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Biomedical subjects

L I Bonchek

Publications and source records attributed to L I Bonchek.

At least 19 recordsLinked to original sources
PubMed1992

A simple and safe technique of left ventricular venting.

Left ventricular venting has many physiologic and practical benefits. A venting technique is described that employs a simple, closed system which allows the perfusionist to monitor left ventricular distention. By monitoring the left ventricular volume the perfusionist can regulate the degree of negative pressure on the vent and thus reduce the chance of air entering the heart.

Coronary Artery Bypass↗
PubMed1992

Technical considerations for coronary artery bypass without cardioplegia.

Coronary artery bypass without cardioplegia remains the preferred technique at many centers around the world. This report describes in detail a technique that emphasizes intermittent cross-clamping of the aorta at mild hypothermia (30 degrees C). Since coronary bypass procedures require brief interruptions of coronary blood flow only for the distal anastomoses, the duration of myocardial ischemia with this technique is not prolonged by unexpected changes in the operative plan. Many bypass grafts can also be carried out without cross-clamping of the aorta by using local control of the coronary arteries. The increasing number of elderly patients with atherosclerotic aortas that cannot be safely clamped makes it helpful for all cardiac surgeons to be familiar with noncardioplegic techniques.

Aorta↗
PubMed1992

Applicability of noncardioplegic coronary bypass to high-risk patients. Selection of patients, technique, and clinical experience in 3000 patients.

Although some surgeons still prefer noncardioplegic coronary bypass, most surgeons are skeptical of its suitability for high-risk patients. We analyzed the first 3000 patients who had primary coronary bypass without cardioplegia since our program's inception. Patients with reoperations, valve operations, or carotid endarterectomies were excluded. Multivariate predictors of operative death included age, sex, left ventricular dysfunction, preoperative intraaortic balloon pumping, and urgency of operation. Eight hundred seventy-nine patients (29%) were more than 70 years of age; 795 (27%) were female; 290 (9.7%) had an ejection fraction less than 0.30, and another 77 (2.6%) had left ventricular aneurysms; 196 (6.5%) had an acute myocardial infarction, and another 397 (13%) had a myocardial infarction less than 1 week preoperatively; 917 (31%) had rest pain in the hospital (preinfarction angina). Only 790 (26%) had elective operations. The overall operative mortality rate was 1.47% (44/3000): The mortality rate for elective operations was 0.5% (4/790); urgent 1.7% (28/1687); emergency 2.3% (12/523). In patients with an ejection fraction less than 0.30 the mortality rate was 6.2% (18/290); with age more than 70 years, it was 3.9% (34 of 879); with acute myocardial infarction it was 3.1% (6/196); and with left ventricular aneurysmectomy it was 1.3% (1/77). Inotropic support after leaving the operating room was needed in 6.6% (199 patients), and 1% (30 patients) required new intraaortic balloon pumping postoperatively (two of these 30 patients died). These results provide reassurance that noncardioplegic coronary artery bypass grafting provides excellent myocardial protection and operating conditions for primary coronary bypass and is particularly suitable for high-risk patients.

Adult↗
PubMed1990

Coronary bypass with substrate-enhanced cardioplegia versus non-cardioplegic technique for early revascularization in acute infarction.

Nine patients chosen at random received substrate enhanced cardioplegia (SECP) for early (less than 4 h) revascularization in acute infarction. A control group of 9 patients with similar clinical characteristics was chosen from the larger group revascularized concurrently with a noncardioplegic technique (NCP). There were no significant differences between the NCP and SECP groups respectively in preoperative clinical parameters such as age (62.8 vs. 62.3 years), sex (7 men, 2 women in both groups), ejection fraction (50% vs. 56%) or number of diseased vessels (2.1 vs 2.3). Intraoperative aortic clamp times were significantly shorter in NCP patients (11 vs. 38 min), and 4 NCP patients had no clamping. The internal mammary artery (IMA) was used in 6 NCP patients and 1 SECP patient (to a nonoccluded branch vessel). Postoperatively, NCP patients had higher peak CPK-MB (284 vs. 190 IU/l), longer use of inotropes (10 vs. 2.7 h) and intraaortic balloon pump (15 vs. 8 h), and a higher ejection fraction before discharge from hospital, but none of these differences were significant. SECP appears to provide better myocardial performance early postoperatively, but lasting benefits were not apparent in this subset of patients with early revascularization. Because the IMA has a powerful effect on long term survival but is very difficult to use with antegrade SECP, we continue to favor the IMA without SECP in hemodynamically stable, young patients (less than 65 years) who are revascularized early after infarction.

Aged↗
PubMed1989

Operative factors, not hemodynamics, modify hormones in repair of coarctation.

This study was designed to evaluate separately the influence of restoration of distal pulse pressure and the influence of factors related to operation upon hemodynamic and hormonal alterations accompanying repair of canine aortic coarctation. Eight normal adult dogs underwent a sham operation and served as controls. In 10 dogs the thoracic aorta was transfected and reanastomosed. In 10 dogs aortic coarctation was created within 1 week of birth by banding the aorta just proximal to the ductus ligament, thereby fixing lumenal diameter at 1 to 2 mm. Studies were performed in the latter animals 18 months after operation. These dogs were subdivided into two groups: one (n = 6) underwent surgical repair of the coarctation; in the other (n = 4), the coarctation was repaired and an occluder was placed on the aorta to maintain distal aortic pulse pressure at its diminished preoperative level. Normal distal pulse pressure was restored in these animals by releasing the occluder 1 week after recovery from the repair of coarctation. Each dog was studied in the conscious state before the definitive procedure and again 24 hr later. Plasma renin activity increased significantly after operation in the sham and in the transection groups. Renin activity and proximal blood pressure were significantly elevated and distal pulse pressure was diminished preoperatively in both the repair and the occluder groups. After their respective definitive procedures, the elevation in renin activity and in proximal pressure persisted in the repair group but decreased in the occluder group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1988

Postoperative fibrous cardiac constriction.

Two patients with postoperative fibrous cardiac constriction are described. Unlike postoperative pericardial or epicardial constriction, the fibrous constricting layer in these patients envelopes the vein bypass grafts and is separate from the pericardium, which is not involved. Surgical management of these patients is difficult and hazardous; a strategy is outlined.

Cardiomyopathies↗
PubMed1988

Left thoracotomy for reoperative coronary bypass.

The left thoracotomy approach for reoperative circumflex coronary revascularization is described in three cases. This approach is an excellent alternative to repeat sternotomy in select patients.

Aged↗