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Biomedical subjects

M H Ellestad

Publications and source records attributed to M H Ellestad.

At least 73 records · Page 4Linked to original sources
PubMed1982

Prospective application of the multivariate approach to enhance the accuracy of the treadmill stress test.

Thirty normal subjects and 84 patients with coronary artery disease were subjected to stress testing and the results assessed by multivariate analysis. Probabilities for the presence or absence of disease were determined based on the results of a previous retrospective study. The multivariate analysis approach significantly improved the sensitivity, from 73% to 88%, and correct classification rate, from 78% to 88%, when compared to the ST response (P less than 0.05). The specificity remained significantly unchanged at 93% and 87% respectively in comparison to the ST response. The predictive value of a positive and negative test were not significantly different from those values from the ST response. Although the probability of disease could separate normal from diseased subjects, it could not separate single vessel from multi-vessel disease. The correct classification rate remained the same for all probabilities greater than or equal to 50% suggesting that a higher probability was not more accurate in detecting disease. The multivariate approach did not improve the accuracy of the stress test over the ST response in women, but the females in this study were a small and highly select group. Multivariate analysis appears to be a valuable method in detecting disease and appears to improve diagnostic accuracy over the ST response alone. However, further studies are needed to determine the final role of such a system, particularly in female subjects.

Adult↗
PubMed1982

Exercise testing in the evaluation of coronary artery disease.

Exercise testing, after having established the indication (Tables 1 and 2) is not only an important method for detection of coronary artery disease, it also enables delineation of exercise capacity and permits assessment of medical and surgical treatment. A subnormal increase in heart rate or blood pressure, or even a decrease in blood pressure, during exercise may frequently be found in patients with known coronary artery disease or in those at high risk of developing subsequent coronary events. Downsloping ST segment depression is highly specific for the presence of coronary artery disease; the specificity of upsloping ST segment depression can be increased on requiring this pattern to consist of a 2 mm depression 0.08 s beyond the J point. Consideration of the QTc interval may also be useful in patients with upsloping ST segment depression. Marked ST segment depression and early onset of ST segment depression during exercise is related to increasing severity of the disease while the duration of ST segment depression bears no certain relevance. ST segment elevation may be associated with transmural myocardial ischemia, left ventricular aneurysm or variant angina. An increase in the R wave amplitude appears indicative of multiple vessel disease, while a reduction in septal Q wave amplitude is suggestive of left anterior descending coronary artery occlusion. The current concept of testing asymptomatic patients for coronary artery disease has low predictive value. Post-myocardial infarction exercise testing is an objective method for evaluation of prognosis and guiding management. In the assessment of the results of aorto-coronary bypass surgery, the finding of persistent angina and/or ST segment depression during exercise is indicative of residual ischemia; normalization of the exercise ECG in the presence of a high-level exercise capacity is usually associated with good coronary perfusion. In order to provide maximum diagnostic utility, exercise testing must take into consideration other clinical findings as well as the prevalence of disease in the respective population. With respect to the coronary angiographic findings as well as the incidence of coronary events, the predictive value of exercise testing may be notably increased on consideration of multiple clinical and exercise variables. The exercise test has evolved into a clinically important noninvasive method for the evaluation of the functional aspects of the heart.

Adult↗
PubMed1981

Septal Q wave in exercise testing: angiographic correlation.

A study of septal Q wave response in lead CM5 was carried out to evaluate its usefulness in predicting coronary artery disease. Q wave amplitude was measured in 50 patients with coronary artery disease and 50 normal subjects before and immediately after exercise. In the 100 patients evaluated with coronary angiography, the septal Q wave in lead, CM5 was smaller in patients with coronary artery disease than in normal subjects at rest (probability [p] less than 0.001) and immediately after exercise (p less than 0.001). An embryonic (0.5 mm) or absent Q wave in lead CM5 was significantly more frequent in patients with coronary artery disease than in normal subjects both at rest (76 versus 48 percent) and after exercise (82 versus 16 percent). The sensitivity for S-T depression was 52 percent, the specificity 74 percent and the predictive value 70 percent. The respective values for Q wave were 82, 88 and 87 percent. These differences were not significant (p less than 0.05). When either a positive S-T or Q wave response was used, the sensitivity increased to 92 percent (p less than 0.05), and the specificity and predictive values remained unchanged (p less than 0.01). An increase in Q wave amplitude with exercise identified a false positive S-T segment response to stress in 75 percent of cases. Absence of the Q wave in lead CM5 with S-T depression after identified a true positive response in 100 percent of cases. These findings suggest that low Q wave voltage and it failure to increase after exercise imply abnormal septal activation, reflecting loss of contraction associated with ischemia. This finding may be a useful marker for ischemia; the increase in the septal Q wave with exercise may be of value in identifying a false positive S-T segment response.

