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Biomedical subjects

P F Cohn

Publications and source records attributed to P F Cohn.

At least 55 records · Page 3Linked to original sources
PubMed1989

The Nifedipine-Total Ischemia Awareness Program: a national survey of painful and painless myocardial ischemia including results of antiischemic therapy.

The Nifedipine-Total Ischemia Awareness Program was designed to evaluate the prevalence, prognostic implications and effect of therapy on painful and painless myocardial ischemic episodes in a nationwide study of patients with angina pectoris. Three hundred forty-eight patients with at least 2 anginal attacks/week while taking antianginal medications were enrolled at 53 participating centers between September 1, 1986 and March 31, 1988; 312 of the 348 patients formed the study group, while 36 patients formed the control group. At least 1 episode of ST-segment depression during two 48-hour periods of Holter monitoring was present in 136 of the 312 patients in the study group. In these 136 patients, there was a total of 372 episodes of ST-segment depression, of which only 69 (18%) were painful; 85% of the 136 patients had either painless episodes only or both painless and painful episodes. Despite apparently adequate antianginal therapy, 48 patients had greater than or equal to 3 episodes of ST-segment depression/48 hours of ambulatory electrocardiographic monitoring, and 38 patients greater than 60 minutes of ST-segment depression. After nifedipine was administered, there was a 23% reduction in the mean number of episodes of ST-segment depression (2.7 +/- 0.3 to 2.1 +/- 0.2, p less than 0.01). The most pronounced effects were found in the 48 patients with greater than or equal to 3 episodes of ST-segment depression and the 38 patients with greater than or equal to 60 minutes of total ischemic time.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1989

Total ischemic burden. Implications for prognosis and therapy.

Patients with silent myocardial ischemia can be classified as one of three clinical types: those who are totally asymptomatic (type 1), those who are asymptomatic after a myocardial infarction (type 2), and those who demonstrate both asymptomatic and symptomatic episodes (type 3). Total ischemic activity may be similar in any given patient, but the ratio of symptomatic to asymptomatic episodes will differ. Prognosis appears dependent on the degree of total ischemic activity plus the extent of coronary artery disease and left ventricular dysfunction. The effects of therapy can be monitored with exercise testing and/or Holter monitoring. Using the latter technique, the largest multicenter study to date, the Nifedipine Total Ischemia Awareness Program, has demonstrated the advantages of adding a calcium antagonist to nitrate and/or beta-blocker therapy regimens in order to maximize the reduction in total ischemic activity in angina patients.

Coronary Circulation↗
PubMed1989

Regional left ventricular filling: does it reflect diastolic abnormalities in contiguous areas of myocardium?

To test the hypothesis that regional left ventricular filling reflects diastolic changes in contiguous areas of myocardium, we performed radionuclide ventriculograms on normal subjects, patients with left anterior descending coronary artery disease, and patients with anteroseptal myocardial infarctions. We reasoned that because diastolic properties of the anteroseptal myocardium should be different in the three groups of patients, regional filling in the anteroseptal area of the left ventricle should also be different, if regional filling does, indeed, reflect diastolic changes in the adjacent myocardium. While anteroseptal regional filling in the normal subjects was different than regional filling in the two patient groups, the degree of filling abnormality was similar in patients with and without myocardial infarctions. Our results suggest that regional left ventricular filling is not exclusively determined by diastolic changes in contiguous areas of myocardium.

Coronary Disease↗
PubMed1988

Silent myocardial ischemia.

Silent myocardial ischemia has emerged from a subject of mainly research interest to one with important clinical implications for practicing physicians. Although the pathophysiologic mechanisms responsible for the absence of pain are still not clear, it is apparent that episodes of silent myocardial ischemia are frequent and occur in many patients with coronary artery disease; episodes occur both in asymptomatic and symptomatic patients; episodes are detectable by various noninvasive and invasive techniques; and episodes appear to have important prognostic implications when combined with the extent of anatomic disease and degree of left ventricular dysfunction. It is expected the rapidly accumulating prognostic data, especially in patients after infarctions and patients with unstable angina, will have a profound effect on the way physicians treat their patients with coronary artery disease.

Angina Pectoris↗
PubMed1988

Effect of coronary artery bypass grafting on left ventricular diastolic function.

Because left ventricular (LV) diastolic function is abnormal in patients with coronary artery disease (CAD), pulsed Doppler echocardiography was used to evaluate LV filling before and after coronary artery bypass grafting (CABG). Filling was evaluated by Doppler in 2 studies: (1) in a group of 41 unpaired patients (11 with angiographically normal coronary arteries, 14 with CAD but without CABG and 16 at 1 week after CABG) and (2) in a group of 12 patients with CAD before and 1 week after CABG. Doppler sampling at the level of the mitral anulus was analyzed for the deceleration half-time and for the ratio of peak late (A) to peak early (E) filling velocity, measures reflecting early ventricular filling and the relative contribution of atrial contraction to ventricular filling. In the first study the deceleration half-time was significantly prolonged in both CAD and CABG groups. The late to early peak transmitral velocity ratio, however, was significantly prolonged only in the nonrevascularized CAD patients. In the second group of CAD patients studied before and 1 week after surgical revascularization, both the late to early peak transmitral velocity ratio and the deceleration half-time showed significant postoperative improvement. Thus, patients with CAD showed impairment in early LV filling and a compensatory increase in the proportion of filling with active atrial contraction. Successful CABG appears to result in normalization of early filling and decreased reliance on active atrial transport.

Coronary Angiography↗
PubMed1988

Detection and prognosis of the asymptomatic patient with silent myocardial ischemia.

