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目的:应用经胸超声心动图观察高频率左心耳起搏致猪慢性心房颤动模型心脏结构和功能的变化。方法:实验于2005-09/2006-08在南京医科大学第一附属医院江苏省实验动物中心完成。①12只苏钟种猪随机分为实验组及对照组各6只,所有动物均开胸,将起搏电极固定在左心耳根部,高频率脉冲发生器植入左侧胸部囊袋。实验组术后恢复1周后起搏器以500次/min的频率快速起搏左心耳8周;对照组始终不起搏。②术后心电图定期监测起搏、心房颤动的发生情况;于术前、起搏后1周、起搏后4,8周超声心动图观察实验动物左房内径、心室收缩及舒张末左房面积、左房和左室射血分数、左室舒张及收缩末内径、左心室短轴缩短率等变化。结果:①实验组5只完成了实验,术后2周复查心电图,1只动物发生房颤,起搏8周3只发生阵发性房颤,1只未发生房颤;对照组则未发生任何心律失常情况。②左心房相关指标:起搏后1周,实验组左房内径、收缩末期左心房面积和舒张末期左房容积均较起搏前增加[(2.70±0.12),(2.50±0.12)cm;(6.78±0.81),(6.21±0.93)cm2;(4.66±0.53),(3.78±0.57)mL;P均<0.05],左房射血分数较起搏前下降[(55.6±6.0)%,(63.8±4.0)%,P<0.01],至起搏4,8周,左房射血分数进一步降低,左房内径等指标则继续增大。③左心室相关指标:起搏后1周,实验组左室舒张、收缩末期内径较起搏前增加[(3.64±0.13),(3.46±0.15)cm;(2.48±0.08),(2.14±0.09)cm;P均<0.01],左心室短轴缩短率和左室射血分数较起搏前下降[(31.6±2.0)%,(37.8±3.0)%;(60.8±2.0)%,(69.2±4.0)%;P均<0.01];至起搏4,8周,左心室短轴缩短率和射血分数进一步降低,左室舒张、收缩末期内径则继续增大,与对照组比较也差异显著(P<0.05,0.001)。结论:①超声心动图是监测房颤模型建立过程中心房、心室结构和功能变化的有效手段。②高频起搏左心耳是建立猪心房颤动模型的有效方法,快速心房起搏可导致左心房左心室增大及心功能减退。
Objective: To observe the change of cardiac structure and function in chronic atrial fibrillation model induced by high frequency left atrial appendage pacing by transthoracic echocardiography. Methods: The experiment was performed at Experimental Animal Center of Jiangsu Province, First Affiliated Hospital of Nanjing Medical University from September 2005 to August 2006. ①12 Suzhong pigs were randomly divided into experimental group and control group, 6 in each. All animals underwent thoracotomy. The pacemaker electrodes were fixed in the root of left atrial appendage and the high frequency pulse generator was implanted in the left thoracic pouch. One week after the operation in the experimental group, the left atrial appendage was pacing rapidly at 500 beats / min for 8 weeks. The control group did not pacing all the time. ② Postoperative electrocardiogram was used to monitor the occurrence of pacing and atrial fibrillation. Preoperative, 1 week after pacing, 4 weeks and 8 weeks after pacing echocardiography was used to observe the left atrium diameter, ventricular systole and left atrium area , Left atrium and left ventricular ejection fraction, left ventricular diastolic and end-systolic diameter, shortening of left ventricular short axis and other changes. Results: ①Experimental group 5 completed the experiment, electrocardiogram was reviewed 2 weeks after surgery, 1 animal had atrial fibrillation, paroxysmal atrial fibrillation occurred 3 weeks after pacing, 1 case did not occur atrial fibrillation; Any arrhythmia situation. ② Left atrial related index: Left atrial diameter, end-systolic left atrium area and end-diastolic left atrium volume in experimental group increased (2.70 ± 0.12) and (2.50 ± 0.12) cm respectively 6.72 ± 0.81), (6.21 ± 0.93) cm2; (4.66 ± 0.53) and (3.78 ± 0.57) mL, P <0.05, respectively. Left atrial ejection fraction decreased 55.6 ± 6.0% 63.8 ± 4.0)%, P <0.01]. Left ventricular ejection fraction was further reduced at 4 weeks and 8 weeks after pacing, and left atrial diameter and other indexes continued to increase. (3) Left ventricular related index: At 1 week after pacing, left ventricular diastolic and systolic diameter in the experimental group increased (3.64 ± 0.13), (3.46 ± 0.15) cm, (2.48 ± 0.08), (2.14 ± 0.09) (P <0.01). The shortening rate of left ventricular short axis and left ventricular ejection fraction decreased compared with that before pacing (31.6 ± 2.0), (37.8 ± 3.0)%, (60.8 ± 2.0)% and ± 4.0)%; P <0.01]. Shortening and shortening of left ventricular shortening and ejection fraction were further reduced at 4th and 8th week of pacing, while diastolic and end systolic diameters of left ventricle continued to increase compared with control group Significant (P <0.05, 0.001). Conclusion: ①Echocardiography is an effective method to monitor atrial and ventricular structure and function changes during the establishment of atrial fibrillation model. ② high-frequency pacing left atrial appendage is to establish an effective method of pig atrial fibrillation model, rapid atrial pacing can lead to left atrial enlargement of the left ventricle and cardiac dysfunction.