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Pretreatment of BAPTA‐AM Suppresses the Genesis of Repetitive Endocardial Focal Discharges and Pacing‐Induced Ventricular Arrhythmia During Global Ischemia
Author(s) -
WU TSUJUEY,
LIN SHIENFONG,
HSIEH YUCHENG,
LIN TUNGCHAO,
LIN JIUNNCHERNG,
TING CHIHTAI
Publication year - 2011
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.2011.02067.x
Subject(s) - medicine , cardiology , endocardium , ventricle , bapta , ischemia , ventricular fibrillation , anesthesia , calcium
BAPTA‐AM and Repetitive Endocardial Focal Discharges. Introduction : In isolated rabbit hearts, repetitive endocardial focal discharges (REFDs) were consistently observed during ventricular fibrillation (VF) with prolonged (>5 minutes) global ischemia (GI). We hypothesized that BAPTA‐AM, a calcium chelator, can suppress these REFDs.Methods and Results : Using a two‐camera optical mapping system, we simultaneously mapped endocardial (left ventricle, LV) and epicardial (both ventricles) activations during ventricular arrhythmia with GI. In 5 hearts (protocol I), we infused Tyrode's solution (no BAPTA‐AM) for ≥30 minutes before the onset of no‐flow GI. In 7 additional hearts (protocol II), BAPTA‐AM (20 μmol/L) was infused for ≥30 minutes before the initiation of GI. In protocol I, sustained VF (>30 seconds) was successfully induced in all 5 hearts with prolonged GI. REFDs were present in >85 % of recording time. In protocol II, however, ventricular arrhythmia was not inducible and REFDs were not observed after 5‐minute GI in 5 hearts. Effects of BAPTA‐AM on intracellular calcium (Ca i ) at the LV endocardium were also evaluated in 5 hearts (protocol III) using dual Ca i /membrane potential mapping. GI, both without and with BAPTA‐AM pretreatment, caused a decrease of Ca i amplitude during S 1 pacing. However, this effect was more pronounced in the hearts with BAPTA‐AM pretreatment (P < 0.001). GI, without BAPTA‐AM pretreatment, caused broadening of Ca i transient. In contrast, GI, with BAPTA‐AM pretreatment, caused narrowing of Ca i transient.Conclusions : BAPTA‐AM pretreatment attenuates Ca i transient, suppressing the genesis of REFDs and pacing‐induced ventricular arrhythmia during GI. These findings support the notion that Ca i dynamics is important in the maintenance of REFDs. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1154‐1162, October 2011)