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Biomedical subjects

P F Cohn

Publications and source records attributed to P F Cohn.

At least 109 records · Page 6Linked to original sources
PubMed1981

Impact of a cardiology data bank on physicians' prognostic estimates. Evidence that cardiology fellows change their estimates to become as accurate as the faculty.

To determine whether physicians would be influenced by the prognostic information in a large coronary artery disease data bank, cardiology faculty and fellows made initial estimates of the prognoses of their patients and then made revised final estimates after seeing the outcome of matched patients (OMP) from the data bank. The faculty cardiologists' original estimates proved to be as accurate as those of the data bank's OMP, and the faculty revised their estimates minimally in response to the data bank's OMP. Conversely, the cardiology fellows' original estimates were less accurate than the data bank's OMP, and under all observed circumstances the fellows responded more to the data bank's OMP than did the faculty. As a result, the accuracy of the fellows' final estimates was similar to the accuracies of both the faculty cardiologists and the data bank's OMP. Computerized data banks seem more likely to have impact when their information is provided to physicians who are relatively inexperienced with the disease in question.

Cardiology↗
PubMed1980

The diagnostic accuracy of combined clinical and noninvasive cardiac evaluation: comparison with findings at cardiac catheterization.

The accuracy of combined clinical and noninvasive cardiac diagnostic evaluation was prospectively examined in 108 consecutive patients referred to the heart station for echocardiographic examination prior to cardiac catheterization. History, physical examination, scalar electrocardiology, chest roentgenography, phonocardiography and pulse recording, and M-mode echocardiography were employed by the heart station cardiologist, who assigned one or more diagnoses to each patient. In addition, one of three management strategies was proposed for each patient: 1) surgery without cardiac catheterization; 2) medical therapy without cardiac catheterization; or 3) cardiac catheterization for clarification of the diagnosis. The results of the combined clinical and noninvasive evaluation were independently reviewed for each patient and compared with the diagnosis determined by cardiac catheterization, results of cardiac surgery, and total hospital course. Diagnostic predictions employing combined clinical and noninvasive cardiac evaluation were completely correct in 86% of patients, and management strategy was correct in 97% of individuals. In approximately one-half of all patients full cardiac catheterization or coronary arteriography was recommended. All management strategy errors and two-thirds of diagnostic errors occurred in patients with mitral regurgitation, aortic regurgitation, or coronary artery disease. Combined clinical and noninvasive evaluation results in accurate diagnostic information adequate for the formulation of appropriate management strategies in the majority of patients, but many individuals with cardiac disease still require invasive evaluation for complete diagnosis.

Adolescent↗
PubMed1980

Effect of Coronary Collateral Vessels on Regional Myocardial Blood Flow in Patients With Coronary Artery Disease.

The effect of radiographically graded coronary collateral vessels on regional myocardial blood flow was evaluated with intracoronary injection of xenon-1233 at rest and during contrast agent-induced coronary hyperemia in 24 patients with coronary artery disease. Eleven patients had no coronary collateral vessels demonstrated radiologically, whereas 13 had such vessels. In 7 of the 13 these were high grade and noncompromised, whereas in 6 they were of lesser grade. Regional myocardial blood flow at rest in patients with and without collateral channels was similar and increased during hyperemia. However, the increase in flow was significantly greater in the patients with high grade noncompromised collateral vessels than in those with lesser grade collateral vessels (80 +/- 16 versus 31 +/- 9 plercent, p < 0.05). To evaluate the functional significance of the high grade noncompromised collateral vessels against that of vessels of lesser grade, various indexes of global and regional ventricular function were compared in the 13 patients in the present study, as well as in 24 patients whose collateral vessels had been subjected to similar grading systems in previous studies of regional myocardial blood flow. There were no significant differences in degree of regional asynergy, ejection fraction or left ventricular end-diastolic pressure between the patients with high and lower grades of collateral vessels. Thus, high grade noncompromised collateral vessels do not appear to have a beneficial effect on resting left ventricular function despite their enhanced vasoldilatory reserve.

Collateral Circulation↗
PubMed1980

Multiple-lead QRS changes with exercise testing. Diagnostic value and hemodynamic implications.

To evaluate the diagnostic potential and hemodynamic significance of exercise-induced multiple-lead QRS changes, we studied exercise test responses in 230 patients with chest pain syndromes undergoing Bruce protocol exercise tests. When increases in the R waves of multiple ECG leads (epsilon R) plus ST segment change greater than 1 mm were present, 74 of 75 patients (99%) had coronary disease; this was a higher percentage than that achieved with either measurement alone or when ST change was combined with increase in R in a single lead. Sixty-four of the 75 patients (85%) had multivessel disease, the most severe form of coronary artery disease. Left ventricular end-diastolic pressure (both at rest and after left ventriculography), presence and degree of resting ventricular asynergy, and ejection fraction were all significantly more abnormal in patients whose epsilon R increased, regardless of ST-segment change. Further, in patients who stopped exercise because of cardiac symptoms, exercise duration and the product of heart rate times blood pressure were significantly lower when epsilon R increased. Thus, the mechanism for the increase in epsilon R with exercise in patients with coronary artery disease appears to be related to abnormalities in left ventricular function.

