Ernst Simonson

Principles and pitfalls in establishing normal electrocardiographic limits

Abstract The three main prerequisites for determination of valid normal limits are adequate sample size, sample composition representative of the average healthy population, and adequate statistical evaluation. In a substantial number of publications, even recent publications, one or the other of these principles (and occasionally all three) have been disregarded. The most common error is inadequate sample size. The minimal sample size of a male adult population for determination of normal limits should exceed 500, and approach 1,000 for a mixed sample of men and women. Constitutional variables affecting the electrocardiogram (relative body weight, age, sex and race) must be considered. In view of the skewed distribution of most electrocardiographic items, 95 or 98 percentiles should be used for determination of valid normal limits. Use of standard deviations (usually ± 2 SD) may result in erroneous limits. The extreme values of the distribution of a sample of healthy persons are not acceptable because they include values from a substantial number of abnormal persons, thus resulting in a large number of false normal diagnoses.

Evaluation of cardiac performance in exercise

The limit of oxygen transport (VO2) and aerobic work capacity is essentially determined by blood flow (cardiac output [CO]), so that maximal VO2 has been used for evaluating cardiac performance. Increase of heart rate is the principal mechanism for increase of cardiac output in exercise and has been used for predicting VO2, with an age correction. There is a nearly linear increase of arteriovenous oxygen difference (ΔA-VO2) with the heart rate or percent of maximal VO2, which is steeper in patients with valvular heart disease, so that the increase of ΔA-VO2 with work load is a valuable index for cardiac compensation-decompensation. As a potentially valuable qualitative criterion, determination of cardiac mechanical efficiency (η) is suggested by the ratio cardiac work (CW = CO × meanaorticpressure)myocardialoxygenconsumption (MVO2) There is a high correlation between MVO2/100 g left ventricular weight and the product heart rate × peak systolic aortic (or brachial artery) pressure × 10-2. Other qualitative criteria are inability to maintain a steady state of VO2, pulmonary ventilation, blood pressure and heart rate in aerobic work, and decrease of utilization of respiratory oxygen. The most important criterion for the inadequacy of myocardial oxygen supply in exercise is the ischemic depression in the S-T segment.

Myocardial infarction in young people—Experience in U.S.S.R.

Abstract The high incidence of myocardial infarction in young people has been of major concern to Russian cardiologists resulting in a large number of publications in the past 15 years. This is a review of the most important Russian publications in regard to the differences in the clinical course, symptoms, complications, precipitating factors, etiology, and mortality rate in young and old patients with myocardial infarctions.

New approach in treatment of cardiac decompensation in U. S. S. R.

Abstract Based on Meersons fundamental work 3,4 on the genesis of ventricular hypertrophy and decompensation, Russian investigators supplemented the conventional therapy of cardiac decompensation with preparations related to the synthesis of protein and nucleic acids. The merit of the supplemental treatment was shown in the clinical course as well as in various objective criteria (blood chemistry, hemodynamics, systolic parameters, ECG). The reported results are highly significant and their method merits trial in other centers.

THE STATE OF SENSORY AND MOTOR CENTERS IN PATIENTS WITH HYPOTHYROIDISM

Excerpt INTRODUCTION Increased fatigability and sluggishness are notable complaints and symptoms of patients with endocrine disturbances, particularly in those with a reduced metabolic rate. Since ...

Comparison of therapeutic effects of coronary drugs in the USSR

T he prevalence of coronary artery disease in urban Union of Soviet Socialist Republics (USSR) population appears to be similar to that in Western European countries and the United States and, therefore, is a problem of major concern. Numerous articles, proceedings of conferences, and monographs on coronary heart disease appeared during the past decade. Naturally, drug therapy plays a substantial part, as demonstrated in the articles by Goldberg,’ Doshitsyn and co-workers2 and in the monographs of Kissin and VotchaL4 However, there does not seem to be a project in the USSR comparable in scale to the National Institutes of Health supported “Coronary Drug Project.” In the United States a massive double-blind therapeutic trial of lipid lowering drugs in coronary disease is in progress. This study known as the Coronary Drug Project has 8,341 male myocardial infarction patients enrolled in 55 centers throughout the country. At the time of enrollment they were between the ages of 30 and 64 years. The drugs under study are: nicotinic acid, clofibrate (Atromid S), estrogen, D-thyroxine (Coloxin), and placebo. The duration of follow-up is set at five years. Events studied include recurrent myocardial infarction, acute coronary insufficiency, angina, and other manifestations of arteriosclerosis, such as electrocardiographic changes, serum lipids, and mortality rates. The study will have completed five years for all patients by 1974 and should answer the question whether such drugs are useful in the therapy of arteriosclerosis, particularly coronary arteriosclerosis. The large control group of patients will provide invaluable information on the natural history of male coronary patients, a necessary yardstick for comparison with coronary patients treated by any means. One of the best controlled recent studies is the comparison of the therapeutic effect of several drugs used in the USSR for treatment of coronary heart disease by Votchal and Goldberg5 of the Central Institute of Postgraduate Medical Education in Moscow. In double-blind technique, the therapeutic effect of preparations-Papaverin, Nospa,* Segontin,t Ustimon,

The influence of age on the fusion frequency of flicker

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