期刊
CIRCULATION RESEARCH
卷 98, 期 4, 页码 E29-E38出版社
LIPPINCOTT WILLIAMS & WILKINS
DOI: 10.1161/01.RES.0000209770.72203.01
关键词
reentry; arrhythmia; cardiac electrophysiology; optical mapping; cell culture
资金
- NHLBI NIH HHS [HL66239] Funding Source: Medline
This study examines how a zigzag pattern of conduction, a form of structural heterogeneity frequently found in old or diseased hearts, affects the vulnerability to reentry during rapid pacing. A central rectangular island ( 8 x 4 mm) containing a predefined zigzag pattern was created in cultured isotropic monolayers of neonatal rat ventricular myocytes. Impulse propagation was optically mapped from 253 sites using voltage- sensitive dye and was anisotropic within the zigzag island. With increasing interval between neighboring transverse connections (a), relative to the distance between longitudinal strands (b), transverse conduction velocity (CV) decreased to 66 +/- 6%, 20 +/- 2%, and 15 +/- 2% of CV in the surrounding isotropic region, whereas longitudinal CV increased to 102 +/- 8%, 113 +/- 12%, and 131 +/- 23% for a:b ratios of 1: 1, 1: 5, and 1: 9, respectively. During rapid pacing, propagation distal to the island was steered from the side of the island with more transverse connections (dominant side) toward the side with fewer connections (weak side). Increased asymmetry in the pattern accentuated this effect, and resulted in increased rate- dependent differences in CV on the 2 sides. Consequently, a functional obstacle formed on the weak side, followed by development of single loop reentry. The reentrant wave revolved around a line of block defined by the border of the island. Reentry chirality was determined by the weak side location, and the pacing rate needed to initiate reentry decreased with increased asymmetry in the pattern. In conclusion, reentry is readily induced by rapid pacing in confluent cardiac cell monolayers containing a central and asymmetric island of zigzag conduction.
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