O'Connell J William, Schreck Carole, Moles Michael, Badwar Nitish, DeMarco Theresa, Olgin Jeffrey, Lee Byron, Tseng Zian, Kumar Uday, Botvinick Elias H
Departments of Medicine (Cardiovascular Division) and Radiology (Nuclear Medicine Section), University of California-San Francisco, UCSF Medical Center, San Francisco, CA, USA.
J Nucl Cardiol. 2005 Jul-Aug;12(4):441-50. doi: 10.1016/j.nuclcard.2005.05.006.
Cardiac resynchronization therapy (CRT) improves symptoms and the survival rate in patients with advanced heart failure by improving synchrony. However, CRT is not always successful, is costly, and is applied without individualization. There is no specific measure of synchrony. The goal of this study was to analyze new quantitative parameters of synchrony and compare them with established measures.
Equilibrium radionuclide angiography, phase angle (Ø), and amplitude quantitate regional contraction timing and magnitude and are the basis for new synchrony (S) and entropy (E) parameters. S is the vector sum of all amplitudes based on the angular distribution of Ø divided by the scalar sum of the length of all vectors. Complete S equals 1, and its absence equals 0. E measures the disorder in the region of interest, is 1 with random contraction and 0 with full synchrony, and differentiates among differing contraction patterns. Left ventricular S and E were measured in 22 normal equilibrium radionuclide angiography studies, where regions of interest were drawn from the left ventricle, left atrium, and background to analyze model ventricles with normal wall motion (N), ventricles with aneurysm (An), ventricles with severe diffuse dysfunction (Diff), and ventricles with severe regional dysfunction (Reg). The new S and E parameters were highly reproducible and well differentiated among N, An, Diff, and Reg, which were not separated by SD Ø (SD of ventricular phase), which has gained popularity as a measure of synchrony.
Unique scintigraphic parameters for the evaluation of ventricular synchrony were derived, and their added value was determine compared with established measures. Indications for pacemaker therapy now include the treatment of severe congestive heart failure (CHF). Atrial triggered biventricular pacemakers reduce CHF symptoms and prolong life in patients with cardiomyopathy, severe CHF, left ventricular (LV) ejection fraction (EF) lower than 35%, and QRS greater than 120 milliseconds. Such pacing, or cardiac resynchronization therapy (CRT), seeks to reduce the heterogeneity and increase the synchrony of ventricular activation, conduction, and contraction. CRT has improved hemodynamics, increased exercise tolerance, reduced symptoms and the need for hospitalization, reversed ventricular remodeling, and reduced the all-cause mortality rate in CHF. However, CRT is costly, fails to improve symptoms or activity level in more than 30% of patients, and is applied blindly without individualization or consideration of lead placement sight. A variety of echocardiographic methods have sought to measure synchrony and its serial changes with CRT. A recent study presented evidence of the poor reproducibility of several widely applied echocardiographic measurements by which to determine ventricular synchrony. Magnetic resonance imaging has excellent resolution of regional wall motion and has been applied to assess ventricular synchrony and its response to pacing therapy. However, these methods are complex and are not well established or widely available, and magnetic resonance imaging has not been widely applied after pacing. An accurate and reproducible method is needed by which to objectively measure regional ventricular synchrony. Phase image analysis, a functional method based on the first Fourier harmonic fit of the gated blood pool time versus radioactivity curve, generates the parameters of amplitude (A), which parallels the extent of regional ventricular contraction or stroke volume, and phase angle (Ø), which represents the timing of regional contraction. It was applied early with demonstrated reproducibility to show the linkage between electrical and mechanical dyssynchrony and to characterize the contraction pattern in heart failure and its alteration with CRT. The SD of ventricular Ø, applied as a marker of synchrony, has been shown to demonstrate the beneficial effects of biventricular pacing, and its strong prognostic value has been shown in patients with congestive cardiomyopathy and CHF, superior to LVEF. The SD Ø may not be optimal for synchrony evaluation. We sought improved, more sensitive parameters to better differentiate synchrony among the spectrum of possible patterns of dyssynergy. We derived, initially evaluated, and here present new synchrony (S) and entropy (E) parameters, based on the phase method, to quantitate regional and global ventricular synchrony and applied them in simulation and clinical protocols.
心脏再同步治疗（CRT）通过改善同步性来改善晚期心力衰竭患者的症状和生存率。然而，CRT并非总能成功，成本高昂，且缺乏个体化应用。目前尚无同步性的具体衡量指标。本研究的目的是分析新的同步性定量参数，并将其与现有指标进行比较。
平衡放射性核素血管造影、相角（Ø）和振幅可定量区域收缩时间和幅度，是新的同步性（S）和熵（E）参数的基础。S是基于Ø的角分布的所有振幅的矢量和除以所有矢量长度的标量和。完全同步时S等于1，不同步时等于0。E测量感兴趣区域的紊乱程度，随机收缩时为1，完全同步时为0，并能区分不同的收缩模式。在22项正常平衡放射性核素血管造影研究中测量了左心室S和E，其中感兴趣区域取自左心室、左心房和背景，以分析具有正常壁运动（N）的模型心室、有室壁瘤（An）的心室、有严重弥漫性功能障碍（Diff）的心室和有严重局部功能障碍（Reg）的心室。新的S和E参数具有高度可重复性，在N、An、Diff和Reg之间有很好的区分度，而它们不能通过作为同步性衡量指标而受到广泛关注的心室相角标准差（SD Ø）来区分。
得出了用于评估心室同步性的独特闪烁显像参数，并与现有指标相比确定了其附加值。目前起搏器治疗的适应证包括治疗严重充血性心力衰竭（CHF）。心房触发双心室起搏器可减轻心肌病、严重CHF、左心室（LV）射血分数（EF）低于35%且QRS大于120毫秒患者的CHF症状并延长其寿命。这种起搏，即心脏再同步治疗（CRT），旨在减少心室激活、传导和收缩的异质性并增加其同步性。CRT改善了血流动力学，提高了运动耐量，减轻了症状并减少了住院需求，逆转了心室重构，并降低了CHF的全因死亡率。然而，CRT成本高昂，超过30%的患者症状或活动水平未得到改善，且盲目应用，未考虑个体化或电极置入部位。多种超声心动图方法试图测量同步性及其随CRT的系列变化。最近一项研究表明，几种广泛应用的用于确定心室同步性的超声心动图测量方法重复性较差。磁共振成像对区域壁运动具有出色的分辨率，并已用于评估心室同步性及其对起搏治疗的反应。然而，这些方法复杂，尚未充分确立或广泛应用，且起搏后磁共振成像未得到广泛应用。需要一种准确且可重复的方法来客观测量区域心室同步性。相位图像分析是一种基于门控血池时间与放射性曲线的一阶傅里叶谐波拟合的功能方法，可生成振幅（A）参数，其与区域心室收缩程度或每搏量平行，以及相角（Ø）参数，其代表区域收缩时间。该方法早期应用时已证明具有可重复性，可显示电和机械不同步之间的联系，并表征心力衰竭中的收缩模式及其随CRT的改变。作为同步性标志物应用的心室Ø标准差已显示出双心室起搏的有益效果，且其在充血性心肌病和CHF患者中具有很强的预后价值，优于左心室射血分数。SD Ø可能并非评估同步性的最佳指标。我们寻求改进的、更敏感的参数，以更好地区分不同协同失调模式下的同步性。我们基于相位法得出、初步评估并在此展示新的同步性（S）和熵（E）参数，以定量区域和整体心室同步性，并将其应用于模拟和临床方案中。
