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Biomedical subjects

L I Bonchek

Publications and source records attributed to L I Bonchek.

At least 73 records · Page 4Linked to original sources
PubMed1982

Prevention of lipid accumulation in experimental vein bypass grafts by antiplatelet therapy.

The ameliorative effect of antiplatelet therapy on atherogenesis of vein grafts was assessed in autologous cephalic veins grafted into femoral arteries of 16 normolipemic and 11 hyperlipemic stump-tailed macaque monkeys. Before grafting, one half of each vein was distended at high pressure (700 mm Hg) and the other half at low pressure (350 mm Hg). Eight normolipemic monkeys were treated with aspirin, 80 mg/day, and dipyridamole, 50 mg/day, and eight were controls. When grafts were harvested at 12 weeks, tissue cholesterol and beta-apoprotein content in grafts from untreated monkeys were significantly higher than in ungrafted, uninjured veins. Antiplatelet therapy eliminated the increase in lipid content of vein segments distended at low pressure, and significantly lowered lipid content of segments distended at high pressure, though not to be control levels of ungrafted veins. Seven of the 11 hyperlipemic monkeys received antiplatelet drugs and four did not. The lipid content of all graft segments was significantly higher than in grafted or ungrafted veins from normolipemic monkeys. Antiplatelet therapy again significantly reduced the lipid content in vein segments distended at both levels of pressure, and also reduced the elevated cholesterol content in ungrafted veins. Although this animal preparation differs in many ways from human coronary bypass operations, these observations may be pertinent to the prevention of atherosclerosis in human vein bypass grafts.

Animals↗
PubMed1982

The third manpower study of thoracic surgery: 1980 report of the Ad Hoc Committee on Manpower of The American Association for Thoracic Surgery and The Society of Thoracic Surgeons.

An ad hoc committee was appointed by The Society of Thoracic Surgeons (STS) in 1977 in order to determine the available manpower and workload of thoracic surgeons in 1976. This committee conducted a survey of the professional activities and geographic location of all known surgeons certified by the American Board of Thoracic Surgery (ABTS) at that time. A summary of this study indicated the available and projected thoracic surgery manpower. The report also determined the present and projected health care needs of the population of the United States through 1993. Because thoracic surgery needs to continue to meet the health care needs of the United States in an appropriate yet economical fashion, the STS and The American Association for Thoracic Surgery (AATS) undertook a joint review to determine again the available manpower and its workload in calendar year 1980. In addition, this study compared its findings with the 1976 report in order to detect changes in the workload and need for thoracic surgical services. A questionnaire was mailed to 3,584 certified thoracic surgeons. There were 2,675 responses. The material was sent to the Academic Computer Services at George Washington University Medical Center for tabulation and data processing. This report summarizes the results of this survey. It also compares these data with those obtained in the 1976 study and, based on this information, attempts to project the thoracic surgery manpower needs in the next decade by using several hypothetical models.

Forecasting↗
PubMed1981

Direct ascending aortic insertion of the "percutaneous" intraaortic balloon catheter in the open chest: advantages and precautions.

When intraoperative balloon pump support is needed for patients who cannot be weaned from cardiopulmonary bypass and when the balloon catheter will not pass retrograde into the aorta from the femoral artery, the catheter must be inserted into the ascending aorta directly. We have found that the new Datascope "percutaneous" balloon catheter offers many advantages for direct insertion into the ascending aorta, but certain precautions are necessary to prevent cerebral emboli when the percutaneous balloon catheter is used this way.

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PubMed1981

Noncoronary collateral distribution in coronary artery disease.

Noncoronary collateral flow is a potential hazard when cold cardioplegia is used for myocardial protection. In this study, noncoronary collateral flow was observed during coronary revascularization in 58 patients. It was distributed significantly (p less than 0.005) toward arteries demonstrating intercoronary collateral flow angiographically - 1.0 of 35 with and 12 of 121 without. Preponderance of coronary collateral flow in hearts with more extensive disease may complicate cardioplegic myocardial protection for such patients.

Collateral Circulation↗
PubMed1981

Coarctation of the aorta and baroreceptor resetting. A study of carotid baroreceptor stimulus-response characteristics before and after surgical repair in the dog.

We studied baroreceptor function in dogs before and after surgical repair of coarctation of the aorta by direct recording of multifiber carotid sinus (CS) nerve activity (NA) during alteration of pulsatile arterial pressure with systemic phenylephrine and nitroprusside, and during static pressure changes using a CS pouch preparation. Coarctation was induced by banding the proximal thoracic aorta in ten 3- to 5-day old puppies. One and one-half years later, five of these coarctated animals were studied before, and five were studied 3-7 months after, surgical repair. Five adult animals also were studied 4-6 months after the proximal thoracic aorta had been banded. Controls were eight normal adult dogs. Threshold pressure at which NA began, saturation pressure at which NA reached a maximum, and slope (% Max NA/mm Hg) of the linear portion of the stimulus-response curve were determined. Pulsatile manipulations of pressure elicited normal sensitivity (slope) in dogs with coarctation but static nonpulsatile pressure changes showed depressed sensitivity compared to controls. After surgical repair, threshold and saturation returned toward normal; sensitivity determined with static pressure manipulations returned to control value. Coarctation reset CS baroreceptors to operate at higher pressures in both puppies and adult dogs and repair of coarctation returned function toward normal. We conclude that resolution of hypertension after repair of coarctation may depend upon baroreceptor readaptation.

