Biomedical subjects

E L Alderman

Publications and source records attributed to E L Alderman.

At least 145 records · Page 8Linked to original sources

PubMed1975

Effect of propranolol on left ventricular function, segmental wall motion, and diastolic pressure-volume relation in man.

Precise quantitation of the effects of the non-selective beta adrenergic blocking drug propranolol (3.15 mg/kg body weight) on left ventricular function, segmental wall motion, and diastolic pressure-volume relation in man has been performed. High fidelity left ventricular pressure measurements and simultaneous single-plane angiocardiograms were recorded on a video disc and volumes calculated by a light-pen computer system. Systolic segmental wall motion was computer analysed using the long axis-quadrasection method. Patients were transvenously atrially paced to maintain a constant heart rate. The haemodynamic effects of propranolol may vary depending upon the extent of pre-existing myocardial disease. In some patients ventricular function, as measured by ejection fraction, may be reduced. This reduction in ejection fraction appears to result from overall reduction in segmental wall motion, but also from accentuation of segmental wall abnormalities. These results are consistent with the thesis that beta adrenergic blocking drugs may inhibit compensatory sympathetic mechanisms. The diastolic effects of propranolol may include quite substantial increases in ventricular volumes in those patients with impaired cardiac function. With respect to the intact human ventricle, propranolol may increase diastolic volume for a given level of ventricular pressure. Thus, in a static sense, the ventricle in these patients could be viewed as being more compliant after propranolol administration. However, the fact that the length-tension relation, as measured by the slope of the logarithmic pressure versus volume plot is unaltered by propranolol, suggests that the muscle comprising the ventricle itself exhibits no alteration in its passive elastic properties.

Angiocardiography↗

PubMed1975

Perioperative myocardial infarction during cardiac surgery. Diagnosis, ECG and enzyme testing.

The detection of perioperative myocardial infarction is complicated by the variety of electrocardiographic changes normally seen concomitantly with cardiac surgery. Unequivocal electrocardiographic diagnoses based on new Q wave development and evolution of ST and T segments are virtually always confirmed by inappropriately high postoperative enzyme test results. For those patients exhibiting nondiagnostic but suggestive electrocardiographic changes, enzyme testing provides a valuable adjunct in determining whether infarction has indeed taken place. Enzyme testing, similarly, in and of itself, cannot provide the dichotomous situation between those patients experiencing infarction and those who are not. SGOT and LDH appear the most reliable indicators of infarction. CPK is quite volatile with sporadic occurrences of high enzyme elevations without obvious clinical or electrocardiographic explanation. The Ck isoenzymes provide a highly specific test for myocardial damage. However, their sensitivity is sufficiently great that a relatively minor cardiac manipulation may result in uninterpretable results.

Angina Pectoris↗

PubMed1975

Dose response effectiveness of propranolol for the treatment of angina pectoris.

Seventeen patients received placebo medication during a 12-week run-in period, followed by four double-blind study periods of six weeks each, during which time placebo, 80 mg, 160 mg and 320 mg propranolol dosages were administered. Examination of the frequency of angina episodes and nonprophylactic nitroglycerin consumption revealed significant beneficial clinical responses for both the 160 and 320 mg dosages. Exercise testing also demonstrated increased exercise tolerance (320 mg dose) with a shift of the exercise end point from pain to fatigue in seven of 17 patients. The interrelationships between propranolol daily dosage, clinical response assessed by percent reduction in anginal episodes, beta-adrenergic blockade measured by percent reduction in exercise heart rate and serum levels were examined. In general, serum levels of 30 ng/ml, when drawn 90 to 180 minutes following the last oral dose, were required to achieve a 25% or greater reduction in angina frequency. Serum levels above 30 ng/ml were similarly correlated with a 20% or greater reduction in exercise heart rate at equivalent levels of exercise. Detailed examination of different patterns of clinical response with respect to beta-blockade, serum levels and oral doses are presented.

Administration, Oral↗

PubMed1975

Measurement of midwall myocardial dynamics in intact man by radiography of surgically implanted markers.