Coronary Angiography↗
PubMed1981

Multivariate approach to the treadmill stress test: prospective study.

The multivariate analysis approach in 30 normal subjects and 84 patients significantly improved the sensitivity and correct classification rate when compared to the stress test (ST) response (p less than 0.05). Although the probability of disease could separate normal from diseased subjects, it could not separate single from multivessel disease. The correct classification rate remained the same for all probabilities greater than or equal to 50%, suggesting that a higher probability was not more accurate in detecting disease. Multivariate analysis appears to be a valuable method in detecting disease and appears to improve diagnostic accuracy over the ST response alone, especially in men.

Adult↗
PubMed1981

Radionuclide angiographic correlation of the R wave, ejection fraction, and volume responses to upright bicycle exercise.

The change in the R wave and the response of the ejection fraction to upright bicycle stress testing with radionuclide angiographic studies were determined for 18 control subjects and 29 patients with coronary arterial disease (70 percent stenosis or more). In the control group, all had an increase in the ejection fraction from 64.8 +/- 7.7 to 75.7 +/- 9.4 percent with stress (P less than 0.01). All control subjects had a decrease in the R wave with exercise. In the group with coronary arterial disease, most patients had a decrease in the ejection fraction averaging from 63.5 +/- 10.9 to 58.6 +/- 12.8 percent (P less than 0.01). An appropriate response of the R wave and ejection fraction (decrease in R wave and increase in ejection fraction or increase in R wave and decrease in ejection fraction) occurred in 23 (79 percent) of 29 subjects (P less than 0.005). The sensitivity, specificity, and predictive value for the response of the ejection fraction were as follows: 83 percent (24/29); 100 percent (18/18); and 100 percent (24/24). Of the patients with coronary arterial disease and an increase in the R wave, 17 (94 percent) had multivessel disease, while six (55 percent) of 11 with a decrease in the R wave had multivessel disease (P less than 0.05). The systolic volume decreased in all control subjects by -15.9 +/- 8.6 units (P less than 0.01) and increased in most of the group with coronary arterial disease by 13.7 +/- 17.8 units (P less than 0.01) in response to stress. There were 20 of 29 patients (P less than 0.05) with an appropriate response of the R wave and systolic volume to stress (increase in R wave and systolic volume or decrease in both). The change in the R wave did not correlate with the change in the diastolic volume with stress (P greater than 0.05). Changes in the R wave with exercise correlate with the change in the ejection fraction (and hence ventricular function) and with the changes in systolic volume, which may be one of the mechanisms of the response of the R wave, suggesting that the change in the R wave is related to changes in contractility. Increase in the R wave with stress suggests multivessel coronary arterial disease.

Adult↗
PubMed1980

Use of the multivariate approach to enhance the diagnostic accuracy of the treadmill stress test.

Twenty-one variables were analyzed in 142 male and 57 female individuals selected in a nonconsecutive fashion from a computerized list of patients with an angiogram and treadmill stress test. Patients were categorized as "normal" or "diseased" on the basis of angiographic results, significant coronary artery disease being defined as 70 percent or greater stenosis of one or more coronary arteries. Ten of the variables in males, and 14 of the 21 variables in females exhibited statistically significant differences between normal and diseased groups in univariate analysis of variance. Multivariate discriminant analysis, however, showed only three variable (duration, infarct by ECG, and ST depression in the immediate recovery period) to be significant in the final ranking for males; while five variables (infarct by history, presence of anginal pain during the test, ST resting changes in the normal individual, infarct by ECG, and age) were significant discriminators in females. For males, the sensitivity was 84%, the specificity was 80%, and the predictive value was 89%. For females, these values were 85%, 94% and 90%, respectively; while the entire group they were 85%, 86%, and 89%. In the classification matrices, males showed a misclassification percentage of 17% while females showed a 9% misclassification rate. Most of the misclassifications occurred with posterior probabilities ranging from 0.5 (50%) to 0.7 (70%); very few patients with high posterior probabilities were misclassified. It is concluded that multivariate discriminant analysis is a reliable means of determining the probability of coronary artery disease in a highly select group of patients; i.e. a large enough number of patients could be correctly classified with a high degree of certainty.

