[Sympathetic reinnervation following heart transplantation--a double-tracer study with 123I-MIBG and 201Tl].

Sympathetic reinnervation was evaluated in 15 patients 2-69 months after heart transplantation using a double-tracer technique with 123I-MIBG and 201Tl. Since MIBG is accumulated in the same manner as norepinephrine it may serve as a tracer of the integrity and function of the sympathetic nervous system. 201Tl was used for landmarking. Planar anterior imaging was performed 15 min and 4 h after i.v. injection of 220 MBq 123I-MIBG and 37 MBq 201Tl. Image quantitation was based on the ratio of myocardial to mediastinal MIBG-uptake. Cardiac regions of interest were defined according to the 201Tl uptake. There was no evidence of sympathetic reinnervation in 8 patients 2-34 months after transplantation. Increased MIBG-uptake could be observed in the anterior basal region in 6 long-term cardiac transplants (37-69 months). One patient with a 59-month-old transplanted heart did not reinnervate. Increased MIBG-uptake in the anterior basal region indicating partial sympathetic reinnervation could be shown in 40% of the investigated patients with an average organ age of 51 months.