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Biomedical subjects

R J Hall

Publications and source records attributed to R J Hall.

At least 199 records · Page 11Linked to original sources
PubMed1979

Evaluation of posterior aortic wall echogram in diagnosis of mitral valve disease.

The clinical usefulness of detecting abnormal movement of the posterior wall of the aortic root by M-mode echocardiography was studied in 93 patients with common cardiac diseases (mitral and aortic valve disease, atrial septal defect, hypertrophic and congestive cardiomyopathy) and in 17 normal subjects. Though abnormally slow (less than 3 cm/s) or prolonged (greater than 240 ms) diastolic movement was confirmed to be common in mitral stenosis, since it occurred in 35 of 36 patients it was non-specific. Similar abnormalities frequently occurred in other patients with, for example, mitral regurgitation, aortic valve disease, after aortic valve replacement, and in both hypertrophic and congestive cardiomyopathy. The severity of mitral stenosis, assessed at operation, could not be accurately predicted from abnormalities of aortic root movement. Information derived from aortic movement was not diagnostic and did not predict severity in isolated mitral regurgitation though both the peak rate of systolic aortic motion and total aortic excursion were significantly greater than normal. We conclude that abnormalities of posterior aortic wall movement are frequent and their specificity and clinical usefulness are limited.

Adolescent↗
PubMed1979

Scintigraphic, electrocardiographic, and enzymatic diagnosis of perioperative myocardial infarction in patients undergoing myocardial revascularization.

To assess the incidence of perioperative myocardial infarction, 214 consecutive patients were evaluated 1-5 days after coronary bypass surgery, using Tc-99m pyrophosphate (TcPPi) myocardial imaging, serial electrocardiograms (ECG), and enzyme levels (SGOT, LDH, CPK). On the basis of the clinical course and scintigraphic, enzymatic, and ECG changes, the diagnosis of perioperative infarction was definite in 17 of 241 cases (7.9%) and probable in six of 241 (2.8%). In all of these 23 patients, TcPPi scans were abnormal; one additional patient had a false-positive scintigram. Only 13 of the 23 had ECG evidence of infarction, but there were no false positives. We set the threshold for abnormality of enzyme changes quite high, owing to experience in more than 900 postoperative patients (SGOT greater than 200, LDH greater than 500, CPK greater than 500 on the same day). Using these criteria, 22 of the 23 infarct patients had abnormal enzymes, and six others were falsely positive. These results indicate a relatively low sensitivity for the ECG in diagnosing perioperative infarction, but the lack of false positives suggests high specificity. The sensitivity and specificity of the enzymes and the TcPPi image were both excellent and quite similar; the main difference was a reduction of certainty of infarction with the enzyme criteria, caused by the six patients whose enzyme values were falsely positive. Considering its sensitivity, specificity, and ability to locate and to a certain extent quantitate necrosis. TcPPi imaging is probably the most valuable means of diagnosing perioperative myocardial infarction.

Clinical Enzyme Tests↗
PubMed1978

Mathematical modeling of lag phases in microbial growth.

This paper describes a mathematical method of the lap phases of Saccharomyces cerevisiae that incorporates the basic concepts previously presented in a two-stage deterministic model for the growth of this organism under conditions of oxygen excess with a sugar as the growth-limiting substrate. The model structure was suggested by an extensive investigation of the causes of the lap phases of S. cerevisiae which found that, in contrast to the traditionally accepted trends, the length of the lap phase was not inoculum-size dependent. This was consistent with other previously published work which suggested that a major factor in the length of the lag phases in S. cerevisiae was the need to synthesize adequate levels of glycolytic and respiratory enzymes. These suggestions were confirmed experimentally with lag-age data. Based on this conclusion a mathematical model was developed incorporating a description of the levels of glycolytic and respiratory enzymes and their effect on the growth rate and metabolism. This model was tested experimentally and the initial results indicate that many aspects of the lag phase of this organism may be described mathematically. The experimental findings further support the concept of primary regulatory control proposed by Bijkerk and Hall.

Glycolysis↗
PubMed1978

Is the treadmill exercise test useful for evaluating coronary artery disease in patients with complete left bundle branch block?

To aid in the study of coronary artery disease, 57 patients with complete left bundle branch block underwent clinical evaluation, treadmill exercise testing and cardiac catheterization. The patients were classified into two groups according to coronary angiographic findings: 30 patients with significant stenosis (70 percent or greater luminal narrowing) of at least one major vessel and 27 with no significant coronary artery disease. There was no difference in age, presenting symptoms or previous medical treatment between the two groups. There were more men in the group with coronary artery disease. Exercise-induced S-T changes were similar in the two groups; the sensitivity and specificity of these changes for the diagnosis of coronary artery disease were unacceptable irrespective of the criterion chosen. With additional S-T depression of either 1 or 2 mm below the baseline value, the predictive accuracy was only 53 percent. Combined exertional chest pain and 1 mm S-T depression increased the predictive accuracy of exercise testing to 71 percent. These data indicate that exercise-induced electrocardiographic changes do not facilitate detection of coronary artery disease in patients with complete left bundle branch block.

Angina Pectoris↗
PubMed1978

Electrophysiological effects of edrophonium in the innervated and the transplanted denervated human heart.

