
plegia or combined retrograde and antegrade cardioplegia as compared to antegrade cardioplegia 7,*. As there is no unequivocal evidence that techniques other than conventional aortic root antegrade cardioplegia are superior, we chose to use techniques that we were familiar with in order to avoid technical problems and risk the prolongation of cross-clamp time in these 3 patients. Our good clinical results obtained from these patients may be criticised as being anecdotal. However, we believe that even with complete occlusion of the LMCA, antegrade cardioplegia through the aortic root is an adequate means of myocardial protection as sufficient collateral flow will have developed in such patients. In the midst of enthusiasm for new methods of myocardial preservation, the use of the time-tested technique of aortic root cardioplegia still merits consideration.
l
References 1. BuckbergGD.
l
2.
3.
4.
5.
6.
7.
8.
Training Position The General Infii At Leeds Position of Registrar in Cardiothoracic Surgery Mr C. Munsch advises that a training position suitable for an Asian or Australasian trainee exists at the Leeds General Intirmary, Yorkshire, U.K. The case load is 650 open-heart patients per year. Please contact: Mr C. Munsch, PRCSE General Infirmary at Leeds Great George St Leeds LSI 3EX
root cardioplegia
Left ventricular subendocardial necrosis. Ann Thorac Surg 1977;24:379-93. Grondin CM, Helias J, Vouhe PE, Robert P. Influence of a critical coronary artery stenosis on myocardial protection through cold potassium cardioplegia. J Thorac Cardiovasc Surg 1981;82:608-1.5. Partington MT, Acar C, Buckberg GD, Julia PL, Kofsky ER, Bugyi HI. Studies of retrograde cardioplegia: I. Capillary blood flow distribution to myocardium supplied by open and occluded arteries. J Thorac Cardiovasc Surg 1989;97:605-12. Hilton CJ, Teubl W, Acker M, et al. Inadequate cardioplegic protection with obstructed coronary arteries. Ann Thorac Surg 1979;28:232-4. Gates RN, Laks H, Drinkwater DC, et al. Gross and microvascular distribution of retrograde cardioplegia in explanted human hearts. Ann Thorc Surg 1993;56:410-7. Partington MT, Acar C, Buckberg GD, Julia PL. Studies of retrograde cardioplegia: II. Advantages of antegradelretrograde cardioplegia to optimize distribution in jeopardized myocardium. J Thorac Cardiovasc Surg 1989;97:613-22. Diehi JT, Eichbom EJ, Konstam MA, et al. Efficacy of retrograde coronary sinus cardioplegia in patients undergoing myccardial revascularization: A prospective random trial. Ann Thorac Surg 1988;45:595-602. Bhayana JN, Kalmbach T, Booth PVM, Mentzer RM Jr, Schimert G. Combined antegradejretrograde cardioplegia for myocardial protection: a clinical trial. J Thorac Cardiovasc Surg 1989;98:956-60.
Cardiac Surgical Research Training The Baker Medical Research Institute A period of laboratory research is desirable in the training of a cardiac surgeon. Such experience is available at the Cardiac Surgical Research Unit at The Baker Medical Research Institute. It is desirable to spend two years in the laboratory, however one year is also useful. This research can lead to a higher degreee (MS, MD or PhD). Support can be obtained from the Royal Australasian College of Surgeons’ Foundation, the National Health and Medical Research Council, the National Heart Foundation, and the Alfred Hospital Research Fund. Surgical trainees interested in research at The Baker Medical Research Institute should contact: Dr Franklin Rosenfeldt The Baker Medical Research Institute PO Box 348 Prahran, Victoria, 3 18 1, Australia 37
F’RCS,
Chee Siong Soo,
MRCP,
Lieng Hsi Ling,
MRCP
Division of Cardiothoracic Surgery and Cardiology Cardiac Department, National University Hospital, Singapore
T
hree cases of coronary artery bypass grafting for complete occlusion of the left main coronary artery are described. Delivery of cardioplegia through the aortic root was used in all 3 cases with no evidence of perioperative myocardial infarction. Despite its theoretical disadvantages, aortic root cardioplegic delivery is an adequate technique of myocardial preservation in the presence of sufilcient collateral vessels. (Asia Pacific J Thorac Cardiovasc Surg 1994;3(1):36-37)
Introduction
Case 3
Patients with complete occlusion of the left main coronary artery (LMCA) seldom present for surgery presumably because most would have died from the disease before they could be investigated. For survivors undergoing angiography, early coronary artery bypass graft (CABG) surgery is recommended. In patients with occlusion of the LMCA, the surgeon’s main concern is in obtaining adequate cardioplegic distribution beyond the obstruction. No previous reports of total occlusion of the LMCA have dealt specifically with the techniques of myocardial preservation in such patients. We report 3 patients with LMCA occlusion who underwent successful CABG surgery and on whom aortic root antegrade cardioplegia was used.
A 60-year-old Malay male with a prior myocardial infarction presented with a l-month history of progressive angina and exertional dyspnea. The echocardiogram revealed a dilated left ventricle, global hypokinesia, an akinetic septum, and mild mitral and tricuspid regurgitation. Coronary angiography showed total occlusion of the LMCA. The right coronary artery had a 75% stenosis in its distal portion and supplied collaterals to the left anterior descending and circumflex arteries. Ventriculography showed an ejection fraction of 24%.
Surgery and Myocardial Protection All 3 patients underwent CABG with saphenous vein grafts. Antegrade cardioplegia using St Thomas’s (II) solution at 4°C was delivered through the root of the aorta after applying the aortic cross clamp. Induction of cardioplegia was 5 min, and subsequent maintenance doses were delivered for 2 min at the completion of each distal anastomosis. Systemic cooling to 25°C was used, and topical cooling was applied with ice-saline. The cross clamp time was 54 min in patient 1 and 39 min in patients 2 and 3. The cardiopulmonary bypass times in patients 1,2 and 3 were 117,76 and 88 min, respectively. One patient developed ventricular fibrillation during surgery while on cardiopulmonary bypass and was cardioverted with a DC shock. None of the patients had perioperative infarction on enzymic or ECG criteria. The 3 patients were taken off inotropic support and extubated within 48 hours of operation. Except for patient 2, who had a bleeding duodenal ulcer, the postoperative courses of the 3 patients were uneventful.
case1 A 64-year-old Chinese male with a 1Zyear history of stable angina pectoris had a strongly positive exercise stress test. Coronary angiography revealed complete occlusion of the LMCA with the right coronary artery supplying extensive collateral vessels to the left anterior descending and circumflex arteries. Left ventriculography showed moderate anterolateral and apical septal hypokinesia.
Case 2 A 60-year-old Chinese male with progressively worsening angina pectoris had ST depression, as shown by the inferior leads of his resting electrocardiogram, and a strongly positive exercise stress test. Coronary angiography showed total occlusion of the LMCA, and a 95% stenosis of the mid-right coronary artery supplying collateral vessels to the left coronary arterial tree. Left ventricular function was preserved.
All 3 patients were discharged by the seventh postoperative day. All patients are well with minimal or no symptoms 1 year after operation.
36
AsiaPacificJ ThoracCardiovascSurg199+3(l)
Sim,Lee, Soo,Ling Aortic
Discusdon Perioperative myocardial damage remains the most common cause of mortality and death following technically successful cardiac operations l. The quest for better techniques of myocardial protection continues to engender much interest and research. In patients with complete occlusion of the LMCA, one of the main concerns is to obtain adequate distribution of the cardioplegic solution beyond the obstructed coronary vessels 2. In cases of LMCA occlusion there is a compelling argument for, and theoretical advantage to, the use of retrograde coronary sinus cardioplegic techniques 3 or antegrade cardioplegic delivery through the vein grafts after completion of the distal anastomosis of each graft. Experimental studies on animals have shown: inadequate distribution of cardioplegia following acute occlusion of coronary arteries; and retrograde perfusion improves delivery and distribution of the cardioplegic solution 4. However, there are significant differences between animals and humans with respect to the microvascular distribution of solutions delivered by the retrograde route 5. Furthermore, the distribution of cardioplegia on experimental models with acute occlusion is very different from that of patients with long-standing coronary artery disease where extensive collateral vessels exist. Consequently, findings in experimental animals should be interpreted cautiously. While being theoretically advantageous, antegrade delivery of cardioplegia through completed grafts may not prove to be superior in practice because the infusion of hyperkalemic cardioplegic solution through vein grafts may damage the endothelium of the vein grafts. Recent studies have provided evidence that myocardial protection is better in experimental models with combined antegrade and retrograde cardioplegia delivery systems 6. There have also been encouraging clinical reports of the superiority of retrograde cardio-
plegia or combined retrograde and antegrade cardioplegia as compared to antegrade cardioplegia 7,*. As there is no unequivocal evidence that techniques other than conventional aortic root antegrade cardioplegia are superior, we chose to use techniques that we were familiar with in order to avoid technical problems and risk the prolongation of cross-clamp time in these 3 patients. Our good clinical results obtained from these patients may be criticised as being anecdotal. However, we believe that even with complete occlusion of the LMCA, antegrade cardioplegia through the aortic root is an adequate means of myocardial protection as sufficient collateral flow will have developed in such patients. In the midst of enthusiasm for new methods of myocardial preservation, the use of the time-tested technique of aortic root cardioplegia still merits consideration.
l
References 1. BuckbergGD.
l
2.
3.
4.
5.
6.
7.
8.
Training Position The General Infii At Leeds Position of Registrar in Cardiothoracic Surgery Mr C. Munsch advises that a training position suitable for an Asian or Australasian trainee exists at the Leeds General Intirmary, Yorkshire, U.K. The case load is 650 open-heart patients per year. Please contact: Mr C. Munsch, PRCSE General Infirmary at Leeds Great George St Leeds LSI 3EX
root cardioplegia
Left ventricular subendocardial necrosis. Ann Thorac Surg 1977;24:379-93. Grondin CM, Helias J, Vouhe PE, Robert P. Influence of a critical coronary artery stenosis on myocardial protection through cold potassium cardioplegia. J Thorac Cardiovasc Surg 1981;82:608-1.5. Partington MT, Acar C, Buckberg GD, Julia PL, Kofsky ER, Bugyi HI. Studies of retrograde cardioplegia: I. Capillary blood flow distribution to myocardium supplied by open and occluded arteries. J Thorac Cardiovasc Surg 1989;97:605-12. Hilton CJ, Teubl W, Acker M, et al. Inadequate cardioplegic protection with obstructed coronary arteries. Ann Thorac Surg 1979;28:232-4. Gates RN, Laks H, Drinkwater DC, et al. Gross and microvascular distribution of retrograde cardioplegia in explanted human hearts. Ann Thorc Surg 1993;56:410-7. Partington MT, Acar C, Buckberg GD, Julia PL. Studies of retrograde cardioplegia: II. Advantages of antegradelretrograde cardioplegia to optimize distribution in jeopardized myocardium. J Thorac Cardiovasc Surg 1989;97:613-22. Diehi JT, Eichbom EJ, Konstam MA, et al. Efficacy of retrograde coronary sinus cardioplegia in patients undergoing myccardial revascularization: A prospective random trial. Ann Thorac Surg 1988;45:595-602. Bhayana JN, Kalmbach T, Booth PVM, Mentzer RM Jr, Schimert G. Combined antegradejretrograde cardioplegia for myocardial protection: a clinical trial. J Thorac Cardiovasc Surg 1989;98:956-60.
Cardiac Surgical Research Training The Baker Medical Research Institute A period of laboratory research is desirable in the training of a cardiac surgeon. Such experience is available at the Cardiac Surgical Research Unit at The Baker Medical Research Institute. It is desirable to spend two years in the laboratory, however one year is also useful. This research can lead to a higher degreee (MS, MD or PhD). Support can be obtained from the Royal Australasian College of Surgeons’ Foundation, the National Health and Medical Research Council, the National Heart Foundation, and the Alfred Hospital Research Fund. Surgical trainees interested in research at The Baker Medical Research Institute should contact: Dr Franklin Rosenfeldt The Baker Medical Research Institute PO Box 348 Prahran, Victoria, 3 18 1, Australia 37