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BACKGROUND: Most of our patients with coronary artery disease have undergone bypass exclusively with purely internal thoracic artery grafts (PITA). Our goal has been to lengthen the time a patient benefits from coronary bypass operations. The present report describes an 8.5-year study of outcomes including mortality and the need for reintervention in patients who have undergone bypass with PITA. METHODS: We studied 897 patients who underwent PITA with a total of 3,784 internal thoracic artery (ITA) grafts (4.2 grafts per patient). Connecting ITA to ITA along with sequential anastomosis made the procedure possible. RESULTS: Early mortality for the group was 2.3%. Freedom from death was 86% and freedom from reintervention was 94% at 5 years after the operation. CONCLUSIONS: The acceptable early and late mortality and the 94% freedom from reintervention as long as 8.5 years after operation in this group of patients inspire us to continue choosing PITA for patients with three-vessel coronary artery disease.

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BACKGROUND: Safe transition from cardiopulmonary bypass to the HeartMate left ventricular assist device without periods of low output, air emboli, or injury to the right ventricle is vital to its successful implantation. A right atrial-to-left ventricular shunt has been developed to purge quickly and completely all air from the system and prevent its reentry, as well as to assist the right ventricle during the transition from cardiopulmonary bypass to the HeartMate. METHODS: From January 1994 through July 1996, we used an extracorporeal membrane oxygenation right atrial-to-left ventricular shunt during 17 HeartMate implantations in 16 patients. The shunt consists of the existing right atrial two-stage cannula, the bypass circuit, and a separate aortic line that fills the left ventricle using a 21F cannula in the lateral ventricular wall. Air is monitored in the heart and aorta using transesophageal echocardiography. RESULTS: Ten of the 16 patients are living and 8 have undergone transplantation. Two patients are still using the device and are awaiting transplantation. None of the patients have experienced postoperative neurologic events suggestive of air emboli. CONCLUSIONS: The extracorporeal membrane oxygenation right atrial-to-left ventricular shunt is simple and inexpensive to construct. It provides for a smoother and safer transition from cardiopulmonary bypass to the HeartMate left ventricular assist device.

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This article describes the development of a new experimental model using rats for the evaluation of small-caliber vascular grafts. By modifying heterotopic heart transplantation, two 1.5- to 2.0-cm long vascular prostheses were interposed between a syngeneic donor heart and the recipient abdominal vessels in the form of vascular bridges. Once blood flow through the vascular grafts was reestablished, the donor heart resumed normal beating. The status of the vascular grafts could be easily monitored by palpation. Occlusion of the grafts stopped donor heart beating without affecting survival of the animals. Once the surgical method was mastered, the postoperative mortality was approximately 10%, and the total procedure took less than 2 hours. Although microvascular surgical technique and equipment are required, this model has several advantages, including easy detection of thrombotic occlusion of the grafts, the use of small animals of defined genetic background, the absence of effect of graft occlusion on the recipient's life, and possible repeated operation on the same animal.

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Rat strains with congenitally reduced total hemolytic complement activity do not reject cardiac xenografts hyperacutely. Prolongation of graft survival in the guinea pig-to-C6-deficient PVG rat donor/recipient combination has been observed. However, experience with this model has been complicated by a high postoperative mortality from respiratory distress. The authors hypothesized that placement of the xenograft resulted in local activation of complement, which contributed to remote pulmonary injury leading to respiratory dysfunction. To test this hypothesis, an attempt was made to reduce early complement component activation with the use of an antibody to rat C3 in C6-deficient PVG recipients. Six of eight untreated C6-deficient PVG recipients died in the immediate postoperative period with vigorously beating heart grafts, whereas only 2 of 14 C6-deficient recipients pretreated with anti-rat C3 antibody died within 24 h postoperatively. Although pretreatment with anti-C3 antibody improved survival of recipients, the duration of cardiac xenograft survival was similar whether the recipients were pretreated or not. The use of anti-C3 antibody in C6-deficient rats is a valid approach to studying xenotransplantation in the absence of hyperacute rejection and has an additional advantage in that it does not require the use of expensive reagents such as cobra venom factor.

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Saphenous vein graft atherosclerosis continues to be the major cause of late failures of coronary artery bypass operations (CABG). The internal thoracic artery (ITA) is an ideal bypass graft because it remains free of atherosclerosis at late follow-up in most patients. Myocardial revascularization with only ITA grafts has developed in an incremental manner from single grafts of the left ITA to the left anterior descending coronary artery (LAD), to use of bilateral, free and sequential ITAs, and now recently to the use of preconstructed grafts that attach the free right ITA to the left ITA. The microanatomy and vascular reactivity of the ITA have been recently defined, and they explain why the ITA remains free of obstruction. Our techniques and results of ITA grafting developed over the past 25 years are presented.

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Selection of the bypass graft that the patient has demonstrated will remain patent and free from critical atherosclerosis is a most important part of coronary artery bypass reoperations. Sixteen patients in whom a patent left internal thoracic artery-left anterior descending coronary artery bypass graft and obstructed or closed saphenous vein grafts to other coronary arteries were visualized underwent reoperation. To reach the inadequately perfused circumflex and right coronary arteries, the right internal thoracic artery was anastomosed to the left internal thoracic artery as a T graft and then was attached to the circumflex and right coronary artery branches. All patients survived the procedure and are free from angina. There were no perioperative myocardial infarctions, and there was no suggestion of hypoperfusion by the grafts. We believe this technique may reduce the incidence of graft failure in patients undergoing reoperative coronary artery bypass grafting.

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We present early results in 486 patients undergoing total coronary artery revascularization using a T-graft constructed from the attached left internal thoracic artery (LITA) and the free right internal thoracic artery (RITA). The anterior and anterolateral areas of the heart are by-passed with the LITA and the inferolateral, inferior and posterior areas are by-passed with the RITA. These patients received an average of 4.34 distal anastomoses with as many as four from each of the limbs of the T-graft. Ages ranged from 29 to 89 years and ejection fractions from 15 to 79%. Sixty-six patients were undergoing first reoperations and 6 received T-grafts at their second reoperation. The mortality at 30 days was 2.3%. Two of 92 women and 9 of 394 men expired. The perioperative infarction rate was 1.2%. Postoperative angiography in 34 patients showed 98.3% of LITA and 86.5% of RITA anastomoses to be patent. There was a slightly higher patency observed in women. The T-graft technique can be applied to nearly all patients with 3 vessel coronary artery disease with low operative mortality. Precise technique with high power magnification is crucial. This procedure has the potential of avoiding further invasive procedures due to graft deterioration in many patients with 3 vessel coronary artery disease.

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The T graft is constructed by anastomosing the proximal end of the free right internal thoracic artery to the side of the attached left internal thoracic artery. Besides adding considerable reach to the right internal thoracic artery, this technique allows the left anterior descending coronary artery and its branches to be bypassed with the attached left internal thoracic artery. Two hundred eight-seven patients, aged 34 to 86 years (mean age, 64.6 years) received an average of 4.4 internal thoracic artery to coronary artery anastomoses. Sixty-nine patients had left main disease, 33 were undergoing first-time reoperations, and two were reoperated on for the second time. Ejection fraction ranged from 0.20 to 0.70. Operative mortality was 1.7%. Twenty-six patients had postoperative graft visualization, and 94.7% of the grafts were open. All 45 bypass grafts from the left internal thoracic artery were patent, and 91% of those from the right internal thoracic artery were unobstructed. This procedure requires technical skill with internal thoracic arteries, but it has the potential of significantly improving long-term event-free survival and reducing the need for reoperation in patients undergoing coronary artery bypass grafting.

