Noninvasive identification of a high risk subset of patients with acute inferior myocardial infarction.
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Biomedical subjects
Publications and source records attributed to D S Berman.
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The hemodynamic effects of a single oral dose of 80 mg of pentaerythritol tetranitrate (PETN) were determined in 16 patients with chronic congestive heart failure over a 5-hour period. PETN produced significant (p < 0.05) decreases in pulmonary capillary wedge pressure (27 to 18 mmHg), right atrial pressure (15 to 9 mmHg), mean systemic arterial pressure (89 to 80 mmHg) and systemic vascular resistance (1812 to 1466 dynes . sec . cm-5). There were significant increases (p < 0.01) in cardiac index (2.0 to 2.3 l/m2/min) stroke volume index (24 to 38 ml/m2) and stroke work index (25 to 31 gm-m/m2). The peak reduction in pulmonary capillary wedge pressure occured two hours after PETN administration and the hemodynamic effects were still apparent at fivae hours following drug ingestion. In nine patients in whom left and right ventricular ejection fractions were determined by radionuclide ventriculography before and after administration of PETN, no significant changes were found in left ventricular ejection fraction (0.22 to 0.24, p. = NS) although a modest increase was noted in right ventricular ejection fraction (0.29 to 0.34 p < 0.05). The data indicates that orally-administered pentaerythritol tetranitrate may produce beneficial effects on preload and afterload in congestive cardiac failure, the duration of which may be five hours or longer.
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The hemodynamic effects of a single oral dose of 80 mg of pentaerythritol tetranitrate (PETN) were determined over a 5-hr period in 16 patients with chronic congestive heart failure. PETN decreased (p < 0.05) pulmonary capillary wedge pressure (27 to 18 mm Hb), right atrial pressure (15 to 9 mm Hg), mean systemic arterial pressure (89 to 80 mm Hg), and systemic vascular resistance (1,812 to 1,466 dynes x sec x cm-5). There were increases (p < 0.01) in cardiac index (2.0 to 2.3 l/m2/min), stroke volume index (24 to 28 ml/m2), and stroke work index (25 to 31 gm-m/m2). Peak reduction in pulmonary capillary wedge pressure occurred 2 hr after PETN and hemodynamic effects were still apparent at 5 hr. In nine patients in whom left and right ventricular ejection fractions were determined by radionuclide ventriculography before and after PETN, no changes were found in left ventricular ejection fraction (0.20 to 0.22, p = NS) although there was a modest increase in right ventricular ejection fraction (0.29 to 0.34, p < 0.05). The data indicate that oral PTEN may induce beneficial effects on preload and afterload in congestive cardiac failure that may last 5 or more hours.
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Analysis of multiple noninvasive tests offers the promise of more accurate diagnosis of coronary artery disease, but discordant test responses can occur frequently and, when observed, result in diagnostic uncertainty. Accordingly, 43 patients undergoing diagnostic coronary angiography were evaluated by noninvasive testing and the results subjected to analysis using Bayes' theorem of conditional probability. The procedures used included electrocardiographic stress testing for detection of exercise-induced ST segment depression, cardiokymographic stress testing for detection of exercise-induced precordial dyskinesis, myocardial perfusion scintigraphy for detection of exercise-induced relative regional hypoperfusion, and cardiac fluoroscopy for detection of coronary artery calcification. The probability for coronary artery disease was estimated by Bayes' theorem from each patient's age, sex, and symptom classification, and from the observed test responses. This analysis revealed a significant linear correlation between the predicted probability for coronary artery disease and the observed prevalence of angiographic disease over the entire range of probability from 0 to 100% (P less than 0.001 by linear regression). The 12 patients without angiographic disease had a mean posttest likelihood of only 7.0 +/- 2.6% despite the fact that 13 of the 60 historical and test responses were falsely "positive." In contrast, the mean posttest likelihood was 94.1 +/- 2.8% in the 31 patients with angiographic coronary artery disease, although 45 of the 155 historical and test responses were falsely "negative." In 8 of the 12 normal patients, the final posttest likelihood was under 10% and in 26 of the 31 coronary artery disease patients, it was over 90%. These estimates also correlated well with the pooled clinical judgment of five experienced cardiologists (P less than 0.001 by linear regression). The observed change in probability for disease for each of the 15 different test combinations correlated with their information content predicted according to Shannon's theorem (P less than 0.001 by linear regression). These results support the use of probability analysis in the clinical diagnosis of coronary artery disease and provide a formal basis for comparing the relative diagnostic effectiveness and cost-effectiveness of different test combinations.
