犬肺静脉肌袖电生理随龄性改变

目的对比研究老龄和成年犬肺静脉肌袖电生理特性.方法采用经导管房间隔穿刺技术,应用程序刺激和短阵快速起搏分别对正常自然老龄和成年实验犬肺静脉、上腔静脉、左房、右房、以及冠状静脉窦的有效不应期、激动传导及心房颤动诱发阈值进行标测.结果老龄犬的左、右心房,上腔静脉,冠状静脉窦和肺静脉的有效不应期较成年犬均有不同程度的缩短,其中左心房,上腔静脉和肺静脉有效不应期的随龄性变化有统计学差异(P＜0.01).老龄犬的肺静脉不应期较其左房的不应期明显缩短,而成年犬肺静脉与左房的不应期则无显著性差异.老龄犬的肺静脉和上腔静脉内激动传导呈显著递减性传导.在多数老龄犬的肺静脉、左心房和上腔静脉,快速短阵起搏及程序刺激能诱发持续时间＞30s的房颤.结论老龄犬肺静脉肌袖有易于房颤发生的电生理变化,提示心脏老龄化可能是房颤发生的潜在基质.

Aging-related electrophysiological changes of pulmonary atrial sleeves in dogs

Objective To detect the aging-related changes in electrophysiologic properties of pulmonary myocardial sleeves in dogs and to seek the experimental evidence for primary or independent factor contributing to atrial fibrillation(AF) incidence. Methods Two 4-electrode catheters were inserted through the right femoral vein and fixed to the upper lateral wall of right atrium and the junction of superior vena cava with right atrium under the guide of fluoroscopy. A decapolar catheter was inserted into the coronary sinus via the internal jugular vein. Transseptal puncture was accomplished and a radiofrequency catheter and a 10-electrode catheter(Lasso) was placed into left atrium and pulmonary vein. Effective refractory period(ERP), conduction property, AF thresholds at different sites were measured by programmed stimulation and short burst stimuli. Results ERPs at pulmonary veins, superior vena cava, two atria and coronary sinus in old dogs were shorter than those in adult group. Among them, the differences in ERPs of left atrium, superior vena cava and pulmonary veins between old and adult dogs had statistical significance(P<0.01). In old group, the ERP of pulmonary veins was shorter than that of left atrium; but in adult group, there was no difference between them. The conduction of impulses in superior vena cava and pulmonary veins in old group showed significant progressive decrement. AF lasting longer than 30 seconds could be induced only at left atrium, superior vena cava and pulmonary veins in old dogs through programmed stimulation and short burst stimuli. In adult dogs, no induced AF occurred in spite of increasing stimulation threshold and rate. Conclusion The aging-related changes in electrophysiological properties of pulmonary myocardial sleeves facilitates the initiation of AF. Aging-related changes of the heart might offer potential substrate for AF.