Hypertensive left ventricular hypertrophy: Relation to peripheral sympathetic drive

OBJECTIVES This study was designed to examine whether the occurrence of lef t ventricular hypertrophy (LVH) in moderate to severe essential hypertensio n (EHT) was associated with alteration in peripheral sympathetic drive. BACKGROUND In hypertension, LVH is an independent predictor of increased mo rbidity and mortality. The reported mechanisms leading to LVH remain unclea r but include hemodynamic and humoral factors. The sympathetic nervous syst em may be important, particularly as catecholamines have been shown to have trophic properties. We tested the hypothesis that sympathetic activity mea sured using microneurography could be different in patients with hypertensi on depending on the presence of LVH. METHODS We examined 28 subjects with moderate to severe EHT (stages 2 to 3; Joint National Committee [JNC]-VI classification). Fourteen had echocardio graphic evidence of LVH (EHT + LVH), while the other 14 subjects (EHT) did not. Subjects were matched in terms of age, body, mass index and levels of arterial blood pressure. Peripheral muscle sympathetic nerve activity was m easured from both multiunit bursts (MSNA) and single unit (s-MSNA) vasocons trictor impulses via the peroneal nerve. RESULTS The mean frequency of s-XISNA and MSNA was greater in the EHT + LVH group than it was in the EHT group (mean SEM +/- 75.9 +/- 6.9 impulses/100 beats vs. 52.1 +/- 2.9 impulses/100 beats, p < 0.001 and 64.2 +/- 5.7 burs ts/100 beats vs. 48.9 +/- 2.8 bursts/100 beats, p < 0.05). CONCLUSIONS These results indicate that, in subjects with moderate to sever e hypertension, the presence of LVH is associated with higher sympathetic d ischarge, evidenced by an increase in unitary firing frequency and also by fiber recruitment. (C) 2001 by the American College of Cardiology.