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This paper compares the clinical and parametric performance, at 140 keV, of three different large-field cameras in a single institution. The instruments tested were the Ohio Nuclear 410, Picker 4/15, and Searle LFOV. There were differences noted in both qualitative and quantitative measurements of physical performance, but these differences could not be demonstrated in clinical studies.
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A multicenter study of rest and exercise thallium-201 myocardial imaging in 190 patients from five centers was performed. Exercise images were obtained after graded treadmill or bicycle stress with use of five different gamma camera models and were interpreted by the originating investigator without knowledge of other clinical data. Of 42 patients with less than 50 percent coronary stenosis, 4 (10 percent) had a resting image defect, 1 (2 percent) a new exercise defect and 5 (12 percent) either a resting or an exercise image defect, or both. Of 148 patients with coronary stenosis of 50 percent or greater, 64, (45 percent) had an image defect in the study at rest, 90 (61 percent) had new or increased defects after exercise, and 115 (78 percent) had resting or exercise defects, or both. New exercise image defects were more common than exercise S-T depression (90 of 148 [61 percent] versus 62 of 148[42 percent]; P less than 0.01). In a second group of 111 patients with acute myocardial infarction studied at three centers, 90 patients (81 percent) had image defects compared with 71 (64 percent) two had new electrocardiographic Q waves (P less than 0.01). Smaller infractions, as assessed with serum enzyme values, and diaphragmatic infarctions were less commonly detected than larger or anterior infarctions. These findings suggest that myocardial imaging complements the electrocardiographic identification of acute myocardial infarction of exericse-induced myocardial ischemia.
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In 53 patients with possible pulmonary embolism, pulmonary abnormalities of 133Xe ventilation and 99Tcm albumin microsphere perfusion scintigraphy were compared with absence or presence of pulmonary emboli documented by concurrent pulmonary angiography. It was found that patients with combined scintigraphy considered as unlikely for pulmonary embolism (ventilation defect larger than perfusion defect) or indicative of pulmonary embolism (ventilation defect smaller than perfusion defect) provide high diagnostic specificity. Patients with equal ventilation-perfusion abnormalities (possible pulmonary embolism) require further evaluation by pulmonary angiography to ascertain diagnosis. Importantly, diagnostic accuracy, using ventilation-perfusion scintigraphy and the quantified method of evaluation delineated, is preserved in patients with severe congestive heart failure.
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A modified classification for interpreting technetium-99m pyrophosphate scintigrams defines the 2+ diffuse pattern of tracer uptake as equlvocal rather than positive for acute myocardial infarction. Results of scintigraphy using this classification were compared with results of standard diagnostic tests for myocardial infarction in 235 patients admitted to a coronary care unit with acute chest pain. Of 81 patients with acute transmural infarction by standard clinical, electrocardiographic and serum enzyme criteria, 76 had a positive, 5 an equivocal and none a negative scintigram. Of 18 with acute nontransmural infarction by standard criteria, 7 had a positive, 9 an equivocal and 2 a negative scintigram. This it was uncommon for a patient with acute myocardial infarction, transmural or nontransmural, to have a definitely negative technetium-99m pyrophosphate study. Ten patients had equivocal evidence of infarction by standard criteria. Of the remaining 126 patients with no evidence of acute myocardial infarction by standard criteria, 87 had a negative, 35 an equivocal and 4 a definitely positive scintigram. Thus the definitely positive scintigraphic pattern was relatively highly specific for acute myocardial infarction. If the 2+ pattern had been considered positive, the specificity of the technique would have been greatly decreased. Computer processing strengthened observer certainty of the visual impression but changed the scintigraphic evaluation in only eight cases. Thus, use of an equivocal pattern renders technetium-99m pyrophosphate imaging both an extremely sensitive and specific method for detecting acute myocardial infarction.