Wang Mei-lian, Zhang Ying, Fan Miao, Guo Ya-jun, Ren Wei-dong, Luo En-jie
Department of Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, No. 92 Beier Road, Heping District, Shenyang 110001, China.
Cardiovasc Ultrasound. 2013 Jan 14;11:3. doi: 10.1186/1476-7120-11-3.
The most widely used experimental models of infective endocarditis (IE) are the rabbit and rat models, in which cardiac valve lesions are induced by a polyethylene catheter introduced into the left ventricle through the aortic valve. Our study was designed to create a rabbit model of IE right-sided with echocardiographic guidance.
Thirty rabbits underwent both catheterization and inoculation (group A). These were divided into three subgroups of ten based on the time of catheter removal (immediately, after 24 h, and after death or moribundity for groups, A(1), A(2), and A(3), respectively). Ten inoculated-only and ten catheterized-only rabbits served as controls. A catheter system consisted of a polyethylene catheter and a guide wire inside it. This system was passed through the rabbits' tricuspid valves under echocardiographic guidance to damage them. The ratio of left ventricle to right ventricle (LV/RV) was measured in a four-chamber view before catheterization and at the time of death or moribundity. The peak velocity of tricuspid regurgitation (V(TR)) was measured in a four-chamber view at the time of catheterization and at the time of death or moribundity. Staphylococcus aureus (ATCC 29213) inoculation was performed 24 h after right heart catheterization to produce IE.
IE was confirmed in 28 of 30 rabbits by macroscopic and histologic examination of tricuspid valves, blood cultures, and bacterial count in cardiac vegetations. Cardiac vegetations were confirmed in 25 of 28 IE rabbits by echocardiography. Enlargement of right ventricle dimension with a significantly decreased LV/RV ratio was confirmed in all IE rabbits at the time of death or moribundity than at the initial state (1.11 ± 0.35 vs. 1.95 ± 0.39, P < 0.01; 1.21 ± 0.34 vs. 1.98 ± 0.35, P < 0.01; 1.04 ± 0.31 vs. 2.00 ± 0.41, P < 0.01 for groups A(1), A(2), and A(3), respectively). V(TR) was significantly higher in all the IE rabbits at the time of death or moribundity than at the time of catheterization (1.89 ± 0.46 vs 0.76 ± 0.45, P < 0.01; 2.04 ± 0.73 vs 0.68 ± 0.66, P < 0.01; 2.24 ± 0.51 vs 0.87 ± 0.55, P < 0.01 for group A(1), A(2), and A(3), respectively).
The models described herein closely reproduced the pathogenesis and pathophysiology of right heart catheter-induced endocarditis in humans. Echocardiographic guidance is helpful in the process of right heart catheterization. Some echocardiographic parameters, such as V(TR) and the LV/RV ratio could be used to assess the success or failure of the IE models.
感染性心内膜炎（IE）最广泛使用的实验模型是兔和大鼠模型，其中通过经主动脉瓣插入左心室的聚乙烯导管诱导心脏瓣膜病变。我们的研究旨在在超声心动图引导下创建右侧IE兔模型。
30只兔子接受了导管插入和接种（A组）。根据拔管时间将它们分为三个亚组，每组10只（分别为A(1)组、A(2)组和A(3)组，拔管时间分别为立即、24小时后以及死亡或濒死时）。另外10只仅接种和10只仅接受导管插入的兔子作为对照。导管系统由一根聚乙烯导管及其内部的导丝组成。该系统在超声心动图引导下穿过兔子的三尖瓣以损伤瓣膜。在导管插入前以及死亡或濒死时，在四腔视图中测量左心室与右心室的比例（LV/RV）。在导管插入时以及死亡或濒死时，在四腔视图中测量三尖瓣反流的峰值速度（V(TR)）。在右心导管插入24小时后进行金黄色葡萄球菌（ATCC 29213）接种以产生IE。
通过三尖瓣的宏观和组织学检查、血培养以及心脏赘生物中的细菌计数，在30只兔子中的28只中证实了IE。通过超声心动图在28只IE兔子中的25只中证实了心脏赘生物。与初始状态相比，所有IE兔子在死亡或濒死时均证实右心室尺寸增大且LV/RV比例显著降低（A(1)组、A(2)组和A(3)组分别为1.11±0.35对1.95±0.39，P<0.01；1.21±0.34对1.98±0.35，P<0.01；1.04±0.31对2.00±0.41，P<0.01）。所有IE兔子在死亡或濒死时的V(TR)显著高于导管插入时（A(1)组、A(2)组和A(3)组分别为1.89±0.46对0.76±0.45，P<0.01；2.04±0.73对0.68±0.66，P<0.01；2.24±0.51对0.87±0.55，P<0.01）。
本文所述模型密切再现了人类右心导管诱导的心内膜炎的发病机制和病理生理学。超声心动图引导在右心导管插入过程中很有帮助。一些超声心动图参数，如V(TR)和LV/RV比例可用于评估IE模型的成败。
