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Biomedical subjects

C E Garber

Publications and source records attributed to C E Garber.

28 records · Page 2Linked to original sources
PubMed1991

The threshold for myocardial ischemia varies in patients with coronary artery disease depending on the exercise protocol.

It is generally accepted that angina pectoris and, presumably, myocardial ischemia occur at a fixed heart rate-systolic blood pressure product in a given patient. This concept of a fixed threshold has recently been challenged. To evaluate the effects of varying exercise intensity on the ischemic threshold, 33 patients with coronary artery disease and provokable myocardial ischemia, documented by thallium-201 myocardial perfusion imaging, underwent two exercise tests 2 to 7 days apart. A symptom-limited incremental treadmill exercise test was followed by a 20 min submaximal treadmill test at an intensity approximating 70% of the peak heart rate attained during the incremental test. During the incremental exercise test, angina pectoris developed in 16 patients and 17 patients were asymptomatic. At least 0.1 mV of ST segment depression developed in all subjects during the incremental exercise test at a mean exercise duration of 5.3 +/- 2.6 min, a rate-pressure product of 19,130 +/- 5,735 and oxygen uptake of 19.6 +/- 7.0 ml/kg per min. During the submaximal exercise test, 28 (85%) of the 33 patients had significant ST segment depression. Of these patients, 24 (86%) were asymptomatic, including 10 patients who had previously reported anginal symptoms during the incremental test. The average time to onset of 0.1 mV ST segment depression during the submaximal test was 8.1 +/- 4.5 min. These changes occurred at a rate-pressure product of 15,250 +/- 3,705 and an oxygen uptake of 14.3 +/- 5.9 ml/kg per min, and were significantly (p less than 0.001) lower than values observed during the graded exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1987

Plasma beta-endorphin levels in silent myocardial ischemia induced by exercise.

Although silent myocardial ischemia is a well recognized phenomenon, the reasons for the lack of symptoms in patients with coronary artery disease (CAD) is unclear. Because the endogenous opioid beta-endorphin has been related to pain modulation, plasma beta-endorphin levels were studied before, during and after exercise-induced ischemia in symptomatic and asymptomatic men. Because beta-endorphin responses have been closely linked to adrenocorticotropic hormone (ACTH) and cortisol responses, these hormones also were measured. Nine symptomatic and 12 asymptomatic patients with a high probability (at least 95%) of CAD and 8 apparently healthy men completed a Bruce protocol treadmill test. Blood samples were drawn before, during and 10 minutes after exercise. During exercise the measured hormones showed no significant increases from basal levels. However, plasma beta-endorphin, ACTH and cortisol levels were significantly elevated (p less than or equal to 0.01) 10 minutes after exercise in all 3 groups. There was no significant difference in plasma beta-endorphin levels during or after exercise between the symptomatic and asymptomatic patients with CAD. Thus, differences in circulating levels of beta-endorphin, ACTH and cortisol are not associated with the presence or absence of pain during exercise-induced myocardial ischemia.

Adrenocorticotropic Hormone↗
PubMed1985

A simple, valid step test for estimating maximal oxygen uptake in epidemiologic studies.

The authors' modification of the Astrand-Rhyming Cycle Ergometer Test is of short duration, has low initial and peak work rates and was in an earlier study applied for population fitness testing (N = 587) at a survey center after other cardiovascular risk factor measures were obtained in the home. To add fitness testing in the home, the authors have designed a safe, brief 10 inch (25.4 cm) high step test for estimating maximal oxygen uptake (VO2max). Measured maximal oxygen uptake for step tests has been shown to be approximately 10% higher than that reported for cycle tests. All test instructions and stepping rates were included on a cassette tape; heart rates were monitored by a digital tachograph during the last 30 seconds of stepping. Maximal oxygen uptake was measured directly on a bicycle, estimated by the step test, and measured by the authors' bike test in 48 men and women aged 19-70 years who took part in a community fitness program in Pawtucket, Rhode Island in January-February 1983. No significant differences in maximal oxygen uptake were found between the bicycle protocols. The step test estimate of maximal oxygen uptake (VO2max) was significantly higher (12%) than directly measured VO2max, reflecting the expected difference between stepping and cycling. The correlation between direct and both estimates was 0.92. The cross-validation correlation between the estimates was 0.98. The authors' protocol provides accurate estimates of maximal oxygen uptake and is safe and suitable for in-the-home assessment of fitness of people aged 19-70 years for epidemiologic studies.

Adult↗
PubMed1984

Circulatory effects of mental stress during exercise in coronary artery disease patients.

We examined the effects of mental stress during steady-state exercise on heart rate, blood pressure, pressure-rate product, and oxygen uptake in 10 coronary artery disease patients. Subjects walked at three mph with grade increases of 4% every two minutes until the target heart rate (60% peak heart rate from a previous symptom-limited exercise test) was reached. A computerized Stroop-Color-Word Test (mental stress) was added one minute after the subject reached steady-state exercise and lasted 11 +/- 4 minutes. When mental stress was added to steady-state exercise it significantly (p less than 0.01) increased the heart rate (101 +/- 15 to 108 +/- 19 beats per min), systolic (154 +/- 26 to 170 +/- 26 mmHg) and diastolic (86 +/- 10 to 92 +/- 13 mmHg) blood pressure, and pressure-rate product (158 +/- 42 to 179 +/- 48 x 10(-2)). This increase in the mean response during exercise and mental stress was not observed for oxygen uptake (17 +/- 6 to 18 +/- 5 ml/kg/min). The circulatory changes probably reflect increased sympathetic activity with both centrally mediated cardioacceleratory (and probably cardiac output) and vasoconstrictor effects during the combination of mental stress and steady-state exercise. The altered hemodynamics without concomitant changes in oxygen uptake has major implications concerning the safety of competitive exercise for people with coronary artery disease.

Adult↗
PubMedDate not supplied

Comparison of exercise, dipyridamole, and adenosine by use of technetium 99m sestamibi tomographic imaging.

BACKGROUND: Pharmacologic stress has been shown in animal studies to induce high degrees of myocardial hyperemia. At these levels of myocardial blood flow, the myocardial uptake of technetium 99m sestamibi may plateau and may affect the diagnostic accuracy. This study compared the effects of myocardial hyperemia induced by exercise, dipyridamole, and adenosine on 99mTc sestamibi tomographic imaging in normal subjects and patients with ischemic coronary artery disease. METHODS AND RESULTS: Twenty subjects (group I, 10 normal subjects; group II, 10 patients with known coronary artery disease) underwent 99mTc sestamibi tomographic imaging after rest, exercise, dipyridamole infusion, and adenosine infusions on separate occasions. Total and background-corrected myocardial counts of the resulting images were calculated. Visual and computer-generated quantitative myocardial perfusion defect analysis was performed in subjects in group II. For subjects in both groups I and II, there were no significant differences in the background-corrected myocardial counts obtained with exercise, dipyridamole, and adenosine stress. There were no significant differences in the myocardial perfusion defects obtained after the three different modes of stress, including percentage defect size, stress deficit percentage, percentage of ischemia, count deficit index, and defect nadir. CONCLUSIONS: The myocardial uptake of 99mTc sestamibi in normal subjects and patients with coronary artery disease is comparable after exercise, dipyridamole, and adenosine stress. In addition, the defect sizes and intensities with 99mTc sestamibi after all forms of stress were equivalent. Thus 99mTc sestamibi, in combination with either adenosine or dipyridamole infusions, provides imaging data equivalent to those with exercise and may be considered an alternative in patients unable to undergo adequate exercise.

Adenosine↗
PubMedDate not supplied

Cardiovascular changes in pregnancy evaluated by two-dimensional and Doppler echocardiography.

During pregnancy significant cardiovascular changes occur. To study these anatomic and physiologic changes we performed two-dimensional and Doppler echocardiography in 28 women during the third trimester (34.4 +/- 1.9 weeks) of pregnancy and then again after delivery (7.8 +/- 2.2 weeks). Fourteen nonpregnant age- and sex-matched subjects served as controls. Left ventricular diastolic and systolic dimensions were similar among pregnant, postpartum, and control subjects. Left atrial area as determined by two-dimensional echocardiography was significantly larger during pregnancy (16.7 +/- 4.0 cm2) compared with measurements postpartum (13.8 +/- 3.1 cm2) and with controls (15.5 +/- 3.5 cm2) (p less than 0.01). Doppler study showed that the ratio of early diastolic flow velocity to late diastolic flow velocity (E/A max) and E/A integral were lower among pregnant subjects (1.3 +/- 0.3, 2.0 +/- 0.5) compared with postpartum subjects (1.6 +/- 0.4, 2.5 +/- 1.5) and controls (1.9 +/- 0.5, 3.0 +/- 0.8) (p less than 0.05). Heart rate was higher among pregnant subjects (84 +/- 10 beats/min) compared with postpartum subjects (70 +/- 16) and controls (69 +/- 13) (p less than 0.05). In summary, in pregnant subjects during late third trimester left ventricular chamber dimensions were similar to these postpartum measurements in control subjects; however, the left atrium is dilated during pregnancy. Although there are significant alterations in Doppler-derived left ventricular diastolic parameters during the third trimester, increased heart rate and a dilated left atrium may explain these findings.

Adult↗
PubMedDate not supplied

Cross-sectional relationship between diet and physical activity in two southeastern New England communities.

The hypothesis that health promotive diets associated with higher levels of habitual physical activity confound the relationship between regular physical activity and health has not been well explored in epidemiologic studies. We evaluated self-reported physical activity, Willett Food Frequency dietary data, sociodemographic and physiologic factors cross-sectionally for 2,004 household survey participants in two southeastern New England communities. We compared the dietary habits of sedentary participants (n = 964) to those of moderately active (n = 600) and very active (n = 440) participants after adjusting for age, gender, education, smoking status, year of survey, and total calories. Our results showed that moderately active and very active participants consumed more fiber, less total fat, and less saturated fat than sedentary participants (P < .01). They also consumed more vitamins (A, C, D, E), beta carotene, and calcium, (P < .01), and ate more fruits and vegetables (P < .001) than sedentary participants. We found these relationships in both New England communities studied. This association between regular physical activity and diet suggests that the relationship of habitual physical activity and chronic disease may be confounded by diet.

Adult↗
PubMedDate not supplied

Developing a competency-based preventive medicine curriculum for medical schools.

Trends in patient morbidity and mortality, cost-effectiveness, and national recommendations mandate that we practice more preventive medicine. To address this need, we set out to develop a comprehensive curriculum in preventive medicine for medical schools. We constructed a competency-based (i.e., performance-based) curriculum with specific educational objectives defined by outcomes. Subject areas were subdivided by life stages, and learning objectives were created separately for epidemiology, assessment, and intervention. We hope that adoption of such an educational blueprint by medical schools will measurably enhance the attitudes, knowledge, and skills necessary for the incorporation of preventive principles into all aspects of clinical medicine.

Clinical Competence↗
PubMedDate not supplied

Coronary care unit requirements of patients with acute myocardial infarction treated with or without thrombolytic therapy: a pilot study.

OBJECTIVE: To determine if patients with acute myocardial infarction who receive thrombolytic therapy require more nursing care hours and a longer length of stay in the coronary care unit than those patients with acute myocardial infarction who do not receive thrombolytic therapy. DESIGN: Retrospective cohort study using the coronary care unit data base and patient classification records. SETTING: Northeastern university-affiliated, community-based, cardiovascular tertiary care center. PATIENTS: All patients admitted to the coronary care unit with a diagnosis of acute myocardial infarction were screened. Of these, 20 patients who also had a patient classification form completed were included in the study. Ten of these patients had received thrombolytic therapy and 10 had not. The patients were grouped according to treatment with a thrombolytic agent or conventional treatment. There was no significant difference in age between the groups (64 +/- 19 years and 67 +/- 15 years). OUTCOME MEASURES: Nursing care hours per patient per day and length of stay per patient in the coronary care unit. RESULTS: On days 1 and 2 of hospitalization, there were no significant differences in total nursing care hours provided per patient per day. On days 3 and 4, those patients who received thrombolytic therapy received fewer nursing care hours compared with those who did not (11.1 and 9.2 vs 13.8 and 12.7 hours per patient day, respectively; p < or = 0.05). Patients who were treated with thrombolytic therapy also had a significantly shorter coronary care unit stay (3.1 vs 4.0 days; p < or = 0.05). CONCLUSION: In this retrospective, observational pilot study, patients who received thrombolytic therapy for treatment of acute myocardial infarction had a significantly shorter coronary care unit stay and required significantly less nursing care on days 3 and 4.

Aged↗