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Biomedical subjects

P S Greenberg

Publications and source records attributed to P S Greenberg.

At least 19 recordsLinked to original sources
PubMed1987

Autonomic responses in chest pain syndromes as compared to normal subjects.

The heart rate response to standing, cough, hand grip, and deep breathing were examined in normal subjects and coronary artery disease patients (greater than 70% diameter narrowing). The heart rate responses to these maneuvers were reduced in coronary patients and in anginal patients with normal coronary angiograms, as compared to normals. Detection (with the heart rate response to standing) was determined by using an RR interval cutoff of 140 ms for males and 120 ms for females discriminated between normals and CAD patients. In men sensitivity was 0.58, specificity 0.87 and CCR 0.75, and in women sensitivity was 0.67, specificity 0.79 and CCR 0.75. These values are similar to those reported for ST segment depression in similar populations. When separating normals from those with 2 and 3 vessel disease--sensitivity is 0.67, specificity 0.87, predictive value 0.71 and CCR 0.80. The response to cough, hand grip, and deep breathing showed similar trends but had less specificity than the response to standing. Thus, the heart rate response to most autonomic maneuvers is blunted in subjects with coronary disease and in those with pain syndromes sent for coronary angiography. These findings need testing in larger populations but autonomic maneuvers fail to discriminate patients with coronary disease from those with normal angiograms presenting with chest pain syndromes.

Adult↗
PubMed1984

Comparison of the multivariate analysis and CADENZA systems for determination of the probability of coronary artery disease.

The accuracy of 2 discriminate systems for diagnosis of coronary artery disease (CAD), multivariate analysis (MVA) and Bayesian analysis (CADENZA), was evaluated in 113 patients undergoing electrocardiographic stress testing and coronary angiography. MVA uses weighting factors (F values) generated from our patient data, whereas CADENZA uses probabilities gleaned from an extensive review of the American literature. Overall accuracy was similar. MVA had a higher sensitivity for 1-vessel CAD (75 versus 33%), but CADENZA was better for determining the severity of CAD. The 2 systems provided posterior probabilities for disease that were highly correlated (r = 0.56; p less than 0.001). Both systems suggest the need for further testing based on the probability generated; herein lies their major strength. The application of such systems should help the clinician reach a diagnosis or make a decision as to management in a cost-effective manner.

Bayes Theorem↗
PubMed1983

Use of multivariate analysis to improve the accuracy of radionuclide angiography with stress in detecting coronary artery disease in men.

A multivariate analysis (MVA) system was derived retrospectively from a population of 76 males with coronary artery disease and 18 control subjects. Posterior probabilities were then derived from such a system prospectively in a new male population of 11 subjects with normal coronary arteries and hemodynamics and 63 patients with coronary artery disease. The sensitivity was 84% compared to that for change in ejection fraction (delta EF) greater than or equal to 5 criterion of 71% (p less than 0.01), the specificity was 91% compared to 73% for the delta EF greater than or equal to 5 criterion (p greater than 0.05), and the correct classification rate was 85% compared to 72% for the delta EF greater than or equal to 5 criterion (p less than 0.01). The significant variables were: change in EF with exercise, percent maximal heart rate, change in end-diastolic volume (delta EDV) with exercise, change in R wave, and exercise duration. Application of the multivariate approach to radionuclide imaging with stress, including both exercise and nuclear parameters, significantly improved the diagnostic accuracy of the test and allowed for a probability statement concerning the likelihood of disease.

Adult↗
PubMed1983

Atrial synchronous ventricular inhibited pacing (VDD): an underutilized mode of pacing.

The design of atrial synchronous, ventricular inhibited (VDD) pacemakers has been improved. Physiologic long-term benefit has now been established, although this mode of pacing accounts for approximately one percent of implanted devices. With the ultimate control of pacemaker-mediated tachycardia through atrial refractory programming close at hand or already available, one might expect an increase in VDD pacing in patients with exercise-induced high degree heart block and stable sinus node function.

Arrhythmias, Cardiac↗
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↗
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

Use of heart rate responses to standing and hyperventilation at rest to detect coronary artery disease: correlation with the S-T response to exercise.

The heart rate responses to standing and to hyperventilation, expressed as a percent change over the sitting heart rate value, were measured in 48 patients with angiographic coronary artery disease (less than or equal to 70 percent luminal narrowing) and 50 young, healthy asymptomatic individuals. When an abnormal response suggesting coronary artery disease was defined as an increase in the heart rate of < 15% over the sitting value and < 20% increase in the heart rate to hyperventilation relative to the sitting value, the sensitivity of such a criterion was 56%, the specificity was 92% and the predictive value was 87%. These values were not significantly different (P > 0.05) from those for the S-T response to exercise, which were 77%, 98%, and 97% respectively. When either a positive S-T response to exercise or a positive response for control heart rate changes to standing and hyperventilation were used as criteria for a positive test, the sensitivity significantly increased to 98% (P < 0.01), while specificity and predictive value remained significantly unchanged (P > 0.05) at 90% for each. The use of the heart rate response to standing and hyperventilation may be a useful test in detecting coronary artery disease in patients unable to undergo stress testing. The use of such heart rate responses in addition to S-T depression with exercise results in a highly sensitive and specific test with great predictive value.

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↗
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↗