Yoshinaga K: Altered sympathetic and vagal modulations of the cardiovascular system in patients with pheochromocytoma: their relations to orthostatic hypotension

To examine sympathetic and vagal cardiovascular regulatory mechanisms in the pathogenesis of orthostatic hypotension in pheochromocytoma, we continuously monitored blood pressure (Finapres) and RR interval (electrocardiogram) in supine and standing positions in 12 patients with pheochromocytoma, 43 patients with essential hypertension, and 30 normotensive subjects. Mayer wave power spectrum of systolic blood pressure variability ('0.1 Hz) and respiratory power spectrum of the RR interval variability ('0.25 Hz) were taken as measures of sympathetic vascular and cardiac vagal modulations, respectively. Systolic blood pressure decreased more upon standing in pheochromocytoma patients (221 6