Effect of endomyocardial laser channels on regional innervation shown with (125)I-MIBG and autoradiography.
The aim of this study was to map regional innervation against regional flow early after laser channel placement using autoradiography in a porcine model.


METHODS
Four juvenile male swine underwent left ventricular mapping using a catheter-based mapping system and laser treatment with 20-30 channels to the mid and distal anterior wall of the left ventricle. Three days later animals were injected with 37 MBq (125)I-metaiodobenzylguanidine (MIBG) followed in 3 h with 1,110 MBq (99m)Tc-sestamibi; 1 h later the animals were killed. Hearts were removed, perfusion fixed, and sliced into 1-cm slices. The slices best showing laser holes were selected, and circumferential sections were taken for autoradiography and hematoxylin-eosin staining. Phosphor screens were exposed for (99m)Tc and (125)I, and images were processed. The MIBG image was subtracted from the methoxyisobutylisonitrile (MIBI) image and vice versa, and color tables were applied to the difference images and overlaid on the perfusion images. Quantitative analysis of the light image data was also performed.


RESULTS
Thirty-three sections from the last 3 experiments were analyzed. Acoustic damage from 30 laser channels was identified from the hematoxylin-eosin sections. Reduced MIBG relative to regional flow was seen in surrounding tissue corresponding to only 1 channel. There was no statistically significant difference in light units expressed as (MIBG - MIBI)/maximal MIBG value between laser channels and unmarked myocardial map regions. The regions identified from the color table on the map as low MIBG relative to MIBI were significantly lower than remaining laser channels and remaining myocardium. Mean light units for the regions with high MIBG relative to MIBI were significantly higher than the remaining laser channels and remaining myocardium.


CONCLUSIONS
Using a high-resolution technique correlated with microscopic pathology in an animal model, there is negligible regional denervation 3 d after placement of endomyocardial laser channels.
Johnson
Lynne L
LL
Rhode Island Hospital, Main Building, Room 208, Brown University, 593 Eddy Street, Providence, RI 02903, USA. Lynne.Johnson@brown.edu
Thambar
Sukumaran
S
Donahay
Tammy
T
Dae
Michael
M
Williams
David O
DO
D019797:3-Iodobenzylguanidine; D000818:Animals; D001345:Autoradiography; D003326:Coronary Circulation; D003714:Denervation; D006321:Heart / Q000000981:diagnostic imaging / Q000294:innervation*; D053685:Laser Therapy; D008297:Male; D009204:Myocardial Revascularization / Q000379:methods; D018919:Neovascularization, Physiologic; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013552:Swine; D017256:Technetium Tc 99m Sestamibi
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine; D017256:Technetium Tc 99m Sestamibi