快速心室起搏犬心房颤动模型研究

Study on the canine model of atrial fibrillation with ventricular tachypacing-induced heart failure

目的建立快速起搏心室致心力衰竭犬房颤模型,研究其电生理及心房结构和功能改变。方法 15只健康杂种犬分两组:对照组6只,实验组9只[240次/min心室起搏(25±3)d]。超声心动图测定起搏前后心房面积、面积缩小分数及左心室功能,利用心内电极测定心房有效不应期、传导速度及房颤诱发情况。结果实验组7只犬完成了实验。快速心室起搏(25±3)d后,犬的收缩末期和舒张末期左、右心房面积显著增大(与起搏前比较,P<0.01),左、右心房面积缩小分数显著减小(左心房:(35.7±1.9)%和(20.7±2.7)%,P<0.01;右心房:(35.0±2.3)%和(18.0±2.3)%,P<0.01),左室射血分数从(65.3±2.1)%降至(31.6±2.8)%(P<0.01)。实验组犬左、右心房有效不应期显著延长,心房内传导速率较对照组减慢。实验组有5只犬诱发出超过30 min的房颤,平均房颤持续时间较对照组显著延长(687±290)s和(13±9)s,P<0.01)。实验组平均房颤持续时间与左、右心房面积及面积缩小分数相关(P<0.05)。结论 快速心室起搏致心衰模型能稳定地诱发出房颤,房颤持续时间与心衰引起的显著心房结构和功能异常相关。

Objective To characterize the alterations of atrial electrophysiology,size and contractility in the canine atrial fibrillation（AF） model with ventricular tachypacing-induced congestive heart failure（CHF）.Methods Fifteen mongrel dogs were randomly divided into experiment group and control group.In experimental dogs（n=9）,the right ventricle was paced at 240 beats per minute for（25±3） d to induce CHF,while no pacing was performed in the control group.Transthoracic echocardiography was performed at baseline and before the end-study.In the terminal study,atrial electrophysiological parameters were measured in the right atrial appendage（RAA）,posterior wall of right atrium（RAPW）,coronary sinus（CS）,left atrial appendage（LAA）,posterior wall of left atrium（LAPW） and left superior pulmonary vein（LSPV） with endocardial leads.AF was induced by programmed electrical stimulation and burst pacing.AF inducibility and mean AF duration（DAF） was determined.Results Seven dogs in the experiment group helped complete the study.Atrial systolic and diastolic areas increased significantly after（25±3） d of rapid ventricular pacing（P〈0.01）.The left and right atrial fractional area shortening（FAS） substantially decreased（left atrial：（35.7±1.9）% vs（20.7±2.7）%,P0.01;right atrial：（35.0±2.3）% vs（18.0±2.3）%,P〈0.01）.The left ventricular ejection fraction（LVEF） decreased from（65.3±2.1）% to（31.6±2.8）%（P〈0.01）.Effective refractory periods（ERP） at 400 ms and 300 ms cycle lengths in both LA and RA were significantly prolonged in dogs with CHF.AERP dispersion increased significantly and conduction velocity decreased apparently.CHF increased DAF from 13±9 seconds in control dogs to 687±290 seconds（P〈0.01）.DAF and LA systolic and diastolic areas were highly correlated in HF dogs（r=0.797,0.828;P〈0.05 for each）.Similar findings were observed for RA areas（r=0.770,0.829;P0.05 for each）.FAS in both atria negatively correlated with DAF（P〈0.05）.Conclusion Ventricular tachypacing-induced CHF strongly increases duration of induced AF,which is correlated with the structural and functional abnormalities in both atria.