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V F Froelicher

Publications and source records attributed to V F Froelicher.

At least 19 recordsLinked to original sources
PubMed1992

Prediction of severe coronary artery disease using computerized ECG measurements and discriminant function analysis.

This study tested the hypothesis that discriminant function analysis of clinical and exercise-test variables including computerized ST measurements could improve the prediction of severe coronary artery disease. Secondary objectives were to demonstrate the effect of digoxin and/or resting electrocardiographic (ECG) abnormalities, and to evaluate the relative importance of ST measurements made during the recovery phase and in the three lead group areas. The design was a retrospective analysis of data collected during exercise testing and coronary angiography. The ECG data were gathered and stored in digital format on optical discs and all ST measurements were made off-line using the authors' own software. Univariate and multivariate analytic methods were used to analyze all pretest characteristics as well as hemodynamic and computerized ECG responses to exercise. A 1,000-bed Veterans Affairs Medical Center served as the setting. The study included 446 male veterans who underwent a sign or symptom limited treadmill exercise test and coronary angiography. Analysis was also performed on a subset of this population formed by excluding patients receiving digoxin or with resting ECGs exhibiting left ventricular hypertrophy or ST depression (n = 328). In the total study population, the authors derived a treadmill score using discriminant function analysis. This score included: (1) the time-slope area in lead V5 during recovery; (2) delta heart rate; (3) angina pectoris during the exercise test; and (4) presence of diagnostic Q waves on the resting ECG. This score was effective in predicting triple vessel/left main disease and outperformed exercise-induced ST depression for predicting severe coronary artery disease. After exclusion of patients with ECGs exhibiting left ventricular hypertrophy or resting ST depression and patients receiving digoxin, discriminant function analysis chose: (1) the time-slope area in lead V5 during recovery and (2) delta heart rate. Exclusion of these patients resulted in a nonsignificant decrease in specificity of all ST criteria. ST-segment amplitude or slope in lead V5 at 3.5 minutes in recovery clearly outperformed the maximal exercise measurements in both groups. Summing the depressions or selecting the most depression in the three areas (ie, lateral-V5, inferior-II, anterior-V2) did not improve test performance. Leads other than V5 did not contain significant diagnostic information. A quantitative approach to exercise testing using discriminant function analysis enhanced the tests' performance for predicting severe coronary disease. The inclusion of patients taking digoxin or with resting ECG abnormalities nonsignificantly decreases the specificity of all ST criteria.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1979

Profiles of radionuclide left ventricular ejection fraction changes induced by supine bicycle exercise in normals and patients with coronary heart disease.

This paper presents the profiles of left ventricular ejection fraction (EF) during and following supine bicycle exercise in normal subjects and in patients with coronary heart disease, as well as the relationship of the described patterns to clinical parameters. Twenty normal men and 40 patients with coronary artery disease were studied using gated equilibrium radionuclide angiography (EQ-EF). In the normals, during exercise, EF increased by a mean of 25% of the resting value, with an increase of no less than 11%. The exercise-limiting symptom in patients with coronary artery disease was angina pectoris in 20 and fatique in the other 20 patients. In the angina patients, there was a mean decrease in EF of 20%, and in the other coronary artery disease patients ejection fraction change little. Only two patients with coronary artery disease increased from a normal resting value to peak exercise by more than 11%, and they had isolated right coronary lesions. An "overshoot" elevation of ejection fraction above resting levels was demonstrated following termination of exercise in most patients. The patients with a significant fall in exercise ejection fraction more frequently had abnormal exercise-induced ECG changes as well as abnormal left ventriculograms and more severe coronary artery disease at cardiac catheterization than the patients with little change in ejection fraction. We conclude that 1) normals could be separated from most patients with significant coronary artery disease in this study population; 2) ejection fraction must be measured at maximal exercise for it to have diagnostic value, since there could be normal rise before and after peak exercise and an abnormal response missed; and 3) the ejection fraction response to exercise reflects the severity of the underlying coronary artery disease. The described patterns of exercise-induced changes in left ventricular ejection fraction are important to consider when using this new technique to diagnose and evaluate patients with coronary artery disease.

