Does selective reduction in filling pressures via lower-body negative pressure reduce cardiac norepinephrine spillover in patients with chronic heart failure?
Selective reduction of cardiac filling pressures without inducing systemic hypotension effectively lowers cardiac sympathetic activity in patients with chronic heart failure.
Background —We studied the cardiac sympathetic response to selective unloading of cardiopulmonary baroreceptors in subjects with normal left ventricular (LV) function and congestive heart failure (CHF). Methods and Results —Eight patients with normal LV function (age 57±5 years, ejection fraction 58±2%) and 8 patients with CHF (age 60±2 years; ejection fraction 19±2%) were studied. Instrumentation consisted of an arterial line, a pulmonary artery catheter, and a coronary sinus thermodilution catheter. The radiotracer technique was used for measurement of cardiac norepinephrine spillover (CANESP) and total-body norepinephrine spillover. Lower-body negative pressure (LBNP) was applied at 2 levels: nonhypotensive and hypotensive LBNP. Nonhypotensive LBNP reduced filling pressures significantly in both groups. Arterial pressure did not change. This reduction in filling pressures caused a significant reduction in CANESP in the CHF group (from 167±53 to 125±37 pmol/min, P <0.05) but no change in the normal LV function group. Hypotensive LBNP caused a significant increase in CANESP in the normal group (73±13 vs 122±27 pmol/min, P <0.05) but no significant change in those with CHF. Conclusions —We conclude that selective reduction in filling pressures lowers cardiac norepinephrine spillover in patients with CHF. These findings suggest that a goal of CHF management should be to reduce cardiac filling pressures while avoiding systemic hypotension.
Azevêdo et al. (Tue,) studied this question.