Department of Biomedical Engineering, Columbia University, New York, NY, USA.
Am J Physiol Heart Circ Physiol. 2009 Dec;297(6):H2220-6. doi: 10.1152/ajpheart.00802.2009. Epub 2009 Oct 23.
The goal of this work was to investigate the hemodynamic effects of simultaneous left ventricular (LV) pacing site (LVPS) and interventricular pacing delay (VVD) variation with biventricular pacing (BiVP) during acute LV failure. Simultaneously varying LVPS and VVD with BiVP has been shown to improve hemodynamics during acute right ventricular (RV) failure. However, effects during acute LV failure have not been reported. In six open-chest pigs, acute LV volume overload was induced by regurgitant flow via an aortic-LV conduit. Epicardial BiVP was implemented with right atrial and ventricular leads and a custom LV pacing array. Fifty-four LVPS-VVD combinations were tested in random order. Cardiac output was evaluated by aortic flow probe, ventricular systolic function by maximum rate of ventricular pressure change, and mechanical interventricular synchrony by normalized RV-LV pressure diagram area. Simultaneous LVPS-VVD variation improved all measures of cardiac function. The observed effect was different for each functional index, with evidence of LVPS-VVD interaction. Compared with effects of LVPS-VVD variation in a model of acute RV failure, hemodynamic changes were markedly different. However, in both models, maximum rate of ventricular pressure change of the failing ventricle was improved with synchronous interventricular contraction, suggesting that, in acute ventricular failure, BiVP can recruit the unstressed ventricle to support systolic function of the failing one. Thus simultaneously varying LVPS and VVD with BiVP during acute ventricular failure can improve cardiac function by "interventricular assist", with hemodynamic effects dependent on the type of failure. This supports the potential utility of temporary BiVP for the treatment of acute ventricular failure commonly seen after cardiac surgery.
本研究旨在探讨急性左心室衰竭时双心室起搏（BiVP）中同时改变左心室起搏部位（LVPS）和室间起搏延迟（VVD）对血流动力学的影响。已有研究表明，BiVP 中同时改变 LVPS 和 VVD 可改善急性右心室衰竭时的血流动力学，但急性左心室衰竭时的效果尚未见报道。在 6 只开胸猪中，通过主动脉-左心室导管的反流血流诱发急性左心室容量超负荷。采用右心房和心室导联以及定制的左心室起搏阵列实施心外膜 BiVP。以随机顺序测试了 54 种 LVPS-VVD 组合。通过主动脉血流探头评估心输出量，通过心室压力变化最大率评估心室收缩功能，通过归一化 RV-LV 压力图面积评估机械性室间同步性。同时改变 LVPS-VVD 可改善所有心功能指标。观察到的效果因每个功能指标而异，存在 LVPS-VVD 相互作用的证据。与急性 RV 衰竭模型中的 LVPS-VVD 变化效果相比，血流动力学变化明显不同。然而，在两种模型中，随着室间收缩同步，衰竭心室的最大心室压力变化率均得到改善，这表明在急性心室衰竭时，BiVP 可以募集未受影响的心室来支持衰竭心室的收缩功能。因此，急性心室衰竭时 BiVP 同时改变 LVPS 和 VVD 可通过“室间辅助”改善心功能，血流动力学效果取决于衰竭类型。这支持了 BiVP 在心脏手术后常见的急性心室衰竭治疗中的潜在应用。
