The effect of chronic mechanical circulatory support on neuroendocrine activation in patients with end-stage heart failure.

Objective: To evaluate if the improvement of patients supported with a Novacor was associated with a normalization in neuroendocrine activity.

Methods: Six patients had a Novacor implanted for end-stage heart failure. Four patients were transplanted after a mean of 4.5 months (range 3-6). One patient was weaned after 5 months and one died of a cerebral haemorrhage 5 weeks after implantation. Analysis of neuroendocrine activity was made prior to implantation and after 14, 30, 60 and 90 days. Levels of aldosterone, renin, cortisol, testosterone and T3 were measured using radio-immunoassays. Twenty-four hour urinary collections were made for assessment of adrenaline and noradrenaline excretion.

Results: Renin activity fell to normal after 14 days (16 +/- 3.0 ng/ml per h to 4.28 +/- 2.1 ng/ml per h, P < 0.05) and was maintained at 90 days. A similar picture was seen with aldosterone (1.5 +/- 0.4 nM to 0.12 +/- 0.07 nM, P < 0.05). Norepinephrine (67.46 +/- 14.1 microg/24 h) and epinephrine 12.9 +/- 2.5 microg/24 h) fell to normal physiological levels during the same time period. Cortisol levels were above normal pre-implantation but fell by day 30 (665.25 +/- 80.0 nM to 461.8 +/- 43.0 nM, P < 0.01). T3 and testosterone were lower than normal pre-implantation (T3 50 +/- 9.5 ng/dl vs. 90-200 ng/dl, testosterone 6.83 +/- 1.7 nM vs. 13-35 nM). T3 normalized after 90 days (81 +/- 11.7 ng/dl) and testosterone after 60 days (16.3 +/- 1.7 nM).

Conclusion: Neuroendocrine function is abnormal in patients with cardiac failure who require circulatory support. The Novacor improved this, but metabolic recovery was delayed. The positive effect on the neuroendocrine axis, in the absence of activation of other endocrine systems, suggests that prolonged support may be well tolerated.