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Biomedical subjects

V Froelicher

Publications and source records attributed to V Froelicher.

At least 55 records · Page 3Linked to original sources
PubMed1987

Influence of exercise training on spatial R-wave amplitude in patients with coronary artery disease.

To evaluate the influence of an exercise program on spatial and left precordial R-wave amplitude among patients with coronary artery disease, computerized electrocardiogram (ECG) data were acquired during maximal treadmill testing before and after 1 yr in 89 patients randomized to either exercise (n = 40) or control (n = 49) groups. Spatial and lateral R-wave amplitudes were derived from the orthogonal Frank (XYZ) lead system. The exercise group significantly increased maximal O2 consumption (0.17 l/min), whereas controls decreased significantly (0.12 l/min, P less than 0.01 between groups). No significant changes in electrocardiographic R-wave voltage measurements occurred within or between groups during the year. It is concluded that exercise training does not result in increases in R-wave voltage in patients with coronary artery disease.

Angina Pectoris↗
PubMed1987

Perceived exertion and gas exchange after calcium and beta-blockade in atrial fibrillation.

Nine male patients (mean age 65 yr) with chronic atrial fibrillation underwent maximal exercise testing during placebo, beta-adrenergic (celiprolol, 600 mg), or calcium (diltiazem, 30 or 60 mg four times daily) channel blockade. The results were analyzed to determine which factors most closely related to ratings of perceived exertion (RPE) during exercise. Heart rate (HR), blood pressure (BP), oxygen uptake (VO2), minute ventilation (VE), and carbon dioxide production (VCO2) were evaluated at rest, 3.0 mph/0% grade, the gas exchange anaerobic threshold (ATge), 80% of placebo maximal O2 uptake, and maximal exercise. Both beta-adrenergic and calcium channel blockade significantly reduced heart rate and systolic blood pressure relative to placebo; these effects were more profound during beta-adrenergic blockade and as exercise progressed. Correlation coefficients and estimates of slope were derived for changes in RPE during exercise vs. changes in HR, VO2, VE, and VCO2 during the three treatments (r = 0.76 to 0.92, P less than 0.001). Although RPE was significantly correlated with HR during placebo and diltiazem therapy (r = 0.45, P less than 0.01), this was not the case during beta-adrenergic blockade (r = 0.31, NS). Slope of the regression lines between RPE and VO2, VE, and VCO2 did not differ between the three treatments. Slope of the regression lines between RPE and HR differed only during calcium channel blockade. Because the presence of atrial fibrillation and beta-adrenergic blockade altered the associations between RPE, VO2, and HR, these results suggest that VE is more closely related to RPE than the other parameters.

Adrenergic beta-Antagonists↗
PubMed1987

A logical approach to screening for coronary artery disease.

Although changes in lifestyle may increase the life expectancy of persons at high risk for coronary disease, there is no cost-effective screening test that can select these persons from the general population. Exercise testing has been considered, but epidemiologic studies have not proved that it effectively identifies persons at risk for myocardial infarction or cardiac death. Theoretically, exercise testing should have limited sensitivity in predicting events because abnormal responses occur only when sufficient atherosclerotic plaque has accumulated to impede coronary flow. Abnormal test responses cannot occur before plaque has reached such dimensions. A test that indicates the presence of any atherosclerotic plaque in the coronary lumen would be more useful than one that indicates compromise of blood flow. Data show that sensitive detection of coronary calcific deposits accurately predicts the presence of atherosclerotic plaque. Sensitive radiographic techniques such as digital subtraction fluoroscopy need to be developed as screening tests. Screening studies should be blinded and include only hard endpoints, and follow-up periods should be no less than 10 years so that the detected disease can develop to its symptomatic endpoint.

Calcinosis↗
PubMed1986

Computer analysis of exercise-induced changes in QRS duration in patients with angina pectoris and in normal subjects.

Exercise-induced changes in QRS duration were assessed in 25 normal subjects and in 17 patients with stable ischemic heart disease. None had bundle branch block or were taking medications, and all patients had angina pectoris induced during the test. QRS duration and ST60 amplitude were measured by computer during rest while standing, at a heart rate of 100 to 110 bpm during exercise, at peak heart rate for the angina patients (mean of 127 bpm), and at the corresponding matched heart rate and peak heart rate for the normals (mean of 174 bpm). As heart rate increased, the patients showed significant ST60 depression. In normal subjects, the QRS duration tended to increase initially but at the matched heart rate level and at peak heart rate it decreased significantly compared to rest (p less than 0.01). The QRS duration in the angina patients increased significantly at the heart rate level of 100 to 110 bpm (p less than 0.05). Of the eight patients who reached a peak heart rate above 127 bpm, six (75%) during that period further increased QRS duration compared to three (12%) of the 25 normal subjects (p less than 0.001). We conclude that a consistent increase in QRS duration during exercise, although subtle, may be a marker of ischemia and consequently a potential diagnostic tool.

Adult↗
PubMed1986

Can myocardial ischemia be recognized by the exercise electrocardiogram in coronary disease patients with abnormal resting Q waves?

This study was performed in order to determine whether exercise-induced myocardial ischemia demonstrated by thallium-201 imaging could be detected by ST segment shifts in patients with abnormal Q waves at rest. Fifty-four patients with coronary artery disease and exercise-induced thallium-201 defects were compared to 22 patients with similar Q wave patterns but without thallium-201 exercise defects and to 14 normal subjects. Exercise data were analyzed visually in the 12-lead ECG and for spatial ST vector shifts. Both ST segment depression observed on the 12-lead ECG and spatial criteria were reasonably sensitive and specific for ischemia when the resting ECG showed no Q waves or inferior Q waves (range 69% to 93%). However, when anterior Q waves were present, ST segment shifts could not distinguish patients with ischemia from those with normal perfusion as determined by thallium imaging.

Adult↗
PubMed1986

Acquired atherosclerotic aortopulmonary fistula presenting as new-onset congestive heart failure.

A middle-aged patient with new-onset congestive heart failure, a loud precordial systolic murmur, and a widened mediastinum on chest radiography is described. Noninvasive studies in addition to the clinical examination suggested an unusual complication of atherosclerotic aortic disease, which was demonstrated at aortography and confirmed at surgery. This case stresses the importance of a careful bedside examination in addition to selective noninvasive studies in patients with new-onset or atypical congestive heart failure.

Aortic Diseases↗
PubMed1985

Can patients with coronary artery disease receiving beta blockers obtain a training effect?

Fifty-nine male volunteers with stable coronary artery disease underwent 1 year of supervised exercise and were compared with 69 similar control patients. Both groups underwent exercise tests initially and at 1 year to determine maximal oxygen uptake. Initial and 1-year tests were performed with patients off all cardiac medications including beta blockers. Although patients had been randomized to exercise intervention, administration of beta blockers was at the prerogative of their physicians. Thirty-seven percent of the trained group and 39% of the control group were taking beta blockers during the year of study. Regardless of whether or not beta blockers were administered, patients in the exercise intervention group had a significant increase in aerobic capacity and improvement in the other hemodynamic markers of training compared with control subjects. Of the trained patients, those on beta blockers were able to comply with the exercise regimen as well as those not taking beta blockers.

Adrenergic beta-Antagonists↗
PubMed1985

Failure of transdermal nitroglycerin to improve exercise capacity in patients with angina pectoris.

Sixteen patients with stable angina pectoris were studied in a double blind crossover manner utilizing treadmill exercise testing with the direct measurement of total body oxygen uptake, 1 and 24 hours after application of a 20 cm2 transdermal nitroglycerin system and identical placebo. Testing was performed after a 3 day lead-in period of treatment with either an active patch or placebo. Points of analysis were peak angina and the submaximal work load occurring at 4 minutes of exercise. No statistically significant differences were observed between nitroglycerin and placebo treatment in any of the rest hemodynamic or peak angina variables at 1 or 24 hours. A significant increase in the rate-pressure product at the submaximal work load was observed 1 hour after transdermal nitroglycerin relative to placebo application. However, no significant differences were observed in any of the other measured variables at the submaximal work load, 1 or 24 hours after nitroglycerin application. The once daily application of a 20 cm2 transdermal nitroglycerin system was ineffective in altering the exercise capacity of patients with angina pectoris. The lack of efficacy at 1 hour appears to be due to inadequate nitroglycerin blood levels; at 24 hours it may be due to tolerance.

Adult↗
PubMed1985

Spatial R wave amplitude changes during exercise: relation with left ventricular ischemia and function.

Thirty patients who exhibited increased and 65 patients decreased spatial R wave amplitude during exercise testing were compared for left ventricular function and ischemic variables. Spatial R wave amplitude was derived from the three-dimensional Frank X, Y, Z leads using computerized methods. All patients had stable coronary artery disease and they were classified into two groups: one that attained a higher (n = 48) and one a lower (n = 47) median value of maximal heart rate during exercise (161 beats/min). Within these two groups, patients with increasing or decreasing spatial R wave amplitude during exercise were analyzed for differences in oxygen consumption, exercise-induced changes in spatial R wave amplitude, ST segment depression laterally (ST60, lead X), ST displacement spatially, left ventricular ejection fraction at rest, change in left ventricular ejection fraction with exercise and thallium-201 ischemia during exercise. Significant differences were demonstrated only in exercise-induced spatial R wave amplitude changes (p less than 0.0001). There was no significant correlation between exercise-induced change in heart rate and change in spatial R wave amplitude in either the group with increasing or the group with decreasing spatial R wave amplitude. It is concluded that changes in spatial R wave amplitude during exercise are not related to ischemic electrocardiographic or thallium-201 imaging changes or to left ventricular ejection fraction determined at rest or during exercise.

Coronary Disease↗
PubMed1985

A randomized trial of the effects of exercise training after coronary artery bypass surgery.

