Total and partial cardiac sympathetic denervation after surgical repair of ascending aortic aneurysm.
Sympathetic cardiopulmonary nerves arise from the cervical sympathetic trunks and travel alongside the great arteries to innervate the ventricles. Because of the proximity of the nerve and artery, cardiac sympathetic denervation may occur in patients who have just undergone surgery for the repair of an ascending aortic aneurysm.


METHODS
To evaluate the cardiac sympathetic activity in aortic aneurysm, we performed cardiac 123I-metaiodobenzylguanidine (MIBG) imaging on 12 patients (mean age +/- SD, 47 +/- 17 y) before and after the surgical repair of an aneurysm. Seven patients scheduled for coronary artery bypass grafting also underwent 123I-MIBG imaging as controls for open-chest surgery. Planar images were obtained at 15 min (early) and 4 h (delayed) after injection of 111 MBq 123I-MIBG, and the cardiac 123I-MIBG uptake was graded quantitatively and visually. The quantitative evaluation was based on the heart-to-mediastinum ratio (H/M), and visual evaluation was performed by assigning a score of 0-3 (0 = absent, 1 = severely reduced, 2 = reduced, and 3 = normal). Heart rate variability using 24-h Holter electrocardiography was analyzed before and after the operation to generate a time-domain index of heart rate variability as an index of autonomic balance.


RESULTS
In patients with aortic aneurysms, both early and delayed H/Ms were significantly decreased after the operation (early H/M: 1.84 +/- 0.16 before vs. 1.40 +/- 0.16 after, P = 0.001; delayed H/M: 1.79 +/- 0.38 before vs. 1.27 +/- 0.18 after, P = 0.004). Visual analysis of 123I-MIBG accumulation in early images showed absence of 123I-MIBG accumulation in 3 of 12 patients, a score of 1 in 7 patients, and a score of 2 in 2 patients. In contrast, no significant difference between H/M before surgery and H/M after surgery was seen in patients who underwent coronary artery bypass grafting. The time-domain index of heart rate variability was significantly lower after the operation than before (135 +/- 40 after vs. 96 +/- 27 before, P < 0.05).


CONCLUSIONS
Cardiac sympathetic nerves are totally or partially denervated after the surgical repair of ascending aortic aneurysm.
Momose
M
M
Department of Radiology, Tokyo Women's Medical University, Japan.
Kobayashi
H
H
Ikegami
H
H
Nagamatsu
H
H
Sakomura
Y
Y
Aomi
S
S
Kasanuki
H
H
Kusakabe
K
K
D019797:3-Iodobenzylguanidine; D000328:Adult; D000368:Aged; D000784:Aortic Dissection / Q000000981:diagnostic imaging / Q000601:surgery; D017545:Aortic Aneurysm, Thoracic / Q000000981:diagnostic imaging / Q000601:surgery*; D002315:Cardiopulmonary Bypass; D016022:Case-Control Studies; D002395:Catecholamines / Q000008:administration & dosage; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000294:innervation*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D018709:Statistics, Nonparametric; D013562:Sympathectomy; D013564:Sympathetic Nervous System / Q000000981:diagnostic imaging*; D015899:Tomography, Emission-Computed, Single-Photon
D002395:Catecholamines; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine