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Biomedical subjects

H W Bender

Publications and source records attributed to H W Bender.

At least 91 records · Page 5Linked to original sources
PubMed1976

Lung water and urea indicator dilution studies in cardiac surgery patients. Comparisons of measurements in aortocoronary bypass and mitral valve replacement.

We measured transpulmonary indicator dilution curves of 51Cr-erythrocytes, 125I-albumin, 14C-urea, and 3H-water before and six and 24 hours after operation in seven patients undergoing aortocoronary bypass (ACB) and eight patients undergoing mitral valve replacement (MVR). We calculated cardiac output (CO), extravascular lung water (EVLW), the difference between 125I-albumin and 51Cr-erythrocyte distribution volumes (EV albumin), the difference between 14C-urea and 51Cr-erythrocyte distribution volumes (EV urea) and 14C-urea extraction (E) and permeability -surface ares (PS) products. Comparisons between 16 ACB studies and 17 MVR studies showed the MVR group to have a higher EVLW (P less than 0.01). Extravascular lung water decreased after operation. The ratio of EV urea to EV albumin averaged 1.35 in the MVR group and 0.91 in the ACB group (P less than 0.001). 14C-urea E was also higher in the MVR group (P less than 0.05), but PS was similar in the two groups. None of the differences was related to the time that studies were done. We showed that EVLW, calculated using both 125I-albumin and 51Cr-erythrocytes as intravascular indicators and measured blood water content, had a constant relationship to EVLW calculated using only 125-I-albumin as the intravascular indicator and neglecting blood water content, over a broad range of cardiac outputs, hematocrist, and lung water volumes. We conclude that patients with mitral valve disease have an increased distribution volume and E for urea, probably due to hemodynamic changes but possibly due to increased vascular permeability. Extravascular lung water decreases after cardiac surgery regardless of the type of operation. A single intravascular indicator is adequate for estimating extravascular lung water in humans.

Adult↗
PubMed1976

Left heart volume characteristics following ventricular septal defect closure in infancy.

Left ventricular and left atrial volume, left ventricular ejection fraction, and left ventricular muscle mass were determined preoperatively and postoperatively in 13 patients who underwent surgical closure of ventricular septal defects in the first two years of life. Left ventricular end-diastolic volume and systolic output averaged 255 +/- 19% (+/- SEM) and 240 +/- 19% of normal, respectively, before operation but fell to within normal limits postoperatively. Left ventricular ejection fraction was normal preoperatively (100 +/- 4% of normal) and remained so after correction (106 +/- 3%, NS). Left ventricular mass was mildly elevated at the preoperative catheterization (271 +/- 21%) and decreased significantly following repair (P less than 0.001). However, the postoperative left atrial volume (147 +/- 14%) remained abnormal (P greater than 0.05). These data suggest that when early surgical closure of a ventricular septal defect is necessary because of failure of medical management, good results with regard to postoperative left ventricular size and function can be expected.

Cardiac Catheterization↗
PubMed1976

Right ventricular volume characteristics before and after palliative and reparative operation in tetralogy of Fallot.

Right heart volume data were obtained in 63 patients with tetralogy of Fallot. The patients were divided into three groups: 1) preoperative tetralogy (N=34); 2) post shunt procedure (N=14); 3A) post repair without outflow patch (N=10); 3B) post repair with an outflow patch (N=8). In Group 1 right ventricular end-diastolic volume (RVEDV), RV ejection fraction (EF), and RV systolic output (SO) were all mildly depressed. In post shunt patients, RVEDV was normal but RVEF remained depressed. RVEDV and RVSO increased following a shunt procedure, and these variables were larger in patients with a large versus a small shunt. In Group 3A RVEDV, RVEF, and RVSO were normal. In contrast in patients in Group 3B, RVEDV was increased averaging 177 +/- 15% of normal RVEF was depressed averaging 0.45 +/- 0.04, and RVSO was normal. RV size and pump function are abnormal in patients whose operation requires an outflow tract patch and the factors which may contribute to these abnormalities include a higher RV peak pressure, pulmonary incompetence, and a larger noncontractile outflow tract. Longitudinal studies relating these variables to clinical performance and exercise testing will be important in assessment of the importance of these abnormalities.

Blood Pressure↗
PubMed1975

Unstable coronary artery disease: comparison of medical and surgical treatment.