Fifty-three male volunteers who had undergone coronary artery bypass surgery were randomized to a medically supervised exercise program (N = 28) or to usual community care (N = 25). They were tested initially and at one year with exercise tests for thallium scintigraphy, maximal oxygen uptake, and electrocardiography. Approximately one third of the patients had signs and/or symptoms of ischemia consistent with incomplete or unsuccessful revascularization. Over the year there were five dropouts, but no major complications occurred. The exercisers attended an average of 82% of the sessions (three times a week) and trained at 80% of their maximal heart rate. Both the exercisers with and those without angina had significant increases in estimated and measured oxygen uptake and significant declines in submaximal and resting heart rate. There was a trend toward improved thallium scans in the exercised patients with angina.

Adult↗
PubMed1984

A randomized trial of exercise training in patients with coronary heart disease.

In order to determine whether or not regular exercise could alter myocardial perfusion or function, we randomized 146 male volunteers with stable coronary heart disease to either a supervised exercise program (n = 72) or to a usual care program (n = 74). Subjects underwent exercise tests initially and one year later. Significant differences between the two groups included improved aerobic capacity, thallium ischemia scores, and ventricular function in the exercise intervention group. It was not possible to classify the conditions of patients as to the likelihood of improvement or deterioration. This study demonstrated changes in myocardial perfusion and function in a select group of middle-aged men with coronary heart disease who underwent a medically appropriate exercise program lasting one year, but these changes were relatively modest.

Adult↗
PubMed1984

Can areas of myocardial ischemia be localized by the exercise electrocardiogram? A correlative study with thallium-201 scintigraphy.

In order to determine whether areas of ischemia identified by thallium-201 scintigraphy could be localized by exercise ECG, we studied 54 patients with stable coronary heart disease. All 54 patients had exercise-induced thallium-201 scintigraphic defects. Their exercise ECG test results were compared to their thallium-201 images and also to 14 low-risk normal subjects. Exercise data were analyzed for spatial ST vector shifts, using a computer program in order to most accurately classify ST segment depression and elevation. Thallium-201 ischemic defects detected in our patients included areas in the septum and the inferior, lateral, and anterior walls. Twenty-six of these 54 patients also had coronary angiography for classification and comparison as having either localized or generalized disease. None of the scintigraphic ischemic sites or angiographic diseased areas could be specifically identified by exercise-induced ST vector shifts. Therefore, the surface exercise ECG has limitations in localizing ischemia to specific areas of the myocardium.

Adult↗
PubMed1984

A randomized trail of the effects of 1 year of exercise training on computer-measured ST segment displacement in patients with coronary artery disease.

As part of a randomized trial of the effects of 1 year of exercise training on patients with stable coronary artery disease, 48 patients who exercised and 59 control patients had computerized exercise electrocardiography performed initially and 1 year later. The patients who had exercise training as an intervention had a 9% increase in measured maximal oxygen consumption and significant decreases in heart rate at rest and during submaximal exercise. ST segment displacement was analyzed 60 ms after the end of the QRS complex in the three-dimensional X, Y and Z leads and utilizing the spatial amplitude derived from them. Statistical analysis by t testing yielded no significant differences between the groups except for less ST segment displacement at a matched work load, but this could be explained by a lowered heart rate. Analysis of variance yielded some minor differences within clinical subgroups, particularly in the spatial analysis. Obvious changes in exercise-induced ST segment depression could not be demonstrated in this heterogeneous group of selected volunteers with coronary artery disease secondary to an exercise program.

Adult↗
PubMed1984

A comparison of the standard 12-lead electrocardiogram to exercise electrode placements.

In order to determine the effect of electrode placement and standing on the 12-lead electrocardiogram required prior to exercise testing, 104 male patients with stable coronary heart disease were studied. Electrocardiograms were recorded with two different placements of the arm electrodes commonly used for exercise testing with the patient supine and standing. These were compared to a standard ECG with the electrodes placed at the wrists and ankles with the patient supine. The four ECGs gathered on each patient were analyzed using standard visual techniques for diagnostic changes and using a computer for analysis of axis, amplitudes, and durations. There were important differences between the standard 12-lead ECG and the ECGs gathered with the pre-exercise test modifications. These differences were minimized by placing the arm electrodes as close to the shoulders as possible and by recording the ECG with the patient supine.

Adult↗
PubMed1984

The reproducibility of hemodynamic, electrocardiographic, and gas exchange data during treadmill exercise in patients with stable angina pectoris.

Fourteen male patients with exercise test-induced angina and ST-segment depression underwent treadmill testing on three consecutive days to evaluate the reproducibility of certain treadmill variables. Computerized ST-segment analysis and expired gas analysis, including anaerobic threshold, were evaluated for reproducibility using an intra-class correlation coefficient analysis. Measured oxygen uptake at peak exercise displayed better reproducibility than total treadmill time, the onset of angina, and the gas exchange anaerobic threshold (ATGE). The double product, heart rate, and ST-segment displacement in lead X were found to be reproducible at peak exercise, the onset of angina, and the ATGE. The incorporation of gas exchange analysis can provide accurate physiologic determinants of exercise capacity in patients with angina pectoris. In addition, noninvasive estimates of myocardial oxygen demand and ischemia can be reproducibly determined. These findings have important implications for the design of studies evaluating the effects of an intervention on angina pectoris.

Adult↗