Electrical conduction in canine pulmonary veins: electrophysiological and anatomic correlation.
BACKGROUND
Paroxysmal atrial fibrillation in patients is often initiated by foci in the pulmonary veins. The mechanism of these initiating arrhythmias is unknown. The aim of this study was to determine electrophysiological characteristics of canine pulmonary veins that may predispose to initiating arrhythmias.


RESULTS
Extracellular recordings were obtained from the luminal side of 9 pulmonary veins in 6 Langendorff-perfused dog hearts after the veins were incised from the severed end to the ostium. Pulmonary veins were paced at the distal end, the ostium, and an intermediate site. During basic and premature stimulation, extracellular electrical activity was recorded with a grid electrode that harbored 247 electrode terminals. In 4 hearts, intracellular electrograms were recorded with microelectrodes. Myocyte arrangement immediately beneath the venous walls was determined by histological analysis in 3 hearts. Extracellular mapping revealed slow and complex conduction in all pulmonary veins. Activation delay after premature stimulation could be as long as 96 ms over a distance of 3 mm. Action potential duration was shorter at the distal end of the veins than at the orifice. No evidence for automaticity or triggered activity was found. Histological investigation revealed complex arrangements of myocardial fibers that often showed abrupt changes in fiber direction and short fibers arranged in mixed direction.


CONCLUSIONS
Zones of activation delay were observed in canine pulmonary veins and correlated with abrupt changes in fascicle orientation. This architecture of muscular sleeves in the pulmonary veins may facilitate reentry and arrhythmias associated with ectopic activity.
Hocini
Mélèze
M
Hôpital Cardiologique du Haut-Lévèque, Pessac, France.
Ho
Siew Y
SY
Kawara
Tokuhiro
T
Linnenbank
André C
AC
Potse
Mark
M
Shah
Dipen
D
Jaïs
Pierre
P
Janse
Michiel J
MJ
Haïssaguerre
Michel
M
De Bakker
Jacques M T
JM
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology*; D018780:Body Surface Potential Mapping; D002304:Cardiac Pacing, Artificial; D004285:Dogs; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008839:Microelectrodes; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000502:physiology; D010477:Perfusion; D011667:Pulmonary Veins / Q000033:anatomy & histology* / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology