PERCUTANEOUS TRANSLUMINAL MITRAL VALVULOPLASTY NORMALIZES BAROREFLEX SENSITIVITY AND SYMPATHETIC ACTIVITY IN PATIENTS WITH MITRAL-STENOSIS

Background In patients with mitral stenosis, reduced cardiac output or altered pulmonary hemodynamics may increase sympathetic nerve activit y. However, the magnitude of the increase in sympathetic activity in s uch patients and the effect of valvuloplasty on this activity are unkn own. Methods and Results We microneurographically measured muscle symp athetic nerve activity before and after mitral valvuloplasty in 10 pat ients (mean +/- SEM age, 48 +/- 2 years) with mitral stenosis and in 1 0 healthy volunteers (47 +/- 4 years); hemodynamic variables were also measured. Baroreflex sensitivity was assessed on the basis of the rat io of the change in heart rate or muscle sympathetic activity to the c hange in mean arterial pressure during intravenous infusion of sodium nitroprusside or phenylephrine. At baseline, muscle sympathetic activi ty was significantly higher in the patients with mitral stenosis than in the control subjects (42.1 +/- 3.2 versus 26.1 +/- 3.7 bursts/min, P < .05). However, there was no significant difference between the gro ups in sympathetic activity at 1 week after valvuloplasty. The reducti on in sympathetic activity after valvuloplasty was maintained for grea ter than or equal to 6 months and correlated with the increase-in card iac index (r = .74, P < .05). Baroreflex sensitivity was significantly lower in the patients than in the control subjects, but after valvulo plasty there was no significant difference in baroreflex sensitivity b etween the groups. Conclusions Sympathetic activity is increased in pa tients with mitral stenosis. Mitral valvuloplasty in such patients res ults in early and long-lasting normalization of sympathetic nerve acti vity, possibly because of an improvement in arterial baroreflex sensit ivity.