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Biomedical subjects

L I Bonchek

Publications and source records attributed to L I Bonchek.

At least 109 records · Page 6Linked to original sources
PubMed1976

A method of outflow tract reconstruction in tetralogy of Fallot with anomalous anterior descending coronary artery.

An anomalous anterior descending coronary artery that arises from the right coronary and crosses the right ventricle outflow tract can compromise corrective operations for tetralogy of Fallot. The only safe method of outflow tract reconstruction reported until now is the use of a tubular graft from the right ventricle to the pulmonary artery. We report successful reconstruction of the outflow tract by placing a standard fabric path under the mobilized anomalous coronary artery. This technique should avoid the late complications of tubular conduits by preserving the natural posterior wall of the outflow tract for growth.

Arteries↗
PubMed1976

Peristernal closure of median sternotomy using stainless steel bands.

Peristernal closure of median sternotomy incisions with interrupted stainless steel bands has proved to be a rapid and safe method for achieving solid internal fixation in approximation of the sternum. The method is particularly useful for obese patients undergoing sternotomy. There have been no instances of wound dehiscence using this technique, and several other advantages over standard forms of sternal closure are apparent. The method is a useful addition to the cardiac surgeon's armamentarium.

Cardiac Surgical Procedures↗
PubMed1976

Baroreflex sensitivity and carotid sinus dimensions in dogs with coarctation.

Baroreflex sensitivity (BRS) has not been assessed in coarctation, though it is diminished in renal and essential hypertension. Previous experimental studies of coarctation have dealt primarily with renal mechanisms of hypertension, and have relied on constricting the aorta in adult animals. We banded the thoracic aorta in newborn puppies, and performed studies 2 yr later. Blood pressure (BP) elevations, abundant chest wall collaterals, the absence of heart failure, and subsequent necropsy confirmed the full syndrome of natural coarctation in all dogs. Transient BP elevations were induced in conscious, unrestrained dogs with intravenous phenylephrine injections. Reflex bradycardia was quantitated by plotting each pulse interval in microseconds against BP of the preceding beat, and expressing BRS as the linear regression coefficient (slope) in ms/mmHg. Mean BRS in 10 dogs with coarctation did not differ significantly (P greater than 0.1) from 8 normal controls. Carotid sinus diameter (CSD) was also assessed. Carotid arteries were fixed in vivo by prolonged exposure to glutaraldehyde to prevent contraction, then were excised and measured in a calibrated microscope. Mean CSD in 10 dogs with coarctation was significantly greater (P less than 0.01) than in 10 control dogs. The unexpectedly normal BRS in experimental coarctation may be due to changes in CSD induced by hypertension; such changes may only develop in growing animals. Experimental studies of coarctation should use a preparation that mimics the natural lesion.

Animals↗
PubMed1976

Complete interruption of the aorta in Noonan's syndrome.

A patient is presented who lived to age 60 with complete interruption of the aorta associated with Noonan's syndrome. On chest x-ray there were calcified mediastinal masses and bilateral rib notching. Angiography demonstrated complete interruption of the aorta with markedly dilated tortuous intercostal arteries. The roentgenographic studies are correlated with the surgical and pathological findings. Noonan's syndrome is discussed.

Aorta, Thoracic↗
PubMed1976

Late results of surgery for left ventricular outflow tract obstruction in children.

Forty-four patients, with a mean age at surgery of 10 years, were followed for 5 to 16 years (mean 9.7 years) after relief of left ventricular outflow tract obstruction. There were no early deaths, but 5 late deaths occurred, 3 following reoperation. Twenty-five patients were recatheterized from 1 to 16 years later (mean 6.6 years). In 21 of 32 patients (66 per cent), a new diastolic murmur followed relief of valvular stenosis; 25 (78 per cent) of these patients had a postoperative diastolic murmur. Seventeen of these 25 (68 per cent) were recatheterized, and 11 of the 17 (65 per cent) had moderate-to-severe aortic incompetence on angiography. Eight patients (18 per cent) have undergone reoperation and 9 more (20 per cent) will have to be reoperated upon soon. Although the aortic valve gradient and left ventricular stroke pressure were reduced in all obstructive types after surgery, left ventricular end-diastolic pressure significantly increased and cardiac index decreased after valvotomy. Cardiomegaly and electrocardiographic (ECG) abnormalities were present in 45 and 66 per cent, respectively, of all postoperative patients. Although 93 per cent of patients may be expected to survive and 82 per cent be reoperation free at 10 years, further surgery thereafter becomes increasingly common. Timely relief of obstruction prevents sudden death and produces excellent symptomatic improvement, but the operation is only palliative. Development of a reliable pediatric valve and ventriculo-aortic conduit may encourage earlier and more aggressive therapy.

