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Cardiac surgery
Cardiac Surgery Irving L Kron, MD, FACS
studied adenosine preconditioning and hypothesized that the mechanism is far more than myocardial KATP channel opening. They studied human atrial trabeculae that were placed in organ baths and paced. Before ischemia and reperfusion, these trabeculae were given either adenosine or diazoxide (a selective mitochondrial KATP channel opener). The adenosine but not the diazoxide-treated trabeculae provided protection against extended ischemia. Pomerantz and colleagues concluded that adenosine preconditioning offers ideal protection for human myocardial tissue after ischemia reperfusion. Ducko and colleagues4 from the Milton S Hershey Medical Center studied a different mechanism of myocardial stunning. They suggested that intracellular calcium overload may be a mechanism in myocardial stunning. They used hyperpolarized arrest with a potassium channel opener to prevent this. They used both a model of rabbit left ventricular myocytes and a parabiotic-isolated rabbit heart preparation. Though the potassium channel openers eliminated intracellular calcium overload, they did not provide improved myocardial protection when compared with St Thomas solution alone. They concluded that intracellular calcium overload may not be a mechanism of myocardial stunning.
The year 2000 has begun, and cardiac surgery is still evolving, but there has been a great deal of reflection on recent innovations. The definition of minimally invasive cardiac surgery is still unclear. Is it best for the patient to have a smaller incision with longer pump times or a larger incision and an operation off bypass? The role of left ventricular restoration and reconstruction for the treatment of heart failure is also still unclear. There continue to be exciting new basic science advances in the areas of gene transfer and myocardial cellular transplantation. MYOCARDIAL PROTECTION There are several exciting experimental and clinical advances in myocardial protection. Thourani and colleagues1 demonstrated that the use of adenosine in blood cardioplegia reduced apoptosis. Apoptosis is a genetically programmed form of cell death. These authors used a dog model of temporary left anterior descending coronary artery occlusion. These animals were placed on bypass and then underwent 2 hours of reperfusion. The authors noted that apoptosis occurred with the use of blood cardioplegia. But adenosine during cardioplegic arrest or during reperfusion reduced the amount of apoptosis. Friehs and colleagues2 from the Beth Israel Deaconess Medical Center used adenosine-enhanced ischemic preconditioning to decrease myocardial infarct size and improve functional recovery. They used an isolated perfused rabbit heart model with 30 minutes of global ischemia followed by 120 minutes of reperfusion. This resulted in marked reduction of functional recovery. Adenosine enhanced by ischemic preconditioning resulted in hearts with full recovery no different from controls. Pomerantz and colleagues3 at the University of Colorado also
GENETIC ENGINEERING AND MYOBLAST TRANSPLANTATION There has been a great deal of experimental interest in gene transfer techniques and myocardial transplantation. Both techniques are the potential future in the treatment of ischemic cardiomyopathy. Sayeed-Shah and colleagues5 from the Brigham and Women’s Hospital examined the influence of proangiogenic gene therapy in conjunction with transmyocardial laser revascularization (TMR) to enhance myocardial revascularization and improve myocardial function. The authors induced gene transfer in CO2-TMR channels in pigs. The authors noted transgene expression in 93% of the TMR-plasmid group. They concluded that trans-
Received October 27, 1999; Accepted October 27, 1999. From the Department of Surgery, University of Virginia Medical Center, Charlottesville, VA. Correspondence address: Irving L Kron, MD, FACS, Department of Surgery, University of Virginia Medical Center, Box 310, Charlottesville, VA 22908. © 2000 by the American College of Surgeons Published by Elsevier Science Inc.
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gene expression is improved by TMR and sustained for 2 weeks after transduction. Stewart and colleagues6 from the University of Pennsylvania studied a different model of induced angiogenesis. The authors used an adenovirus with hepatocyte growth factor as the transgene in rabbits. The hearts were injected with the previously mentioned technique of gene transfer. Six weeks after injection, animals underwent a constrictor on the left circumflex artery. The authors noted significant increases of small and medium-sized arterioles in the ischemic region compared with controls at the time of sacrifice. They also noted a significant reduction in infarct size in the circumflex distribution in the genetically manipulated animals. Clearly, these animals had marked improvement because of the genetic manipulation. Atkins and colleagues7 from Duke University studied the concept of cellular cardiomyoplasty. They developed a rabbit model of myocardial infarction with circumflex marginal coronary ligation. This was followed by myocardial injection of autologous skeletal myoblasts. Their data suggested that the myoblasts improve regional systolic and diastolic performance in this infarction model. They concluded that this technique could be used as an adjunct to surgical revascularization. Hutcheson and colleagues8 from Duke University studied which cell would be most useful in a cryoinjured rabbit heart. They noted that the skeletal myoblasts improved function in chronically injured myocardium, and the fibroblast transfer did not. They concluded that the type of cell source would be important in experimental techniques of chronic myocardial injury. ISCHEMIC HEART DISEASE Englemann and colleagues9 from Springfield, MA, performed a very important study on ideal perfusion temperature. They randomized coronary bypass graft patients to undergo perfusion with warm, tepid, or cold temperatures. They noted that there was persistent neurologic dysfunction that was not related to stroke at 1 month in 36% of the patients studied. Perfusion temperature had no relationship to this neurologic dysfunction, but fibrinolytic activity was greatest in the warm group. They concluded that tepid perfusion was best for routine coronary bypass surgery. There has been a great deal of interest in the incidence and causes of stroke after
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coronary bypass surgery. John and colleagues10 from Columbia studied more than 19,000 patients who underwent coronary artery bypass grafting (CABG) in the New York State database during 1995. They noted that 1.4% of all of these patients suffered a stroke. The patients who had a stroke were older and had a longer duration of cardiopulmonary bypass. The various variables that predicted stroke included a calcified aorta, previous stroke, presence of carotid disease, and diabetes. Stroke increased the hospital mortality to 25% as compared with 2% for the rest of the population. Though the previous manuscript demonstrated that carotid disease was associated with a higher stroke rate in coronary bypass patients, a metaanalysis by Borger and colleagues11 from Toronto further clouded the issue. They performed a computerized Medline search to compare both combined and staged CABG-carotid endarterectomy patient cohorts. Fifteen studies were identified with a total of 911 combined patients as compared with 912 staged patients. Their metaanalysis revealed a trend toward increased risk of stroke, death, and combined stroke or death for patients undergoing combined procedures. The stroke rate was 5.5% versus 3.4% for combined versus staged surgery. The mortality was 4.7% versus 3.2%. They concluded from this analysis that combined procedures did more poorly than staged ones. There are several other controversies in ischemic heart disease. Blackstone and Lytle12 studied whether extensive arterial grafting lowers the incidence of reintervention in patients who have undergone coronary bypass. They studied 2,001 patients who underwent bilateral internal thoracic artery conduits and 8,123 patients receiving single conduits. They concluded that bilateral internal thoracic arteries provided better survival and fewer reinterventions. But this effect was not realized in the older age group because of poor survival and fewer reinterventions. Scott and colleagues13 from the Cleveland Clinic also examined the effects of incomplete revascularization. They studied a group of 2,072 patients who underwent primary isolated internal mammary to left anterior descending coronary artery bypass from 1971 to 1997. They noted that 26% of these patients would now be considered as having two-vessel disease and 13% would be considered to have three-vessel disease. They exam-
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ined longterm survival and concluded that residual circumflex or left main disease markedly reduced late survival. TMR has been advocated as a technique for reducing angina in patients who are not otherwise graftable because of diffuse coronary artery disease. This has been a controversial subject because it is not clear if these holes stay open, and it is possible that the mechanism of reduction of angina does not relate to increased coronary blood flow. Allen and colleagues14 reported a multiinstitutional randomized trial of 266 patients who were randomized to TMR with CABG versus CABG alone. This was in a group of patients who had one or more ischemic areas not amenable to CABG. The CABG-TMR group had an operative mortality of 1.5%, which was significantly lower than the CABG alone group, which was 7.5%. The 3-month mortality remained significantly lower for the TMR-CABG group at 3% as compared with 10% for the CABG alone group. The authors concluded that TMR with CABG is safe and reduces operative mortality compared with CABG alone in patients who cannot undergo complete revascularization. The greatest controversy in ischemic heart disease is determining what is truly minimally invasive. Last year, there was much reporting on the Heartport technology, which essentially suggests that a smaller incision with percutaneously placed cardiopulmonary bypass technology may be superior to standard cardiopulmonary bypass. This socalled “keyhole” surgery was attempted with varying results by many surgeons. A recent Wall Street Journal article15 suggested that at least half of the 500 surgeons trained in the Heartport procedure (developed by Dr John Stevens, Stanford University, Stanford, CA) have abandoned it. But there are still many surgeons who practice the technique and believe that it provides a great advantage to the patient. More recently, off-pump coronary bypass for multivessel disease has increased. Cartier and colleagues16 from Montreal reported 230 off-pump CABGs. An average of 2.88 grafts per patient were performed. They suggested that complete revascularization could be achieved in 91% of the patients using coronary artery stabilization techniques. The average ischemic time was approximately 30 minutes and 68% of patients did not require transfusion. This new technology for off-pump bypass
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clearly uses a larger incision than Heartport technology. It is suggested by those who practice these techniques that this is superior for the patient because of the lack of cardiopulmonary bypass. The exact role of these various technologies is still not clear. VALVULAR HEART SURGERY One of the most exciting experimental areas in valve surgery is the tissue-engineered heart valve. In theory, one could produce a valve that has the ability to grow and not undergo any rejection phenomena. Stock and colleagues17 from Boston Children’s Hospital have described the technique of developing a three-leaflet pulmonary conduit. They used endothelial cells from carotid artery segments and implanted them on biodegradable polymers. These were implanted in animals on a beating heart using cardiopulmonary bypass. The authors noted that all animals survived the procedure, and postoperative echocardiography demonstrated no thrombus and mild valvular regurgitation. The authors demonstrated that the three-leaflet valve could be constructed from autologous cells and can function in the pulmonary circulation. Another reassessment relates to the exact indications for the Ross procedure. In the Ross procedure, the native pulmonary valve is taken as a cylinder and reimplanted in the aortic position. The pulmonary valve is replaced with a homograft. The procedure generally has been used in children and young patients who would prefer not to have anticoagulation. David and colleagues18 recently presented information demonstrating that the pulmonary autograft (PA) may dilate in certain cases after the Ross procedure. They studied 113 patients who underwent the Ross procedure over a 7-year period. There was only one operative death and one early failure from acute dilatation of the PA. In terms of valvular insufficiency, the results were excellent. There was minimal aortic insufficiency noted postoperatively. Unfortunately, the PA dilator became quite abnormal (greater than 39 mm) in 17 patients. A preoperative bicuspid aortic valve with a large aortic annulus (greater than 27 mm) was a predictor of this PA dilatation. There were two studies that compared minimally invasive aortic valve replacement to standard
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sternotomy. The first was a randomized trial by Aris and colleagues19 from Barcelona, Spain. They randomized 40 patients who underwent isolated aortic valve replacement. The minimally invasive group had the operation performed through a ministernotomy and the remaining 20 patients underwent standard median sternotomy. There were two hospital deaths in each group, but the major issue was that the ischemic time was longer in the minimally invasive group. Otherwise, there were no differences in terms of blood loss, pain, cosmetic appraisal by the patient, or extubation time. The authors concluded that ministernotomy does not present a distinct advantage to conventional surgery. An opposing viewpoint was given by Byrne and colleagues20 from the Brigham and Women’s Hospital. These authors retrospectively analyzed 19 conventional and 20 minimally invasive isolated elective reoperative aortic valve replacements. There were no deaths in either group. But the minimally invasive reoperative aortic valve replacements reduced blood loss, transfusion needs, and total operative duration. They concluded that a hemiresternotomy was superior to conventional full resternotomy for reoperative aortic valve replacement. SURGICAL THERAPY FOR HEART FAILURE There has been a great deal of excitement about performing conventional surgery rather than transplantation in patients with congestive heart failure. Over the last couple of years, the Batista procedure (resection of the circumflex distribution of heart muscle to reduce the ventricular cavity size) has improved cardiac performance. The best overall results in terms of operative mortality were by McCarthy and colleagues21 from the Cleveland Clinic. But longterm results have not been as good. McCarthy presented longterm results with the Batista procedure at the 1999 American Association for Thoracic Surgery Adult Cardiac Surgery Symposium. The authors demonstrated very low perioperative mortality (3.2%), but 16% required bridge transplantation with a left ventricular assist device perioperatively. The ejection fraction improved from 13% to 21% at 12 months. But the survival rate starts falling after 12 months. At 24 months survival was 71% but freedom from heart failure of any cause decreased to 50% at 12
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months and only 38% at 24 months. The authors concluded that the major issue is one of selection. There were some longterm survivors that were free of heart failure but it was not certain which of those patients could be predicted preoperatively. In contradistinction to the Batista procedure, the Dor procedure has been reintroduced at many centers. Dor originally described this technique of an endoventricular patch to reduce the size of the left ventricle in patients with ischemic cardiomyopathy. He recently discussed his results and techniques with this procedure, noting an operative mortality at 7%.22 Buckberg23 described in detail the concepts of reducing the spherically shaped ventricle into a normal ellipse. Buckberg emphasized the avoidance of cardioplegia to improve results with this procedure. Suma and colleagues,24 from Japan, presented their results with 27 patients undergoing what they call the endoventricular circular patch plasty. They noted an operative mortality of 5% in elective patients, but 60% in emergency patients. The ejection fraction increased from 23% preoperatively to 38% postoperatively. It is clear that left ventricular restoration in patients with ischemic cardiomyopathy may have a role in avoiding transplantation. Another exciting area is the use of a left ventricular-assist device (LVAD) in patients with dilated cardiomyopathy. In general, these devices have been used as a bridge transplantation with excellent results. But Hetzer and colleagues,25 from Berlin, noted that 21 patients with end-stage cardiomyopathy who have been supported by LVADs were able to have their LVAD removed after complete cardiac recovery. Of this group of patients, six had recurrence of heart failure and five of these six underwent transplantation. Eleven patients have enjoyed essentially normal heart function. The authors concluded that chronically unloading these ventricles might cause longterm improvement in cardiac function. Finally, cardiac transplantation still holds a great deal of interest and is still undergoing transformation. Pham and colleagues26 from the University of Pittsburgh reported a trial combining donor bone marrow infusion and heart transplantation to increase donor cell microchimerism. They described 29 patients who received heart transplantation and infusion of unmodified donor bone marrow. This was compared with another group of 24 patients who did not receive the donor bone mar-
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row. Survival rates were similar between the groups at 90% and 80%, respectively, but the bone marrow infusion seemed to reduce the incidence of acute rejection. Pham and colleagues26 hope that this will have a positive effect on the late development of coronary allograft vasculopathy. THORACIC AORTA Despite a great deal of experience with surgery of descending aneurysms, paraplegia still remains a significant complication. Gangemi and colleagues27 from the University of Virginia suggested that the spinal cord could be protected using retrograde venous perfusion during thoracic aortic clamping. In a rabbit model, they studied N-methyl-D-aspartate receptor antagonist, MK-801. Four groups of rabbits were studied. The control group received no intervention during 45 minutes of clamping. Group 2 received warm systemic MK-801 infusion. Group 3 received retrograde infusion of saline and group 4 received retrograde infusion of MK-801. The authors noted that the retrograde MK-801 was markedly successful in preventing paraplegia in this rabbit model. It was statistically more efficacious than the systemic use of MK-801. The authors postulated retrograde perfusion of this antagonist might provide neurologic protection during thoracoabdominal aneurysm. Walinsky and colleagues28 from Johns Hopkins used a swine model to study glutamate-mediated excitotoxicity during thoracic aortic clamping. These animals were subjected to 1 hour of normothermic ischemia by crossclamping the thoracic aorta beyond the left subclavian. Control animals received crossclamp only, and the experimental animals received inhibitors for glutamate. They noted significant improvement in the experimental animals, though most of the experimental animals suffered some neurologic damage. Coselli and colleagues29 from Houston demonstrated improved results in clinical thoracoabdominal aortic aneurysm resection. They describe 1,140 consecutive patients undergoing repair of thoracoabdominal aortic aneurysms (TAAs). The hospital mortality was 7%. The overall incidence of postoperative paraplegia was 4.8%. Paraplegia risk was 1.4% for TAA type IV as compared with 8.2% for TAA type II. These authors clearly have set the standard for this type of operation. They did suggest that patients with type II TAA were the highest risk
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in terms of spinal cord protection and hospital mortality. Ross and colleagues30 from the University of Virginia compared two groups of patients undergoing operation for thoracoabdominal aneurysm. Both underwent the clamp and sew technique without adjuncts, but the second group had an aggressive approach to reimplanting intercostal arteries. They noted minimal spinal cord injury and a lower mortality in this second group of patients, even with the clamp and sew technique. But they did conclude that the more extensive thoracoabdominal aneurysms probably would need some additive procedures to improve the paraplegia rate. Finally, there was a study comparing two techniques for performing aortic arch replacement that required hypothermic circulatory arrest. Okita and colleagues31 from Japan randomized groups to either retrograde cerebral perfusion versus selective antegrade cerebral perfusion. Twenty-two patients underwent retrograde cerebral perfusion and 25 patients underwent selected antegrade cerebral perfusion. There were two deaths that occurred in the selective cerebral perfusion group. Stroke incidence was the same in both groups of patients, but the incidence of transient brain dysfunction was significantly higher in the retrograde cerebral perfusion group at 36.3% versus 8% in the antegrade group. The authors concluded that antegrade cerebral perfusion reduced the incidence of transient brain dysfunction. CONGENITAL HEART DISEASE One of the greatest changes this past year was the improvements in results for the Norwood procedure for hypoplastic left heart syndrome. Daebritz and colleagues32 reported 194 stage 1 Norwood procedures performed between 1990 and 1998. Operative survival was lower for patients with hypoplastic left heart syndrome: 63.4% versus 81% for other conditions. They concluded that the presence of a left ventricle is the single most important predictor of survival. Williams and colleagues33 from New York studied 62 patients who underwent staged repair for hypoplastic left heart syndrome. They noted a 56% survival beyond stage 2 and stage 3 was above 96%. The authors noted that the survival after stage 1 still remains uncertain and needs improvement. Though the inpatient costs are com-
