Impact of gender on benefits of exercise training on sympathetic nerve activity and muscle blood flow in heart failure.

AIMS: We compared the effects of exercise training on neurovascular control and functional capacity in men and women with chronic heart failure (HF). METHODS AND RESULTS: Forty consecutive HF outpatients from the Heart Institute, University of Sao Paulo, Brazil were divided into the following four groups matched by age: men exercise-trained (n = 12), men untrained (n = 10), women exercise-trained (n = 9), women untrained (n = 9). Maximal exercise capacity was determined from a maximal progressive exercise test on a cycle ergometer. Forearm blood flow was measured by venous occlusion plethysmography. Muscle sympathetic nerve activity (MSNA) was recorded directly using the technique of microneurography. There were no differences between groups in any baseline parameters. Exercise training produced a similar reduction in resting MSNA (P = 0.000002) and forearm vascular resistance (P = 0.0003), in men and women with HF. Peak VO(2) was similarly increased in men and women with HF (P = 0.0003) and VE/VCO(2) slope was significantly decreased in men and women with HF (P = 0.0007). There were no significant changes in left-ventricular ejection fraction in men and women with HF. CONCLUSION: The benefits of exercise training on neurovascular control and functional capacity in patients with HF are independent of gender.

Increased muscle sympathetic nerve activity predicts mortality in heart failure patients.

BACKGROUND: Previous studies have associated neurohumoral excitation, as estimated by plasma norepinephrine levels, with increased mortality in heart failure. However, the prognostic value of neurovascular interplay in heart failure (HF) is unknown. We tested the hypothesis that the muscle sympathetic nerve activity (MSNA) and forearm blood flow would predict mortality in chronic heart failure patients. METHODS: One hundred and twenty two heart failure patients, NYHA II-IV, age 50+/-1 ys, LVEF 33+/-1%, and LVDD 7.1+/-0.2 mm, were followed up for one year. MSNA was directly measured from the peroneal nerve by microneurography. Forearm blood flow was obtained by venous occlusion plethysmography. The variables were analyzed by using univariate, stepwise multivariate Cox proportional hazards analysis, and Kaplan-Meier analysis. RESULTS: After one year, 34 pts died from cardiac death. The univariate analysis showed that MSNA, forearm blood flow, LVDD, LVEF, and heart rate were significant predictors of mortality. The multivariate analysis showed that only MSNA (P=0.001) and forearm blood flow (P=0.003) were significant independent predictors of mortality. On the basis of median levels of MSNA, survival rate was significantly lower in pts with >49 bursts/min. Similarly, survival rate was significantly lower in pts with forearm blood flow <1.87 ml/min/100 ml (P=0.002). CONCLUSION: MSNA and forearm blood flow predict mortality rate in patients with heart failure. It remains unknown whether therapies that specifically target these abnormalities will improve survival in heart failure.

Exercise training restores baroreflex sensitivity in never-treated hypertensive patients.

The effects of exercise training on baroreflex control of sympathetic nerve activity in human hypertension are unknown. We hypothesized that exercise training would improve baroreflex control of muscle sympathetic nerve activity (MSNA) and heart rate (HR) in patients with hypertension and that exercise training would reduce MSNA and blood pressure (BP) in hypertensive patients. Twenty never-treated hypertensive patients were randomly divided into 2 groups: exercise-trained (n=11; age: 46+/-2 years) and untrained (n=9; age: 42+/-2 years) patients. An age-matched normotensive exercise-trained group (n=12; age: 42+/-2 years) was also studied. Baroreflex control of MSNA (microneurography) and HR (ECG) was assessed by stepwise intravenous infusions of phenylephrine and sodium nitroprusside and analyzed by linear regression. BP was monitored on a beat-to-beat basis. Exercise training consisted of three 60-minute exercise sessions per week for 4 months. Under baseline conditions (before training), BP and MSNA were similar between hypertensive groups but significantly increased when compared with the normotensive group. Baroreflex control of MSNA and HR was similar between hypertensive groups but significantly decreased when compared with the normotensive group. In hypertensive patients, exercise training significantly reduced BP (P<0.01) and MSNA (P<0.01) levels and significantly increased baroreflex control of MSNA and HR during increases (P<0.01 and P<0.03, respectively) and decreases (P<0.01 and P<0.03, respectively) in BP. The baseline (preintervention) difference in baroreflex sensitivity between hypertensive patients and normotensive individuals was no longer observed after exercise training. No significant changes were found in untrained hypertensive patients. In conclusion, exercise training restores the baroreflex control of MSNA and HR in hypertensive patients. In addition, exercise training normalizes MSNA and decreases BP levels in these patients.