Adult↗
PubMed1980

Clinical profile of restrictive cardiomyopathy.

The characteristic hemodynamic features of restrictive cardiomyopathy (normal or reduced cardiac index, normal ventricular systolic function, and "dip and plateau" early in diastole) are traditionally associated with pathologic evidence of inflammation, infiltration and fibrosis. Prognosis is usually poor. Nine patients with restrictive hemodynamic features were recently identified in our laboratory; six were males, three were females, and ages ranged from 23-57 years (mean 47 years). Only one was asymptomatic. Chest pain, dyspnea on exertion and fatigue were the most common symptoms. Echocardiography revealed various degrees of left ventricular wall thickening, but no significant pericardial effusion, pericardial thickening or calcification. Mean left ventricular end-diastolic pressure was 25 mm Hg, cardiac index 2.8 l/min/m2 and ejection fraction 0.63. Endomyocardial and pericardial biopsies, obtained in two patients, were normal. Follow-up (mean 22 months, range 16-42 months) revealed no cardiac deaths. These findings support the hypothesis that the restrictive hemodynamic profile does not necessarily indicate the presence of a specific pathologic process in the subendocardium or myocardium and that the prognosis is not necessarily ominous. The common pathophysiologic feature for this syndrome appears to be reduced ventricular diastolic compliance, but the etiology in many cases is unclear.

Adult↗
PubMed1979

Significance of reduced regional myocardial blood flow in asynergic areas evaluated with intervention ventriculography. Results of studies combining washout of xenon-133 and postextrasystolic potentiation.

Nineteen patients with coronary artery disease were studied to determine the significance of reduced regional myocardial blood flow (50 ml/min per 100 g or less) in areas of abnormal wall motion. Regional myocardial blood flow was measured in four regions of the left ventricle with an Anger camera after the injection xenon-133 into the left main coronary artery. Abnormal wall motion was evaluated with biplane left ventriculography at rest and during postextrasystolic potentiation, a potent inotropic stimulus. Abnormal wall motion was defined as hemiaxis shortening of less than 20 percent. Four hemiaxes were designated as corresponding to the four regions of myocardial blood flow. Of 76 hemiaxes evaluated in the 19 patients, 54 manifested normal wall motion and 22 abnormal wall motion; 8 of the 22 hemiaxes had reduced regional myocardial bood flow. In these 8, hemiaxis shortening increased 6 +/- 2 percent (mean +/- standard error of the mean) above values at rest during postextrasystolic potentiation (with normalization of hemiaxis shortening in only 1 of the 8), compared with an increase of 19 +/- 4 percent (P less than 0.001) in the 12 hemiaxes with borderline regional myocardial blood flow (with normalization of hemiaxis shortening in 9 of the 12, P less than 0.05). These results indicate that the presence of reduced regional myocardial blood flow in areas of abnormal wall motion usually predicts a poor response to post-extrasystolic potentiation, whereas abnormal wall motion without reduced regional myocardial blood flow usually predicts a good response. The combination of reduced regional myocardial blood flow and abnormal wall motion suggests scarred and nonviable myocardium.

Adult↗
PubMed1979

Regional ejection fraction: a quantative radionuclide index of regional left ventricular performance.

Radionuclide measurements of regional left ventricular ejection fraction were evaluated as a quantitative index of regional left ventricular function. Left ventricular regional ejection fractions were derived from background-corrected, time-activity curves in 43 patients assessed by both gated equilibrium radionuclide angiocardiography and left ventricular contrast angiography. From a single, modified left anterior oblique projection, the regional change in background corrected counts was determined in each of three anatomic regions. The normal range for regional radionuclide ejection fraction was determined in 10 patients with normal contrast ventriculograms and without obstructive coronary artery disease at coronary arteriography. Regional ejection fraction was compared with percent segmental axis shortening and extent of akinetic segments in corresponding regions of the contrast ventriculogram. Radionuclide and roentgenographic methods were in agreement as to the presence or absence of abnormal wall motion in 83 of 99 left ventricular regions (84%) in 33 patients evaluated prospectively. Comparison of regional ejection fraction demonstrated significant differences between regions with roentgenographically determined normokinesis (75 +/- 3%, mean +/- SEM), hypokinesis (44 +/- 3%, p less than 0.0005) and akinesis (24 +/- 5%, p less than 0.005). We conclude that the left ventricular regional ejection provides a reliable quantitative assessment of regional left ventricular performance.

Adult↗