Objective: To study the effects of cardiac resynchronization therapy (CRT) with different pacing rates and modes on MTWA.
Methods: From March, 2012 to October, 2014, 43 patients who received CRT or CRT-D implantation in the first affiliated hospital, Nanjing Medical University were studied. Time-domain MTWA test were assessed following CRT implantation. MTWA was measured at 90 min(-1) and 110 min(-1) by treadmill exercise test with GE CASE 8000 during CRT-on (BIV biventricular) and CRT-off (RA right atrial) pacing modes. The comparsion of MTWA values between different pacing mode and pacing rates were analyzed. According to the heart function classification the patients were divided into 3 groups. The correlation between MTWA and cardiac function was analyzed.
Results: MTWA-AAI was significantly increased compared to MTWA-BIV at the pacing rate of 90 min(-1) [(11.27±9.94) µV vs (7.09±7.16) µV, P=0.001]. The value of MTWA at pacing rate of 110 min(-1) was nonsignificantly higher than MTWA during AAI pacing [(16.91±12.51) µV vs (15.58± 10.97) µV, P=0.517]. The value of MTWA at pacing rate of 110 min(-1) was higher than MTWA at pacing rate of 90 min(-1) during AAI or BIV (P<0.05). MTWA-AAI and MTWA-BIV in group of NYHA IV were higher than those in group of NYHA II (P<0.05).
Conclusion: Biventricular pacing mode at lower pacing rates can significantly attenuate MTWA. The value of MTWA is associated with the severity of CHF.
目的：研究慢性心力衰竭患者心脏再同步化治疗(cardiac resynchronization therapy，CRT)术后不同起搏模式与不同起搏频率对微伏级T波电交替(microvolt T-wave alternans，MTWA)的影响。方法：收集2012年3月至2014年10月在南京医科大学第一附属医院植入CRT或带除颤功能的三腔起搏器(cardiac resynchronization therapy-defibrillator，CRT-D)患者43例。所有患者于术后接受MTWA时域法检测，分别在起搏频率90，110 min−1时测定MTWA，起搏模式为 CRT-ON和CRT-OFF状态下即在双心室(BIV)或右心房(AAI)起搏时测定MTWA。比较不同起搏模式与不同起搏频率下MTWA数值。根据纽约心脏病协会(NYHA)心功能分级将43例患者分为3组(II级、III级和IV级)，分析MTWA数值与心功能的相关性。结果：起搏频率90 min−1时，MTWA-AAI较MTWA-BIV明显增加[(11.28±9.94) µV vs (7.09±7.16) µV，P=0.001]；起搏频率110 min−1时，MTWA-BIV与MTWA-AAI数值比较无明显差异[(16.91±12.51) µV vs (15.58±10.97) µV，P=0.571] 。相同起搏模式时，起搏频率110 min−1时的MTWA数值较起搏频率90 min−1时增加(P<0.05)。NYHA心功能分级IV组MTWA-AAI和MTWA-BIV数值均高于II组(P<0.05)。结论：心脏再同步化治疗BIV低频率起搏模式可减小MTWA数值；MTWA数值与慢性心力衰竭患者心力衰竭程度相关。.