Does cardiac pacing reproduce the mechanism of focal impulse initiation?

被引:5
作者
Macchi, E
Baruffi, S
Rossi, S
Miragoli, M
Bertuzzi, A
Musso, E
Corradi, D
Di Gregorio, F
机构
[1] Univ Studi, Dipartimento Biol Evolut & Funz, Sez Fisiol, I-43100 Parma, Italy
[2] Univ Studi, Dipartimento Patol & Med Lab, Sez Anat & Istol Patol, Parma, Italy
[3] Med Clin Res, Sarmeola di Rubano, Italy
关键词
cardiac pacing; focal activity; breakthrough point; epicardial mapping; cardiac electrophysiology;
D O I
10.1016/j.jelectrocard.2004.08.038
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Stimulation of myocardium by either a native pacemaker or an artificial stimulus requires the initiation of a self-propagating wave of depolarization originating from the site of initial activation. In the present study we perform artificial stimulation at a site of focal discharge with the aim to compare the two mechanisms of impulse formation. High resolution epicardial mapping in senescent rat hearts provided examples of focal discharge during sinus rhythm at a single epicardial breakthrough (BKT) point emerging from an isolated Purkinje-ventricular muscle junction (PMJ) site. Stimulation was also performed at the same BKT point and potential distributions recorded during spontaneous and artificial stimulation were compared. During excitation latency, the negative potential pattern was elongated perpendicularly to fiber direction at both pacing and BKT point, in agreement with virtual cathode membrane polarization predicted by the bidomain model during point stimulation. During impulse initiation, activation wave fronts were initially circular around pacing site or BKT point and then elongated along local fiber direction. The similarity between impulse initiation during focal discharge and point stimulation in cardiac muscle suggests that high resolution pace mapping studies can help to elucidate the mechanism of abnormal impulse formation.
引用
收藏
页码:135 / +
页数:10
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