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Biomedical subjects

R M Engelman

Publications and source records attributed to R M Engelman.

At least 199 records · Page 11Linked to original sources
PubMed1975

A method of closed-chest cannulation of the left atrium for left atrial-femoral artery bypass.

A large-bore polyvinyl catheter was devised for passage into the left atrium by means of a modified transseptal catheterization technique. This was performed without difficulty using both pulsatile and nonpulsatile bypass in the closed-chest animal as well as in 3 terminally ill patients. Blood was drained from the left atrium and returned to the femoral artery through an extracorporeal circuit. The shock syndrome produced by coronary embolization in dogs was successfully managed in this fashion. The results of the clinical trials were encouraging. Assisted left heart circulation using a closed-chest left atrial-femoral artery bypass seems feasible by this technique.

Animals↗
PubMed1975

The effect of normothermic anoxic arrest and ventricular fibrillation on the coronary blood flow distribution of the pig.

Normothermic anoxic arrest of 15 and 30 minutes, repeated for up to a total of 90 minutes of anoxia was employed in 24 pigs. The purpose was to determine the effect of varying the duration of anoxia on coronary blood flow, coronary vascular resistance, and the distribution of coronary flow to the free wall of the ventricle. Five minutes of reperfusion at pressures of 50 and 100 mm. Hg with the ventricle fibrillating, was employed between each anoxic interval. Results were compared to control studies performed during ventricular fibrillation without anoxic arrest in 12 pigs. Prolonging the anoxic interval to 30 minutes served to create a maldistribution of coronary flow away from the left ventricular endocardium and to reduce the reactive hypermic response to anoxia. Increasing the perfusion pressure to 100mm. Hg accentuated these changes. Both light and electron microscopy of sections demonstrated edema and early myocardial necrosis in the subendocardial layer of the left ventricle subjected to repeated 30 minute intervals of anoxia at a high perfusion pressure. We postulate that repeated anoxic insults with inadequate repayment of oxygen debt results in subendocardial edema, a decrease in perfusion, increasing necrosis, and further edema. A myocardial infarction must result if this vicious cycle cannot be interrupted.

Animals↗
PubMed1975

Esophagogastrostomy. Analysis of 55 cases.

At the New York University Medical Center from January, 1969, through December, 1973, esophagogastrostomies were performed in 56 patients. In 30 (Group A), fundoplications were combined with the esophagogastrostomies; in the other 26 (Group B), esophagogastrostomies only were performed. These two groups have been compared in an effort to determine the effectiveness of fundoplication in preventing gastric reflux following esophagogastrostomy. The operative mortality rate (10 per cent) and the 3 year survival rate (20 per cent) were approximately equal in the two groups. Clinical evidence of reflux was noted in 10 per cent of Group A and 47 per cent of Group B patients, while complications of reflux were noted in 5 per cent of Group A and in 33 per cent of Group B patients. The results of the present study suggest that fundoplication, while not prolonging survival, does prevent the symptoms and complications of gastric reflux and improves the quality of survival in these unfortunate patients. This leads us to recommend the routine use of fundoplication with esophagogastrostomy in patients with carcinoma of the esophagus and gastric cardia.

Adenocarcinoma↗
PubMed1975

The significance of coronary arterial stenosis during cardiopulmonary bypass.

Myocardial infarction may develop during an uneventful open-heart operation. In order to better understand this complication, we undertook an experimental study. The left circumflex coronary artery of 20 dogs was narrowed to 50 per cent of its area by a metal screw clamp to produce a localized coronary stenosis. Regional myocardial perfusion in the distribution of both the stenotic circumflex and normal left anterior descending (LAD) coronary arteries was measured by injection of a radioactive-labeled microsphere (15 +/- 5 mu). Circumflex coronary artery flow was measured with an electromagnetic flow probe. An epicardial electrogram was recorded in the distribution of the left circumflex. Measurements of regional myocardial perfusion, circumflex flow, and the epicardial electrogram were performed in each animal during the control (prebypass) state and during cardiopulmonary bypass with a beating and fibrillating ventricle. Half the animals had cardiopulmonary bypass performed at 50 mm. Hg perfusion pressure and half at 100 mm. Hg. The animals were put to death at the end of the study, and the hearts were sectioned, weighed, and counted. A cast was made of the stenotic circumflex coronary artery, the degree of stenosis is measured, and the per cent area stenosis calculated. The study showed that the effect of a 50 per cent coronary stenosis in reducing distal flow is apparent only during cardiopulmonary bypass at reduced pressure. The mechanism whereby a myocardial infarction develops during cardiopulmonary bypass could evolve from the development of a "critical" stenosis out of a mild-moderate one at a reduced perfusion pressure during cardiopulmonary bypass.

Animals↗
PubMed1975

Allogeneic unresponsiveness to orthotopic cardiac transplants in DL-A-identical radiation chimeras.

Nine Cooperstown beagles of known DL-A genotypes were exposed to supralethal total-body irradiation and received bone-marrow allografts from DL-A-identical donors. Four to 5 months later, the resulting chimeras received orthotopic cardiac allografts from their corresponding donors of marrow. Six chimeras died of operative complications in the immediate postoperative period. The other 3 chimeras survived from 173 to 547 days; 1 dog died at 173 days as a result of right-sided heart failure, secondary to stenosis at the site of the pulmonary artery anastomosis. The other two recipients continue to be active and healthy at 545 and 547 days. The results indicate that dogs can be rendered specifically tolerant to orthotopic cardiac allografts by supralethal total-body irradiation and the transplantation of marrow obtained from the prospective allograft donor.

Animals↗
PubMed1974

The long-term influence of coronary bypass grafts on myocardial infarction and survival.

Approximately 1,000 coronary bypass procedures were performed at New York University between February 1968 and December 1973. This report reviews all elective operations performed for angina between 1968 and 1972, a total of 448 patients. In this five-year period the percentage of diseased arteries bypassed rose from 40% to 84%, and operative mortality decreased from 28% to less than 3%. There were a total of 28 operative deaths, mostly from myocardial infarction and low cardiac output. Operability was nearly 95%. The only fixed contraindication was chronic congestive failure. Over one-half of the patients had an abnormal ventriculogram, and there was some history of mild congestive failure in nearly 20%. Elevation of left ventricular end-diastolic pressure above 20 mm before operation was associated with a higher operative mortality, but the late mortality was similar to those with a normal preoperative end-diastolic pressure. In 383 surviving patients, angina was eliminated or greatly improved in 86%, unimproved in 12% and worse in 2%. Late angiograms were performed on 201 patients, studying a total of 445 venous grafts with an overall patency rate of 71%. Graft occlusion was sporadic and unpredictable, but over 90% of patients with multiple grafts remained with at least one patent graft. A late myocardial infarction occurred in 32 out of 420 patients surviving operation, and was fatal in eight. The cumulative incidence over a period of five years was 17%. Twenty-three deaths occurred following discharge from the hospital. Life-table analyses showed a five-year survival of 77% when all deaths were included, and a five-year cardiac survival of 81% when non-cardiac deaths were withdrawn alive at the time of death. The expected survival in a comparable population group without coronary disease was 92%, while data published by Sones of patients treated without operation showed a five-year cardiac survival of 66%. Current operative techniques have an operative mortality of 2-3% and a subclinical infarction rate of 5-10%. The ideal graft is yet evolving, but data with internal mammary artery grafts are most encouraging. A future goal should be a five-year graft patency of at least 80%. Because many infarcts probably develop from a relatively small decrease in coronary blood flow, either during rest or mild activity, the likelihood that future data will demonstrate a marked increase in longevity with bypass grafting is great.

Adult↗