Minakawa Masahito, Robb J Daniel, Morital Masato, Koomalsinghl Kevin J, Vergnat Mathieu, Gillespie Matthew J, Gorman Joseph H, Gorman Robert C
J Heart Valve Dis. 2014 Nov;23(6):713-20.
Ischemic mitral regurgitation (IMR), the incidence of which is increasing, results from annular and subvalvular remodeling after myocardial infarction (MI). Although a sheep model of IMR has been used extensively over the past two decades, the ventricular, coronary and leaflet anatomy in sheep is significantly different from that in humans. In contrast, pigs are more similar to humans with regard to these parameters, and therefore may serve as a better animal to test emerging new technologies designed to treat IMR.
Twenty-nine pigs (body weight 30-35 kg) underwent left thoracotomy and ligation of the mid main circumflex and distal right posterior descending coronary arteries to create a posterolateral MI. Of these pigs, 18 were used for acute data acquisition, while 11 surviving animals in the chronic group were assessed at eight weeks after MI. Real-time three-dimensional echocardiography was performed at baseline, and at 30 min and eight weeks after MI, to assess geometric changes in the mitral annulus, mitral leaflets and left ventricle.
Compared to baseline, the MR grade was increased significantly at eight weeks (0.7 + 0.5 versus 2.0 +/- 1.2), together with a significant decrease in left ventricular ejection fraction (40.3 +/- 6.6% versus 25.8 +/- 7.7%). Significant increases were also noted at eight weeks in the commissural width (30.1 +/- 3.2 mm versus 35.1 +/- 2.9 mm) and septolateral diameter (25.0 +/- 2.0 mm versus 33.8 +/- 5.9 mm), with a resultant increase in mitral annular area (596 +/- 85 versus 931 +/- 181 mm3) and a decrease in the annular height to commissural width ratio (15.7 +/- 2.6% versus 13.7 +/- 1.9%). The mitral valve tenting volume was also increased significantly (1577 +/- 645 versus 2440 +/- 755 mm3). The distance between the papillary muscle tips at baseline and at eight weeks was increased significantly (23.9 +/- 2.5 versus 30.9 +/- 5.2 mm), as was the distance between the posterior papillary muscle tip and the posterior commissure (20.9 +/- 2.7 versus 24.1 +/- 2.8 mm).
The surgical model described here reliably replicates the changes seen in humans with IMR. Hence, this model can be used for further studies of the pathophysiology of IMR, and of any novel interventions in this challenging clinical area.
缺血性二尖瓣反流（IMR）的发病率呈上升趋势，它是心肌梗死（MI）后瓣环及瓣下结构重塑所致。尽管在过去二十年中，IMR的绵羊模型已被广泛应用，但绵羊的心室、冠状动脉及瓣叶解剖结构与人类有显著差异。相比之下，猪在这些参数方面与人类更为相似，因此可能是测试旨在治疗IMR的新兴新技术的更优动物。
29头猪（体重30 - 35千克）接受左胸切开术，并结扎左回旋支中段和右后降支远端冠状动脉以造成后外侧心肌梗死。其中，18头猪用于急性数据采集，而慢性组的11头存活动物在心肌梗死后八周进行评估。在基线、心肌梗死后30分钟和八周时进行实时三维超声心动图检查，以评估二尖瓣环、二尖瓣叶和左心室的几何变化。
与基线相比，八周时二尖瓣反流分级显著增加（0.7 + 0.5对2.0 +/- 1.2），同时左心室射血分数显著降低（40.3 +/- 6.6%对25.8 +/- 7.7%）。八周时还观察到瓣叶联合宽度（30.1 +/- 3.2毫米对35.1 +/- 2.9毫米）和间隔外侧直径（25.0 +/- 2.0毫米对33.8 +/- 5.9毫米）显著增加，导致二尖瓣环面积增加（596 +/- 85对931 +/- 181立方毫米），瓣环高度与瓣叶联合宽度之比降低（15.7 +/- 2.6%对13.7 +/- 1.9%）。二尖瓣瓣叶帐篷样容积也显著增加（1577 +/- 645对2440 +/- 755立方毫米）。基线和八周时乳头肌尖端之间的距离显著增加（23.9 +/- 2.5对30.9 +/- 5.2毫米），后乳头肌尖端与后瓣叶联合之间的距离也显著增加（20.9 +/- 2.7对24.1 +/- 2.8毫米）。
此处描述的手术模型可靠地复制了人类IMR中所见的变化。因此，该模型可用于进一步研究IMR的病理生理学以及这一具有挑战性临床领域的任何新型干预措施。
