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Biomedical subjects

P F Cohn

Publications and source records attributed to P F Cohn.

At least 127 records · Page 7Linked to original sources
PubMed1978

"Silent" myocardial ischemia during and after exercise testing in patients with coronary artery disease.

Although many patients with coronary artery disease (CAD) have a positive exercise test without pain, the frequency and significance of this "silent" ischemia is unclear. Therefore, we studied 122 consecutive clinically stable patients with angiographically defined CAD (greater than 75 per cent luminal stenosis) and a positive exercise test. Seventy-eight patients had pain or anginal equivalent during or after a positive exercise test; 44 did not, including 32 (26 per cent) with no symptoms at all. Patients were evaluated as to age, sex, prior myocardial infarction, congestive failure, hypertension, diabetes mellitus, and digoxin or propranolol therapy--in addition to anginal symptoms before, during, or after the exercise itself. Extent of CAD, presence of collaterals, and left ventricular ejection fraction were also determined. All exercise tests were evaluated for evidence of ST-T abnormalities or prior infarction on the control ECG as well as peak heart rate during exercise and post-exercise degree of ST segment depression. There were no significant differences between patients with and without exercise-induced pain in regard to any of the clinical and angiographic features noted above, demonstrating that "silent" myocardial ischemia during or after exercise testing is not uncommon and is not readily attributable to any obvious clinical or catheterization findings. Further studies are necessary to determine if patients with evidence of "silent" myocardial ischemia are especially prone to sudden death.

Angina Pectoris↗
PubMed1978

Value of the QRS complex in assessing left ventricular ejection fraction.

The relation between electrocardiographic findings and the angiographic left ventricular ejection fraction and the augmented ejection fraction after a premature ventricular contraction was investigated in 73 patients with documented chronic coronary artery disease. The patients were separated into four groups according to the presence or absence of abnormal Q waves. Twenty-four patients had diaphragmatic myocardial infarction, 21 had anterior myocardial infarction, 15 had both and 13 had no myocardial infarction. There was no statistically significant differences in cardiac index, left ventricular end-diastolic pressure or number of coronary vessels showing critical narrowing in the four groups. The sum of R waves (in mv) in leads aVL, aVF and V1 to V6 (sigmaR) was correlated with the ejection fraction (EF) and the augmented ejection fraction (EFa). EF in percent = 6.6 sigmaR mv + 9.4 (no. =73, r = 0.61); and EFa in percent = 8.6 sigmaR mv + 11.0 (no. = 73, r = 0.77). Among patients with sigmaR of less than 4.0 mv, augmented ejection fraction was less than 0.45 in 73 percent; among patients with sigmaR of 4.0 mv or more the augmented ejection fraction was greater than 0.45 in 93 percent (P less than 0.001). Thus, the sigmaR, calculated from six precordial and two augmented leads in patients with chronic coronary artery disease, correlated with both ejection fraction and augmented ejection fraction. The electrocardiogram in patients with coronary artery disease may prove useful as a simple, readily available and noninvasive guide in the assessment of left ventricular function in patients with coronary artery disease.

Blood Pressure↗
PubMed1978

Value of a noninvasively induced ventricular extrasystole during echocardiographic and phonocardiographic assessment of patients with idiopathic hypertrophic subaortic stenosis.

Fifteen patients with idiopathic hypertrophic subaortic stenosis had a ventricular extrasystole induced with a new external mechanical cardiac stimulator during noninvasive evaluation of left ventricular outflow tract obstruction. Ten patients were monitored with simultaneous echocardiogram, phonocardiogram and indirect carotid pulse tracing; five were monitored with the phonocardiogram and indirect carotid pulse tracing alone. Nine of the 15 patients showed obstruction in the beat after the ventricular extrasystole, as defined by appearance of the characteristic bifid carotid pulse contour and, where recorded, an increase in systolic anterior motion of the mitral valve on echocardiography. Six patients did not show obstruction. All nine patients with obstruction had greater than 20 msec prolongation of uncorrected systolic ejection time in the post-extrasystolic beat of the carotid pulse tracing. Change in the uncorrected ejection time was + 0.038 +/- 0.15 second (mean +/- standard deviation) in these nine patients compared with -0.003 +/- 0.005 second in the six not showing obstruction (P less than 0.01). Six patients underwent cardiac catheterization: Three patients without obstruction after a noninvasively induced ventricular extrasystole had no obstruction at catheterization and three patients with obstruction after noninvasively induced ventricular premature beats demonstrated obstruction at rest or after provocative maneuvers during catheterization. These results indicate that the noninvasive induction of a ventricular extrasystole is a useful and easily performed procedure for both diagnosing and evaluating the dynamic left ventricular outflow tract obstruction of idiopathic hypertrophic subaortic stenosis.

