Richard H. Wasserburger

Value of oral potassium salts in differentiation of functional and organic T wave changes

Abstract Ten grams of oral potassium salts were administered to 60 patients with functionally inverted (anxiety induced) left ventricular T waves, to 119 patients with organically inverted T waves and 4 patients with inverted T waves of indeterminate etiology. All functionally inverted T waves were reverted to normal 90 minutes after ingestion of K+. The T wave inversion resulting from 10 to 15 seconds of brisk hyperventilation likewise was abolished. Organic T waves of myocardial infarction were generally unaltered following ingestion of K+. Several of the inverted T waves due to infarction showed increased negativity. On the other hand, inverted T waves over the “fringe areas” of lateral wall ischemia in either anterior or posterior wall infarction occasionally showed a tendency to normalization. In a single instance of an acute posterior wall infarction, K+ ingestion improved the T wave contour in lead II only. Of the 40 instances of acute myocardial ischemia, 32 showed no change; 2 showed slightly increasing T wave negativity; 4 showed improvement although not normalization of the ischemie zone; and 2 showed normalization. In 1 of these last 2 patients the control tracing had shown almost complete resolution of the ischemie episode. Ten instances of left bundle branch block, 10 of digitalis effect and 2 of subacute pericarditis showed no alteration of T wave polarity following K+ ingestion. As previously noted in the literature, electrocardiograms of left ventricular preponderance showed the greatest variability of T wave configuration following K+ ingestion. Eight tracings showed no change; 1 showed slight improvement and 3, moderate improvement. None, however, showed complete normalization. The K+ salt was generally well tolerated when administered 1 1 2 hours following the noon meal. It must be regarded as a potentially dangerous drug, particularly in patients with acute ischemie episodes. Adequate renal function is a prerequisite for the test. This procedure appears to be of considerable clinical usefulness in evaluating T wave abnormalities of obscure etiology. It should not, however, usurp clinical judgment since the results to date are purely empirical and lack a sound pathophysiologic basis.

PROMINENT PRECORDIAL T WAVES AS AN EXPRESSION OF CORONARY INSUFFICIENCY.

Abstract The sudden appearance of tall or peaked T waves may be the earliest electrocardiographic expression of acute myocardial ischemia and impending myocardial infarction. They are most apt to be seen in records taken during or within several hours of the onset of the chest pain. The “modus operandi” of this puzzling electromotive phenomenon, abetted by a review of pertinent experimental data, remains unanswered and offers a challenge for continued basic and sophisticated research. Most of the investigators believed that these acutely peaked T waves were due to acute subendocardial ischemia, but this was based more on electromotive hypothesis than fact. The sudden shift of the intracellular potassium seemingly plays a key role.

Potassium-loading test in the differentiation of T wave abnormalities

Abstract This report summarizes our experience with the oral potassium-loading test in a group of patients who presented with abnormal T wave inversion on routine resting electrocardiograms. The test empirically normalizes most T wave abnormalities that are unassociated with clinically demonstrable heart disease, particularly the T wave changes induced by brief hyperventilation or by anxiety reactions. The response to the test procedure is dosage-dependent and is not related to a nonspecific osmolar load. It is recommended that the oral potassium-loading test not be utilized as a clinical testing procedure. Although the results frequently clarify the significance of T wave abnormalities in asymptomatic patients, false positives and false negatives will occur. At best, awareness of this study will recall to the clinicians mind that anxiety, hyperventilation and standing may result in T wave abnormalities entirely similar to those of an acute myocardial ischemic episode, pericarditis or myocarditis.

The standard 12-lead scalar electrocardiogram, an assessment of left ventricular performance

Summary The results of standard 12 lead scalar electrocardiograms were correlated with left ventricular performance as reflected in the determinations of left ventricular end diastolic pressure at rest, ejection fraction and in the qualitative evaluation of left ventricular systolic wall motion. The study group included 55 patients who had at least 50% obstruction of one or more of the three major coronary arteries. The cardiothoracic ratio and a coronary artery index, expressing the residual patency of the three major coronary arteries, were also determined for each patient. The results indicate that normal left ventricular systolic wall motion can only be expected when the electrocardiogram is normal or reveals only minor repolarization abnormalities. Such an electrocardiogram favors but does not guarantee normal wall motion. Corresponding areas of abnormal left ventricular wall motion were observed in all cases with electrocardiographic evidence of a transmural anterior wall infarction and in the great majority of cases with an inferior wall infarction. Electrocardiographic evidence of a single transmural myocardial infarction was associated with a mean ejection fraction of 52% which was 10% less than that observed with a normal electrocardiogram and with only repolarization abnormalities. The reduction in ejection fraction was most marked in those with transmural anterior wall infarctions and in those with multiple transmural infarctions. The left ventricular end diastolic pressure was similar in those patients with and without electrocardiographic evidence of a transmural myocardial infarction. However, the mean left ventricular end diastolic pressure was significantly lower in those with inferior wall infarctions (13 mmHg) than in those with anterior wall infarctions (18mm Hg.). The total coronary artery index was not significantly different in patients with and without electrocardiographic evidence of a transmural myocardial infarction.