Albert B. Iben

Cardiac transplantation in man

Abstract The primary surgical aspects of cardiac transplantation in nine patients are presented. Most organ donors required vasopressor support prior to transplantation and in three reversible cardiac arrest occurred. Postoperative complications of wound healing have necessitated modification of cannulation technics for cardiopulmonary bypass to avoid peripheral incisions. Postoperative disturbances in cardiac rhythm may be minimized by appropriate tailoring of the right atrium of the donor. In all cases satisfactory myocardial preservation has been achieved with local hypothermia alone. In the immediate postoperative period management has included the use of right ventricular pacing, isoproterenol, and intravenous digitalization in most recipients. Postoperative complications have included immediate failure of the homograft in one patient, requiring retransplantation six hours postoperatively. Infectious complications have been most frequent and contributed directly to death in four patients. At the present time three patients survive at five and a half, four, and three months postoperatively.

Saphenous vein bypass graft for refractory angina pectoris: Physiologic evidence for enhanced blood flow to the ischemic myocardium

Twentieth Annual Scientific Session American College of Cardiology The Sheraton Park Hotel, Washington, D.C., February 3 to 7, 1971 Saphenous Vein Bypass Graft for Refractory Angina Pectoris: Physiologic Evidence for Enhanced Blood Flow to the lschemic Myocardium EZRA A. AMSTERDAM, MD; ALBERT IBEN, MD; EDWARD J. HURLEY, MD, FACC; EDWARD MANSOUR, MD; JAMES L. HUGHES, MD; ANTONE F. SALEL, MD; ROBERT ZELIS, MD; DEAN T. MASON, MD, FACC, Davis, California Although surgical approach to symptomatic coronary artery disease is now extensively applied in patients with severe angina pectoris, objective documentation of the efficacy of this method has been lacking. Thus, we studied 20 consecutive patients with severe angina pectoris and angiographically documented coronary artery disease who underwent aorta to right and/or left cbronary artery saphenous vein anastomoses. Detailed determinations were made of preand postoperative (6 to 10 weeks) exercise capacity and hemodynamics with use of the upright bicycle ergometer. The heart ratemean systemic intraarterial pressure product x 10-Z (RPP) was assesged as an index of myocardial oxygen consumption (MVO,). Before surgery, intravenously administered propranolol, 0.1 mg/kg, delayed the onset of exercise-provoked angina pectoris from 6.8 to 8.2 mindtes (P <O.Ol), whereas the RPP fell from 144 to 119 (P <0.02), the response characteristic of propranolol-induced reduction of MVO,. Strikingly, after surgery, angina disappeared and could not be provoked by exercise, which was limited only by leg fatigue. Rise in myocardial blood flow was indicated by increase of the RPP from 144 (preoperative angina threshold) to 179 (level of postoperative leg fatigue) (+24%, P <0.05). In addition, electrocardiographic ischemic ST-T changes of exercise cleared or improved. These early postoperative results indicate that this technique increases myocardial oxygen delivery and is superior for relief of refractory angina in surgically amenable coronary artery disease compared to beta adrenergic blockade, which acts by reducing myocardial oxygen requirements. Asynchrony of Conduction and Reentry 1 GARY J. ANDERSON, MD: KALMAN GREENSPAN, PhD, FACC; J. BANDURA, BA, Indianapolis, Indiana Disturbances of conduction may be one of the mechaVOLUME 26, DECEMBER 1970 Abstracts are listed alphabetically according to first author. nisms of arrhythmias which are due to reentry. We explored this problem in the distal branches of the canine conducting system utilizing microelectrodes and Purkinje ‘bundle preparations resembling a “T” configuration. Such a preparation permits assessment of differential conduction velocities in Purkinje branches originating from a common bundle in response to premature stimuli (S,). Equal depression of conduction in branches distal to a common bundle was observed at wide coupling intervals (S,-S,). With progressive narrowing of the SZ-S1 coupling intervals, in the range of 160 to 200 msec, asynchrony of conduction appeared. This was due to decremental conduction occurring in 1 branch. For example, at a coupling interval of 189 msec the disparity of activation was 27 msec. Decreasing the S2-S1 coupling to 188 msec induced a 37 msec disparity of activation. Thus, an additional 10 msec disparity was induced by a 1 msec decrease in S2-S1 interval. These differential conduction velocities induced disparities of endocardial activation times in excess of 50 to 75 msec. In fibers exhibiting preferentially depressed conduction, local block and reentrant excitation were observed with further decrease in the coupling interval. Furthermore, reentry was critically dependent upon the basic (S,) rate such that shortening or prolongation abolished the reentrant beats. The results of these studies indicate that asynchronous conduction may be induced by narrow coupling of premature stimuli which in turn result in reentry. Electrophysiologic Correlate of Exit Block in

Aortic valve replacement with the fresh valve homograft.

Abstract Forty patients with isolated aortic valve disease have undergone valve replacement with the fresh aortic homograft. Five hospital deaths (12.5 per cent) and one late death occurred. None was due to homograft dysfunction. The surviving patients are all either asymptomatic or greatly improved. Three patients were discharged from the hospital with diastolic murmurs (one in the past thirty-one patients.) Seven additional patients developed diastolic murmurs one and one-half to four months postoperatively. None has signs of significant aortic insufficiency. The technic of insertion with a double suture line and the use of relatively fresh, sterilely collected valves appear to be important in minimizing the incidence of immediate diastolic murmurs. No instance of homograft deterioration has appeared in up to ten months of observation. Available evidence indicates that fresh homograft valves maintain a more normal histologic structure and are less subject to late degenerative changes than valves sterilized with betapropiolactone and/or freeze-dried.

Aortic Homografts for Mitral Valve Replacement

THE ORIGINAL technique for correction of cardiac valve insufficiency employed fresh semilunar valve homografts in the descending aorta. Some patients in this original series continue to survive with competent valve grafts 15 years after implantation.1 Subsequently, mechanical prostheses of several types and tissue valves, prepared in diverse fashions, have been implanted successfully into all intracardiac positions. Although there is no unanimity of opinion, some evidence suggests the superiority of fresh aortic homografts. The late complications following the use of mechanical prostheses persist. Complications with the ballcage valve approach 30% after 3 to 5 years of follow-up in our series. A real appreciation of the magnitude of the late complication rate demands a reappraisal of present valve replacement techniques in all centers concerned with cardiovascular surgery for acquired valve disease. In the search for an improved mitral valve replacement at the Stanford Medical Center, the logical first choice was the fresh aortic homograft. Following its successful use in 12 consecutive canine experiments, the fresh aortic homograft was employed as a mitral replacement in man.2