Adult↗
PubMed1979

Normal electrocardiographic waveform characteristics during treadmill exercise testing.

Forty asymptomatic male patients at low risk for cardiovascular disease completed maximal treadmill testing. Electrocardiograms from leads CC5, CM5, V5, Yh and Z were recorded across multiple pretest, exercise and recovery conditions. ECG waveforms were subsequently digitized, averaged and processed to provide Q-, R-, S- and T-wave amplitudes, ST-segment means and slopes, and QS- and RT-interval durations. Average R-wave amplitude increased during early exercise and then dramatically decreased to maximum effort. Average S-wave amplitude became greater as exercise progressed. Average J junction was slightly positive before exercise, became negative during exercise (except lead Z) and returned to zero after exercise. The ST-segment slope increased dramatically with progressive exercise. The response of T-wave amplitude, RT and QS intervals are also described. Separately, 22 asymptomatic male subjects each completed two maximal treadmill tests 2 weeks apart. ECG data acquisition and processing were similar to those noted above. Pooled, within-subject estimates of variability were computed for the ECG leads, ECG measurements and protocol conditions. These variability estimates are useful for interpreting ECG responses to exercise testing.

Adult↗
PubMed1977

New practical treadmill protocol for clinical use.

A new continuous treadmill protocol (USAFSAM) has been designed using a constant treadmill speed (3.3 miles/hour) and regular equal increments in treadmill grade (5%/3min). The constant treadmill speed requires only initial adaptation in patient stride, reduces technician adjustments and produces less electrocardiographic motion artifact than do protocols using multiple or higher treadmill speeds, or both. The regular equal increments in treadmill grade are easy to implement and provide a larger number of work loads than do protocols that are discontinuous or require larger changes in work load. The USAFSAM protocol was compared with the older Balke-Ware protocol in 26 healthy men (aged 30 to 59 years). Each fasting subject completed two maximal treadmill tests from each protocol. Measurements included minute heart rate from the electrocardiogram, auscultatory blood pressures and oxygen consumption obtained with standard techniques. Similarities in between-protocol measurements for submaximal and maximal treadmill efforts were impressive; differences were small and unimportant. Further, both protocols showed equal reproducibility for the measurements noted. Importantly, time to maximal effort was reduced by 24% with the USAFSAM protocol. The USAFSAM treadmill protocol has since been used in more than 500 clinical and screening examinations, thus confirming its advantages and practicality for routine clinical stress testing. Normal reference values previously established for the Balke-Ware protocol are shown to apply to the new USAFSAM protocol as well.

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PubMed1977

The electrocardiographic response to maximal treadmill exercise of asymptomatic men with left bundle branch block.

This study presents the results of maximal treadmill testing and coronary angiography in 31 asymptomatic USAF aircrewmen with acquired left bundle branch block. There were two subgroups: 26 men with normal coronary angiography and five men with significant angiographic coronary angiography and five men with significant angiographic coronary artery disease. The mean amount of maximal ST-segment depression induced by treadmill exercise was --0.5 mv. for both groups and the range in the normal subgroup was --0.3 to --1.0 mv. No significant differences were found between the groups. We concluded that apparently healthy, asymptomatic men with acquired left bundle branch block can have considerable ST-segment depression in response to maximal treadmill testing and that their ST-segment response cannot be used to make diagnostic decisions about them.

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PubMed1977

Angiographic findings in asymptomatic aircrewmen with electrocardiographic abnormalities.

Cardiac catheterization was used to evaluate 298 asymptomatic, apparently healthy aircrewmen with electrocardiographic abnormalities. These men were identified from annual electrocardiograms and exercise tests used to screen for latent heart disease. Data from 27 additional symptomatic aircrewmen who underwent cardiac catheterization because of mild probable angina pectoris are also included. The men were grouped according to major reason for cardiac catheterization. The order of groups by increasing prevalence of coronary artery disease was as follows: abnormal treadmill test (labile lead only), supraventricular tachycardia, right bundle branch block, left bundle branch block, abnormal treadmill test, ventricular irritability, probable infarct and angina. Approximately 60 percent of the men were completely free of angiographic coronary artery disease. Risk factors and other possible causes for the electrocardiographic abnormalities are discussed. The electrocardiographic abnormalities studied have a poorer predictive value for coronary artery disease in asymptomatic apparently healthy men than in a hospital or clinic population.

