EFFECTS OF CAROTID BARORECEPTOR STIMULATION ON REGIONAL SYMPATHETIC ACTIVITY IN CHRONIC HEART FAILURE

Abstract

Objective: Carotid baroreceptor stimulation (BAT) exerts in heart failure (CHF) sympatho-inhibitory effects. No information is available, however, on whether these effects have a regional or a more generalized behaviour. Design and method: In 9 CHF patients (age 58.3 ± 252 yrs, mean ± SD) we recorded via the microneurographic technique muscle and skin sympathetic nerve traffic (MSNA and SSNA, respectively) before, 6 and 12 months following BAT. Measurements included left ventricular ejection fraction (LVEF), brain natriuretic peptide BNP (elisa), 6-minute walking test (6WT), New York Heart Association (NYHA) class, Minnesota score, together with routine laboratory variables. 10 age-matched CHF patients not underwent BAT served as controls. Results: BAT caused significant increase in LVEF (from 33.4 ± 5.1 to 37.1 ± 5.4%, P < 0.05) and in 6 WT, and a significant reduction in the Minnesota score and in NYHA class (from 3.3 ± 0.4 to 2.4 ± 0.4 a.u), unaltering BNP. MSNA, but not SSNA, was markedky activated in CHF. BAT caused a significant reduction in MSNA 6 and 12 months follow-up (from 70.7 ± 2.7 to 47.0 ± 4.3 and 44.1 ± 3.5 bursts/100heartbeats, means ± SD, P < 0.05). This effect was not accompanied by any significant change in SSNA (from 11.3 ± 2.1 to 11.5 ± 1.7 and 11.6 ± 2.1 bursts/minute, P = NS). A significant correlation was found between baseline MSNA values and the MSNA changes after BAT, which were also related to the LVEF modifications. No significant change in the various variables was detected in the control group followed for a 12 month observation. Conclusions: These data provide the first evidence that BAT exerts heterogeneous effects on sympathetic cardiovascular drive, inducing a marked reduction in MSNA but not in SSNA, which appears to be within the normal range in this condition. These effects may depend on the different reflex modulation regulating neuroadrenergic drive in these cardiovascular districts.