Pulmonary vein isolation by radiosurgery: implications for non-invasive treatment of atrial fibrillation.
OBJECTIVE
Electrical isolation of the pulmonary veins (PVs) has been established in clinical routine as a curative treatment for atrial fibrillation (AF). While catheter ablation carries procedural risks, radiosurgery might be able to non-invasively induce lesions at the PV ostia to block veno-atrial electrical conduction. This porcine feasibility and dose escalation study determined the effect of radiosurgery on electrophysiologic properties of the left atrial-PV junction.


RESULTS
Eight adult Goettingen mini-pigs underwent electrophysiological voltage mapping in the left atrium and the upper right PV. Radiation was delivered with a conventional linear accelerator. A single homogeneous dose ranging from 22.5 to 40 Gy was applied circumferentially to the target vein antrum. Six months after radiosurgery, electrophysiological mapping was repeated and a histological examination performed. Voltage mapping consistently showed electrical potentials in the upper right PV at baseline. Pacing the target vein prompted atrial excitation, thus proving veno-atrial electrical conduction. After 6 months, radiation had reduced PV electrogram amplitudes. This was dose dependent with a mean interaction effect of -5.8%/Gy. Complete block of atrio-venous electrical conduction occurred after 40 Gy dose application. Histology revealed transmural scarring of the targeted PV musculature with doses >30 Gy. After 40 Gy, it spanned the entire circumference in accordance with pulmonary vein isolation.


CONCLUSIONS
Pulmonary vein isolation to treat AF can be achieved by radiosurgery with a conventional linear accelerator. Yet, it requires a high radiation dose which might limit clinical applicability.
Medizinische Klinik II, Universitaetsklinikum Schleswig-Holstein, Campus Luebeck, Ratzeburger Allee 160, 23560 Luebeck, Germany frank.bode@uk-sh.de.
Frank
F
Bode
Klinik für Strahlentherapie, Universitaetsklinikum Schleswig-Holstein, Campus Luebeck, Germany.
Oliver
O
Blanck
Institut für Pathologie, Universitaetsklinikum Schleswig-Holstein, Campus Luebeck, Germany.
Maximilian
M
Gebhard
Klinik für Radiologie und Nuklearmedizin, Universitaetsklinikum Schleswig-Holstein, Campus Luebeck, Germany.
Peter
P
Hunold
Klinik für Anaesthesiologie, Universitaetsklinikum Schleswig-Holstein, Campus Luebeck, Germany.
Martin
M
Grossherr
Klinik für Anaesthesiologie, Universitaetsklinikum Schleswig-Holstein, Campus Luebeck, Germany.
Sebastian
S
Brandt
Institut für Biometrie und Statistik, Universitaetsklinikum Schleswig-Holstein, Campus Luebeck, Germany.
Reinhard
R
Vonthein
Medizinische Klinik II, Universitaetsklinikum Schleswig-Holstein, Campus Luebeck, Ratzeburger Allee 160, 23560 Luebeck, Germany.
Holger
H
Thiele
Klinik für Strahlentherapie, Universitaetsklinikum Schleswig-Holstein, Campus Luebeck, Germany.
Juergen
J
Dunst
Klinik für Strahlentherapie, Universitaetsklinikum Schleswig-Holstein, Campus Luebeck, Germany.
Dirk
D
Rades
D000200:Action Potentials; D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000601:surgery*; D002304:Cardiac Pacing, Artificial; D004307:Dose-Response Relationship, Radiation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005240:Feasibility Studies; D023421:Models, Animal; D011667:Pulmonary Veins / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D013552:Swine; D013556:Swine, Miniature; D013997:Time Factors
Ablation; Atrial fibrillation; Pulmonary vein isolation; Radiation; Radiosurgery