Detection of asymptomatic silent ischemia relies mainly on exercise screening procedures in (1) selected patient subgroups with increased likelihood of having latent coronary artery disease and (2) patients after infarction with uncomplicated courses. Prognosis in these patients varies, depending on the extent of disease and left ventricular dysfunction. The worst prognosis is found in patients with prior infarctions, 3-vessel disease and poor exercise tolerance. Prognosis is excellent in totally asymptomatic patients with only 1-vessel disease and good ventricular function.

Adult↗
PubMed1988

Indications for treatment of silent myocardial ischemia.

A rational approach to treatment of silent myocardial ischemia is based on an appreciation of those factors influencing prognosis in the three types of patients that clinicians see with this disorder: those who are totally asymptomatic (type 1), those who are asymptomatic following myocardial infarction (type 2), and those who have angina and silent myocardial ischemia (type 3). Prognosis in type 1 and type 2 patients is generally good, except when triple vessel or left main disease is present. Risk factor modification and anti-ischemic medication should be employed in these patients, with serious consideration given to revascularization procedures. The latter approach is less controversial in type 3 patients who have frequent episodes of silent myocardial ischemia, especially if high dose anti-ischemic agents fail.

Coronary Disease↗
PubMed1988

Total ischemic burden: effect of vasoactive agents.

Treatment of the total ischemic burden is dependent on adequate documentation of both painful and painless episodes of myocardial ischemia, an understanding of the pathophysiologic mechanisms involved, and knowledge of prognosis for affected patients. Because a vasoconstrictive component appears to be an important element in the genesis of many episodes of myocardial ischemia, those vasoactive drugs that produce increased flow in the coronary circulation should be clinically useful. Nitrates and calcium blockers--especially nifedipine--have been found to be particularly valuable in this regard in both experimental and clinical trials.

Animals↗
PubMed1987

Characteristics of silent myocardial ischemia during out-of-hospital activities in asymptomatic angiographically documented coronary artery disease.

Ambulatory electrocardiographic monitoring is useful in documenting characteristics of both painful and silent myocardial ischemia occurring during out-of-hospital activities in patients with angina and coronary artery disease (CAD), but few data are available concerning silent myocardial ischemia during ambulatory electrocardiographic monitoring in asymptomatic patients with CAD. Accordingly, 480 hours of ambulatory electrocardiographic monitoring were recorded in 10 asymptomatic patients with CAD not receiving cardiac drugs (48 hours/patient). All 10 patients had silent myocardial ischemia on treadmill exercise testing, with initial ST-segment depression at 2 to 6 minutes in 7 patients and more than 6 minutes in 3 patients. During ambulatory electrocardiographic monitoring, 64 episodes of silent myocardial ischemia (1 mm of ST-segment depression for at least 1 minute) were recorded, ranging from 1 to 17 episodes/patient/48 hours. Of the 64 silent myocardial ischemic episodes, 30 (47%) occurred between 6 am and noon. Duration of silent myocardial ischemia was 798 minutes (range 1 to 80). ST-segment depression ranged from 1 to 4.5 mm. Heart rate at onset of the episodes on ambulatory electrocardiographic monitoring ranged from 65 to 150 beats/min (mean 98), which was significantly less than that during treadmill exercise testing in the same patients (mean 120). At cardiac catheterization, 7 patients had 2- or 3-vessel CAD and 3 had 1-vessel CAD. Thus, silent myocardial ischemia is common during daily life in asymptomatic CAD patients with positive treadmill exercise tests.

Activities of Daily Living↗
PubMed1987

Total ischemic burden: pathophysiology and prognosis.

Myocardial ischemia is caused by decreased supply (primary ischemia), increased demand (secondary ischemia) or a combination of the two (mixed ischemia). The sum of all episodes--with or without pain--constitutes the total ischemic burden. During out-of-hospital activities, many episodes occur at lower than expected heart rates, suggesting that a vasoconstrictive component is involved in the genesis of such episodes. These silent attacks may be even more important clinically than painful attacks. It has been suggested that silent myocardial ischemia has an adverse impact on prognosis in patients with totally asymptomatic ischemia or asymptomatic postinfarction ischemia. Further, it has been shown that there is a direct relation between the duration and frequency of silent myocardial ischemia and subsequent cardiac events in patients with unstable angina. Therefore, aggressive therapy may be warranted in certain groups of patients in whom silent myocardial ischemia constitutes a significant part of the total ischemic burden.

Coronary Disease↗
PubMed1987

Silent ischemia: a timely aspect in coronary artery disease.

The phenomenon of silent myocardial ischemia is defined as a transient alteration in myocardial perfusion, function or electrical activity in the absence of chest pain or the usual anginal equivalents. Patients may be classified as having one of three types of silent ischemia: type 1-asymptomatic with no history of myocardial infarction or angina; type 2-asymptomatic with previous myocardial infarction; type 3-angina is present in addition to asymptomatic ischemic episodes. Based on exercise testing, silent ischemia has been found in 2.5% of asymptomatic middle-aged men; a substantial number of such subjects subsequently incur cardiac events. In patients with type 2 silent ischemia, post-infarction mortality appears markedly higher than in cohorts without silent ischemia. In type 3 patients, 75 to 80% can be found to have silent ischemic episodes in addition to typical anginal attacks, the frequency of which may be up to three or four times that of the latter counterpart. In persons with coronary artery disease who succumb to sudden cardiac death, 25% have never had clinical symptoms suggesting that there may be a great number of persons with silent disease in the population at large.

Angina Pectoris↗