Relation of systemic sympathetic nervous system activation to echocardiographic left ventricular size and performance and its implications in patients with mitral regurgitation

We have previously demonstrated that the systemic sympathetic nervous syste m (SNS) is activated in proportion to an increase in cineventriculographic left ventricular (LV) end-systolic volume and decrease in ejection fraction (EF) in patients with chronic mitral regurgitation (MR). However, the rela tion between noninvasive echocardiographic measures of LV size and performa nce and systemic SNS activation and their clinical implications in patients with MR is not known. We studied 17 MR patients with echocardiography, art erial norepinephrine (NE) sampling, and [H-3]-NE infusions and arterial blo od sampling to determine NE kinetic parameters using a 2-compartment analys is, including extravascular NE release rates (NE2, index of SNS activity) a nd the metabolic clearance rate from the vascular compartment. The arterial NE values correlated with LV end-systolic dimensions (r = 0.50, p = 0.04), but not with LV end-diastolic dimensions, and EF or fractional shortening measures. The NE2 values correlated with LV end-systolic dimensions (r = 0. 53, p = 0.03) and inversely with LVEF (r = -0.45, p = 0.07) and fractional shortening (r = 0.43, p = 0.08) measures, but not with LV end-diastolic dim ensions. The metabolic clearance rate values showed an inverse correlation with LV end-diastolic (r = -0.52, p = 0.03) and end-systolic (r = -0.49, p = 0.04) dimensions, but not with LV performance measures. The increase in N E, values was progressive as the LV end-systolic dimensions increased and m ore marked at LV end-systolic dimensions greater than or equal to 40 mm. Th us, activation of the SNS is related to an increase in echocardiographic LV end-systolic dimensions and a decrease in LV performance measures in chron ic MR. (C) 2000 by Excerpta Medico, Inc.