Abnormalities, Multiple↗
PubMed1975

Postoperative hemodynamic and electrophysiologic evaluation of the interatrial baffle procedure.

Hemodynamic and electrophysiologic studies were performed in 11 children with dextrotransposition of the great arteries an average of 26 months after the interatrial baffle procedure and, in 2 patients, additional closure of a ventricular septal defect. All children are clinically well. Right to left shunts ranging from 28 to 63 percent of systemic blood flow were found at the superior vena caval-baffle junction in four children. The superior vena caval-baffle gradient averaged 7 mm Hg (range 0 to 22). Right ventricular stroke work index averaged 39 g-m/beat per m2 and right ventricular end-diastolic pressure 9 mm Hg. These values were not significantly different from the values for the systemic left ventricle in a comparable group of normal children (average left ventricular stroke work index 45 g-m/beat per m2 and average left ventricular end-diastolic pressure 8 mm Hg). Cardiac index, heart rate and arteriovenous oxygen difference were also normal. No child has complete heart block. His bundle recording demonstrated normal H-V intervals (range 27 to 40 msec); 4 of the 11 had a prolonged A-H interval. Left ventricular systolic pressure was less than 40 mm Hg in all but two children who had significant subpulmonary stenosis. Pulmonary vascular resistance averaged 1.9 units and was decreased in all children. We conclude that up to 37 months postoperatively, despite some residual abnormalities, the clinical and hemodynamic condition of these children is excellent.

Angiocardiography↗
PubMed1975

Ball valve prostheses: current appraisal of late results.

Advanced actuarial techniques are used to analyze late results in 912 patients who had isolated mitral or aortic valve replacement with ball valve prostheses from 1965 to 1974. Experience with noncloth-covered and cloth-covered valves is compared in terms of late survival, rate of thromboembolic complications and reoperation and the influence of anticoagulation. The cloth-covered prostheses have substantially reduced the incidence of emboli after mitral valve replacement (1.9 vs. 6 emboli per 100 patient years) and have thus far eliminated emboli after aortic valve replacement in patients receiving warfarin. Patients with a cloth-covered aortic valve who did not receive warfarin had nine emboli per 100 patient years. The safety of cloth-covered valves is clearly enhanced by warfarin therapy; the efficacy of anti-platelet drugs is still uncertain. Strut cloth wear was found at reoperation in 10 patients. This should be prevented in the new model 2400 composite strut ("track") valve by a narrow metal track on the inner surface of each strut. The substantial recent reductions in operative mortality and in prosthesis-related complications pose important questions regarding timing of operations and selection of prostheses. These decisions must be individualized for each patient on the basis of a thorough analysis of late results using modern statistical methods.

Aortic Valve↗
PubMed1975

Left main coronary artery disease. Risks of angiography, importance of coexisting disease of other coronary arteries and effects of revascularization.

To elucidate the determinants of the poor prognosis of patients with left main coronary artery disease and to assess the efficacy of diagnostic and therapeutic interventions the angiographic features and clinical course of 58 patients with left main coronary artery disease studied between September 1967 and June 1974 were analyzed. Eighty-three coronary arteriograms were obtained in these 58 patients using the Judkins technique; there were no immediate complications although one patient died 3 days after study. Previously cited predictors of left main coronary artery, unstable or nonexertional angina and marked S-T segment depression with exercise were found in a minority of patients; thus, the presence of the disease could not reliably be predicted before arteriographic study. Coexisting disease was found in either two or three other coronary arteries in 46 of 58 patients; only 2 patients had isolated left main coronary artery disease. Because the criteria for operability have changed in recent years, current criteria without knowledge of the treatment actually given or its outcome. The condition of 10 of 58 patients was judged inoperable in retrospect because of severe coexisting distal coronary artery disease (8 patients) or ventricular dysfunction (2 patients). Of 19 patients whose condition was judged operable in retrospect but who were treated without surgery, 9 died, 8 within 18 months; 10 have survived 12 to 83 months. Another 27 patients with a condition judged operable in retrospect had received saphenous vein bypass grafts. In this group, there were four operative and three late deaths. The severity of angina decreased in survivors treated surgically but was unchanged in survivors treated without surgery. The improvement in survival rates of surgically treated patients was not statistically significant. The data indicate that coronary arteriography can be performed at low risk with the Judkins technique even though preangiographic prediction of left main coronary artery disease is unreliable. Coexisting disease in oter major coronary arteries is an important determinant of the poor prognosis of patients with left main coronary artery disease and precludes surgery in 13 percent. Isolated left main coronary artery disease is uncommon. Surgical therapy relieves symptoms more effectively than nonsurgical therapy.

