TUESDAY MORNING, MAY 9, 1978

8:30 A.M. Scientific Session - Ballroom

15. A Randomized Study of Cold Cardioplegia for Coronary Artery Bypass Grafting

VINCENT R. CONTI*, ENRIQUE BERTRANOU*,

EUGENE H. BLACKSTONE*and STAN B. DIGERNESS*,

Birmingham, Alabama

Sponsored by John W, Kirklin, Birmingham, Alabama

Intraoperative myocardial care in 34 consecutive patients scheduled for 2 to 4 distal coronary anastomoses by 3 surgeons (participating surgeons were Drs. J. W. Kirklin, R. B. Karp, and N. T. Kouchoukos) was randomized between cold cardioplegia (Group A, 17 patients) and the technique usually employed by the surgeon (Group B, 17 patients, 14 of whom had a single cold ischemic cardiac arrest period, and 3 had intermittent aortic cross-clamping). Cold cardioplegia included a single period of aortic cross-clamping with 1) rapidly induced and strictly maintained cardioplegia and myocardial cooling (10° to 19°C septal temperature) by intra-aortic injection of 150 ml/min/m² body surface area for 2 min of an 8°C asanguineous hyperkalemic (30 mEqk⁺) solution, 2) supplemental measures to insure this state during the entire arrest period (topical cooling, systemic perfusion at 20°-24°C and low flow, and when necessary cardioplegic reinfusion), and 3) maintenance of moderately low perfusion pressure and moderate hypothermia (30°C) during the first 2 min of reperfusion. Postoperative cardiac index was inversely related to cross-clamp time only in Group B (r = -0.53, p=0.03). Duration and quantity of release of CK-MB heart specific isoenzyme was twice as great in B, but there was considerable scatter (p=0.5). CK-MB was present for <12 hrs in 11 patients, Group A (65%), and 6 (35%) of B (p=0.08). Total LDH and SCOT were lower in Group A. 13 (76%) patients in Group A were free of any postoperative ECG ischemic changes vs 8 (47%) in B (p=0.08). We conclude that cold cardioplegia gave better protection against myocardial damage, and better operating conditions for the surgeon, than our previous methods. It did not eliminate myocardial damage, perhaps because of occasional imperfect use of the method, left ventricular overdistension during arrest and reperfusion, or too long a period of spontaneous ventricular fibrillation just before and after aorta cross-clamping.

*By invitation

16. Constant Pressure Aortic Root Perfusion vs. Cardioplegia and Hypothermia-A Comparison of Myocardial Protection

JOSEPH N. CUNNINGHAM, JR. *, JABER S. ABBAS*,

PETER X. ADAMS*, IRA NATHAN*, ILENE KLUGMAN*

and FRANK C. SPENCER, New York, New York

Coronary perfusion and hypothermic cardioplegia have both been widely used as effective methods of myocardial protection during aortic valve replacement. A theoretical objection to coronary perfusion is that it is not synchronized with cardiac contractions. Accordingly, a special pump was designed for these experiments to provide perfusion at a constant range of pressure.

Twenty dogs were studied during 4 hours of cardiopulmonary bypass (CPB). In Grp. I (6 dogs), no manipulations were carried out and hearts were allowed to beat in a perfused, vented, normothermic, non-working state. Grp. II (7 dogs), underwent 2 hours of cross-clamping and coronary perfusion with the system described providing constant aortic root pressure (80-100 mm Hg.). Coronary blood flow was regulated by intrinsic changes in coronary vascular resistance. In Grp. Ill (7 dogs) potassium arrest (30 mEq. of K⁺/L of Plasmalyte @ 4°C.) and profound hypothermia (<20° C.) were employed during 2 hours of uninterrupted aortic occlusion. Functional and metabolic measurements were made at the onset and end of CPB. Changes from baseline values in each group are listed below:

A significant degree of ventricular dysfunction occurred following 4 hours of CPB alone, perhaps from emboli, edema, or unknown causes. It was significant that constant pressure coronary perfusion resulted in a similar injury after 2 hours of aortic occlusion. Potassium cardioplegia, by contrast, during a 2 hour period of aortic occlusion provided a much greater degree of myocardial protection; perhaps both by limiting the degree of ischemic injury directly or as a result of exclusion of the heart from the circulating blood in the pump oxygenator system.