In eighty-eight patients with arteriographic findings of obstructive coronary artery disease and the clinical picture of unstable angina pectoris, a decision on operative or nonoperative management was made by the attending physician. Fifty-three of them subsequently underwent aortocoronary saphenous vein bypass grafting and 35 were continued on a program of medical therapy. A marked difference in the course after the first 30 days was noted, with most of the surgically managed patients being either asymptomatic or greatly improved following coronary artery bypass. Two-thirds of the medically treated patients had persistent severe angina pectoris and non was asymptomatic in a follow-up period averaging 20 months. There were 2 late deaths in the medical group and none in the surgical group. These findings indicate that coronary artery bypass operations can be performed with low risk during the unstable phase of coronary artery disease and that relief of angina can be anticipated. In contrast, nonoperative management of unstable coronary artery disease carries an appreciable risk of death or myocardial infarction, and the majority of patients treated nonoperatively continue to experience angina.

Adult↗
PubMed1975

Abnormalities of right ventricular function following Mustard's operation for transposition of the great arteries.

Postoperative data were obtained at cardiac catheterization in twelve patients studied 6-29 months following Mustard's operation for transposition of the great arteries (TGA) to assess the incidence and severity of abnormalities of right ventricular (RV) function. Age at operation was 5-13 months in seven patients (infant group) and 19-25 months in the remaining five patients. RV end-diastolic volume (EDV) decreased in all patients following surgery and averaged 123% of normal in the postoperative group (NS). RV ejection fraction (EF) was depressed postoperatively averaging 0.45 (69% of normal (P less than 0.001) as was RV systolic output (78% of normal, P less than 0.01). LVEDV averaged 65% of normal (P less than 0.001), LVEF 0.67 (103% of normal, NS), and LV systolic output 67% of normal (P less than 0.001) following operation. Left atrial (systemic venous) volume was decreased in all postoperative patients averaging only 39% of normal (P less than 0.001). A high incidence (greater than 50%) of partial baffle obstruction was found and LV systolic output showed a significant negative correlation with baffle gradients. The low output postoperatively may be related to decreased LV filling pressure, a small LV reservoir, and thus a small atrial "booster pump." Pressure-velocity indices of RV contractile function in four patients showed a poor correlation with pump function. Long-term follow-up will be required to determine the clinical significance of the abnormalities of venous return and ventricular function.

Cardiac Output↗
PubMed1975

Depression of human myocardial contractility with "respiratory" and "metabolic" acidosis.

The effect of a similar degree of "respiratory" and "metabolic" acidosis was studied in seven isolated in vitro human pectinate muscles and eight ventricular muscle bundles. Either "respiratory" or "metabolic" acidosis (from 7.36 plus or minus 0.03 to 7.01 plus or minus 0.02 and 6.98 plus or minus 0.03, respectively) depressed in vitro contractility in human atrial or ventricular muscle to a similar extent. Previous contradictory responses of myocardial tissue to alterations in pH appear to be the result of species differences.

Acidosis↗
PubMed1975

Effect of blood flow rate on subendothelial proliferation in venous autografts used as arterial substitutes.

The effect of augmented and reduced blood flow rates through autogenous vein grafts (AVG) on the histological characteristics of veins used for arterial substitutes was studied in 22 dogs. In each animal autogenous jugular veins were implanted as conduits to replace excised segments of both iliac arteries. In one group (control) blood flow through the AVG conduits was not modified, but in the remaining animals blood flow rate was either augmented by a distal femoral arteriovenous fistula or reduced by a distal arterial stenosis. In the control group in which there was no modification of blood flow, subendothelial proliferative lesions (SEPL) were found in the vein graft, and typical SEPL were found at each anastomosis. However, in those animals in which blood flow was reduced by an average of 44% through the graft, SEPL were more numerous throughout the length of the vein graft, and the anastomotic SEPL were more prominent. In contrast, those animals in which a unilateral distal arteriovenous fistula augmented blood flow through the AVG (average 6.7-fold increase), no SEPL were detected along the length of the graft. Although SEPL were present at the suture lines, the lesions were much less prominent. These findings suggest that the magnitude and distribution of SEPL in AVG are determined, in part, by the rate of blood flow through the graft.

Animals↗