Norepinephrine levels in the coronary sinus in patients with cardiovascular diseases at rest and during isometric handgrip exercise

In order to evaluate cardiac sympathetic nerve activity, plasma norepinephrine levels in the coronary sinus (NE_CS) and in the artery (NE_A) were determined in 24 subjects with cardiovascular diseases and in six with functional murmur. The resting NE_CS was greater than NE_A in 14 subjects with normal left ventricular end-diastolic pressure (LVEDP) (p < 0.01) and/or in 22 with normal cardiac index (p < 0.05), whereas NE_CS was not significantly different from NE_A in the remaining patients with elevated LVEDP and/or with reduced cardiac index. Isometric handgrip exercise increased both NE_CS and NE_A (p < 0.001). When subjects were divided into two groups according to the slope of the ventricular function curve (Δ stroke work index/ΔLVEDP), NE_CS during exercise was greater than NE_A in the group having slopes of 1.0 or more (p < 0.01), but neither values significantly differed in the group with slopes of less than 1.0. In the latter group, cardiac NE overflow rate calculated from the difference between NE_CS and NE_A multiplied by coronary sinus plasma flow, was significantly less than that of the former group before and during handgrip (p < 0.05 and p < 0.01, respectively). These results suggest that cardiac norepinephrine release into the coronary sinus is reduced in patients with impaired cardiac function.