Department of Pediatric Cardiology, Oregon Health & Science University, Portland, Oregon 97239-3098, USA.
JACC Cardiovasc Imaging. 2010 Mar;3(3):227-34. doi: 10.1016/j.jcmg.2009.09.027.
To compute left ventricular (LV) twist from 3-dimensional (3D) echocardiography.
LV twist is a sensitive index of cardiac performance. Conventional 2-dimensional based methods of computing LV twist are cumbersome and subject to errors.
We studied 10 adult open-chest pigs. The pre-load to the heart was altered by temporary controlled occlusion of the inferior vena cava, and myocardial ischemia was produced by ligating the left anterior descending coronary artery. Full-volume 3D loops were reconstructed by stitching of pyramidal volumes acquired from 7 consecutive heart beats with electrocardiography gating on a Philips IE33 system (Philips Medical Systems, Andover, Massachusetts) at baseline and other steady states. Polar coordinate data of the 3D images were entered into an envelope detection program implemented in MatLab (The MathWorks, Inc., Natick, Massachusetts), and speckle motion was tracked using nonrigid image registration with spline-based transformation parameterization. The 3D displacement field was obtained, and rotation at apical and basal planes was computed. LV twist was derived as the net difference of apical and basal rotation. Sonomicrometry data of cardiac motion were also acquired from crystals anchored to epicardium in apical and basal planes at all states.
The 3D dense tracking slightly overestimated the LV twist, but detected changes in LV twist at different states and showed good correlation (r = 0.89) when compared with sonomicrometry-derived twist at all steady states. In open chest pigs, peak cardiac twist was increased with reduction of pre-load from inferior vena cava occlusion from 6.25 degrees +/- 1.65 degrees to 9.45 degrees +/- 1.95 degrees . With myocardial ischemia from left anterior descending coronary artery ligation, twist was decreased to 4.90 degrees +/- 0.85 degrees (r = 0.8759).
Despite lower spatiotemporal resolution of 3D echocardiography, LV twist and torsion can be computed accurately.
从三维（3D）超声心动图计算左心室（LV）扭转。
LV 扭转是心脏功能的一个敏感指标。基于传统的二维方法计算 LV 扭转既繁琐又容易出错。
我们研究了 10 头开胸猪。通过临时控制下腔静脉阻塞来改变心脏的前负荷，通过结扎左前降支冠状动脉来产生心肌缺血。在飞利浦 IE33 系统（马萨诸塞州安多弗的飞利浦医疗系统）上，通过心电图门控获取 7 个连续心跳的金字塔容积，并对其进行拼接，重建全容积 3D 环。将 3D 图像的极坐标数据输入到 MatLab（马萨诸塞州纳蒂克的 MathWorks，Inc.）中实现的包络检测程序中，并使用基于样条的变换参数化的非刚性图像配准来跟踪散斑运动。获得 3D 位移场，并计算心尖和基底平面的旋转。LV 扭转是通过心尖和基底旋转的净差得出的。在所有状态下，还从附着在心外膜的晶体中获取心脏运动的超声心动图数据。
3D 密集跟踪略微高估了 LV 扭转，但检测到不同状态下的 LV 扭转变化，并在所有稳定状态下与超声心动图衍生的扭转显示出良好的相关性（r = 0.89）。在开胸猪中，随着下腔静脉阻塞从 6.25 度+/-1.65 度减少到 9.45 度+/-1.95 度，峰值心脏扭转增加。左前降支冠状动脉结扎引起心肌缺血时，扭转减小到 4.90 度+/-0.85 度（r = 0.8759）。
尽管 3D 超声心动图的时空分辨率较低，但可以准确计算 LV 扭转和扭距。
