John S. Ladue

The Significance of the Serum Glutamic Oxalacetic Transaminase Activity Following Acute Myocardial Infarction

The serum glutamic oxalacetic transaminase rose two to 20 times normal in 74 of 75 patients who had acute transmural myocardial infarction. The height of the enzymatic activity was roughly proportional to the size of the infarct. Serum glutamic oxalacetic transaminase is unaffected by angina pectoris, coronary insufficiency, heart failure, or digitalis in the absence of active heart cell injury. Experimental myocardial infarction is followed consistently by a two to twenty-fold increase in serum glutamic oxalacetic transaminase activity. Increase in the serum activity of this enzyme appears to be a useful index of the presence of active heart muscle injury.

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.

The Precordial Electrocardiogram during Exercise

C ONTINUOUS recording of the precordial electrocardiogram during vigo-ous exereise has been tested in 150 persons through the use of a new lead system, a new method of electrode attachment, and special types of electrodes and electrode paste. This technic has resulted in tracings that are almost free of skeletal muscle potentials and baseline shift in subjects performing the Masters 2-step test. Many studies of the electrocardiogram taken after the completion of exercise have been reported. 4 While much valuable information has been acquired from the postexercise electrocardiogram, the test has distinct limitations. The technic is not without hazard, since patients with heart disease may develop serious reactions before the completion of the exercise.12 Consequently patients with abnormal resting electrocardiograms are not usually tested. Continuous recording of the electrocardiogram during the actual performance of exercise may have the following potential advantages: significant changes may develop during but not after the exercise; the test can be terminated at the first evidence of definite electrocardiographic abnormality or perhaps safely continued beyond any limits previously prescribed; the prompt recognition and timing of the earliest electrocardiographic manifestations of ischemia or arrhythmia permit greater flexibility in the amount of

Variations in serum glutamic oxaloacetic transaminase activity in experimental and clinical coronary insufficiency, pericarditis, and pulmonary infarction.

Previous studies have demonstrated consistent rises in serum activity of the enzyme, glutamic oxaloacetic transaminase (SGO-T), following myocardial necrosis of various etiologies. The present study demonstrates markedly different findings in experimental and clinical coronary insufficiency, pericarditis, and pulmonary infarction unless concomitant myocardial necrosis was present. This seems to be a valuable means of differentiating clinical problems in which the presence of myocardial injury is suspected as the basis of the patients chest pain.

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.

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.

Failure of safflower oil hyperlipemia to inhibit limitation of the size of experimental streptokinase-treated myocardial infarction☆

Abstract A total of 20 dogs were given 400 c.c. of high-unsaturated safflower oil three hours before experimental production of acute myocardial infarction. Ten were given streptokinase and ten were not treated. Autopsy findings were highly significant since only one of the ten treated dogs developed a transmural infarct, whereas all of the ten untreated or control dogs showed large transmural infarctions. The infarcts in the treated animals were small, spotty, nonconfluent, and frequently subendocardial. The fact that the protective effect of streptokinase occurred in nine dogs without significant change in circulating FA suggests that therapeutic thrombolysis occurred at the tissue level by activation of fibrinolysin contained in the clots in the coronary circulation. These findings suggest that hyperlipemia due to unsaturated fat does not inhibit FA at the tissue level. Striking was the absence of microthrombi in all dogs, treated or untreated, whose hyperlipemia was due to safflower oil in contrast to the microthromboses seen in animals (treated or untreated) with saturated hyperlipemia. 10