Tiny radiopaque helices (0.85 times 1.5 mm) of pure tantalum wire were implanted by means of a simple insertor instrument into the left ventricular myocardium in 24 patients at the time of cardiac surgery. The markers were positioned in such a way as to outline the profile of the left ventricle when viewed in a 30 degree right anterior oblique projection. Biplane studies showed that all markers could be placed very nearly in a plane using the surface anatomy of the heart as a guide to implantation. Implantation of markers required approximately two minutes. No intraoperative or postoperative complications ascribable to the markers have occurred. They remain firmly in place and allow acquisition of a noninvasive ventriculogram at any time after surgery. The dynamic geometry of the left ventricle was determined by analysis of cineradiograms of these markers. Utilization of a single-plane (right anterior oblique) cineradiogram to obtain measurements of major transverse ventricular diameters, mean circumferential shortening, and circumferential shortening velocity results in underestimation of lenghts by 1.4%, overestimation of shortening by 1.2% of end-diastolic length, and overestimation of velocity by 0.05 circ/sec, when compared with values obtained simultaneously from biplane cineradiograms.

Cardiac Surgical Procedures↗

PubMed1975

Analysis of left ventricular function in response to afterload changes in patients with mitral stenosis.

In order to assess left ventricular function in patients with rheumatic mitral stenosis, left ventricular function curves (plotting stroke work index vs left ventricular end-diastolic pressure) were constructed using angiotensin to augment, and nitroprusside to reduce, afterload. Hemodynamic responses to these alterations in afterload were measured. Resting ejection fractions and qualitative assessment of left ventricular angiographic contraction abnormalities were also determined. Changes in left ventricular end-diastolic pressure following afterload interventions could be linearly related to changes in mean aortic pressure, but mitral valve gradients were unaffected. Afterload reduction with nitroprusside did not augment cardiac output. Afterload elevation with angiotensin significantly depressed both cardiac output and calculated mitral valve areas. Patients with normal resting ejection fractions evidenced normal ventricular function curves and those with depressed ejection fractions showed flat or declining function curves. Contraction abnormalities, generally in the posterobasal area, correlated well with abnormal left ventricular function curves.

Adult↗

PubMed1975

Changes in survival and symptom relief in a longitudinal study of patients after bypass surgery.

The first 350 patients having coronary surgery at Stanford Medical Center (excluding patients with aneurysmectomy or valve replacement) have been followed sequentially utilizing a computer-based information system. Our experience spans 72 months (900 patient-years), with an average follow-up of 30 months. Hospital mortality was 4.9%. Actuarial analysis revealed survival of 91% at 1 year and 80% at 6 years. Forty patients (11.5%) had 43 late myocardial infarctions, of which 5 were fatal. Analyses of selected patient subgroups revealed significantly poorer survival in patients with prior myocardial infarction (P less than 0.05), significant congestive heart failure, or mitral regurgitation (P less than 0.01). Survival in multigrafted (and multivessel) patients was not significantly different from survival in single-grafted (predominantly single-vessel) patients. Actuarial studies suggest improved survival in patients with multivessel disease after coronary artery surgery. Between an initial evaluation at 9 months postoperatively (range: 2 to 40 months) and the most recent evaluation after 30 months (range: 6 to 72 months), 13% of patients showed further clinical improvement, 47% were unchanged, while 40% deteriorated with respect to chest pain. We conclude that initial symptomatic benefits may not be maintained in late follow-up studies owing to progression of underlying vascular disease.

Adult↗

PubMed1975

Evaluation of portable radionuclide method for measurement of left ventricular ejection fraction and cardiac output.

Seventeen patients with coronary artery, valvular, or myopathic heart disease were studied to determine correlations of the cardiac output and ejection fraction when comparing the results obtained with a portable probe technique using 113mIn with those obtained with standard methods (cineangiographic, Fick, and dye dilution). With ejection fractions ranging from o.10 to 0.85, the coefficient of correlation was 0.90 when comparing cineangiographic and radionuclide techniques. Cardiac output determinations by the radionuclide technique also correlated well with standard methods (r equals 0.88). The radionuclide method shows promise as an accurate, safe, and simple method in the evaluation of cardiac function at the bedside.

Angiocardiography↗

PubMed1975