Arrhythmogenic substrate of the pulmonary veins assessed by high-resolution optical mapping.
BACKGROUND
It has recently been recognized that atrial fibrillation can originate from focal sources in the pulmonary veins (PVs). However, the mechanisms of focal atrial fibrillation have not been well characterized. We assessed the electrophysiological characteristics of the PVs using high-resolution optical mapping.


RESULTS
Coronary-perfused, isolated whole-atrial preparations from 33 normal dogs were studied. Programmed electrical stimulation was performed, and a 4-cm2 area of the PV underwent optical mapping of transmembrane voltage to obtain 256 simultaneous action potentials. Marked conduction slowing was seen at the proximal PV, compared with the rest of the vein, on both the epicardial (31.3+/-4.47 versus 90.2+/-20.7 cm/s, P=0.001) and endocardial (45.8+/-6.90 versus 67.6+/-10.4 cm/s, P=0.012) aspects. Pronounced repolarization heterogeneity was also noted, with action potential duration at 80% repolarization being longest at the PV endocardium. Nonsustained reentrant beats were induced with single extrastimuli, and the complete reentrant loop was visualized (cycle length, 155+/-30.3 ms); reentrant activity could be sustained with isoproterenol. Sustained focal discharge (cycle length, 330 to 1100 ms) was seen from the endocardial surface in the presence of isoproterenol; each focus was localized near the venous ostium.


CONCLUSIONS
The normal PV seems to have the necessary substrate to support reentry as well as focal activity. Although reentry occurred more distally in the vein, focal activity seemed to occur more proximally.
Arora
Rishi
R
Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Verheule
Sander
S
Scott
Luis
L
Navarrete
Antonio
A
Katari
Vikram
V
Wilson
Emily
E
Vaz
Dev
D
Olgin
Jeffrey E
JE
D000200:Action Potentials; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology; D001281:Atrial Fibrillation / Q000209:etiology; D016275:Atrial Function; D002304:Cardiac Pacing, Artificial; D046508:Culture Techniques; D004285:Dogs; D004553:Electric Conductivity; D004558:Electric Stimulation; D004594:Electrophysiology; D007545:Isoproterenol / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D055095:Optics and Photonics; D011667:Pulmonary Veins / Q000187:drug effects / Q000502:physiology*; D012680:Sensitivity and Specificity
D007545:Isoproterenol