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Fixed-rate pulsatile cardiopulmonary bypass may improve subendocardial perfusion during ventricular fibrillation and has been employed during intermittent aortic cross-clamping. Variable-rate pulsatile left heart bypass that is governed by venous inflow and is asynchronous to the electrical activity of the heart is currently used in clinical practice. To study the effect of fixed-rate pulsation on myocardial metabolism during left heart bypass, six adult pigs underwent alternating periods of pulsatile (PLS) and nonpulsatile (NPLS) centrifugal pump left atrial-to-aortic bypass in randomized block design. Coronary sinus, aortic, and bypass circuit flows were recorded. Oxygen content and lactate concentration of coronary sinus and aortic blood were measured. Pulsatility index and pulse power index during pulsatile bypass were 4.4 and 4.7 (cycles/s)2, respectively. Percent bypass was maximal at a mean pulsation rate of 41.3 and averaged 92.2 and 91.3 for PLS and NPLS, respectively. Myocardial oxygen consumption per minute was reduced 14.3% during NPLS but was unchanged during PLS compared to control (CTRL). Percent lactate extraction was significantly lower than CTRL during NPLS only. Competition for inflow with the ejecting heart appeared to limit circuit pulsation rate and pulse power index. Fixed-rate pulsation is ineffective in reducing myocardial metabolism and should be avoided in left heart bypass.

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Coronary angiography defines the location and size of obstructive lesions, but does not assess their physiological significance. To assess a new method to measure the blood-flow waveform, reversed saphenous vein grafts from the left subclavian artery to the left anterior descending coronary artery were placed in five mongrel dogs. Contrast material was injected selectively into the vein graft while obtaining fluoroscopic images from AP and 45 degrees LAO projections. Blood flow was measured under baseline, low-flow, and hyperemic conditions using an electromagnetic flow probe (EM). Seventeen radiographic determinations of mean blood flow (range 18-130 ml/min) were linearly correlated to simultaneous EM measurements (r = 0.91 and 0.88, respectively). Contrast material injections changed EM flow measurements by an average of 35%, which though large, is less than with other radiographic methods. The computed blood-flow waveforms had a time resolution of 1/30 sec and were in good agreement with EM waveforms measured simultaneously. Clinical application of this radiographic method for determining the blood-flow waveform may allow early prediction of coronary artery bypass graft closure.

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Survival data were reviewed for 3330 open cardiac procedures from 1975 through 1984 at the William S. Middleton Memorial Veterans Hospital, Madison, Wis, and the University of Wisconsin Hospitals and Clinics, Madison. Respective operative survivals were 98.6% and 98.7% for myocardial revascularizations with vein graft or internal mammary artery (CABG), 96.2% and 96.8% for CABG reoperation, 97.8% and 95.9% for aortic valve replacement, 96.3% and 90.3% for aortic valve replacement plus CABG, 100.0% and 94.9% for mitral valve replacement, and 100.0% and 82.9% for mitral valve replacement plus CABG. There were no significant differences in six-year survival curves between hospitals despite threefold differences in average annual caseload (88 vs 294). This suggest that residency-directed cardiac surgery programs can function equally as well at a Veterans Administration hospital as at an affiliated university hospital.

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There is no significant difference in hemolysis between pediatric centrifugal pumps and roller pumps during ECMO of 8 hours duration in rabbits or in comparable 24 hour isolated pump circuits. There is also no significant difference in heat production by either pump. Reports of severe hemolysis using the centrifugal pump in neonatal ECMO are likely due to other factors. Proper cannula selection and positioning are important measures to reduce hemolysis by minimizing circuit pressure and maximizing venous return. Avoidance of inadvertently high rotor speed in the centrifugal pump is also recommended.

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Two patients who underwent "redo" aortic graft replacement in which the original thrombosed graft was oversewn but not removed subsequently developed graft-enteric erosions that involved the oversewn graft. Each patient underwent successful removal of all intraabdominal graft material, oversewing of the aortic stump and extraanatomical bypass. These cases emphasize the need to remove any defunctionalized graft material and to cover all new and retained graft with soft tissue at the time of aortic graft reoperation if graft-enteric erosion is to be avoided.

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