Saturday, October 11, 2008

Partial cardiac sympathetic denervation after bilateral thoracic sympathectomy in humans

Upper thoracic sympathectomy is used to treat several disorders. Sympathetic nerve fibers emanating from thoracic ganglia innervate the heart.
METHODS: Nine patients with previous upper thoracic sympathectomies (four right-sided, one left-sided, four bilateral) underwent thoracic 6-[18F]fluorodopamine scanning between 1 and 2 hours after injection of the imaging agent. In each case, a low rate of entry of norepinephrine into the arm venous drainage (norepinephrine spillover) verified upper limb sympathectomy. Data were compared with those from the interventricular septum of patients with cardiac sympathetic denervation associated with pure autonomic failure and from normal volunteers. RESULTS: All four patients with bilateral sympathectomy had low septal myocardial 6-[18F]fluorodopamine-derived radioactivity (2,673 +/- 92 nCi-kg/cc-mCi at an average of 89 minutes after injection) compared with normal volunteers (3,634 +/- 311 nCi-kg/cc-mCi at 83 minutes, N = 22, P = .007) and higher radioactivity than in patients with pure autonomic failure (1,320 +/- 300 nCi-kg/cc-mCi at 83 minutes, N = 7, P = .003).
CONCLUSIONS: Bilateral upper thoracic sympathectomy partly decreases cardiac sympathetic innervation density.