Correlation between anatomy and electrical activation in canine pulmonary veins.
BACKGROUND
The roles of complex muscle sleeve geometry and fiber orientation in the pulmonary veins (PVs) in wave-front propagation are poorly understood.


RESULTS
We mapped the left superior PV (LSPV, n=7) and left inferior PV (LIPV, n=4) of dogs with 420 bipolar electrodes (1-mm resolution) and performed detailed histological examination. In the anterior LSPV-left atrial (LA) junction, myocardial muscle fibers were oriented perpendicular to PV blood flow. A wedge filled with connective tissues led to a complete muscle separation or an abrupt increase in muscle thickness between the PV and LA (0.42+/-0.12 versus 2.0+/-0.31 mm, P<0.01). Distal LSPV pacing resulted in conduction block at the anterior PV-LA junction, with double potentials. In contrast, the posterior LSPV-LA junction showed gradual muscle thickening and a fiber orientation parallel to the blood flow. The maximum PV muscle thickness in the anterior PV-LA junction is thinner than that in the posterior junction (0.83+/-0.15 versus 1.3+/-0.38 mm, P<0.01). Distal LIPV pacing showed multiple PV-LA breakthroughs, with segmental conduction block in the anterior PV-LA junction. The conduction block corresponded to segmental PV-LA muscle disconnection. Complex fiber orientations in the PV muscle sleeves away from the PV-LA junction were responsible for intra-PV conduction delay or block during rapid PV pacing.


CONCLUSIONS
We conclude that segmental muscle disconnection and differential muscle narrowing at PV-LA junctions and complex fiber orientations within the PV provide robust anatomical bases for conduction disturbance at the PV-LA junction and complex intra-PV conduction patterns.
Hamabe
Akira
A
Division of Cardiology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, Calif 90048, USA.
Okuyama
Yuji
Y
Miyauchi
Yasushi
Y
Zhou
Shengmei
S
Pak
Hui-Nam
HN
Karagueuzian
Hrayr S
HS
Fishbein
Michael C
MC
Chen
Peng-Sheng
PS
D000818:Animals; D016275:Atrial Function; D018780:Body Surface Potential Mapping; D002304:Cardiac Pacing, Artificial; D017630:Connexins / Q000032:analysis / Q000276:immunology; D004285:Dogs; D004553:Electric Conductivity; D006325:Heart Atria / Q000033:anatomy & histology; D006327:Heart Block / Q000473:pathology / Q000503:physiopathology; D007150:Immunohistochemistry; D011667:Pulmonary Veins / Q000033:anatomy & histology* / Q000294:innervation / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000166:cytology; D000097003:Gap Junction alpha-5 Protein
D017630:Connexins; D000097003:Gap Junction alpha-5 Protein