Angina Pectoris↗
PubMed1975

Late complications of aortic valve replacement with cloth-covered, composite-seat prostheses. A six-year appraisal.

Advanced actuarial techniques are used to analyze early and late results in a closely followed series of 396 patients who received a cloth-covered, composite-seat aortic prosthesis. Late mortality and various complications are carefully assessed, and most late deaths are seen to be unrelated to the prosthesis. One hundred sixteen patients with Model 2310-2320 prostheses who received warfarin postoperatively had no thromboembolic complications in 360 patient-years of follow-up (average, 3.1 years per patient); 134 patients who had the same prosthesis but did not receive warfarin had 9 emboli per 100 patient-years (average follow-up, 1.7 years per patient; total, 228 patient-years). By comparison, in 9 years' experience with non-cloth-covered Model 1200-1260 valves, 132 patients had 4.0 emboli per 100 patient-years (average follow-up, 5.1 years; total, 673 patient-years). The safety of cloth-covered valves is clearly enhanced by concomitant use of anticoagulants; the possibility that antiplatelet drugs may suffice has not yet been demonstrated. Strut cloth wear was found at reoperation in 10 patients. The Model 2400 composite strut ("track") valve with a narrow metal track on the inner surface of each strut prevents this complication.

Adolescent↗
PubMed1975

An improved statistical method for assessing the results of operation.

The advantages of the acturarial method of analyzing postoperative survival are now widely accepted. In evaluating the late results of heart valve replacement operations, however, certain nonfatal complications must also be considered. The use of individual event-free rates does not portray individual risk, since some valves have multiple complications. By using cummulative complication-free rates, however, it is possible to estimate the percentage of valves active and free from certain major complications for each postoperative interval. A series of actuarial curves is used, each of which represents a different major complication. These curves are subtracted progressively from the total of valves at risk, and an acturial representation of complication-free survival results.

Heart Valve Prosthesis↗
PubMed1975

Abnormalities of renal perfusion and the renal pressor system in dogs with chronic aortic coarctation.

To clarify the role of the renin-angiotensin system in coarctation hypertension, 2-year-old inbred dogs with chronic neonatally induced thoracic aortic coarctation were subjected to 6 days of rigorous salt restriction. The following parameters were then measured: glomerular filtration rate, renal plasma flow, plasma renin activity, plasma renin concentration, renin reactivity, and renin substrate concentration. Glomerular filtration rate and renal plasma flow were significantly lower in salt-restricted coarcted dogs: 3.0 +/- 0.2 and 9.0 +/- 1.5 ml/min kg-1, respectively, compared with values of 4.0 +/- 0.2 (P less than 0.005) and 13.2 +/- 0.6 (P less than 0.025) ml/min kg-1 in salt-restricted controls. Plasma renin activity was abnormally high in experimental dogs: 13.5 +/- 2.5 vs. 4.5 +/- 1.5 ng angiotensin I/ml hour-1 in controls (P less than 0.005). In addition, a significant elevation of renin reactivity (indicating a relative increase in circulating accelerators or a relative decrease in inhibitors of the renin reaction) was apparent in the plasma of coarcted dogs. Plasma renin concentration was elevated but to an insignificant degree in coarcted dogs, and renin substrate concentration was comparable with that of controls. The impaired renal perfusion and abnormal elevation of plasma renin activity during salt restriction is analogous to clinical and experimental observations in hypertensive states associated with total renal underperfusion and supports a major role for the renal pressor system in the pathogenesis of coarctation hypertension. The insignificant elevation of plasma renin concentration is not incompatible with this view. The demonstration of increased renin reactivity in coarctation hypertension provides additional evidence that acceleration of the renin reaction is common to all hypertensive states.

Angiotensin II↗