Adult↗
PubMed1977

The detection of asympatomatic coronary artery disease.

In summary, near-maximal or maximal exercise testing has a sensitivity of approximately 60% and a specificity of approximately 90% for coronary atherosclerotic heart disease. When screening asympatomatic men with exercise testing, an abnormal response identifies a group of men at very high risk for coronary artery disease. However, the predictive value limitations are obvious and the false-positive problem must be realized. At present, there is no second line of noninvasive studies that can separate an exercise-test false positive from a true positive with certainty. Risk-factor consideration may help separate them; The sensitivity limitations of exercise testing must be especially considered when evaluating people at high risk for CAD. An abnormal test response does not absolutely predict the presence of CAD and a normal response does not rule out its possibility. In appropriate instances where coronary angiography can be performed at minimal risk and when it is justified for reasons of public safety or individual well-being, this procedure can give a reasonably definitive answer. Creation of iatrogenic "cardiac cripples" can be the most common complication of screening tests and should be avoided. Therefore, good clinical judgment needs to be used in conjunction with any screening test.

Adult↗
PubMed1977

The response of healthy men to treadmill exercise.

Heart rates, blood pressures, and functional responses to submaximal, maximal and postexertional treadmill testing are presented for a group of 704 healthy, asymptomatic aircrewmen referred to the USAF School of Aerospace Medicine. The indicated measurements are individually described by the use of percentiles. These data provide the practicing clinician with an accurate and complete description of the response of healthy men to treadmill exercise.

Adult↗
PubMed1977

The electrocardiographic response to maximal treadmill exercise of asymptomatic men with right bundle branch block.

This study presents the results of maximal treadmill testing and cardiac catheterization in 40 asymptomatic and apparently healthy men with acquired right bundle-branch block. Eight of the men had significant angiographic coronary artery disease, and six of the eight only had single-vessel disease. The 40 men had normal maximal oxygen consumptions, normal maximal heart rates, and normal maximal blood pressure responses; none of the men had abnormal ST-segment changes in response to maximal treadmill testing. Thus, the sensitivity of exercise testing for coronary artery disease in men with right bundle branch block is uncertain. However, the apparently high specificity of exercise testing demonstrated by this study necessitates further evaluation for coronary artery disease in men with right bundle branch block who develop abnormal ST-segment depression in response to exercise testing.

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PubMed1977

Does exercise conditioning delay progression of myocardial ischemia in coronary atherosclerotic heart disease?

The data regarding the effect of physical of physical conditioning on the progression of myocardial is chemia, although suggestive of a favorable influence, are in no way definitive. Efforts to alter the physical activity habits of our population should not supersede efforts directed to alter the major risk factors. The emphasis in the prevention of coronary atherosclerotic heart disease for the general public should be on the well established cardinal risk factors, that is, hypercholesterolemia, hypertension, and cigarette smoking. The National Postinfarction Rehabilitation Study, when completed, may demonstrate how physical conditioning influences the progression of myocardial ischemia. However, "moderate activity is a part of a balanced satisfying living and is the safe and sane hygienic prescription of the thoughtful physician for his patients, the high risk and the healthy alike.

Adult↗
PubMed1977

Clinical medicine review: three unique presentations of ischemic heart disease.

Unstable angina pectoris, Prinzmetal variant angina, and ischemic heart disease with normal coronary arteries, are three unique syndromes of ischemic heart disease that have recently become better understood. With the recognition of their manifestations, the combination of modern medical techniques and collaborative epidemiological studies should eventually lead to their early diagnosis, optimal treatment, and possible prevention.

Acute Disease↗