Diurnal Variation of Plasma Catecholamines and Systolic Time Intervals

¹ Cardiology Section Medical Service, Long Beach Veterans Administration Hospital, the Medical Service White Memorial Hospital. the Universitv of California College of Medicine, Irvine and the university of Southern California CoIIege of Medicine
² Chief of Cardiology, Long Beach Veterans Administration Hospital: Adjunt Associate Professor of Medicine. University of California College of Medicine, Irvine
³ Chief of Medicine, White Memorial Hospital; Assistant Professor of Medicine. University of Southern California College of Medicine
⁴ Research Cardiopulmonary Technician, Long Beach Veterns Administration Hospital

Plasma catecholamines were obtained and systolic time intervals recorded in five normal subjects and five patients with coronary disease in the supine position at 8 AM, 12 PM, 4 PM, 8 PM, 10 PM, 12 AM, 2 AM, 4 AM, and 8 AM. Systolic time intervals were later obtained in ten additional patients with coronary disease every 30 minutes from 12 AM through 4 AM and from 8 AM through 12 PM. A significant diurnal variation in plasma norepinephrine was found in two of ten subjects and a significant diurnal variation in plasma epinephrine in a third subject. No correlation was found between plasma catecholamine levels and systolic time intervals. The external isovolumic contraction time (EICT) was significantly prolonged in 9 of 15 patients (60 percent) with coronary disease during 12 AM through 4 AM. These findings suggest a decrease in left ventricular contractility occurring in many patients with coronary disease during 12 AM through 4 AM.

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