WEDNESDAY MORNING, APRIL 18, 1973

8:30 A.M. Scientific Session

Regency Ballroom

29. Liquid Membrane Oxygenator

HERBERT W. WALLACE,* MARC T. ZUBROW,* HELENE BROOKS,*

WILLIAM J. ASHER,* NORMAN N. LI* and T. PETER STEIN,*

Philadelphia, Pennsylvania

Sponsored by William S. Blakemore

A new concept of blood oxygenation based on the encapsulation of gas bubbles within a thin film of inert fluorochemical avoids a blood-gas interface but allows adequate gas transfer. The encapsulated bubbles are passed countercurrent to the blood flow. Oxygen passes through the liquid membrane into the blood, and CO₂ takes the reverse course. The bubbles emerge from the blood phase and collapse, releasing CO₂. The fluorochemical is reused. In vitro experiments demonstrated the method's feasibility (estimated O₂ transfer ≥ 100 cc/min/m2). The compalibility of fluorochemical and blood was evaluated with a device designed to generate a continuous blood-fluorochemical interface. There were no measured untoward effects of fluorochemical upon human blood (24 parameters studied) during 24-hour exposure of over 52 m² of interface at 25 C. In vivo all ten dogs survived 4 hours of veno-venous perfusion (200 cc/min). No alterations of 24 blood parameters occurred acutely or during a four- to six-week period of follow-up. The animals were sacrificed, and no gross or microscopic alterations of organs were detected. A prototype oxygenator is now undergoing in vitro and in vivo evaluation. The initial results have been promising and will be discussed.

*By invitation

30. The Lande'-Edwards Membrane Oxygenator During Heart Surgery: Oxygen Transfer, Microemboli Counts and Bender Gestalt Visual Motor Test Scores

ROBERTO. CARLSON,* ARNOLD J. LANDE',* JAMES BAXTER,*

RUSSELL H. PATTERSON, JR.,* and C. WALTON LILLEHEI,

New York, New York

In 130 patients, 7-103 Kg, the Lande'-Edwards Membrane Oxygenator provided simple, safe, total cardiopulmonary support (3M2 membrane/40 kg). Venous blood drained through the membranes into a reservoir by gravity only and was pumped back into the patient.

Maximum oxygen transfer was 52/ml/min/M2 of membrane, range 12-52 depending on temperature and body weight. At moderate hypothermia (30°C), venous saturation was 85% and arterial 100%. Partial support was provided during warming in larger patients to reduce the number of oxygenator units needed. At mild hypothermia (33-36°C) maximum oxygen transfer measured was 312 ml/min/6M2 membrane (range 35-53).

Decreased morbidity of the membrane compared with the bubble oxygenator was evidenced by decreased microemboli counts, e.g., comparable counts per minute with membrane were 1500 v.s. 18,000 with bubble oxygenator. Use of a microfilter (Pall) reduced these counts by 90% in both. Postoperative visula motor function (Bender-Gestalt) deteriorated in 9% (membrane) and 40% (bubble) patients. This membrane provided safe total cardiopulmonary support for heart surgery and is recommended for decreased morbidity particularly in complex operations.

*By invitation

31. Intraaortic Balloon Assist for Postcardiotomy Cardio-genic Shock

R. L. BERGER and V. K. SAINI,* Boston, Massachusetts

Intraaortic balloon pump (IABP) support was provided in eleven patients with cardiogenic shock following coronary artery bypass grafts, resection of left ventricle, mitral valve surgery or a combination of these operations. Nine of the eleven could not be weaned from cardiopulmonary bypass (CPB) as evidenced by a systolic pressure of less than 75 mm. of Hg. and a left atrial pressure of greater than 24 mm. of Hg. in spite of maximal volume and pressor therapy. Institution of IABP converted the nonpulsatile flow of CPB into a pulsatile one, raised the arterial and lowered the left atrial pressures and allowed discontinuation of CPB. Eight of the nine patients left the operating room and four became long term survivors. Aortocoronary bypass graft flow was measured with electromagnetic probes in one patient and IABP produced a 60% increase in flow. Two of the eleven patients sustained cardiac arrest on the first and second postoperative days and remained in deep shock following resuscitation. IABP support produced initial improvement but ultimately both died. Extensive documentation of clinical, hemodynamic and metabolic changes were obtained in all cases. This experience indicates that IABP can be instrumental in salvaging postcardiotomy cardiogenic shock patients.

*By invitation

32. Objective Assessment of the Effects of Aorto-Coronary Bypass Operation on Cardiac Function

HOOSHANG BOLOOKI,* LEONARD SOMMER,* STEVEN MALLON,*

ABELARDO VARGAS* and MICHAEL GILL,* Miami, Florida

Sponsored by Gerard A. Kaiser

Controversy exists as to the actual effects of direct myocardial revasculariza-tion on cardiac function. In order to evaluate this subject more precisely, we have studied eleven parameters of cardiac function (as a pump and as a muscle) and left ventricular compliance in twenty consecutive patients before and within 4-10 months after successful myocardial revascularization. Eight patients were operated because of acute cardiac ischemia-preinfarction angina (Group A) and twelve had surgery because of chronic intractable angina pectoris (Group B). Postoperatively, all these patients were free of angina and had returned to work; also arteriograms had shown patency of all grafts. After surgery, cardiac index (CI), myocardial contractility (Vmax, dp/dt/Kp), left ventricular end-diastolic pressure (Edp) and compliance (dp/dv) among other parameters, showed insignificant changes in either group. Statistical analysis of data was carried out in a number of ways using various classifications. There was an increase in Vmax in 4 of 8 (50%) of patients in Group A as opposed to 3 of 12 (25%) of patients inGroup B. Left ventricular compliance was unchanged in Group A, but had decreased by 50% or more in one-half of patients in Group B. CI had increased by 25% or more in 6 of 7 patients (in both groups) who had a control CI below 2.5 L/min/m2(P < 0.02). In this group, however, the stroke volume remained unchanged. These results indicate that direct myocardial revascularization produces an excellent palliation of anginal symptoms, but the postoperative improvement in cardiac function is most likely to occur in that group of patients who are suffering from acute cardiac ischemia.

*By invitation

33. Preinfarction Angina Pectoris-A Surgical Emergency

R. R. GOODIN,* T. V. INGLESBY,* A. M. LANSING *

and M. W. WHEAT, JR., Louisville Kentucky

From November, 1971, to September, 1972, 19 patients with preinfarction angina pectoris, 11.3% of patients studied because of coronary atherosclerosis, were studied by cardiac catheterization and coronary arteriography. All patients were candidates for aorto-coronary bypass surgery if technically feasible.

Twelve patients had saphenous vein aorto-coronary bypass graft surgery with one death and good clinical results in the 11 survivors. Seven patients were not operated upon and in five of these patients there have occurred 3 deaths and 2 non-fatal myocardial infarctions during the first three months of follow-up.

From a clinical standpoint, severity and duration of pain, frequency of pain and EKG changes, the two patient groups could not be differentiated. Fifty percent of operated and 57% of non-operated patients had had previous myocardial infarctions. The average number of vessels with over 50% occlusion was 2.17% in operated and 2.85% in non-operated group. Sixty-seven percent of operated and 71% of non-operated patients had abnormal contractions by left ventricular cineangiography. These preliminary results suggest that once the diagnosis of preinfarction angina pectoris is established and appropriate studies carried out, the patient's best interests are served by immediate aorto-coronary artery bypass surgery.

*By invitation

34. Surgical Treatment of Ventricular Irritability

E. D. MUNDTH, M. J. BUCKLEY, R. W. DeSANCTIS,*

W. M. DAGGETT and W. G. AUSTEN, Boston, Massachusetts

Myocardial revascularization and/or resection of a ventricular aneurysm appears to be an effective method of treating persistent and medically refractory ventricular irritability (VI) following acute myocardial infarction (AMI). Nine patients with medically refractory VI, varying from 2 days to 6 weeks post-AMI, have undergone cine coronary arteriography and left ventricular angiography and surgical treatment. Five of the nine patients were less than 2 weeks post-AMI. They were all hemodynamically unstable and 3 were in cardiogenic shock. All 5 had institution of intra-aortic balloon pump assistance (IABPA) with hemody-namic improvement but had persistent VI despite antiarrhythmic drug therapy and appropriate electrical pacing. The other four patients demonstrated intractable VI 2 to 6 weeks post-AMI. IABPA was used in one patient in this group to facilitate management during diagnostic study and induction of anesthesia as well as postoperatively. Seven of nine patients had a demonstrable left ventricular aneurysm. Aneurysmectomy was carried out in 7 patients and was combined with 1,2 or 3 vein bypass grafts in 3. Revascularization alone was carried out in 2 patients. Six of nine patients have survived. VI was improved and readily manageable in all 6 survivors. In 4 of the 6 survivors postoperative VI was managed with minimal antiarrhythmic therapy. Left ventricular function has been good or excellent in all 6 survivors.

*By invitation

35. Serial Angiographic Evaluation of Aortocoronary Vein Grafts in Sixty Consecutive Patients, Two Weeks, One Year, and Three Years after Operation

CLAUDE M. GRONDIN,* JEAN-PAUL MARTINEAU,*

CLAUDE MEERE* YVES R. CASTONGUAY,* GILLES LEPAGE*

and PIERRE R. GRONDIN, Montreal, Quebec, Canada

Although early results in aortocoronary vein grafts (ACVG) have been promising, critical appraisal must await long term studies.

Serial angiographic studies were conducted in 60 consecutive patients who underwent ACVG at the Montreal Heart Institute. All patients were studied two weeks, one year, and three years after operation. Occlusion occurred in 7 of the 91 grafts on the initial study and in 8 additional grafts on the second study. On this second study, most grafts displayed diffuse reduction in caliber-average reduction: 30 percent. In 3 grafts, reduction in caliber was greater than 75 percent. Two years later, all 3 grafts were occluded.

Except for these 3 grafts and 2 additional grafts which became occluded, there was no further attrition rate or reduction in caliber-segmental or diffuse-after one year in the remaining 71 grafts. The overall patency rate was therefore 92.3 percent after two weeks, 82.5 percent after one year, and 77 percent after three years. Hence the occlusion rate of ACVG after one year was only 5.5 percent.

These results indicate that the initial enthusiasm for ACVG was not unwarranted.

*By invitation

36. Coronary Bypass Grafting in 376 Consecutively Operated Patients with Three Operative Mortalities

JOHN E. HUTCHINSON, III,* GEORGE E. GREEN,

HAROUTUNE A. MEKHJIAN* and HARVEY G. KEMP,*

New York, New York

In the twenty-one month period from January, 1971, to September, 1972, 376 patients had coronary bypass grafts performed for coronary atherosclerosis. Three hundred and seventy-three patients were discharged from the hospital (alive) and three patients died. The operative mortality in this consecutively ^. erated group was 0.8%. Four late deaths have occurred to date, two of them (being) due to pulmonary emboli, one due to hepatitis, and the fourth to myocardiai infarction.

In this series, single grafts were performed in 60 patients, double grafts in 185, triple grafts in 121 patients, and quadruple grafts in ten patients. Included in this consecutive series are twenty-four patients with threatened infarction syndromes and twenty patients with diffuse scarring of the left ventricle.

We feel that the major factors accounting for this low mortality are (1) Increased experience in the performance of small vessel anastomosis. (2) Total avoidance of endarterectomy. (3) The performance of the distal coronary anastomosis with ventricular fibrillation rather than anoxic cardiac arrest. (4) The use of the internal mammary arteries and small veins from the lower legs as the bypass conduits of choice.

The specific details of these factors will be discussed.

*By invitation