A mechanism for immediate reduction in mitral regurgitation after cardiac resynchronization therapy - Insights from mechanical activation strain mapping
A mechanism for immediate reduction in mitral regurgitation after cardiac resynchronization therapy - Insights from mechanical activation strain mapping
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DOI：
10.1016/j.jacc.2004.07.036
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发表时间：
2004-10-19
影响因子：
24
通讯作者：
Gorcsan, J
中科院分区：
文献类型：
--
作者：
Kanzaki, H;Bazaz, R;Gorcsan, J
目的采用机械激活应变标测的新方法，验证心脏再同步治疗(CRT)后二尖瓣返流(MR)的即时减少是由于乳头肌插入部位协调时间的改善所致。背景心力衰竭合并左束支传导阻滞的患者经常从CRT中受益，但减少MR的作用和机制尚不清楚。分别于CRT前即刻、CRT后即刻和CRT后第二天进行超声心动图多普勒和应变成像，并与10名正常对照组进行比较。结果容积法测得的二尖瓣返流持续减少：返流体积从40+/-20ml降至24+/-17ml，返流分数从40+/-12%降至25+/-14%(均为P<；0.001与基线比较)。正常对照组有均匀的节段峰值时间应变，所有节段之间只有12+/-8英寸的差异。相比之下，基线状态的CRT患者乳头肌插入部位之间的时间延迟为106ms+/-74ms(P<；0.001与正常相比)。心脏再同步化治疗后乳头肌延迟时间缩短至39+/-43ins(P<；0.001与基线相比)，且与二尖瓣返流分数的降低显著相关(r=0.77，P<；0.001)。结论心脏再同步治疗显著并立即降低MR。(C)2004年，由美国心脏病学会基金会提供。
OBJECTIVES We tested the hypothesis that an immediate reduction in mitral regurgitation (MR) after cardiac resynchronization therapy (CRT) results from improved coordinated timing of the papillary muscle insertion sites, using the novel approach of mechanical activation strain mapping.BACKGROUND Heart failure patients with left bundle branch block often benefit acutely from CRT; however, the role and mechanism of reduction of MR are unclear.METHODS Twenty-six consecutive patients undergoing CRT with at least mild MR were studied (ejection fraction 24 +/- 6%; QRS duration 168 +/- 30 ms). Echocardiographic Doppler and strain imaging was performed immediately before and the day after CRT, as well as in 10 normal control subjects. Mechanical activation sequence maps were constructed using longitudinal strain from 12 basal and mid-LV sites, with color coding of time-to-peak strain.RESULTS Mitral regurgitation by the volumetric method consistently decreased after CRT: regurgitant volume from 40 +/- 20 ml to 24 +/- 17 ml and regurgitant fraction from 40 +/- 12% to 25 +/- 14% (both: p < 0.001 vs. baseline). Normal controls had uniform segmental time-to-peak strain, with a difference of only 12 +/- 8 ins between all segments. In contrast, CRT patients at baseline had a 106 +/- 74 ms time delay between papillary muscle insertion sites (p < 0.001 vs. normal). This interpapillary muscle time delay shortened after CRT to 39 +/- 43 ins (p < 0.001 vs. baseline) and was significantly correlated with reductions in mitral regurgitant fraction (r = 0.77, p < 0.001).CONCLUSIONS Cardiac resynchronization therapy significantly and immediately reduced MR. Improved coordinated timing of mechanical activation of papillary muscle insertion sites appears to be a mechanistic contributor to immediate MR reduction by CRT. (C) 2004 by the American College of Cardiology Foundation.