Pathological effects of pulmonary vein beta-radiation in a swine model.
BACKGROUND
Atrial fibrillation (AF) may be triggered by ectopic beats originating in sleeves of atrial myocardium entering the pulmonary veins (PVs). PV isolation by means of circumferential ostial or atrial radiofrequency ablation is an effective but also a difficult and long procedure, requiring extensive applications that can have serious potential complications. Our objective was to examine pathological effects of PV beta-radiation, particularly the ability to destroy PV myocardial sleeves without inducing PV stenosis and other unwanted effects, in order to establish its potential feasibility for the treatment of AF.


RESULTS
Ten minipigs were studied. A phosphorus-32 source wire centered within a 2.5-mm diameter balloon catheter (Galileo III Intravascular Radiotherapy System, Guidant, Santa Clara, CA, USA) was used to deliver beta-radiation to the superior wall of the right PV trunk. Pathological analysis was performed either immediately after ablation (2 pigs) or 81 +/- 27 days later (8 pigs). Acute effects of PV beta-radiation consisted of endothelial denudation covered by white thrombus, elastic lamina disruption, and PV sleeve necrosis. Late effects consisted of mild focal neointimal hyperplasia that reduced the PV luminal area by only 1.3 +/- 1.8%, elastic lamina thickening, and PV sleeve fibrosis. Four of these 8 PVs were completely re-endothelized. Lesions were transmural in 6 of 10 radiated PVs and segmental, involving 28 +/- 7% of the right PV perimeter.


CONCLUSIONS
Intravascular beta-radiation can induce transmural necrosis and fibrosis of PV myocardial sleeves without PV stenosis and other unwanted effects, which supports a potential usefulness of this energy source in the treatment of AF.
Pérez-Castellano
Nicasio
N
Unit of Arrhythmias, Cardiovascular Institute, San Carlos University Hospital, Madrid, Spain. nperez.hcsc@salud.madrid.org
Villacastín
Julián
J
Aragoncillo
Paloma
P
Fantidis
Panayotis
P
Sabaté
Manel
M
García-Torrent
Maria J
MJ
Prieto
Carlos
C
Corral
José M
JM
Moreno
Javier
J
Fernández-Ortiz
Antonio
A
Vano
Eliseo
E
Macaya
Carlos
C
D000818:Animals; D001281:Atrial Fibrillation / Q000532:radiotherapy / Q000601:surgery; D001610:Beta Particles; D001918:Brachytherapy; D017115:Catheter Ablation / Q000379:methods*; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005240:Feasibility Studies; D023421:Models, Animal; D011667:Pulmonary Veins / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects*; D011859:Radiography; D013552:Swine; D013556:Swine, Miniature