Myocardial lactate metabolism during isometric hand grip test. Comparison with pacing tachycardia

Twenty-five patients with chest pain were studied by left ventriculography and coronary arteriography. Myocardial metabolic studies were done during control state, pacing tachycardia, isometric hand grip at 30 per cent of maximum force, and combined hand grip plus pacing tachycardia. Nine patients had myocardial lactate abnormality (group 1) as evidenced by myocardial lactate production or decreased extraction (less than 10%). Though tension time index and triple product (left ventricular ejection time times HR times systolic pressure) as determinants of myocardial oxygen consumption were highest during combined hand grip plus pacing tachycardia, myocardial lactate abnormalities were most frequent during pacing tachycardia. The present study indicates that isometric hand grip even if performed during pacing tachycardia is not a sensitive test for detection of myocardial lactate abnormalities. The rising level of arterial lactate during isometric hand grip is the most likely mechanism of positive myocardial arteriovenous lactate difference.