李虹道
[摘要] 心脏再同步化治疗(CRT)是治疗慢性心力衰竭的常用方法之一,优化CRT的特殊参数AV 间期和心室间期可增加患者获益,本文对CRT的房室(A-V)间期和心室(V-V)间期的优化现状综述如下。
[关键词] 心脏再同步化治疗;间期优化
[中图分类号] R541.6 [文献标识码] A [文章编号] 2095-0616(2014)10-39-04
[Abstract] Cardiac resynchronization therapy (cardiac resynchronization therapy, CRT) is one of the common methods of treatment chronic heart failure,specific parameters of optimizing CRT between AV interval and ventricular were benefit to patients.This article summarized follows of the current status quo of optimized CRT of atrioventricular (AV) interval and ventricular (VV) period.
[Key words] Cardiac resynchronization therapy;Interval optimization
慢性充血性心力衰竭(CHF)常伴传导异常,导致房室、室间和(或)室内运动不同步[1-3]。心脏再同步治疗(CRT)为近年来治疗CHF的常用方法之一,其通过增加左室起搏,设定较短的房室及适当的V-V间期而实现房室和室间的同步运动,恢复房室、室间和室内运动的同步性[4-9]。研究表明,优化A-V间期和心室间期可增加左室充盈,提高患者对CRT的应答率[10]。1 A-V间期优化
A-V间期优化分为无创、有创,其中心导管测量左室内压最大上升速率(dP/dTmax)为有创检查,受设备技术等条件限制不易为患者接受,但准确性较高[11]。CT、MRI、核素扫描等虽为无创检查,但费用较高,均不如在超声指导下优化实用,故间期优化被推荐为目前常用的方法。A-V间期优化前要求患者在平静状态至少休息10min。以往的研究通过测得dP/dTmax评价下面4种优化方法,结果显示,以二尖瓣前向血流VTI最为精确[12]。
1.1 最大心输出量法
以主动脉瓣血流速度时间积分(VTI)评价心输出量,于心尖五腔切面记录主动脉瓣前向血流频谱,测量其VTI,并参考二尖瓣血流频谱,主动脉瓣前向血流VTI最大时对应的A-V间期为优化的A-V间期[13]。1.3 二尖瓣前向血流速度时间积分法
逐渐滴定A-V间期测量二尖瓣前向血流VTI,以获得最大二尖瓣VTI的A-V间期为最佳A-V间期[15]。
1.4 二尖瓣血流频谱法
Meluzin等[16]报道的“二尖瓣返流法”,先设定一个保证完全夺获心室的较长的A-V间期,然后测量A峰结束至出现左室收缩期二尖瓣返流的时间间期,两间期之差为最佳A-V间期。
1.5 心音图法
第一心音振幅和A-V间期成“S”型曲线关系,A-V间期在“S”型曲线的拐点与超声优化的A-V间期及最大主动脉瓣前向血流速度积分呈正相关[16]。
1.6 光电容积脉搏波法
该方法能识别CRTA-V间期变化引起的主动脉脉压的变化,为一种无创的CRT优化方法,具有很高的特异性[17]。
1.7 心阻抗图法
心阻抗图法(impedance cardiogram,ICG)是根据胸腔电阻抗的动态变化来测定心功能的一种非创伤性方法,其可以检测心阻抗的变化判断心输出量的变化[18]。
其通常在A-V间期优化的基础上进行,多数双室顺序起搏间期优化后为左室优先起搏,少数则需设置为右室优先,使心室达到最大程度同步化,从而提高CRT的血流动力学效应[20-21]。Sogaard等[22]报道对于间隔及下壁延迟者实施右室优先双室顺序起搏可以取得较好的血流动力学效应。
2.1 最大心输出量法
通过顺序程控多个V-V间期,以主动脉瓣前向血流速度时间积分(LVOT-VTI)最大时的心V-V间期为最佳V-V间期[24-25]。
2.2 最大化心室同步法3 存在的问题及展望
CRT需要在心超下进行繁琐的A-V及V-V间期优化,尚无统一技术指标及标准[31],耗时且受患者体位、探头角度等因素影响,难以实现个体化、动态优化[31,33],存在CRT的疗效发挥不充分的情况。另外,为保证起搏夺获心脏,CRT的A-V间期一般设置较短,多为100~120ms[35-36],然而,固定且较短的A-V间期及心室起搏与房室结优先,动态的A-V间期的生理性起搏原则不符,从而削弱CRT的疗效,甚至可能部分解释CRT治疗无应答[37]。因此,恢复房室结及双心室生理性传导顺序的希氏束起搏会更符合生理性起搏原则,有望提高CRT的应答率并精简CRT的优化程序。
综上所述,对接受CRT的CHF患者优化A-V间期和V-V间期可进一步改善患者的血流动力学。近年来已开发出多种无创方法用于间期优化,其中,心脏超声是目前较为公认和常用的方法,但较为繁琐,耗时费力,很难实现A-V间期和V-V间期优化的个体化和动态化,随着技术的不断发展有望开发出更为简便,精确的优化方法。
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(收稿日期:2014-03-21)