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Biomedical subjects

R A Bruce

Publications and source records attributed to R A Bruce.

At least 145 records · Page 8Linked to original sources
PubMed1976

Correlation of polarcardiographic criteria for myocardial infarction with arteriographic and ventriculographic findings (substantiation of transmural and presentation of non-transmural criteria).

Sensitivity and specificity of polarcardiographic criteria for myocardial infarction were compared with those of electrocardiographic criteria in 108 patients with chest pain syndromes who were referred for coronary arteriography and left ventriculography. With the combination of total occlusion of at least one coronary artery and abnormal systolic contraction of at least part of the left ventricle as the best available documentation of myocardial disease, sensitivity and specificity were 70% and 67%, respectively, using electrocardiographic criteria and 80% and 73% using polarcardiographic criteria, for both anterior and inferior myocardial infarction. Another polarcardiographic criterion--rightward shift in R latitude at 10 msec after onset of QRS--occurred concurrently with vessel occulusion in 16 of 17 patients (94%), in four of whom this was the only objective evidence of myocardial infarction, and three of whom there was no manifest abnormality of wall contraction. This criterion is considered evidence of non-transmural myocardial infarction, probably in the subendocardial layer near the apex of the left ventricle. When such evidence is added, sensitivity of polarcardiographic criteria increased to 84%, and specificity decreased to equal that of the electrocardiographic criteria (67%).

Adult↗
PubMed1976

Improvement in exertional left ventricular dysfunction after revascularization.

The case is reported of a 63-year-old white man with mild angina pectoris, whose systolic pressure fell 30 mmHg (4-0 kPa) with maximal exercise, without chest pain but with accompanying dizziness. Grafting the internal mammary arteries into the mid left anterior descending and obtuse marginal arteries improved regional myocardial perfusion and increased maximal cardiac output 24 per cent and maximal systolic pressure 32 per cent.

Blood Pressure↗
PubMed1976

Fractures of the edentulous mandible: the Chalmer J. Lyons Academy study.

Results of a study show a 20% incidence of nonunion of fractures of atrophic edentulous mandibles. Accurate bony reduction is essential in elderly paatients with thin mandibles. Closed reduction should be tried first as open reduction tends to limit vascular supply to the fracture. Maintenance of periosteal coverage seems advisable if open reduction is necessary. Bone grafting should be considered unless contraindicated because of the patient's age or physical condition. Wire mesh is preferable to bone plates for stability.

Adolescent↗
PubMed1976

Low-level dynamic exercises for earlier cardiac rehabilitation: aerobic and hemodynamic responses.

Three different kinds of low-level exercise (one arm and two leg exercises) and a low-level treadmill test were designed for patients recovering from acute myocardial infarction; noninvasive circulatory and aerobic responses to these activities were evaluated in healthy subjects. Exercise systolic pressure-rate product (X 10(-2)) were, respectively, 92 +/- 16, 98 +/- 10, 106 +/- 22 and 129 +/- 17 for the four activities studied. Exercise metabolic rates were 1.56 +/- 0.16, 1.99 +/- 0.22, 1.68 +/- 0.25 and 2.74 +/- 0.32 METS (multiples of the observed resting oxygen requirements). Additionally, arteriovenous oxygen difference, cardiac output, stroke volume, mean systemic and mean pulmonary pressures were measured in four coronary patients as they performed the leg exercises. It is hoped that this study will provide a basis for applying these different forms of exercise to patients recovering from an acute myocardial infarction, even when they are confined to bed, in order to advance the onset of cardiac rehabilitation. In a similar way, the new low-level treadmill test may be indicated for the same patients to assess the safety of discharging them from the hospital and permitting unsupervised ambulatory activity at home.

Adult↗
PubMed1975

Cardiac limitation to maximal oxygen transport and changes in components after jogging across the US.

Observations were made before and 3-5 days after prolonged endurance jogging an average of 42 miles/day, 6 days/wk for 2.5 mo by a young male adult who voluntarily initiated a run across the United States. Both arterial PO2 and lactic acid increased. In each instance, the first limitation in circulatory delivery of oxygen was a plateau in stroke volume and cardiac output. Afterward, pulse deficit and systemic arterial pressure fell with exercise and heart rate accelerated. Although there was no change in oxygen transport (Q X CAO2), a reduction in stroke volume was exactly balanced by a rise in arterial oxygen content. Vital capacity, residual volume, and total lung capacity and diffusion capacity for carbon monoxide, hematocrit, and red cell mass increased, while plasma volume diminished and heart size and total blood volume were unchanged.

Adult↗
PubMed1975

Seven-year follow-up of cardiovascular study and maximal exercise of Chinese men.

A seven-year follow-up in 1973 of a prospective cardiovascular study of 1820 initially, healthy, middle-aged Chinese men of 40-59 years of age identified 1745 (95.9%) known survivors, 49 (2.7%) interim deaths, and 26 (1.4) who could not be traced. Of the survivors, 1462 (83.8%) were re-examined, 292 (16.7%) had another treadmill test of maximal exercise, and 283 (16.2%) failed to return for re-examination. On the basis of interim surveillance of hospital admissions, questionnaires and re-examination, a greater incidence of noncardiovascular events (338 or 18.6%) than evidence of cardiovascular disease (220 or 12.1%) was found while the majority (1021 or 56.1%) remained healthy. Total mortality was 0.29 for men under 50 and 0.76 per 100 person-years for men of 50 or more years of age. Only nine, or 18.4% of the deaths were due to cardiovascular causes, and unexpectedly for this population sample, only three were attributed to stroke. When cardiovascular morbidity was related to presence of ST depression after maximal exercise, to hypertension at rest by WHO criteria, to both findings, or to absence of either on initial intake examination, incidence increased from 2.3% for NEITHER group, to 5.7% for ST group, to 11.9% for HT group, and to 25.0% for BOTH groups. Re-examination revealed more evidence of cardiovascular disease than did surveillance of hospital admissions. Additional to effects of aging and mild adiposity, longitudinal changes in blood pressure and ST depression, increasing in the NEITHER group, but less frequent in the other groups, showed some evidence of regression toward the mean, as well as emerging disease and the confounding effects of uncontrolled treatment of hypertension in many. The potential for prediction of subsequent cardiovascular morbidity or mortality appeared stronger for hypertension than for postexertional ST depression, although the two were additive in this population, which is more prone to hypertension and stroke but now is developing clinical manifestations of coronary heart disease more frequently.

Adult↗