Adolescent↗
PubMed1978

Severe stenosis occurring in antibiotic sterilised homograft valves.

This paper describes 3 patients who developed late severe stenosis in fresh antibiotics sterilised homograft valves. Two were in the aortic position and one in the mitral. All 3 patients underwent successful reoperation. This complication has not been previously reported in valves prepared by this method.

Adult↗
PubMed1978

Effect of nitroprusside on regional myocardial blood flow in coronary artery disease. Results in 25 patients and comparison with nitroglycerin.

The effect of nitroprusside on regional myocardial specific blood flow (RMBF) was evaluated in 25 patients with the xenon-133 washout technique. Six patients were normal (group 1), six patients had coronary artery disease without collateral vessels (group 2), and thirteen patients had coronary artery disease with collateral vessels (group 3). In group 1, RMBF was unchanged following nitroprusside. RMBF decreased significantly in both group 2 and group 3, including seven patients in group 3 with high-grade collateral vessels. The results were compared to the effect of nitroglycerin in 31 patients previously studied using the same technique. Mean arterial pressure and pressure-rate product were comparably reduced by both drugs. In contrast to the findings with nitroprusside, after sublingual nitroglycerin RMBF decreased markedly in normals and increased in patients with coronary artery disease and high-grade collaterals. The data suggest that nitroprusside may primarily affect resistance vessels within the coronary circulation, as opposed to the effect of nitroglycerin on conductance vessels. Thus, nitroprusside could result in redistribution of blood flow away from ischemic areas and potentially increase ischemic injury in some patients with coronary artery disease.

Blood Pressure↗
PubMed1978

A multivariate approach for interpreting treadmill exercise tests in coronary artery disease.

To determine the value of a multivariate approach for the analysis of the treadmill exercise tolerance test (ETT), 237 patients referred for evaluation of chest pain who underwent a standard Bruce protocol ETT and coronary arteriography were studied. Predictive value of a positive ETT was 0.78 (43/55) using 1.0--1.9 mm ST segment depression criterion, 0.97 (59/61) using greater than or equal to 2.0 mm ST segment depression. When the 1.0--1.9 mm ST criterion was combined with peak systolic blood pressure-heart rate product (double product) less than or smaller than 23,000, exercise duration less than 6 minutes, and ST depression for greater than 3 minutes into recovery, predictive value improved to 0.89 in 18 patients with any two of the above. Predictive value for multivessel disease was also improved using non-ST criteria. Predictive value of a negative ETT for absence of coronary artery disease was 0.60 (29/48), and was 0.86 (12/14) if double product was greater than or equal to 30,000. Presence of chest pain during ETT did not improve predictive value of any type of test. Digitalis ingestion in 33 patients was not associated with decreased predictive value of a positive test. These data suggest that the predictive value of both positive and negative ETT in a symptomatic population can be improved with a multivariate approach.

Angina Pectoris↗
PubMed1978

Hemodynamic monitoring in patients with hypotension after myocardial infarction. The role of the medical center in relation to the community hospital.

Patients who develop hypotension after acute myocardial infarction are frequently transferred to medical centers for hemodynamic monitoring. To see if this practice is justified, we reviewed our experience with hemodynamic monitoring over a two-year period. Of 40 patients who underwent hemodynamic monitoring for hypotension, 28 were transferred from other institutions. Eleven (39 percent) of these 28 patients had a pulmonary capillary wedge pressure of 16 mm Hg or less. Ten (91 percent) of these 11 survived, compared with one survivor (8 percent) in the 13 transferred patients with a pulmonary capillary wedge pressure of 17 mm Hg or more (P less than 0.001). The pulmonary capillary wedge pressure did not correlate well with the presence of a third heart sound on physical examination or with chest x-ray films. All hypotensive patients with a low pulmonary capillary wedge pressure received fluids to expand the blood volume as their major form of therapy. Thus, hemodynamic monitoring in patients with hypotension clarifies their status regarding blood volume and identifies those who will benefit from expansion of this volume. Transfer of hypotensive patients for hemodynamic monitoring seems justified, as their status regarding volume of blood is frequently difficult to ascertain by noninvasive means.

Adult↗
PubMed1978

Myocardial revascularization in patients with multivessel coronary artery disease and minimal angina pectoris.

