Effects of hypertension and obesity on the sympathetic activation of heart failure patients.

Previous studies have shown that congestive heart failure is characterized by sympathetic and reflex dysfunctions. Whether these alterations are potentiated in the presence of obesity and hypertension, two conditions that also display neuroadrenergic abnormalities and markedly increase the risk of heart failure, is unknown. In 14 healthy control subjects (C; age, 55.1+/-3.0 years; mean+/-SEM), 13 lean hypertensive subjects (H), 15 obese normotensive subjects (O), 14 lean normotensive subjects with congestive heart failure (CHF, New York Heart Association class II), 14 lean hypertensive subjects with CHF (CHFH), 14 obese normotensive subjects with CHF (CHFO), and 13 obese hypertensive subjects with CHF (CHFOH), all age-matched with C, we measured mean blood pressure (Finapres), heart rate (ECG), and muscle sympathetic nerve traffic (MSNA, microneurography) at rest and during baroreflex testing. Compared with C, body mass index was similarly increased in O, CHFO, and CHFOH, whereas mean blood pressure was similarly increased in HF, CHFH, and CHFOH, and left ventricular ejection fraction (echocardiography) was similarly reduced in CHF, CHFH, CHFO and CHFOH. Compared with C, MSNA was significantly increased in O, H, and CHF (43.0+/-2.2 versus 54.1+/-2.8, 53.1+/-2.5, and 57.4+/-2.8 bursts/100 heart beats, P<0.01). When O or H was combined with CHF, the MSNA increase was significantly more pronounced and maximal when O and H were concomitantly associated with CHF. Baroreflex sensitivity was reduced in O and H, with a further reduction in CHF and a minimal value in CHFOH. These data show that the sympathetic activation characterizing CHF is markedly potentiated when O and H alone or combined together are associated with a low cardiac output state and that this may depend on an arterial baroreflex impairment.