Alvin H. Freiman

The exercise electrocardiogram: Differences in interpretation: Report of a technical group on exercise electrocardiography

Abstract Exercise electrocardiography is a valuable clinical tool with which quantitative evaluations and comparisons are now being attempted in many fields of cardiovascular investigation. Among a series of studies by a technical group on exercise electrocardiography, an assessment was made of observer variation in the clinical interpretation of ST-T responses during and after exercise. Interobserver variation among 14 cardiologists was great; individually assigned frequencies of abnormal responses after exercise in a mixed sample of records ranged from 5 to 58 per cent. Disagreement was greater for the diagnosis made during than for that made after exercise. Introbserver variation was also so great that use of the same observer for all exercise electrocardiographic readings would not necessarily provide acceptable reliability. The chief factors in disagreement were the lack of defined criteria for interpretation, in particular uncertainty about the significance of J-point ST-T depression, and technical quality of the records. Observer agreement was substantially increased when records were coded by unambiguous criteria or when simple measurements were made of the ST-T response after exercise.

Fibrinolytic (Plasmin) Therapy of Experimental Coronary Thrombi with Alteration of the Evolution of Myocardial Infarction

To explore the possibilities of fibrinclytic therapy of coronary thrombosis, experimental studies were carried out to document lysis of coronary thrombi and to investigate the effect of fibrinolytic blood upon myocardial infarction. Serum-induced coronary thrombi were produced by a new technic and were followed by serial coronary arteriography. Control animals were compared to animals in which significant fibrinolytic activity had been induced by systemic infusions of plasmin. Tissue studies suggest that plasmin may change the evolution of early infarction. Whether these changes will ultimately result in salvage of ischemic tissue will be determined by studies now in progress.

Serum Activity Patterns of Glutamic Oxaloacetic Transaminase, Glutamic Pyruvic Transaminase and Lactic Dehydrogenase Following Graded Myocardial Infarction in Dogs

Following experimental myocardial infarction in the dog elevations of serum levels of glutamic-oxaloacetic transaminase (SGO-T), glutamic-pyruvic transaminase (SGP-T) and lactic dehydrogenase (SLD) were consistently noted in decreasing order. Evidence is presented that leakage into the serum from the damaged myocardium plays an important role in these elevations. This concept is supported by analyses of original tissue to blood enzyme concentration gradients, activities of homogenates of infarcts of varying ages, simultaneous measurements of coronary sinus and peripheral venous blood following infarction and contrasting results in man and the dog following infarction.

Factors affecting the formation and dissolution of experimental thrombi

Abstract The use of the serum-induced clot as a standard experimental model has been found to be highly satisfactory. In twenty-two dogs the effectiveness of fibrinolytic therapy of fresh clots was studied. Systemic fibrinolysin therapy was found to be effective in dissolving such clots, although local administration of fibrinolysin to the clot was found to result in even more rapid lysis. No difference was found in the susceptibility of fresh arterial and venous clots to treatment. In twenty-one dogs the effect of the age of the clot in relation to treatment with fibrinolysin was studied. Clots treated within four days of formation were susceptible to partial or total dissolution. The effect of hyperfibrinogenemia on clot dissolution was studied in ten dogs. Clots formed in the hyperfibrinogenemic state were significantly more resistant to fibrinolytic therapy.

Studies on the Production of Intravascular Thrombi and Their Treatment with Fibrinolysin

In 22 dogs, the effect of fibrinolysin therapy of fresh intravascular clots was evaluated by serial angiograms and autopsies. The average time required for dissolution of such clots, when treated by systemic plasmin, was 4 hours and 45 minutes, while the average time necessary for lysis with local fibrinolytic therapy was 2 hours 10 minutes. Treatment of fresh venous and arterial clots did not disclose any significant difference in susceptibility to lysis. In 21 dogs, the effect of age of the clot on the effectiveness of plasmin therapy was studied in clots formed with serum and morrhuate. Clots treated within 4 days of formation were susceptible to dissolution, although clots treated after 3 days did not uniformly undergo complete lysis. The serum-induced clots were more amenable to fibrinolytic therapy than were those formed with morrhuate.

The electrocardiogram during exercise

Abstract A system is described for recording the electrocardiogram during exercise. This system involves the use of pliable stainless steel mesh electrodes, suitable electrode positioning, recording of the signal on magnetic tape and appropriate filtering. Through the use of these technics, a satisfactory electrocardiographic signal can be obtained during the physical exercises described.

Effect of increased fibrinogen concentration on the lysis of in vivo thrombi.

The dissolution of clots formed at normal fibrinogen levels and in hyperfibrinogenemia was studied in 10 dogs receiving a standard course of fibrinolytic treatment. A significantly increased resistance of clots formed at high fibrinogen levels to fibrinolytic therapy was found.

The dynamic exercise electrocardiogram.

Since our previous report, more than 300 electrocardiograms have been obtained on patients performing vigorous exercise (1). The purpose of this communication is to describe the method in detail, indicate the trend of normal variations, and discuss some of the findings in patients with abnormalities of the cardiovascular system. Prior efforts a t recording electrocardiograms during exercise have been only partially successful, since the resultant tracings have contained artifacts inherent in the system used (2-4). The two major difficulties that have been overcome in recording the electrocardiogram during exercise are skeletal muscle potentials and baseline shifts (Fig. I ) . Skeletal muscle artifacts have been eliminated by attaching the electrodes to areas of the body which are virtually free of skeletal muscles; baseline shifts can be avoided by proper fixation of the electrodes to the skin. Because of the location of the electrodes, the technic is referred to as the Ear-Ensiform-Precordial (EEP) system.

Techniques for the use of the digital computer as an aid in the diagnosis of heart disease

The rapid computational capabilities and large storage capacity of the digital computer can provide the physician with a powerful tool for diagnostic procedures. Numerous techniques are available that can be used in attempts to use the digital computer as an aid in diagnosis [1]. For this reason, a study in the use of a general-purpose digital computer in analyzing physiological waveforms of the heart and their relationship to cardiovascular pathology has been undertaken, and a pattern recognition program for automatically recognizing clinically useful parameters in the electrocardiogram (ECG) has been developed. The techniques presented are components of a system that can be used as an automated aid for the physician in his diagnostic process [2].