Sympathetic Denervation and Reinnervation After the Maze Procedure

We evaluated serial changes in cardiac sympathetic nerve distribution using 1 2 3 I-metaiodobenzylguanidine ( 1 2 3 I-MIBG) after the Maze procedure. The Maze procedure, in which multiple incisions are made in the atrium, has been concomitantly performed with mitral valve (MV) surgery in an attempt to eliminate atrial fibrillation (AF). Although attenuation of the sinoatrial node response to exercise and a reduction of left ventricular function (left ventricular ejection fraction [LVEF]) in early stages after the Maze procedure have been suggested, factors leading to these changes have not been clarified. Methods: Thirteen patients with MV disease were enrolled in this study. Six of them had undergone MV surgery and the Maze procedure (Maze +), and 7 had undergone MV surgery without the Maze procedure (Maze-). All patients underwent cardiac 1 2 3 I-MIBG imaging preoperatively and 10 d and 1 y after surgery to assess 1 2 3 I-MIBG uptake (heart-to-mediastinum count ratio of early planar images [H/M]) and the washout rate (WR). Radionuclide ventriculography was also performed to calculate LVEF 3 d after each 1 2 3 I-MIBG imaging. Results: The LVEF of the Maze+ group significantly decreased 10 d after surgery (44.2 ′ 4.8; mean ′ SO) compared with that before surgery (60.3 ′ 6.9; P < 0.05) and significantly increased at 1 y (65.2 ′ 2.9) compared with that at 10 d (P < 0.05). In the Maze- group, there was no significant change 10 d (53.0 ′ 12.3) and 1 y (58.6 ′ 4.8) after surgery compared with that before surgery (60.4 ′ 4.6) (P = not significant, each). In the Maze + group, the H/M (1.51 ′ 0.18) was significantly lower at 10 d after than that at the preoperative stage (1.90 ′ 0.25; P < 0.05) but significantly recovered at 1 y (2.23 ′ 0.18; P < 0.05) with a similar transient increase in the WR (36.7% ′ 6.1% at preoperative stage; 46.9% ′ 3.4% at 10 d; 39.9% ′ 6.5% at 1 y; P < 0.05, each). On the other hand, the Maze- group did not show a significant change in the H/M (1.94 ′ 0.32, 2.06 ′ 0.18, and 2.13 ′ 0.17, respectively; P = not significant, each) but did exhibit a significant decrease in the WR (40.4% ′ 5.1%, 37.0% ′ 5.1%, and 32.9% ′ 2.5%, respectively; P < 0.05, each). Changes in the H/M of both groups significantly correlated with the change in LVEF (r = 0.82; P < 0.05), and the WR showed a significant inverse correlation with changes in the LVEF (r = -0.81; P < 0.05). Conclusion: Cardiac sympathetic nerves were denervated at early stage and reinnervated at late stage after the Maze procedure. Such adrenergic nerve changes may be correlated, at least in part, with changes in left ventricular function after this procedure.