Animals↗
PubMed1981

Long-term follow-up of survivors of prehospital sudden coronary death.

Fifty-two survivors of prehospital sudden coronary death (SCD) were studied with angiography and cardiac catheterization. Coronary bypass surgery (CAB) was performed and combined with medical therapy in 24 patients and 28 patients were treated with medical therapy alone. Severity of coronary artery disease (CAD), left ventricular function, and clinical characteristics are described in the surgical and medical groups. Most patients had at least two-vessel CAD and left ventricular dysfunction was common. Nineteen of the 24 surgical (79%) and 17 of the 28 medical patients (60%) had a primary dysrhythmia without an associated acute myocardial infarction (MI) as the cause of their SCD. After a maximal follow-up of 80 months (mean 38.2 months in surgical group, 32.2 months in medical group), there have been 12 deaths. Eight of the 10 cardiac deaths occurred in patients showed initial SCD was related to ventricular fibrillation (VF) not associated with acute MI. Four of these 10 deaths were in the surgical group and six were in the medical group. Two surgical patients died in the early postoperative period; the other two died from recurrent VF 36 and 48 months after SCD. No perioperative or postsurgical MIs have occurred and only two patients have angina. In the medical group, five of the six deaths were caused by recurrent VF. Twelve patients have symptoms: angina in eight, heart failure in five and myocardial infarction in three. Nine of the 12 surgical patients (75%) who were employed before their SCD are still employed, while seven of 15 medical patients (47%) are employed. We conclude that the majority of survivors of prehospital SCD have severe CAD, although an associated acute MI at the time of SCD is uncommon. Coronary bypass surgery can be successfully performed in many of these patients and most are asymptomatic after surgery. The long-term results appear encouraging, although further studies are necessary to confirm these results.

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PubMed1981

An improved method of topical cardiac hypothermia.

Current methods of myocardial protection usually employ together with topical hypothermia by pericardial lavage. Pericardial lavage is inconvenient, inconsistent, and noisy: it wastes blood: it cannot cool the right ventricle effectively. We use a new myocardial protection jacket to cool the heart during operation other than simple coronary bypass procedures. Myocardial temperatures are maintained at 7 degrees to 14 degrees C indefinitely without reinfusion of cardioplegia solution. The jacket is a more convenient and much more effective method of obtaining profound topical hypothermia.

Cardiac Surgical Procedures↗
PubMed1980

Noncardiogenic pulmonary edema and peripheral vascular collapse following cardiopulmonary bypass: rare protamine reaction?

Four instances of severe anaphylactoid reaction occurring subsequent to cardiopulmonary bypass are described. These catastrophic reactions, from which 2 patients died, took place approximately an hour following administration of protamine and were characterized by marked peripheral vasodilatation, loss of capillary membrane integrity, and fulminant noncardiogenic pulmonary edema. Primary cardiac depression was not evident. We hypothesize that protamine was the causative agent in these unusually severe reactions. Differential diagnosis from other causes of acute cardiorespiratory dysfunction depended on early assessment of pulmonary artery and left ventricular filling pressures, cardiac output, respiratory mechanics, and arterial blood gases. Therapy was difficult; success in 1 of the patients seemed to have been effected in part by prompt administration of high-dose corticosteroids and maintenance of peripheral vascular tone with an alpha-adrenergic agonist.

Aged↗
PubMed1980

Prevention of endothelial damage during preparation of saphenous veins for bypass grafting.

Abundant experimental evidence indicates that damage to vascular endothelium decreases intimal fibrinolytic activity, causes mural platelet and fibrin deposition, encourages proliferation of the exposed subintimal fibrocytes and smooth muscle cells, and increases endothelial permeability. These processes lead to thrombosis, subendothelial hyperplasia, or accelerated atherosclerosis. We have demonstrated in monkeys that distention of veins at high pressures (700 mm Hg), as commonly done clinically in preparation for coronary bypass, causes severe damage to the endothelium (as seen by scanning electron microscopy), and increased lipid uptake by the vein wall. The endothelium of veins distended at lower pressures (300-400 mm Hg) was not significantly different from that of undistended veins. Because of the potential late consequences of early endothelial damage to vein grafts, distention of veins before grafting to overcome spasm and to identify leaks must be done at controlled pressures. A convenient balloon device has been developed which limits the maximum pressure that can be applied when the vein is dilated.

Animals↗
PubMed1980

Aspergillus terreus infective endocarditis on a porcine heterograft valve.

We present the first reported case of Aspergillus endocarditis occurring on a porcine heterograft prosthesis and discuss the literature regarding both Aspergillus endocarditis and endocarditis on a porcine valve. A 65-year-old man underwent aortic valve replacement with a porcine heterograft. Several weeks later he exhibited signs of infection and then of valve failure. Upon removal, the porcine valve substance was found to be grossly infiltrated and destroyed by the Aspergillus organism. The porcine valve has an excellent reputation of being resistant to infection and relatively easy to sterilize by medical management alone. Several surveys attest to the low incidence of endocarditis. Because of our experience with the destruction caused by Aspergillus, however, and because antimicrobials generally fail to eradicate this organism, we urge prompt operation to remove the heterograft valve involved with infection by this organism. The valve diseased with Aspergillus should be replaced with a mechanical prosthesis. In the aortic position, extra-anatomic replacement should be considered to facilitate eradication of periannular infection postoperatively.

Aged↗