Validation of Premature Ventricular Contraction-induced Cardiomyopathy on a Swine Model

背景资料。频繁的室性早搏(PVCs)可导致左心功能不全或 心肌病(CM)，简称聚氯乙烯-心肌病(PVC-CM)。负责此CM的机制是 不清楚。一种PVC-CM犬模型不仅是证明可以在正常结构中诱导出PVC-CM的关键 心脏，但也确定可能解释LV发展的初步细胞和分子特征 功能障碍。直到最近，一种替代的PVC-心肌病模型已经在猪身上被描述出来。 这一模型似乎具有与犬类模型相似的超声心动图特征，尽管分子特征 仍然不为人所知。本研究的主要目的是在猪模型上验证PVC-CM。 假设。我们的主要假设是，与PVC-CM犬模型类似，猪模型将 结果表明：1)早期轻度至中度左心功能不全、轻度二尖瓣反流和舒张期功能不全 耦合的PVC，而与晚期耦合的PVC相比，早期的PVC表现出较少的左室不同步程度 静脉曲张(目标1)；2)白细胞介素性和肿瘤坏死因子-α信号的增加，而间质的减少 发育、神经元投射延伸和肌肉收缩基因(目标2)；3)二分体中类似的变化， 以Cav1.2、JPh-2、L型钙离子通道错位下调为特征 钙离子诱导的钙释放受损的BIN1的二联体和减少；3)；和4)最低限度的慢性 要开发聚氯乙烯-CM，需要暴露25%的聚氯乙烯负荷(目标4)。 目的1.验证PVC-CM猪模型的心脏结构变化及早搏后的影响 PVC-CM发展中的增强作用和PVC偶联区间。 目的2.在猪模型中确认与PVC-CM相关的转录图谱。 目的3.证实PVC的结构和分子变化，包括它们在PVC病理生理学中的作用 CM，并在猪模型上停止PVC后恢复。 目的4.验证PVC负荷、基线超声心动图、血流动力学和分子特征 在相同的异位情况下，预测猪模型中PVC-CM的发展或对其的恢复能力。 方法：研究方法。56只动物将接受起搏器植入，以复制频繁的室性异位(PVCs)。他们 将随机分为5组：1)晚期偶联50%PVCs(n=13)，2)早期偶联50%PVCs(n=13)，3) 早期结合型PVCs 33%组(n=10)，早期结合型25%组(n=10)，4)假手术组(n=10)。在12个月结束的时候- 每周PVC期间，每组暴露于50%的5只动物将允许一个恢复期(禁用PVCs) 负荷组和假手术组(图6)。一系列的心脏评估和活组织检查将使我们能够评估左心功能， 转录图谱，二聚体结构，钙瞬变(EC偶联)，JPH-2和Cav1.2表达的变化， 各组PVC-CM在基线和不同时间点的功能、分布及其介体。 意义重大。这项建议旨在验证大多数超声心动图、血流动力学、分子和 在一种新的PVC-CM猪模型中显示了细胞变化。一种新的猪PVC-CM模型将提供：1) 在哺乳动物中证实了这一临床实体，2)扩大了我们对pvc机制的理解。 作为猪的CM有一些有利的技术和程序，如用AAV-9病毒转染法进行修饰 细胞和分子表达，但最重要的是尽量减少使用独特和特殊的大 像狗这样的物种。了解PVC-CM的机制将有助于我们识别高危患者 开发PVC-CM，但最重要的是找到未来预防和治疗PVC-CM对象的靶点。

Background. Frequent premature ventricular contractions (PVCs) can cause LV dysfunction or cardiomyopathy (CM), referred to as PVC-cardiomyopathy (PVC-CM). The mechanism responsible this CM is unclear. A PVC—CM canine model was key not only to prove that PVC-CM can be induced in a normal structural heart, but also to identify preliminary cellular and molecular features that may explain the development of LV dysfunction. Until recently an alternative PVC-Cardiomyopathy model has been described in the swine species. This model appears to have similar echocardiographic features to the canine model, although molecular features remain unknown. The main objective of this study is to validate a PVC-CM in a swine model. Hypotheses. Our main hypotheses is that similar to the PVC-CM canine model, the swine model will demonstrate: 1) mild to moderate LV dysfunction, mild mitral regurgitation and diastolic dysfunction in early- coupled PVC, while early PVCs will demonstrate less degree of LV dyssynchrony when compared to late-coupled PVCs (Aim 1); 2) an increase in interleukin and TNF-alpha signaling, while a decrease in mesenchyme development, neuron projection extension and muscle contraction genes (Aim 2); 3) similar changes in the dyad, characterized by decrease in ICaL and down-regulation of Cav1.2, JPH-2, L-type Ca2+ channel misplacement out of the dyad and decrease in BIN1 with impaired Ca2+-induced Ca2+-release (Aim 3); 3); and 4) a minimum chronic exposure of 25% PVC burden is required to develop PVC-CM (Aim 4). Aim 1. Validate the cardiac structural changes in a PVC-CM swine model and impact of post-extrasystolic potentiation and PVC coupling interval in the development of PVC-CM. Aim 2. Confirm Transcriptomic profiling associated with PVC-CM in the swine model. Aim 3. Corroborate the structural and molecular changes including their role on the pathophysiology of PVC- CM and recovery upon PVC cessation in the swine model. Aim 4. Validate PVC burden, baseline echocardiographic, hemodynamic and molecular features that can predict the development of, or resilience to PVC-CM in the swine model despite identical ventricular ectopy. Methods. 56animals will undergo pacemaker implant to reproduce frequent ventricular ectopy (PVCs). They will be randomized to one of 5 groups: 1) late-coupled 50% PVCs (n=13), 2) early-coupled 50% PVCs (n=13), 3) early-coupled PVCs 33% PVCs (n=10), early-coupled 25% PVCs (n=10), or 4) sham (n=10). At the end of a 12- week PVC period, a recovery phase (disabling PVCs) will be allowed in 5 animals of each group exposed to 50% burden and sham group (Fig. 6). Serial cardiac evaluation and biopsies will allow us to assess LV function, transcriptomic profile, dyad structure, Ca2+ transients (EC coupling), changes in JPH-2 and Cav1.2 expression, function and distribution and their mediators at baseline and different time points of PVC-CM in all groups. Significance. This proposal is designed to validate most echocardiographic, hemodynamic, molecular and cellular changes demonstrated in a new PVC-CM Swine model. A new swine PVC-CM model will provide: 1) corroboration of this clinical entity in mammalians, 2) expand our understanding of the mechanism t of PVC- CM as swine has some favorable techniques and procedures, such as viral transfection with AAV-9 to modify cellular and molecular expression, but most importantly 3) minimize the use of a unique and special large species such as the dog. Understanding the mechanism of PVC-CM will help us to identify high-risk patients to develop PVC-CM, but most importantly find future targets to prevent and treat subjects with PVC-CM.