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Biomedical subjects

R A Bruce

Publications and source records attributed to R A Bruce.

At least 127 records · Page 7Linked to original sources
PubMed1979

Noninvasive screening criteria for enhanced 4-year survival after aortocoronary bypass surgery.

Two thousand one men with coronary heart disease (CHD) who were enrolled in the Exercise Testing Registry of the Seattle Heart Watch had symptom-limited maximal exercise tests at the initial clinical examination and follow-up surveillance of subsequent mortality for 4.1 +/- 1.6 years. When subdivided into three mutually exclusive subgroups, 636 patients did not have exertional myocardial ischemia, left ventricular dysfunction or cardiomegaly; 885 without cardiomegaly had only exertional ischemia; 480 had left ventricular dysfunction by either cardiomegaly and/or two noninvasive exertional criteria, with or without exertional myocardial ischemia. Three hundred thirty-one men had aortocoronary bypass surgery, while 1670 remained unopened for at least 4 years. Only 34% of the operated patients who had left ventricular dysfunction, as defined, showed a marked improvement in 4-year survival rates (p less than 0.01). Differences in the annual CHD mortality rates in relation to surgical treatment in the other two groups were not statistically significant. Restricting the analysis to a subset of patients who had invasive studies did not alter the conclusion. Accordingly, we suggest the use of noninvasive criteria to aid preliminary screening of patients for invasive studies and surgical treatment.

Adult↗
PubMed1978

Exercise testing as a predictor of heart disease and sudden death.

Analysis of data obtained from symptom-limited exercise testing and standard clinical evaluation has identified certain variables as having marked prognostic significance in coronary disease, making it possible to separate patients at highest risk of sudden death from the vast majority. The way is thus opened for focusing aggressive preventive efforts upon the group most likely to achieve the greatest benefit.

Age Factors↗
PubMed1978

Physiologic improvement following coronary artery bypass surgery.

In this study the effects of coronary artery bypass surgery on ventricular function were evaluated at rest by quantitative analysis of segmental wall motion on cineventriculography, and during maximal treadmill exercise by measurement of serial cardiac outputs (Fick method) with the use of indwelling pulmonary artery and radial artery catheters. The patient had single vessel coronary disease and exertional angina. Following placement of a bypass graft to the proximally occluded left anterior descenting coronary artery, and despite the presence of arterial hypoxemia secondary to interstitial pulmonary fibrosis, a striking increase in maximal cardiac output occurred, mediated by a rise in both maximal heart rate and stroke volume. In this patient, resting ventricular volumes and ejection fraction were normal both before and after surgery, but preoperative abnormalities in extent of segmental wall motion, identified quantitatively, were restored to normal after bypass grafting. These investigations indicate that bypass surgery can provide substantial physiologic benefits in addition to providing subjective relief of anginal symptoms.

Aged↗
PubMed1977

Noninvasive predictors of sudden cardiac death in men with coronary heart disease. Predictive value of maximal stress testing.

In a follow-up study of 1,852 men with coronary heart disease, 195 deaths occurred within the first 3 years (33 +/- 13 months [mean +/- standard deviation]). Analysis of these cases indicated that the risk of sudden cardiac death in ambulatory men with clinical manifestations of coronary heart disease may be readily estimated from noninvasive clinical and exercise criteria. The important predictors are indexes of the severity of coronary heart disease and impairment of peak left ventricular function demonstrated with symptom-limited maximal exercise. The advantages of these predictors are that they may be elicited on the initial study as well as on follow-up noninvasive examinations of ambulatory patients. The appearance of nonelectrocardiographic predictors in serial examinations may provide an indication for invasive studies and be a more important finding than the ischemic S-T reponse to exertion.

Adult↗
PubMed1977

Variations in and significance of systolic pressure during maximal exercise (treadmill) testing.

Variations in clinical noninvasive systolic pressure at the point of symptom-limited exercise on a treadmill were examined in six groups of subjects: 5,459 men and 749 women classified into three categories each. Among the men, 2,532 were asymptomatic healthy, 592 were hypertensive and 1,586 had clinical manifestations of coronary heart disease (that is, typical angina pectoris, prior myocardial infarction or sudden cardiac arrest with resuscitation). Among the women, 244, 158 and 347 were in the corresponding clinical categories. None had had cardiac surgery; all had follow-up status ascertained by periodic mail questionnaires. Reported deaths were reviewed and classified by three cardiologists; 140 deaths were attributed to coronary heart disease, 118 of them in the men classified as having coronary heart disease. The majority of maximal systolic blood pressure readings were reported to the nearest centimeter rather than millimeter of pressure. Retesting of 156 persons from 1 to 32 months later showed that pressure values agreed within 10 percent in two thirds, the overall mean difference was only 8.6 mm Hg and the correlation at maximal exercise was superior to that of the resting observations just before exercise. Hypertensive patients had a significantly greater body weight than normotensive persons. Among men, the lowest maximal systolic pressure was observed in the group with coronary heart disease; among women, the lowest mean pressure was found in the healthy group. Patients with coronary heart disease were slightly older, and only the women showed a significant correlation in maximal pressure with age. Only 5 percent of the variation in maximal systolic pressure in the patients with coronary heart disease was due to a shortened duration of exercise. Maximal systolic pressures correlated fairly well (r equals 0.46 to 0.68 for the various groups) with resting systolic pressure, and this relation was independent of the diagnosis of cardiovascular disease in both men and women. Relations between pressure and the number of stenotic coronary arteries and imparied ejection fraction at rest were examined in 22 men without and 182 men with coronary artery disease. Lower maximal systolic pressures were often associated with two or three vessel disease or reduced ejection fraction, or both. The prognostic value of maximal systolic pressure for subsequent death due to coronary heart disease was examined in the men with coronary heart disease. The annual rate of sudden cardiac death decreased from 97.9 per 1,000 men to 25.3 and 6.6 per 1,000 men as the range of maximal systolic pressure increased from less than 140 to 140 to 199 and to 200 mm Hg or more, respectively. Cardiomegaly, Q waves in the resting electrocardiogram and persistent postexertional S-T depression were more common in men with the lowest systolic pressure at maximal exercise.

Adult↗
PubMed1977

Exertional hypotension and postexertional ventricular fibrillation in stress testing.

Six men, clinically diagnosed as having coronary heart disease, had postexertional ventricular fibrillation after maximal exercise testing. The common featureof their treadmill performance was "exertional hypotension," that is, a decrease or a limited increase (10 mm Hg) in systolic blood pressure. All six men were successfully resuscitated with electircal defibrillation. The major indication for electrocardiographic monitoring is the detection of major ventricular arrhythmias and changes in QRS-ST-T of acute myocardial infarction or severe ischemia, all of which are urgent indications for stopping exertion. Close supervision both during and after exercise testing is essential, particularly in men with severe coronary artery disease; monitoring of changes in systolic pressure during and shortly after exercise testing is as important as searching for changes in the -S-T segment.

Adult↗
PubMed1977

Differences in cardiac function with prolonged physical training for cardiac rehabilitation.

Ten men aged 40 to 68 years with clinical manifestations of cardiovascular disease and who had participated for 2 to 59 months in a physical training program for cardiac rehabilitation were studied. All 10 underwent measurements of maximal oxygen uptake and invasive studies of cardiac output, using the direct Fick method, at rest and at graded levels of exercise in the upright posture. Of four men who left the training program, three continued activities individually. Physiologic measurements were repeated after a lapse of 13 to 38 months (average 23 months). The rate of change in maximal oxygen uptake relative to normal changes with aging was decelerated in four men over an average of 21.8 months and was accelerated in six men over an average of 23.2 months. At comparable oxygen requirements of exercise, stroke volume and cardiac output were unchanged in the former group but significantly decreased in the latter. Arterial oxygen content and arteriovenous oxygen difference increased in both groups. These results show that prolonged physical training results in physiologic adaptations of cardiac rehabilitation even though deterioration of cardiac function with advancing disease is probable in some patients.

Adult↗
PubMed1977

Exercise and VPCs.

Explore the source record for details and available documents.

Arrhythmias, Cardiac↗
PubMed1977

Near-maximal exercise responses in health and disease in middle-aged Chinese men.

Cardiovascular, aerobic, and ventilatory responses to a multistage treadmill test of near-maximal exercise were determined in 208 middle-aged Chinese men to provide standards in health, and to identify differences in relation to hypertension, coronary heart disease, chronic pulmonary disease and stroke. Except in patients with hypertension, exercise duration was shortened and symptom-limited oxygen uptake was reduced in all disease groups. Unexpectedly, stroke patients exhibited lower heart rate responses to exercise than did patients with coronary heart disease.

Adult↗
PubMed1977

Progressive ambulation and treadmill testing of patients with acute myocardial infarction during hospitalization: a feasibility study.

Symptoms, signs, hemodynamic and electrocardiographic responses of 12 patients with acute myocardial infarction were studied before, during and after three activities: activity I, sitting upright; activity II, walking to the adjacent toilet; and activity III, walking on a treadmill set at 1.2 mph (1.9 km/hr) at 0, 3 and 6% successive gradients. The three activities were studied respectively at three, six and ten days (means) after infarction. Weakness was the most commonly occurring symptom. Mean systolic blood pressure fell 9 mm Hg upon assumption of the upright position (activity I) and was sustained for the five minutes of sitting. The systolic blood pressure drop was only 3.5 mm Hg with activity II. During activity III, one patient developed angina. Between rest and the 6% treadmill gradient, systolic blood pressure, heart rate and pressure-rate product rose 29 mm Hg, 26 beats/minute and 64 units, respectively. Electrocardiographic evidence of ischemia was observed in two patients during activity I, in two patients during activity II, and in one patient during activity III, but was insufficient for stopping the activities. Similarly, two patients developed minor arrhythmias, one with activity I and one with activity III. The use of this low-level treadmill test before discharging the patient from the hospital proved to be safe and feasible for obtaining objective data to assess the patients' ability to perform activities requiring equal exertion at home. Successful performance of these three activities before leaving the hospital should provide useful criteria for discharge of a patient with myocardial infarction.

Aged↗
PubMed1976

Comparison of active participants and dropouts in CAPRI cardiopulmonary rehabilitation programs.

Of 547 men and 56 women enrolled up to April 1974 in Cardiopulmonary Research Institute (CAPRI) community programs for cardiopulmonary rehabilitatation, 84.5 percent had clinical manifestations of coronary heart disease. These medically supervised programs of physical training involved 30 to 60 minutes of graded levels of working, calisthenics and, if indicated, jogging for 3 mornings/week. Altogether 352 (58.4 percent) dropped out after an average of 8.6 months for men and 5.7 months for women. The remaining 230 men and 21 women remained active for 22 and 20 months, respectively. In retrospect, there were few minor differences between active participants and dropouts in physical characteristics, clinical diagnoses and responses to exercise testing on enrollment. Elapsed time to morbidity tended to be longer in active persons than in dropouts. Over one half of active men and about one third of dropouts were working. Of six early deaths, one occurred before training was instituted, and five within the first 2 weeks of training. Among men, the respective total mortality rates were 2.7 and 4.7/100 person-years for active participants and dropouts; among women, the rates were 0 and 3.8 respectively. Whereas 24 episodes of cardiac arrest occurred in 13 men, with three fatalities outside the training program, in 11 instances of exertional arrest during class training all defibrillations were successful. Without this benefit of medical supervision there would have been little difference in mortality experience.

Animals↗
PubMed1976

Elevated arterial pressure and postexertional ST-segment depression in middle-aged women.

Of ten healthy women, 43 to 61 years of age, four exhibited 1 mm. or more of upsloping ST-segment depression after maximal exercise, using the Bruce multistage treadmill protocol; the other six did not. Cardiac output (direct Fick) was not different in the two groups, wither at rest or during exercise. The women with ST-positive responses were older (56 vs. 51 years) and heavier (relative weights 109 per cent vs. 102 per cent), and their resting mean systemic pressures were higher. Their systemic and pulmonary mean arterial pressures during the last five minutes of upright exercise were significantly higher (P less than 0.001) than those in the ST-negative group. Although the ratio of systemic to pulmonary mean arterial pressures was higher at rest, it progressively fell during exercise in the ST-positive group. Polarcardiographic display of the Frank ECG during the first 3 minutes of recovery after maximal exercise showed significant differences between the ST and T of the two groups. At initial recovery, MS-phi greatly exceeded 10.6 mV. which is sensitive PCG ischemic exercise criterion in the ST-positive group. Although the number of observations is limited, it is concluded that greater hemodynamic stress imposed on the subendocardium by elevated pressures, rather than by any significant functional evidence of restriction in coronary blood flow, probably explains much of the postexertional ST-segment depression after maximal exercise.

Adult↗
PubMed1976

Polarcardiographic criteria for myocardial infarction in Chinese men.

Polarcardiograms (PCG) derived from xyz leads of the Frank electrocardiogram (ECG) were recorded in the supine position in 1264 initially healthy middle-aged Chinese men who had been under continuing medical surveillance and were re-examined seven years later. Polarcardiographic criteria for myocardial infarction (MI) were demonstrated in 97 men (7.7%), but only 15 of them showed diagnostic Q waves in the electrocardiogram (ECG). Polarcardiographic criteria for MI were independent of age, but ranged from 4.3% in 464 apparently normal men to 38% in 21 men with manifestations of ischemic heart disease. The possible association of polarcardiographic criteria and a history of smoking was limited to those with clinical evidence of heart disease. The "false positive" rate of 4.3% in clinically normal men was similar to that reported in younger Canadians and in Cretan population samples.

Adult↗