*By invitation

17. Effect of Crossclamp Time, Temperature and Cardioplegic Agents on Myocardial Function after Global Anoxia

HAROLD KAY*, FREDERICK LEVINE*, JOHN FALLON*,

GEIR GRÖTTE*, ERIC BUTCH ART*, SUBBA RAO*,

TERRY McENANY, GERALD AUSTEN and

MORTIMER BUCKLEY, Boston, Massachusetts

In order to determine the importance of different protective techniques on the ability of the canine myocardium to maintain functional, metabolic and ultrastructural integrity following global anoxia, 228 dogs were studied varying temperature (37°, 28°, 11°C), anoxic time (0, 60, 90, 120 minutes), and cardioplegic agents (K⁺ [KCP], Mg⁺⁺, and procaine [PROC]). Change in left ventricular function was defined as the arithmetic difference in the center of mass between pre- and post-anoxic Sarnoff curves and expressed as percent recovery of function. Anoxic metabolism was monitored by lactate, pyruvate and oxygen washout curves. Electron microscopic changes were evaluated from ventricular biopsies.

After 90-120 minutes of crossclamp, only dogs with hypothermia (HYP) and KCP were able to significantly recover pre-ischemic function (28°C - 86%, 11°C - 93%, p<.01). HYP alone (28° or 11°C) preserved 87% of function after 60 minutes of crossclamp. PROC supplemented the protection of HYP + KCP (p<.01), but by itself was not effective (p>.05). Pretreatment with glucose-insulin-potassium, hydrocortisone, creatinine phosphate, citrate or propranolol did not alter the protective effect of HYP + KCP (p>.05). Pretreatment with isoproterenol, morphine or halothane decreased the protective effect of HYP + KCP (p<.01).

Inadequately protected groups (normothermia or hypothermia without KCP) showed more myocytic (intracellular edema, myofibrillar dissolution, loss of mitochondrial cristae and accumulation of dense granules, and partial dehiscence of intercalated discs) and capillary endothelial damage (capillary endothelial swelling, bleb formation and rupture) than the HYP + KCP groups.

No technique of myocardial protection studied completely preserved LVF, however, the combination of HYP, KCP and PROC resulted in maximal LVF recovery following crossclamp for up to 120 minutes.

*By invitation

18. Blood Cardioplegia - A Superior Method of Myocardial Protection

DAVID M. FOLLETTE*, DONALD G. MULDER, JAMES V. MALONEY, JR.

and GERALD D. BUCKBERG, Los Angeles, California

A new safe, effective method of producing a quiet, bloodless heart for two or more hours has been developed experimentally and used clinically. Aliquots of oxygenated blood from the heart/lung machine are altered (calcium chelation, Ca++ 0.6m Eq/ℓ; alkalinization, pH 7.8; hyperkalemia, 30m Eq/ℓ; and cooling, 22°C) and infused by the perfusionist from the pump console into the proximal aortic root or coronary ostia (during aortic valve replacement) every 20 min.

Experimental: Of 17 dogs placed on cardiopulmonary bypass, 7 received continuous coronary perfusion for 3 hours. In 10 dogs, the aorta was clamped for 2 hours (myocardial temperature 22°C) and 150 cc of pump blood injected into the aortic root every 20 minutes. In 5 dogs this blood was unaltered (simulating intermittent release of the aortic clamp) while in 5 others the blood was modified with the carioplegic additives. The best myocardial protection occurred with blood cardioplegia with near-normal compliance (84% recovery*) and normal left ventricular (LV) contractility and maintenance of adenosine tri-phosphate (ATP). In contrast, with continuous coronary perfusion, ATP and contractility were preserved but compliance was reduced 50%*. With intermittent 22°C ischemia, severe depression of ATP (42%), compliance (75%*), and contractility (62%*) occurred.