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parable with costs for cardiac transplantation, outpatient costs are quite low. After the patient goes through stage 1, there are far better results for stages 2 and 3. Douglas and colleagues,34 from Ann Arbor, presented results of the hemi-Fontan procedure for hypoplastic left heart syndrome. Between 1993 and 1998, 114 patients with hypoplastic left heart syndrome underwent the hemi-Fontan procedure. The mean age was 5.5 months. Hospital survival was 98%. Seventy-five of these patients have undergone the Fontan procedure with survival of 93%. There is still a great deal of controversy about the best technique for Fontan procedure. Marcelletti and colleagues35 presented a multicenter study of revision of a previous Fontan to total extracardiac cavopulmonary anastomosis. Twenty-four patients underwent revision of previously placed atrial pulmonary connections to extracardiac Fontan. The results were quite good. There were three deaths; two occurred in the hospital and one occurred later. All surviving patients were improved to functional class 1 or 2 except for one patient who required transplantation. There have been improvements in the results of two other conditions. Jahangiri and colleagues36 from Boston Children’s described the repair of truncal valve and associated interrupted arch in neonatal truncus arteriosus. They described 50 patients who underwent surgical repair of truncus; 9 patients had interrupted arch and 14 patients were diagnosed with truncal valve regurgitation. Overall survival was 96%. The two patients who died had had truncal valve regurgitation but did not undergo repair of these valves. The authors concluded neither interrupted arch nor the need for repair of truncal valve insufficiency are contraindications to repair truncus arteriosus. Finally, Nicholson and colleagues37 from Westmead, Australia, described a new approach to repair atrioventricular septal defect. They described 47 consecutive patients who underwent repair of the AV canal using a single patch. The authors performed the procedure by directly suturing the atrial ventricular valve leaflets to the crest of the ventricular septum and then used a single patch to repair the atrial septel defect part of the defect. There were two deaths in the series. There was no heart block and there were no significant residual ventricular septal defects or left ventricular out-flow tract obstructions seen. Only three patients had moderate
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or greater mitral valve regurgitation. These results certainly are analogous to other modern reported results with this defect. References 1. Thourani V, Wang N, Ronson R, et al. Myocardial apoptosis after surgical revascularization is attenuated by adjunct adenosine in blood cardioplegia. Surg Forum 1999;L:105. 2. Friehs I, Toyoda Y, McCully J, Levitsky S. Blockade of mitochondrial KATP channels modulates infarct size reduction but not enhanced post-ischemic functional recovery in adenosine enhanced ischemic preconditioning. Surg Forum 1999;L:92. 3. Pomerantz B, Cleveland J Jr, Garlid K, et al. Adenosine mediated cardiac preconditioning extends beyond opening of the mitochondrial KATP channel in human myocardium. Surg Forum 1999;L:94. 4. Ducko C, Sun X, Vigilance D, et al. Potassium channel openers avoid intracellular calcium accumulation during hyperkalemic cardioplegic arrest but do not prevent myocardial stunning. Surg Forum 1999;L:101. 5. Sayeed-Shah U, Mann M, Martin J, et al. “Turbo-TMR”—gene therapy enhanced TMR produces sustained benefit in the treatment of ischemic heart disease. Surg Forum 1999;L:117. 6. Stewart A, Crawford C, Sweeney H, Gardner T. Hepatocyte growth factor mediates therapeutic coronary angiogenesis. Presented at the American College of Surgeons Surgical Forum, San Francisco, CA. October 13, 1999. 7. Atkins B, Hutcheson K, Hueman M, et al. Autologous skeletal myoblast transplantation improves myocardial performance in severely infarcted rabbit myocardium. Surg Forum 1999;L:126. 8. Hutcheson K, Atkins B, Heuman M, et al. Significance of cell type in regenerating function myocardium comparison of myoblasts vs. fibroblasts in a rabbit model of cell transfer to injured myocardium. Surg Forum 1999;L:173. 9. Engelman R, Pleet A, Rousou J, et al. The J. Maxwell Chamberlain Memorial Paper: the influence of cardiopulmonary bypass perfusion temperature on neurologic and hematologic function after coronary artery bypass grafting. Presented at the Society for Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 25, 1999. 10. John R, Choudhri A, Weinberg A, et al. Multicenter review of preoperative risk factors for stroke after CABG. Presented at the Society for Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 26, 1999. 11. Borger M, Weisel R, Cohen G, et al. Coronary bypass and carotid endarterectomy: increased risk of combined surgery by meta-analysis. Presented at the Society for Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 26, 1999. 12. Blackstone E, Lytle B. Competing risks after bypass surgery: the influence of death on reintervention. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. 13. Scott R, Blackstone E, McCarthy P, et al. Isolated LITA to LAD: late consequences of incomplete revascularization. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. 14. Allen K, Delrossi A, Realyvasquez F, et al. Transmyocardial revascularization combined with coronary artery bypass grafting versus bypass grafting alone: a prospective, randomized multicenter trial. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999. 15. King R Jr. Second opinion—keyhole heart surgery arrived with fanfare, but was it premature? The Wall Street Journal, May 5, 1999. 16. Cartier R, Brann S, Dagenais F, et al. Systematic off-pump coronary artery revascularization in multi-vessel disease: experience of 230 cases. Presented at The American Association for Tho-
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17.
18.
19.
20.
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22.
23. 24.
25.
26.
27.
racic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. Stock U, Nagashima M, Khalil P, et al. Tissue engineered three leaflet heart valves. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 21, 1999. David T, De Sa M, Omran A, et al. Dilation of the pulmonary autograft following the Ross procedure. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999. Aris A, Camara M, Montiel J, et al. Ministernotomy versus median sternotomy for aortic valve replacement: a prospective, randomized study. Presented at The Society of Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 26, 1999. Byrne J, Aranki S, Couper G, Cohn L. Minimally-invasive reoperative aortic valve replacement reduces blood loss and transfusion requirements. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999. McCarthy P. New surgical options for the failing heart. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, Adult Cardiac Surgery Symposium, New Orleans, LA, April 18, 1999. Dor V. Endoventricular circular patch plasty for surgical treatment of large left ventricle wall asynergies. Presented at The American Association for Thoracic Surgery 79th Annual Meeting Adult Cardiac Surgery Symposium, New Orleans, LA, April 18, 1999. Buckberg G. Basic concepts. Presented at The American Association for Thoracic Surgery 79th Annual Meeting Adult Cardiac Surgery Symposium, New Orleans, LA, April 18, 1999. Suma H, Isomura T, Horii T, et al. Choice of non-transplant cardiac surgical procedures for end-stage cardiomyopathy. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999. Hetzer R, Mueller J, Weng Y, et al. Mid-term follow-up of patients who had LVAD removal following cardiac recovery in end-stage dilated cardiomyopathy. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999. Pham S, Rao A, Zeevi A, et al. A clinical trial combining donor bone marrow infusion and heart transplantation: intermediateterm results. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. Gangemi J, Kern J, Kron I, et al. Retrograde venous perfusion of an NMDA receptor antagonist provides spinal cord protection during aortic crossclamping. Surg Forum 1999;L:183.
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28. Walinsky P, Peck E, Slusher B, et al. NAALADase inhibition protects against spinal injury during aortic cross-clamping. Surg Forum 1999;L:184. 29. Coselli J, LeMaire S, Pagan J, et al. Mortality and paraplegia following thoracoabdominal aortic aneurysm repair: a risk factor analysis based on contemporary results. Presented at The Society of Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 25, 1999. 30. Ross S, Kron I, Parrino P, et al. Preservation of intercostal arteries during thoracoabdominal aortic aneurysm surgery: a retrospective study. J Thorac Cardiovasc Surg 1999;118:17–25. 31. Okita Y, Minatoya K, Tagusari O, et al. Prospective randomized comparative study of brain protection in total aortic arch replacement: deep hypothermic circulatory arrest with retrograde cerebral perfusion or selective antegrade cerebral perfusion. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. 32. Daebritz S, Nollert G, Khalil P, et al. Results of Norwood stageone operation: comparison of hypoplastic left heart syndrome with other malformations. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. 33. Williams D, Ng J, Crawford E, et al. Repair of the hypoplastic left heart: survival, quality-of-life, and cost. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. 34. Douglas W, Mosca R, Goldberg C, Bove E. The hemi-Fontan procedure for hypoplastic left heart syndrome. Presented at The Society of Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 25, 1999. 35. Marcelletti C, Hanley F, Mavroudis C, et al. Revision of previous Fontan connections to total extracardiac cavopulmonary anastomosis: a multicenter study. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999. 36. Jahangiri M, Zurakowski D, Del Nido P, et al. Repair of the truncal valve and associated interrupted arch in neonates with truncus arteriosus. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999. 37. Nicholson I, Nunn G, Sholler G, et al. Simplified single patch technique for the repair of atrioventricular septal defect. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999.
studied adenosine preconditioning and hypothesized that the mechanism is far more than myocardial KATP channel opening. They studied human atrial trabeculae that were placed in organ baths and paced. Before ischemia and reperfusion, these trabeculae were given either adenosine or diazoxide (a selective mitochondrial KATP channel opener). The adenosine but not the diazoxide-treated trabeculae provided protection against extended ischemia. Pomerantz and colleagues concluded that adenosine preconditioning offers ideal protection for human myocardial tissue after ischemia reperfusion. Ducko and colleagues4 from the Milton S Hershey Medical Center studied a different mechanism of myocardial stunning. They suggested that intracellular calcium overload may be a mechanism in myocardial stunning. They used hyperpolarized arrest with a potassium channel opener to prevent this. They used both a model of rabbit left ventricular myocytes and a parabiotic-isolated rabbit heart preparation. Though the potassium channel openers eliminated intracellular calcium overload, they did not provide improved myocardial protection when compared with St Thomas solution alone. They concluded that intracellular calcium overload may not be a mechanism of myocardial stunning.
The year 2000 has begun, and cardiac surgery is still evolving, but there has been a great deal of reflection on recent innovations. The definition of minimally invasive cardiac surgery is still unclear. Is it best for the patient to have a smaller incision with longer pump times or a larger incision and an operation off bypass? The role of left ventricular restoration and reconstruction for the treatment of heart failure is also still unclear. There continue to be exciting new basic science advances in the areas of gene transfer and myocardial cellular transplantation. MYOCARDIAL PROTECTION There are several exciting experimental and clinical advances in myocardial protection. Thourani and colleagues1 demonstrated that the use of adenosine in blood cardioplegia reduced apoptosis. Apoptosis is a genetically programmed form of cell death. These authors used a dog model of temporary left anterior descending coronary artery occlusion. These animals were placed on bypass and then underwent 2 hours of reperfusion. The authors noted that apoptosis occurred with the use of blood cardioplegia. But adenosine during cardioplegic arrest or during reperfusion reduced the amount of apoptosis. Friehs and colleagues2 from the Beth Israel Deaconess Medical Center used adenosine-enhanced ischemic preconditioning to decrease myocardial infarct size and improve functional recovery. They used an isolated perfused rabbit heart model with 30 minutes of global ischemia followed by 120 minutes of reperfusion. This resulted in marked reduction of functional recovery. Adenosine enhanced by ischemic preconditioning resulted in hearts with full recovery no different from controls. Pomerantz and colleagues3 at the University of Colorado also
GENETIC ENGINEERING AND MYOBLAST TRANSPLANTATION There has been a great deal of experimental interest in gene transfer techniques and myocardial transplantation. Both techniques are the potential future in the treatment of ischemic cardiomyopathy. Sayeed-Shah and colleagues5 from the Brigham and Women’s Hospital examined the influence of proangiogenic gene therapy in conjunction with transmyocardial laser revascularization (TMR) to enhance myocardial revascularization and improve myocardial function. The authors induced gene transfer in CO2-TMR channels in pigs. The authors noted transgene expression in 93% of the TMR-plasmid group. They concluded that trans-
Received October 27, 1999; Accepted October 27, 1999. From the Department of Surgery, University of Virginia Medical Center, Charlottesville, VA. Correspondence address: Irving L Kron, MD, FACS, Department of Surgery, University of Virginia Medical Center, Box 310, Charlottesville, VA 22908. © 2000 by the American College of Surgeons Published by Elsevier Science Inc.
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gene expression is improved by TMR and sustained for 2 weeks after transduction. Stewart and colleagues6 from the University of Pennsylvania studied a different model of induced angiogenesis. The authors used an adenovirus with hepatocyte growth factor as the transgene in rabbits. The hearts were injected with the previously mentioned technique of gene transfer. Six weeks after injection, animals underwent a constrictor on the left circumflex artery. The authors noted significant increases of small and medium-sized arterioles in the ischemic region compared with controls at the time of sacrifice. They also noted a significant reduction in infarct size in the circumflex distribution in the genetically manipulated animals. Clearly, these animals had marked improvement because of the genetic manipulation. Atkins and colleagues7 from Duke University studied the concept of cellular cardiomyoplasty. They developed a rabbit model of myocardial infarction with circumflex marginal coronary ligation. This was followed by myocardial injection of autologous skeletal myoblasts. Their data suggested that the myoblasts improve regional systolic and diastolic performance in this infarction model. They concluded that this technique could be used as an adjunct to surgical revascularization. Hutcheson and colleagues8 from Duke University studied which cell would be most useful in a cryoinjured rabbit heart. They noted that the skeletal myoblasts improved function in chronically injured myocardium, and the fibroblast transfer did not. They concluded that the type of cell source would be important in experimental techniques of chronic myocardial injury. ISCHEMIC HEART DISEASE Englemann and colleagues9 from Springfield, MA, performed a very important study on ideal perfusion temperature. They randomized coronary bypass graft patients to undergo perfusion with warm, tepid, or cold temperatures. They noted that there was persistent neurologic dysfunction that was not related to stroke at 1 month in 36% of the patients studied. Perfusion temperature had no relationship to this neurologic dysfunction, but fibrinolytic activity was greatest in the warm group. They concluded that tepid perfusion was best for routine coronary bypass surgery. There has been a great deal of interest in the incidence and causes of stroke after