Mortality risk in coronary artery disease (CAD) is more closely related to angiographic findings of multiple coronary artery obstructions and left ventricular asynergy than to the severity of angina pectoris, the major symptom of CAD. Since coronary revascularization surgery is most frequently performed to relieve chest pain, there are few reports evaluating the results of coronary artery bypass surgery in patients with minimal or no angina pectoris but with anatomically severe disease. From July, 1970, through December, 1976, 844 patients had coronary artery bypass surgery performed at the Peter Bent Brigham Hospital for chronic or unstable angina pectoris. Twenty patients (2.3%) were operated on because of severe coronary obstruction but who had minimal or no angina. Fourteen patients underwent coronary arteriography because of a positive exercise tolerance test, and six because of a prior myocardial infarction. All but one patient had multivessel CAD, and four patients had significant left main coronary lesions. There was no operative mortality. One late death occurred 5 years postoperatively, for a 5.0% cumulative mortality. Average follow-up has been 34 months (range, 19 to 80 months). Of 12 patients with both pre- and postoperative exercise tests, eight have reverted to normal, and four show a less ischemic response to exercise. Coronary revascularization may have a beneficial effect on the patient with "asymptomatic" but anatomically severe CAD.

Adult↗
PubMed1978

Noncardiac surgery in patients with coronary artery disease. Risks, precautions, and perioperative management.

Patients with coronary artery disease face increased risks when they undergo noncardiac surgery. This is attributable to the cardiovascular stress imposed by the surgical procedure and the effects of anesthetic agents on the cardiovascular system. Several approaches to managing patients with coronary artery disease before, during, and after noncardiac surgery include "prophylactic" myocardial revascularization procedures, digitalization, use of propranolol hydrochloride, and insertion of temporary intravenous pacemakers.

Anesthesia↗
PubMed1977

Effect of sublingually administered nitroglycerin on regional myocardial blood flow in patients with coronary artery disease.

The effect of sublingually administered nitroglycerin on regional myocardial specific blood flow (in ml/min per 100 g tissue) was evaluated with a xenon-133 washout technique in 31 patients in a resting nonstressed state. Eight patients had normal coronary arteriograms (Group 1), 12 had coronary artery disease without collateral vessels (Group 2) and 11 had coronary artery disease with collateral vessels (Group 3). Although nitroglycerin caused a similar decrease in mean arterial blood pressure and blood pressure-heart rate product in all three groups, the decrease in regional myocardial blood flow was significantly less in Group 3 (-8+/-6% [mean+/-standard error of the mean]) than in Group 1 (-31+/-5%), P less than 0.05); an intermediary decrease occurred in Group 2 (-23+/-5%). Within Group 3, there was a mean increase in regional myocardial blood flow after nitroglycerin in the five patients whose collateral vessels were of a higher angiographic grade and arose from non-stenosed coronary arteries, whereas a reduction was observed in the six patients with none or only one of these findings (+10+/-7% versus -23+/-3%, P less than 0.001). This study suggests that even in the resting state, in some patients with coronary artery disease enhancement of regional myocardial blood flow can occur after sublingual administration of nitroglycerin and is probably mediated through well functioning collateral vessels. It is possible that the drug's effects on both the coronary and systemic circulation may relieve angina in some patients with coronary artery disease.

Administration, Oral↗
PubMed1977

Comparison between regional myocardial blood flow measurements and results of exercise tests.

The relationship between regional myocardial blood flow and the results of exercise tests were evaluated in 54 patients, 40 of whom had angiographically demonstrated coronary artery disease (CAD) and 14 had normal angiograms. After 20 patients had 2-step tests, 20 had bicycle ergometry, and 14 had treadmill tests, regional myocardial specific blood flow (RMBF) at rest was determined by selective injections of xenon-133 into the left coronary artery and quadrantic washout measured with an Anger camera. RMBF (ml/min/100 gm, mean +/- SE) was significantly lower in patients with coronary artery disease (72 +/- 3) than in normals (91 +/- 7, p less than .05) but RMBF in 12 CAD patients with negative exercise tests (75 +/- 6) was similar to regional myocardial blood flow in 28 coronary artery disease patients with positive exercise tests (71 +/- 4). Degree of ST depression did not influence results. Although measurement of RMBF and exercise testing are both useful procedures in the evaluation of patients with CAD, the data in the present study indicate the RMBF measurements at rest cannot predict the result of the postexercise ECG and vice versa.

Coronary Angiography↗
PubMed1977

The prevalence of angina pectoris and abnormal coronary arteriograms in severe aortic valvular disease.

In order to relate the frequency of angina pectoris to associated coronary artery disease, 66 consecutive patients with severe aortic valvular disease were studied by cardiac catheterization, including coronary angiography. Angina pectoris was found in 63 per cent of patients with predominant aortic stenosis, 62 per cent with aortic regurgitation, and 67 per cent with mixed disease. Associated coronary artery disease (larger than or equal to 75 per cent luminal stenosis) ranged from 14 to 28 per cent and averaged 20 per cent for the entire group of 66 patients. Only one patient without angina had significant coronary artery stenosis. Our studies indicate that angina pectoris is equally common in all forms of severe aortic valve disease and is usually not associated with significant coronary artery disease.

Adult↗