Department of Surgery, Columbia Presbyterian Medical Center, New York, New York; Department of Surgery, Duke University Medical Center, Durham, North Carolina.
J Surg Res. 2013 Dec;185(2):645-52. doi: 10.1016/j.jss.2013.06.038. Epub 2013 Jul 9.
Biventricular pacing (BiVP) improves cardiac output (CO) in selected cardiac surgery patients, but response remains variable, necessitating a better understanding of the mechanism. Accordingly, we used speckle tracking echocardiography (STE) to analyze BiVP during acute right ventricular pressure overload (RVPO).
In nine pigs, the inferior vena cava (IVC) was snared to decrease CO and establish a control model. Heart block was induced, the pulmonary artery snared, and BiVP initiated. Echocardiograms of the left ventricular midpapillary level were taken at varying atrioventricular delay (AVD) and interventricular delay (VVD) for STE analysis of regional circumferential strain (CS) and radial strain (RS). Echocardiograms were taken of the left ventricular base, midpapillary, and apex during baseline, IVC occlusion, and each BiVP setting for STE analysis of twist, apical and basal rotations, CS, RS, and synchrony. Indices were correlated against CO with mixed linear models.
During IVC occlusion, CO correlated with twist, apical rotation, RS, RS synchrony, and CS (P < 0.05). During RVPO with BiVP, CO only correlated with RS synchrony and CS (P < 0.05). During AVD and VVD variations, CO was associated with free wall RS (P < 0.008). CO correlated with septal wall CS during AVD variation and free wall CS during VVD variation (P < 0.008).
In an open chest model, twist, RS, RS synchrony, and CS analyzed by STE may be noninvasive surrogates for changes in CO. During RVPO, changes in RS synchrony and CS with varying regional strain contributions may be the primary mechanism in which BiVP improves CO. Lack of correlation of remaining indices may reflect postsystolic function.
双心室起搏（BiVP）可改善某些心脏手术患者的心输出量（CO），但反应仍存在差异，因此需要更好地了解其机制。相应地，我们使用斑点追踪超声心动图（STE）来分析急性右心室压力超负荷（RVPO）期间的 BiVP。
在 9 头猪中，结扎下腔静脉（IVC）以降低 CO 并建立对照模型。诱导心脏传导阻滞，结扎肺动脉，启动 BiVP。在不同的房室延迟（AVD）和室间隔延迟（VVD）下获取左心室中间段乳头肌水平的超声心动图，用于 STE 分析局部圆周应变（CS）和径向应变（RS）。在基线、IVC 闭塞和每个 BiVP 设置期间，获取左心室基底、中间乳头肌和心尖的超声心动图，用于 STE 分析扭转、心尖和基底旋转、CS、RS 和同步性。用混合线性模型将指标与 CO 相关联。
在 IVC 闭塞期间，CO 与扭转、心尖旋转、RS、RS 同步性和 CS 相关（P < 0.05）。在 RVPO 期间进行 BiVP 时，CO 仅与 RS 同步性和 CS 相关（P < 0.05）。在 AVD 和 VVD 变化期间，CO 与游离壁 RS 相关（P < 0.008）。在 AVD 变化期间，CO 与间隔壁 CS 相关，在 VVD 变化期间，CO 与游离壁 CS 相关（P < 0.008）。
在开胸模型中，STE 分析的扭转、RS、RS 同步性和 CS 可能是非侵入性的 CO 变化替代指标。在 RVPO 期间，随着区域性应变贡献的变化，RS 同步性和 CS 的变化可能是 BiVP 改善 CO 的主要机制。其余指标缺乏相关性可能反映了收缩后功能。