Adult↗
PubMed1980

Permanent pacemaker implantation using the femoral vein: a preliminary report.

A permanent pacemaker was implanted through the femoral vein in 23 patients using the percutaneous puncture technique. The pulse generator was placed in the lower abdominal wall. The method is simple and reduces the time necessary to accomplish implantation. Catheter extrusion in one patient was easily corrected. Another patient had late thrombophlebitis, possibly unrelated to the procedure. Catheter dislodgement occurred in four (4) patients and penetration of the right atrial appendage and right ventricular apex each occurred once. We believe these problems can be circumvented with more experience and expect the femoral approach to be a simple and practical method permanent pacemaker implantation.

Abdominal Muscles↗
PubMed1980

Ability of the R-wave change during stress testing to accurately detect coronary disease in the presence of left bundle branch block at rest.

The treadmill stress test and antiographic records of 18 patients with left bundle block on resting ECG were reviewed retrospectively. Thirteen of the patients had significant coronary artery disease defined as greater than or equal to 70% cross-sectional narrowing of one or more vessels, while 5 patients were hemodynamically and angiographically normal. The R-wave and ST-segment response to exercise were determined in each case and compared. A positive R-wave response was an exercise-induced increase or no change in amplitude over the baseline level, while a positive ST-segment response was greater than or equal to 2 mm of excerise-induced depression over the baseline level. The sensitivity for the R-wave response was 69% (9 of 13), the specificity was 100% (5 of 5), and the predictive value was 100% (9 of 9). For ST depression these values were 46% (6 of 13), 40% (2 of 5)8 and 67% (6 of 9). Although the number of patients in this study is small--a reflection of the fact that ST depression in the presence of left bundle branch block with exercise is associated with many false positive responses and hence less referral for stress testing--it appears that the R-wave response to exercise in the presence of left bundle branch block can accurately detect coronary artery disease.

Adult↗
PubMed1980

National survey of exercise stress testing facilities.

This report surveys the method, volume, protocol, criteria for a positive test, and complications of 518,448 exercise stress tests at 1,375 centers. Exercise test capacity was estimated at 2,147,450. An even distribution of bicycle, Master and treadmill testing was seen by regions within the country. The majority were using the Bruce protocol. The S-T segment depression of .5 mm was considered positive by 4.6 percent; 1.0 mm by 75.4 percent; 1.5 mm by 14.0 percent, and 2.0 mm or greater by 11.9 percent of the centers. Complications were 3.58 infarctions, 4.78 serious arrhythmias, and 0.5 deaths per 10,000 tests. Total of all complications was 8.86 per 10,000 tests. We conclude that exercise stress testing has increased with office-based testing undergoing the greatest expansion. This has been associated with few complications and greater safety.

Exercise Test↗
PubMed1979

Chronotropic incompetence in exercise testing.

Patients with chronotropic incompetence, defined as a failure of the heart rate response to exercise to rise to within two standard deviations of the expected increase with exercise, where studied and compared to patients with known coronary disease by angiogram with and without ST segment depression. 72% of the patients with chronotropic incompetence but without ST depression had significant coronary heart disease. The demonstration of chronotropic incompetence in exercise testing has important predictive implications and should be looked upon as carefully as ST segment changes. There was no evidence of SA node ischemia in these patients. Intrinsic heart rate measurements done in this study suggest autonomic dysfunction as a possible pathophysiologic mechanism for chronotropic incompetence. The heart rate response to exercise may be a useful predictor of the presence and severity of coronary disease. Therefore, a predicted heart rate response with standard deviation for age and sex should be included as part of the stress test protocol.

Adult↗
PubMed1979

Predicting coronary artery disease with treadmill stress testing: changes in R-wave amplitude compared with ST segment depression.

