Electrocardiographic changes during hyperventilation resembling myocardial ischemia in patients with normal coronary arteriograms.

The effect of brief hyperventilation on the precordial T waves of 350 normal adults is described. Evidence is presented that brief hyperventilation initiates a vagal reflex which results in the T-wave inversion. Supportive data are also given to exclude respiratory alkalosis as a possible mechanism. Caution is advised in interpreting isolated T-wave inversions as indicative of organic heart disease. It is proposed that isolated T-wave inversion be deleted as a criterion for a "positive" exercise test.

The Effect of Hyperventilation on the Normal Adult Electrocardiogram

The symptom patterns of the hyperventilation syndrome have been recognized for many years. 1-5 Some workers have reported abnormal lowering or inversion of the T-wave and, less frequently, depression of the ST segment in the routine electrocardiogram of many patients with this syndrome or with anxiety and emotional instability. 6-13 These changes are readily reproduced by voluntary hyperventilation. Several others have observed similar changes of the T-wave in the electrocardiogram of certain normal persons during voluntary hyperventilation. 14,15 The purpose of this report is (1) to describe the electrocardiographic abnormalities during voluntary hyperventilation in 20 patients with the hyperventilation syndrome and the effects of inhalation of CO 2 and administration of various drugs in these changes; (2) to present the changes of serum electrolytes, respiratory gases, and pH of the blood in these patients during hyperventilation, with or without inhalation of CO 2 ; (3) to postulate a possible mechanism for the electrocardiographic changes, and (4)

Hyperventilation Syndrome: Changes in the Electrocardiogram, Blood Gases, and Electrolytes During Voluntary Hyperventilation; Possible Mechanisms and Clinical Implications

A group of 40 patients who have “ischemic” electrocardiographic (that is, 1 mm flat S-T segment depression) responses to exercise but who do not fulfill the usual criteria for ischemic heart disease are discussed. These patients have been followed up for a minimum of 3 years and clinical findings of ischemic heart disease have not developed. It is suggested that they have vasoregulatory abnormalities. Vasoregulatory abnormalities include an unusual increase in heart rate on standing, ST-T segment changes on standing, “ischemic” electrocardiographic changes unaccompanied by chest discomfort occurring early in exercise and disappearance of “ischemic” changes as exercise proceeds. Propranolol administration tends to abolish the changes, and the Valsalva maneuver temporarily restores the electrocardiographic changes toward normal. Recognition of this syndrome, its possible causes, and the importance of proper counseling and recommendations in management are discussed briefly.

Thomas H. Lorenz

Papers

The effect of hyperventilation and pro-banthine on isolated RS-T segment and T-wave abnormalities