Background: Transplantation of stem cells into infarct myocardium results in improved myocardial function. However, arrhythmogenicity of stem cell transplanted site (SCTS) still are unknown. We investigated the electrical coupling with normal myocardium and arrhythmogenicity of SCTS in infarct left ventricle (LV) of rat. Methods: The Rat infarct model was made by cryoinjury at anterior wall of LV. Bone marrow stem cells (1x10⁷) were transplanted into infarct border zone (BZ) of LV. The inducibility of ventricular tachycardia (VT) or fibrillation (VF) was evaluated with rapid ventricular pacing (RVP) of 75ms for 5 seconds. The anterior wall of LV including SCTS was mapped with optical mapping technique. We compared the inducibility of VT/VF and data of optical mapping between control (n=5), cyoinjury (n=6), stem cell transplantation group (n=6). Results: The inducibility of VT/VF was 12.8% (6/47 RVP), 34.6% (18/52 RVP), and 47.2 % (25/53 RVP) in control, cryoinjury, and stem cell transplantation group, respectively. Cryoinjury and stem cell transplantation group had higher VT/VF inducibility than control (p=0.01). During sinus rhythm (SR), the depolarization of normal myocardium, BZ and SCTS occurred simultaneously. The repolarization of BZ was delyed with 50짹26ms than normal (p=0.03). However, SCTS showed shorter repolarization time compared to BZ (-43짹19ms, p=0.03). APD70 of SCTS was also shorter than BZ during SR and VT (table, p=0.001). Conduction block was observed in SCTS and BZ during VT. However, the reentry around SCTS was not observed. Conclusions: Stem cell transplation in rat infarct model did not influence the inducibility of VT/VF. The electrical conduction of SCTS was more improved than BZ during SR. There was no evidence of augmentation of arrhythmia by SCTS in rat infarct model.
#Comparison of APD70 during SR and VT among three groups