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coronary bypass surgery. John and colleagues10 from Columbia studied more than 19,000 patients who underwent coronary artery bypass grafting (CABG) in the New York State database during 1995. They noted that 1.4% of all of these patients suffered a stroke. The patients who had a stroke were older and had a longer duration of cardiopulmonary bypass. The various variables that predicted stroke included a calcified aorta, previous stroke, presence of carotid disease, and diabetes. Stroke increased the hospital mortality to 25% as compared with 2% for the rest of the population. Though the previous manuscript demonstrated that carotid disease was associated with a higher stroke rate in coronary bypass patients, a metaanalysis by Borger and colleagues11 from Toronto further clouded the issue. They performed a computerized Medline search to compare both combined and staged CABG-carotid endarterectomy patient cohorts. Fifteen studies were identified with a total of 911 combined patients as compared with 912 staged patients. Their metaanalysis revealed a trend toward increased risk of stroke, death, and combined stroke or death for patients undergoing combined procedures. The stroke rate was 5.5% versus 3.4% for combined versus staged surgery. The mortality was 4.7% versus 3.2%. They concluded from this analysis that combined procedures did more poorly than staged ones. There are several other controversies in ischemic heart disease. Blackstone and Lytle12 studied whether extensive arterial grafting lowers the incidence of reintervention in patients who have undergone coronary bypass. They studied 2,001 patients who underwent bilateral internal thoracic artery conduits and 8,123 patients receiving single conduits. They concluded that bilateral internal thoracic arteries provided better survival and fewer reinterventions. But this effect was not realized in the older age group because of poor survival and fewer reinterventions. Scott and colleagues13 from the Cleveland Clinic also examined the effects of incomplete revascularization. They studied a group of 2,072 patients who underwent primary isolated internal mammary to left anterior descending coronary artery bypass from 1971 to 1997. They noted that 26% of these patients would now be considered as having two-vessel disease and 13% would be considered to have three-vessel disease. They exam-
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ined longterm survival and concluded that residual circumflex or left main disease markedly reduced late survival. TMR has been advocated as a technique for reducing angina in patients who are not otherwise graftable because of diffuse coronary artery disease. This has been a controversial subject because it is not clear if these holes stay open, and it is possible that the mechanism of reduction of angina does not relate to increased coronary blood flow. Allen and colleagues14 reported a multiinstitutional randomized trial of 266 patients who were randomized to TMR with CABG versus CABG alone. This was in a group of patients who had one or more ischemic areas not amenable to CABG. The CABG-TMR group had an operative mortality of 1.5%, which was significantly lower than the CABG alone group, which was 7.5%. The 3-month mortality remained significantly lower for the TMR-CABG group at 3% as compared with 10% for the CABG alone group. The authors concluded that TMR with CABG is safe and reduces operative mortality compared with CABG alone in patients who cannot undergo complete revascularization. The greatest controversy in ischemic heart disease is determining what is truly minimally invasive. Last year, there was much reporting on the Heartport technology, which essentially suggests that a smaller incision with percutaneously placed cardiopulmonary bypass technology may be superior to standard cardiopulmonary bypass. This socalled “keyhole” surgery was attempted with varying results by many surgeons. A recent Wall Street Journal article15 suggested that at least half of the 500 surgeons trained in the Heartport procedure (developed by Dr John Stevens, Stanford University, Stanford, CA) have abandoned it. But there are still many surgeons who practice the technique and believe that it provides a great advantage to the patient. More recently, off-pump coronary bypass for multivessel disease has increased. Cartier and colleagues16 from Montreal reported 230 off-pump CABGs. An average of 2.88 grafts per patient were performed. They suggested that complete revascularization could be achieved in 91% of the patients using coronary artery stabilization techniques. The average ischemic time was approximately 30 minutes and 68% of patients did not require transfusion. This new technology for off-pump bypass
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clearly uses a larger incision than Heartport technology. It is suggested by those who practice these techniques that this is superior for the patient because of the lack of cardiopulmonary bypass. The exact role of these various technologies is still not clear. VALVULAR HEART SURGERY One of the most exciting experimental areas in valve surgery is the tissue-engineered heart valve. In theory, one could produce a valve that has the ability to grow and not undergo any rejection phenomena. Stock and colleagues17 from Boston Children’s Hospital have described the technique of developing a three-leaflet pulmonary conduit. They used endothelial cells from carotid artery segments and implanted them on biodegradable polymers. These were implanted in animals on a beating heart using cardiopulmonary bypass. The authors noted that all animals survived the procedure, and postoperative echocardiography demonstrated no thrombus and mild valvular regurgitation. The authors demonstrated that the three-leaflet valve could be constructed from autologous cells and can function in the pulmonary circulation. Another reassessment relates to the exact indications for the Ross procedure. In the Ross procedure, the native pulmonary valve is taken as a cylinder and reimplanted in the aortic position. The pulmonary valve is replaced with a homograft. The procedure generally has been used in children and young patients who would prefer not to have anticoagulation. David and colleagues18 recently presented information demonstrating that the pulmonary autograft (PA) may dilate in certain cases after the Ross procedure. They studied 113 patients who underwent the Ross procedure over a 7-year period. There was only one operative death and one early failure from acute dilatation of the PA. In terms of valvular insufficiency, the results were excellent. There was minimal aortic insufficiency noted postoperatively. Unfortunately, the PA dilator became quite abnormal (greater than 39 mm) in 17 patients. A preoperative bicuspid aortic valve with a large aortic annulus (greater than 27 mm) was a predictor of this PA dilatation. There were two studies that compared minimally invasive aortic valve replacement to standard
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sternotomy. The first was a randomized trial by Aris and colleagues19 from Barcelona, Spain. They randomized 40 patients who underwent isolated aortic valve replacement. The minimally invasive group had the operation performed through a ministernotomy and the remaining 20 patients underwent standard median sternotomy. There were two hospital deaths in each group, but the major issue was that the ischemic time was longer in the minimally invasive group. Otherwise, there were no differences in terms of blood loss, pain, cosmetic appraisal by the patient, or extubation time. The authors concluded that ministernotomy does not present a distinct advantage to conventional surgery. An opposing viewpoint was given by Byrne and colleagues20 from the Brigham and Women’s Hospital. These authors retrospectively analyzed 19 conventional and 20 minimally invasive isolated elective reoperative aortic valve replacements. There were no deaths in either group. But the minimally invasive reoperative aortic valve replacements reduced blood loss, transfusion needs, and total operative duration. They concluded that a hemiresternotomy was superior to conventional full resternotomy for reoperative aortic valve replacement. SURGICAL THERAPY FOR HEART FAILURE There has been a great deal of excitement about performing conventional surgery rather than transplantation in patients with congestive heart failure. Over the last couple of years, the Batista procedure (resection of the circumflex distribution of heart muscle to reduce the ventricular cavity size) has improved cardiac performance. The best overall results in terms of operative mortality were by McCarthy and colleagues21 from the Cleveland Clinic. But longterm results have not been as good. McCarthy presented longterm results with the Batista procedure at the 1999 American Association for Thoracic Surgery Adult Cardiac Surgery Symposium. The authors demonstrated very low perioperative mortality (3.2%), but 16% required bridge transplantation with a left ventricular assist device perioperatively. The ejection fraction improved from 13% to 21% at 12 months. But the survival rate starts falling after 12 months. At 24 months survival was 71% but freedom from heart failure of any cause decreased to 50% at 12
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months and only 38% at 24 months. The authors concluded that the major issue is one of selection. There were some longterm survivors that were free of heart failure but it was not certain which of those patients could be predicted preoperatively. In contradistinction to the Batista procedure, the Dor procedure has been reintroduced at many centers. Dor originally described this technique of an endoventricular patch to reduce the size of the left ventricle in patients with ischemic cardiomyopathy. He recently discussed his results and techniques with this procedure, noting an operative mortality at 7%.22 Buckberg23 described in detail the concepts of reducing the spherically shaped ventricle into a normal ellipse. Buckberg emphasized the avoidance of cardioplegia to improve results with this procedure. Suma and colleagues,24 from Japan, presented their results with 27 patients undergoing what they call the endoventricular circular patch plasty. They noted an operative mortality of 5% in elective patients, but 60% in emergency patients. The ejection fraction increased from 23% preoperatively to 38% postoperatively. It is clear that left ventricular restoration in patients with ischemic cardiomyopathy may have a role in avoiding transplantation. Another exciting area is the use of a left ventricular-assist device (LVAD) in patients with dilated cardiomyopathy. In general, these devices have been used as a bridge transplantation with excellent results. But Hetzer and colleagues,25 from Berlin, noted that 21 patients with end-stage cardiomyopathy who have been supported by LVADs were able to have their LVAD removed after complete cardiac recovery. Of this group of patients, six had recurrence of heart failure and five of these six underwent transplantation. Eleven patients have enjoyed essentially normal heart function. The authors concluded that chronically unloading these ventricles might cause longterm improvement in cardiac function. Finally, cardiac transplantation still holds a great deal of interest and is still undergoing transformation. Pham and colleagues26 from the University of Pittsburgh reported a trial combining donor bone marrow infusion and heart transplantation to increase donor cell microchimerism. They described 29 patients who received heart transplantation and infusion of unmodified donor bone marrow. This was compared with another group of 24 patients who did not receive the donor bone mar-
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row. Survival rates were similar between the groups at 90% and 80%, respectively, but the bone marrow infusion seemed to reduce the incidence of acute rejection. Pham and colleagues26 hope that this will have a positive effect on the late development of coronary allograft vasculopathy. THORACIC AORTA Despite a great deal of experience with surgery of descending aneurysms, paraplegia still remains a significant complication. Gangemi and colleagues27 from the University of Virginia suggested that the spinal cord could be protected using retrograde venous perfusion during thoracic aortic clamping. In a rabbit model, they studied N-methyl-D-aspartate receptor antagonist, MK-801. Four groups of rabbits were studied. The control group received no intervention during 45 minutes of clamping. Group 2 received warm systemic MK-801 infusion. Group 3 received retrograde infusion of saline and group 4 received retrograde infusion of MK-801. The authors noted that the retrograde MK-801 was markedly successful in preventing paraplegia in this rabbit model. It was statistically more efficacious than the systemic use of MK-801. The authors postulated retrograde perfusion of this antagonist might provide neurologic protection during thoracoabdominal aneurysm. Walinsky and colleagues28 from Johns Hopkins used a swine model to study glutamate-mediated excitotoxicity during thoracic aortic clamping. These animals were subjected to 1 hour of normothermic ischemia by crossclamping the thoracic aorta beyond the left subclavian. Control animals received crossclamp only, and the experimental animals received inhibitors for glutamate. They noted significant improvement in the experimental animals, though most of the experimental animals suffered some neurologic damage. Coselli and colleagues29 from Houston demonstrated improved results in clinical thoracoabdominal aortic aneurysm resection. They describe 1,140 consecutive patients undergoing repair of thoracoabdominal aortic aneurysms (TAAs). The hospital mortality was 7%. The overall incidence of postoperative paraplegia was 4.8%. Paraplegia risk was 1.4% for TAA type IV as compared with 8.2% for TAA type II. These authors clearly have set the standard for this type of operation. They did suggest that patients with type II TAA were the highest risk
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in terms of spinal cord protection and hospital mortality. Ross and colleagues30 from the University of Virginia compared two groups of patients undergoing operation for thoracoabdominal aneurysm. Both underwent the clamp and sew technique without adjuncts, but the second group had an aggressive approach to reimplanting intercostal arteries. They noted minimal spinal cord injury and a lower mortality in this second group of patients, even with the clamp and sew technique. But they did conclude that the more extensive thoracoabdominal aneurysms probably would need some additive procedures to improve the paraplegia rate. Finally, there was a study comparing two techniques for performing aortic arch replacement that required hypothermic circulatory arrest. Okita and colleagues31 from Japan randomized groups to either retrograde cerebral perfusion versus selective antegrade cerebral perfusion. Twenty-two patients underwent retrograde cerebral perfusion and 25 patients underwent selected antegrade cerebral perfusion. There were two deaths that occurred in the selective cerebral perfusion group. Stroke incidence was the same in both groups of patients, but the incidence of transient brain dysfunction was significantly higher in the retrograde cerebral perfusion group at 36.3% versus 8% in the antegrade group. The authors concluded that antegrade cerebral perfusion reduced the incidence of transient brain dysfunction. CONGENITAL HEART DISEASE One of the greatest changes this past year was the improvements in results for the Norwood procedure for hypoplastic left heart syndrome. Daebritz and colleagues32 reported 194 stage 1 Norwood procedures performed between 1990 and 1998. Operative survival was lower for patients with hypoplastic left heart syndrome: 63.4% versus 81% for other conditions. They concluded that the presence of a left ventricle is the single most important predictor of survival. Williams and colleagues33 from New York studied 62 patients who underwent staged repair for hypoplastic left heart syndrome. They noted a 56% survival beyond stage 2 and stage 3 was above 96%. The authors noted that the survival after stage 1 still remains uncertain and needs improvement. Though the inpatient costs are com-