In order to determine the mechanism of action of edrophonium on the cardiac conduction system, we used His bundle recording and pacing techniques to examine the electrophysiological effect of edrophonium in 6 patients undergoing diagnostic evaluation for coronary artery disease and in 9 cardiac transplant recipients who were free of acute graft rejection. After control measures were made of sinus cycle length, conduction intervals, and conduction system refractory periods, edrophonium was administered by constant intravenous infusion, and all electrophysiological measurements were repeated. In the normally innervated patients, edrophonium significantly increased sinus cycle length from 778 +/- 21 ms to 883 +/- 36 ms (P less than 0.01), AH interval from 88 +/- 11 ms to 100 +/- 12 ms (P less than 0.01), and AV nodal functional refractory period from 351 +/- 44 ms to 391 +/- 36 ms (P less than 0.05). In the patients with transplanted hearts, edrophonium had no electrophysiological effect other than increasing the cycle length of the remnant recipient atrium from 722 +/- 21 ms to 798 +/- 31 ms (P less than 0.01). We conclude that the electrophysiological effects of edrophonium in man are mediated primarily through autonomic innervation of the heart.

Autonomic Nervous System↗
PubMed1978

Direct myocardial revascularisation: experience with 9364 operations.

Between July 1968 and December 1976, 9364 consecutive patients with coronary insufficiency underwent direct myocardial revascularisation using aortocoronary bypass (ACB). Among these patients 8017 had ACB alone, and the remaining 1347 had ACB in addition to correction of other cardiac and vascular lesions. In the series of patients having ACB alone the hospital (early) mortality was 3.9%, but for 2383 surgical patients in 1976 this figure was 2.2%. Operative mortality was higher for women (6.85%) than for men (3.5%), but late survival was about the same for both sexes. Among surviving patients 88% were improved or symptom-free after undergoing ACB. According to our data, at the end of eight years 80% of the patients will be survivors. These results, when compared with other series of patients treated medically, indicate the superiority of surgical treatment both in terms of symptomatic relief and also in increased life expectancy.

Adult↗
PubMed1978

Late deterioration in tetralogy of Fallot: unusual findings and successful correction.

A patient with tetralogy of Fallot who underwent a successful Blalock shunt procedure as a child was evaluated 28 years later because of clinical deterioration. Results of cardiac catheterization and angiography disclosed, in addition to a functioning shunt, evidence of an infundibular, subvalvular tumor and a large anastomosis between the left circumflex coronary artery and the bronchial arteries of the right lung with the possibility of "coronary steal". At operation, the Blalock and coronary-to-bronchial artery anastomoses were ligated; and total correction was performed including resection of the pulmonary valve and infundibulum, excision of the tumor, closure of the ventricular septal defect, and application of an outflow patch to enlarge the pulmonary annulus. The patient was discharged nine days after surgical correction.

Adult↗
PubMed1977

A mechanistic model of the aerobic growth of Saccharomyces cerevisiae.

A two-stage deterministic model of the growth of Saccharomyces cerevisiae is presented. The cell cycle of this organism was used to suggest the basic model structure. The model represents the preparatory processes of substrate uptake and conversion separately from replication and division. The regulation of the fraction of the culture devoted to each of these broad areas of metabolism, and the overall growth rate, is related to the nature and availability of the energy substrate. The simulation of respiration and glycolysis is achieved by including two alternative energy producing pathways. The regulation of these pathways is described in terms of the postulated primary regulation of the proportion of the culture required for substrate uptake and conversion, and the overall kinetic constants for each pathway. This regulation is dictated primarily by the growth rate rather than the nature or concentration of the energy substrate. The model successfully describes both batch and continuous growth of S. cerevisiae under conditons of glucose limitation and oxygen excess. A preliminary assessment indicates that adjustment of the relevant parameters will allow the model to describe the growth of S. cerevisiae on other sugars and under oxygen limitation. Similarly the model could be expected to describe the growth characteristics of other yeast species.

Aerobiosis↗
PubMed1977

The effect of chronic frusemide administration on intracellular potassium, sodium and pH of cardiac and skeletal muscle.

1. Chronic administration of frusemide in large doses of 4 mg day-1 kg-1 for 3 weeks caused a significant reduction of cell water in rabbit cardiac and skeletal muscle. Intracellular Na+ concentration, intracellular pH and extracellular space was unchanged in both tissues. Intracellular K+ concentration increased slightly in both cardiac and skeletal muscle. 2. It is concluded that frusemide does not reduce intracellular K+ concentration in cardiac or skeletal muscle of normal animals receiving a normal oral potassium intake.

Animals↗
PubMed1977

Long-term prognosis of treated acute massive pulmonary embolism.

Seventy-two patients surviving initial treatment by pulmonary embolectomy, streptokinase, or heparin for acute massive pulmonary embolism have been reviewed 1 to 9 years later. Of these patients, 17 had additional cardiorespiratory disease. There were 12 late deaths (41% of those patients with, and 9% of those patients without additional cardiorespiratory disease). No death was due to chronic pulmonary hypertension, and none to certain recurrence of pulmonary embolism. The causes of death were malignant disease (6 patients), cardiopulmonary disease other than pulmonary embolism (4 patients), and 'sudden' (2 patients). Though venous interruption surgery was not used, and long-term anticoagulation rare, the incidence of possible or probable recurrent embolism was low (6%). There was no definite evidence of persistence or subsequent development of pulmonary hypertension after treatment in any patient. Resolution of embolism as judged by symptoms, signs, electrocardiogram, and chest x-ray examination was almost always complete. Some pulmonary arteriograms 1 to 6 months after initial treatment showed minor abnormalities, but others at a later date were normal. Perfusion lung scans carried out 1 to 8 years after initial treatment often showed minor abnormalities.

Adult↗