Williams Lynne K, Ellery Susan, Patel Kiran, Leyva Francisco, Bleasdale Robert A, Phan Thanh T, Stegemann Berthold, Paul Vince, Steendijk Paul, Frenneaux Michael
Department of Cardiovascular Medicine, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Circulation. 2009 Oct 27;120(17):1687-94. doi: 10.1161/CIRCULATIONAHA.108.799395. Epub 2009 Oct 12.
Cardiac resynchronization therapy produces both short-term hemodynamic and long-term symptomatic/mortality benefits in symptomatic heart failure patients with a QRS duration >120 ms. This is conventionally believed to be due principally to relief of dyssynchrony, although we recently showed that relief of external constraint to left ventricular filling may also play a role. In this study, we evaluated the short-term hemodynamic effects in symptomatic patients with a QRS duration <120 ms and no evidence of dyssynchrony on conventional criteria and assessed the effects on contractility and external constraint.
Thirty heart failure patients (New York Heart Association class III/IV) with a left ventricular ejection fraction < or =35% who were in sinus rhythm underwent pressure-volume studies at the time of pacemaker implantation. External constraint, left ventricular stroke work, dP/dtmax, and the slope of the preload recruitable stroke work relation were measured from the end-diastolic pressure-volume relation before and during delivery of biventricular and left ventricular pacing. The following changes were observed during delivery of cardiac resynchronization therapy: Cardiac output increased by 25+/-5% (P<0.05), absolute left ventricular stroke work increased by 26+/-5% (P<0.05), the slope of the preload recruitable stroke work relation increased by 51+/-15% (P<0.05), and dP/dtmax increased by 9+/-2% (P<0.05). External constraint was present in 15 patients and was completely abolished by both biventricular and left ventricular pacing (P<0.05).
Cardiac resynchronization therapy results in an improvement in short-term hemodynamic variables in patients with a QRS <120 ms related to both contractile improvement and relief of external constraint. These findings provide a potential physiological basis for cardiac resynchronization therapy in this patient population.
心脏再同步治疗对QRS波时限>120 ms的有症状心力衰竭患者可产生短期血流动力学及长期症状改善/降低死亡率的益处。传统观点认为这主要是由于不同步的缓解，尽管我们最近表明减轻左心室充盈的外部限制也可能起作用。在本研究中，我们评估了QRS波时限<120 ms且按传统标准无不同步证据的有症状患者的短期血流动力学效应，并评估了对收缩性和外部限制的影响。
30例左心室射血分数≤35%、窦性心律的心力衰竭患者（纽约心脏协会III/IV级）在起搏器植入时进行了压力-容积研究。在双心室和左心室起搏前及起搏期间，从舒张末期压力-容积关系测量外部限制、左心室搏功、dP/dtmax以及可募集搏功与前负荷关系的斜率。在心脏再同步治疗期间观察到以下变化：心输出量增加25±5%（P<0.05），绝对左心室搏功增加26±5%（P<0.05），可募集搏功与前负荷关系的斜率增加51±15%（P<0.05），dP/dtmax增加9±2%（P<0.05）。15例患者存在外部限制，双心室和左心室起搏均使其完全消除（P<0.05）。
心脏再同步治疗可使QRS<120 ms的患者短期血流动力学变量得到改善，这与收缩性改善和外部限制的减轻有关。这些发现为该患者群体的心脏再同步治疗提供了潜在的生理基础。