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parable with costs for cardiac transplantation, outpatient costs are quite low. After the patient goes through stage 1, there are far better results for stages 2 and 3. Douglas and colleagues,34 from Ann Arbor, presented results of the hemi-Fontan procedure for hypoplastic left heart syndrome. Between 1993 and 1998, 114 patients with hypoplastic left heart syndrome underwent the hemi-Fontan procedure. The mean age was 5.5 months. Hospital survival was 98%. Seventy-five of these patients have undergone the Fontan procedure with survival of 93%. There is still a great deal of controversy about the best technique for Fontan procedure. Marcelletti and colleagues35 presented a multicenter study of revision of a previous Fontan to total extracardiac cavopulmonary anastomosis. Twenty-four patients underwent revision of previously placed atrial pulmonary connections to extracardiac Fontan. The results were quite good. There were three deaths; two occurred in the hospital and one occurred later. All surviving patients were improved to functional class 1 or 2 except for one patient who required transplantation. There have been improvements in the results of two other conditions. Jahangiri and colleagues36 from Boston Children’s described the repair of truncal valve and associated interrupted arch in neonatal truncus arteriosus. They described 50 patients who underwent surgical repair of truncus; 9 patients had interrupted arch and 14 patients were diagnosed with truncal valve regurgitation. Overall survival was 96%. The two patients who died had had truncal valve regurgitation but did not undergo repair of these valves. The authors concluded neither interrupted arch nor the need for repair of truncal valve insufficiency are contraindications to repair truncus arteriosus. Finally, Nicholson and colleagues37 from Westmead, Australia, described a new approach to repair atrioventricular septal defect. They described 47 consecutive patients who underwent repair of the AV canal using a single patch. The authors performed the procedure by directly suturing the atrial ventricular valve leaflets to the crest of the ventricular septum and then used a single patch to repair the atrial septel defect part of the defect. There were two deaths in the series. There was no heart block and there were no significant residual ventricular septal defects or left ventricular out-flow tract obstructions seen. Only three patients had moderate
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or greater mitral valve regurgitation. These results certainly are analogous to other modern reported results with this defect. References 1. Thourani V, Wang N, Ronson R, et al. Myocardial apoptosis after surgical revascularization is attenuated by adjunct adenosine in blood cardioplegia. Surg Forum 1999;L:105. 2. Friehs I, Toyoda Y, McCully J, Levitsky S. Blockade of mitochondrial KATP channels modulates infarct size reduction but not enhanced post-ischemic functional recovery in adenosine enhanced ischemic preconditioning. Surg Forum 1999;L:92. 3. Pomerantz B, Cleveland J Jr, Garlid K, et al. Adenosine mediated cardiac preconditioning extends beyond opening of the mitochondrial KATP channel in human myocardium. Surg Forum 1999;L:94. 4. Ducko C, Sun X, Vigilance D, et al. Potassium channel openers avoid intracellular calcium accumulation during hyperkalemic cardioplegic arrest but do not prevent myocardial stunning. Surg Forum 1999;L:101. 5. Sayeed-Shah U, Mann M, Martin J, et al. “Turbo-TMR”—gene therapy enhanced TMR produces sustained benefit in the treatment of ischemic heart disease. Surg Forum 1999;L:117. 6. Stewart A, Crawford C, Sweeney H, Gardner T. Hepatocyte growth factor mediates therapeutic coronary angiogenesis. Presented at the American College of Surgeons Surgical Forum, San Francisco, CA. October 13, 1999. 7. Atkins B, Hutcheson K, Hueman M, et al. Autologous skeletal myoblast transplantation improves myocardial performance in severely infarcted rabbit myocardium. Surg Forum 1999;L:126. 8. Hutcheson K, Atkins B, Heuman M, et al. Significance of cell type in regenerating function myocardium comparison of myoblasts vs. fibroblasts in a rabbit model of cell transfer to injured myocardium. Surg Forum 1999;L:173. 9. Engelman R, Pleet A, Rousou J, et al. The J. Maxwell Chamberlain Memorial Paper: the influence of cardiopulmonary bypass perfusion temperature on neurologic and hematologic function after coronary artery bypass grafting. Presented at the Society for Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 25, 1999. 10. John R, Choudhri A, Weinberg A, et al. Multicenter review of preoperative risk factors for stroke after CABG. Presented at the Society for Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 26, 1999. 11. Borger M, Weisel R, Cohen G, et al. Coronary bypass and carotid endarterectomy: increased risk of combined surgery by meta-analysis. Presented at the Society for Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 26, 1999. 12. Blackstone E, Lytle B. Competing risks after bypass surgery: the influence of death on reintervention. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. 13. Scott R, Blackstone E, McCarthy P, et al. Isolated LITA to LAD: late consequences of incomplete revascularization. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. 14. Allen K, Delrossi A, Realyvasquez F, et al. Transmyocardial revascularization combined with coronary artery bypass grafting versus bypass grafting alone: a prospective, randomized multicenter trial. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999. 15. King R Jr. Second opinion—keyhole heart surgery arrived with fanfare, but was it premature? The Wall Street Journal, May 5, 1999. 16. Cartier R, Brann S, Dagenais F, et al. Systematic off-pump coronary artery revascularization in multi-vessel disease: experience of 230 cases. Presented at The American Association for Tho-
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28. Walinsky P, Peck E, Slusher B, et al. NAALADase inhibition protects against spinal injury during aortic cross-clamping. Surg Forum 1999;L:184. 29. Coselli J, LeMaire S, Pagan J, et al. Mortality and paraplegia following thoracoabdominal aortic aneurysm repair: a risk factor analysis based on contemporary results. Presented at The Society of Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 25, 1999. 30. Ross S, Kron I, Parrino P, et al. Preservation of intercostal arteries during thoracoabdominal aortic aneurysm surgery: a retrospective study. J Thorac Cardiovasc Surg 1999;118:17–25. 31. Okita Y, Minatoya K, Tagusari O, et al. Prospective randomized comparative study of brain protection in total aortic arch replacement: deep hypothermic circulatory arrest with retrograde cerebral perfusion or selective antegrade cerebral perfusion. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. 32. Daebritz S, Nollert G, Khalil P, et al. Results of Norwood stageone operation: comparison of hypoplastic left heart syndrome with other malformations. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. 33. Williams D, Ng J, Crawford E, et al. Repair of the hypoplastic left heart: survival, quality-of-life, and cost. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 20, 1999. 34. Douglas W, Mosca R, Goldberg C, Bove E. The hemi-Fontan procedure for hypoplastic left heart syndrome. Presented at The Society of Thoracic Surgeons 35th Annual Meeting, San Antonio, TX, January 25, 1999. 35. Marcelletti C, Hanley F, Mavroudis C, et al. Revision of previous Fontan connections to total extracardiac cavopulmonary anastomosis: a multicenter study. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999. 36. Jahangiri M, Zurakowski D, Del Nido P, et al. Repair of the truncal valve and associated interrupted arch in neonates with truncus arteriosus. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999. 37. Nicholson I, Nunn G, Sholler G, et al. Simplified single patch technique for the repair of atrioventricular septal defect. Presented at The American Association for Thoracic Surgery 79th Annual Meeting, New Orleans, LA, April 19, 1999.