Coronary angiograms and treadmill stress tests were reviewed independently in 108 nonconsecutively selected cases. There were 16 patients (15%) with infarcts on ECG. Changes in R-wave amplitude and ST segments during exercise were evaluated to determine the sensitivity and specificity of each as a predictor of coronary artery disease (CAD). ST segment changes had a sensitivity of 49%, and a specificity of 74%. The sensitivity increased to 55% when infarcts were excluded. R-wave amplitude changes had a sensitivity of 68% and a specificity of 84%. The sensitivity increased to 78% when infarcts were excluded. An index formed by the sum of the change in R-wave amplitude and the magnitude of ST segment change yielded a sensitivity of 76% and specificity of 78%. The sensitivity increased to 84% when infarcts were excluded. There was no statistical difference between specificities for each criteria. Of those patients with an R-wave amplitude decrease, 69% had no coronary artery atherosclerosis, while 31% had significant lesions. Of those patients with no change or an increase in R-wave amplitude, 83% had coronary artery atherosclerosis, while 17% were normal. Of the 83% with coronary artery atherosclerosis, 81% had two and three vessel disease, while only 19% had single vessel disease. No change or an increase in R-wave amplitude during treadmill stress testing is a more reliable indicator of CAD in our laboratory than ST segment changes.

Adult↗
PubMed1979

Cardiac dysfunction in a patient with familial hypokalemic periodic paralysis.

A 19-year-old white man with familial hypokalemic periodic paralysis developed evidence of cardiac dysfunction during a episode of flaccid paralysis. This consisted of elevated total creatine phosphokinase (CPK), an increased myocardial fraction of CPK (myocardial band), alteration in the lactic dehydrogenase isoenzyme pattern, severe bradycardia, and evidence of left ventricular dysfunction. These findings, in conjunction with selected cases from the literature, suggest the possibility that cardiomyopathy may be a heretofore unrecognized complication of this disorder.

Adult↗
PubMed1978

Significance of changes in R wave amplitude during treadmill stress testing: angiographic correlation.

Coronary angiograms and treadmill stress tests were reviewed in 89 patients. Changes in R wave amplitude were measured in the control and immediate postexercise periods. Of 45 patients with normal coronary arteries, 41 (91 percent) had a decrease in R wave amplitude (P less than 0.01); 3 (7 percent) had an increase in amplitude, including 2 with abnormal left ventriculograms. The remaining patient (2 percent) had abnormal wall motion but no change in R wave amplitude. Among the 44 patients with significant coronary artery disease (70 percent or greater luminal narrowing in one or more vessels), R wave amplitude increased after exercise in 26 (59 percent) with more severe coronary artery disease. R wave amplitude decreased in 18 patients (41 percent) with normal or minimally abnormal resting ventriculograms and less severe coronary artery disease (P less than 0.01). Changes in R wave amplitude reflect ventricular function, an increase in R wave amplitude reflecting more severe dysfunction and severe coronary narrowing. A decreased R wave amplitude indicates normal or minimal dysfunction and is strongly associated with normal coronary angiograms.

Adult↗
PubMed1978

Significance of chest pain during treadmill exercise: correlation with coronary events.

A follow-up study of 1,402 patients with a positive maximal treadmill stress test was made to evaluate the significance of angina during the test. Life tables were constructed and evaluated for significance of age, sex and work load at onset of angina. Coronary events (myocardial infarction, progression of angina and coronary death) were twice as frequent in subjects with angina and S-T segment depression as in those without angina. The increased incidence in 4 years held for all coronary events and was still doubled at 7 years for progression of angina and coronary death. The incidence of coronary events was more than twice as great when the angina was induced by a light work load (4 metabolic equivalents = METS) as when it was induced by a heavy work load (8 to 9 METS). Men aged 41 to 50 years having angina during exercise testing had a 3-fold greater incidence of coronary events and a 4-fold greater incidence of myocardial infarction compared with their counterparts who had S-T segment depression alone. In this study, angina during exercise testing identified 85% of true positive tests for coronary artery disease, whereas S-T depression alone identified only 64% of such tests. Thus, angina during exercise testing increases the sensitivity of the test and identifies cohorts of subjects at high risk for subsequent coronary events.

Age Factors↗