Clinical: The hospital course of 148 consecutive, nonrandomized patients was alanyzed. In the 77 patients with continuous coronary perfusion or intermittent ischemia, there were 59 coronary artery bypass grafts (CABG), 15 aortic valve replacements (AVR) and 3 AVR+ CABG. In 71 patients undergoing prolonged aortic clamping (longest 124 minutes) with blood cardioplegia, there were 55 CABG, 11 AVR and 5 AVR + CABG. Risk factors and bypass times were comparable in both groups. The average ischemic time was much longer on the blood cardioplegic group (43±33 vs 19±18 min*, 2 S.D.). Despite longer ischemia, results with blood cardiplegia were superior in regard to postoperative CPK (796 u/ℓ vs 1251 u/ℓ*), SCOT (59 u/ℓ vs 99 u/ℓ*), infarct rate (ECG, 1/71 vs 11/77*), cardiac output (5.2 vs 3.9 /min*), need for circulatory support (1/71 vs 6/77*), and mortality (1/71 vs 5/77*).

We conclude that blood cardioplegia, both experimentally and clinically, offers better myocardial protection and operating conditions than does intermittent ischemia or continuous coronary perfusion.

*p<0.05

INTERMISSION - VISIT EXHIBITS

*By invitation

19. Surgical Correction of Chronic Post-Embolic Obstructions of the Pulmonary Arteries

C. CABROL*, A. CABROL*, G. TROUILLET*,

I. GANDJBAKHCH*, G. GUIRAUDON*, M. F. MATTEI*,

J. ACAR*and P. GODEAU*, Paris, France

Sponsored by Pierre Grondin, Montreal, Quebec, Canada

Following episodes of pulmonary embolisms, the presence of blood clots in the pulmonary arteries leads to severe respiratory insufficiency and to chronic right heart failure. Medical therapy at that stage has little or no value and attempts at surgical correction have been followed by variable results.

We have operated upon 16 such patients, 9 men and 7 women with ages from 23 to 68. All had severe dyspnoea, 14 chronic cor pulmonale, 6 were suffering from mental disturbances with syncopes and 4 had severe cardiac failure. The presence of clots was demonstrated by pulmonary angiography and the permeability of the distal arterial bed was ascertained by selective injection of the bronchial arteries. The surgical procedure was performed in all cases but 2 through a lateral thoracotomy approaching distally the obstructed arterial branches. Ligation of the I.V.C. was always added to prevent recurrences. Operative mortality included 6 patients: 3 from R.H. failure, 1 from acute pulmonary oedema, 1 from hemothorax and 1 following a pyothorax. Ten patients are surviving after 9 months to 10 years. One is still limited because of significant pleuro-pulmonary sequelae. Six are enjoying good results with marked improvement in their functional limitations, a significant drop in the P.A.P. and radiological permeability of previously obstructed arteries. Three are in excellent conditions i.e. they are completely asymptomatic, have a normal P.A.P. and an entirely normal pulmonary angiogram.

*By invitation

20. Conservative Management of Uremic Pericardial Effusions

E. M. KWASNIK*, J. K. KOSTER, JR. *, J. M. LAZARUS*,

L. J. SLOSS*, R. B. B. MEE*. L. H. CORN and

J. J. COLLINS, JR., Boston, Massachusetts

Although there has been a recent trend toward early operative treatment of uremic pericardial effusions unresponsive to intensified dialysis, this approach may be unnecessarily aggressive. Review of 787 chronic dialysis patients since 1968 has shown 54 patients (5.8%) to have developed 56 episodes of large pericardial effusion. All were managed by increasing the frequency of dialysis and, if the effusion failed to diminish, or if life-threatening signs of tamponade developed, pericardiocentesis was performed. In 62% (35/56) the effusion resolved with increased dialysis. In 38% (21/56), pericardiocentesis was performed with 57% (12/21) requiring only one aspiration. During a mean followup of 34 months (2-100 months) only 5.5% (3/54) have undergone operation: 1 partial pericardiectomy incidental to pulmonary decortication and 2 pericardiectomies for late (3 months and 5 months respectively) constriction. There were 5 complications of pericardiocentesis. One pneumothorax, 1 pneumoperitoneum, 1 costochondritis, and 2 myocardial punctures without sequelae. The 1 death related to pericardial effusion in this series occurred in a home dialysis patient who arrived in the Emergency Room moribund.

Our experience suggests that the great majority of uremic pericardial effusions can be effectively controlled with simple needle aspiration by experienced personnel, and that pericardial resection is usually not necessary.

11:15 A.M. ADDRESS OF HONORED SPEAKER

CARDIAC SURGERY - THE GOLDEN YEARS

Mr. Donald Ross

London, England

*By invitation