经导管主动脉瓣置换的动物实验方法
Establishment of an experimental animal model for transcatheter aortic valve replacement
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摘要: 目的:建立经导管主动脉瓣置换（transcatheter aortic valve replacement,TAVR）的动物实验方法,确定适合于TAVR的实验动物模型及主动脉根部造影的最佳投照体位。方法:选用健康绵羊15只（体质量40～45 kg）,于颈中、下1/3处到胸骨上窝区间,通过超声心动图和血管超声分别测量绵羊主动脉瓣环直径和颈总动脉直径。分离绵羊颈总动脉,于直视下测量其直径。穿刺颈总动脉,送入猪尾巴导管,行左心室造影,确定主动脉根部最佳投照体位并进行影像学分析。行颈总动脉横切口,依次置入20F和24F介入式大动脉支架（主动脉覆膜支架）输送鞘,观察能否顺利通过。分别在置入前后,经胸超声心动图（TTE）测量主动脉瓣有效瓣口面积（effective orifice area,EOA）、返流百分比、心率,经心导管测量主动脉收缩压（aortic systolic pressure,ASP）、主动脉舒张压（diastolic aorticpressure,DAP）、平均主动脉压（mean aortic pressure,MAP）、左心室收缩压（left ventricular systolic pressure,LVSP）、左室舒张末压（left ventricular end diastolic pressure,LVEDP）。结果:用超声心动图测得收缩期主动脉瓣环直径为（24.98±2.41）mm,舒张期主动脉瓣环直径为（19.82±2.14）mm。用血管超声测得颈中、下1/3处颈总动脉直径为（5.61±0.50）mm,颈总动脉胸廓入口处直径为（9.16±0.84）mm。解剖直视下测得的颈中、下1/3处颈总动脉直径为（5.90±0.64）mm。15只绵羊均可经颈总动脉成功置入20F输送鞘,13只绵羊可成功置入24F输送鞘。造影结果显示,右前斜位2.5°±3°、头足位7.1°±6°,可清楚显示绵羊左、右冠脉的开口及主动脉根部的解剖形态。术后存活绵羊（14只）主动脉瓣的EOA、返流百分比、心率、ASP、DAP、MAP、LVSP、LVEDP与术前测量值差异均无统计学意义。结论:经绵羊颈总动脉可建立逆行TAVR实验模型,右前斜位2.5°±3°、头足位7.1°±6°,可获得良好的主动脉根部影像,满足应用介入瓣膜输送系统进行TAVR动物实验研究的需要。Abstract: AIM:To establish an experimental animal model of transcatheter aortic valve replacement（TAVR） and to determine the optimal projecting position for aortic root angiography.METHODS:Fifteen healthy adult sheep were selected.From the lower 1/3 neck to the suprasternal fossa,the diameter of the aortic annulus and carotid artery were measured by echocardiography and vascular ultrasound,respectively.Common carotid artery was then dissected and measured under direct vision.Left ventriculography via the same carotid artery using a pigtail catheter was performed and the best projecting position for demonstrating the aortic root was evaluated.Both 20 French（F） and 24F catheter delivery sheaths were inserted through the dissected carotid artery.The effective orifice area（EOA）,reflux percentage,heart rate,systolic aortic pressure（SAP）,diastolic aortic pressure（DAP）,mean aortic pressure（MAP）,left ventricular systolic pressure（LVSP）,and left ventricular end diastolic pressure（LVEDP） were evaluated pre-and postoperatively by transthoracic echocardiography（TTE） and cardiac catheter technology.RESULTS:Echocardiography showed that the diameter of systolic aortic annulus and diastolic aortic annulus at suprasternal fossa was（24.98±2.41） mm and（19.82±2.14） mm,and vascular ultrasound showed that the diameter of carotid artery at the lower 1/3 neck and thoracic entrance was（9.16±0.84） mm and（5.61±0.50） mm,respectively.By direct vision,diameter of the carotid artery was（5.90±0.64） mm.The 20F catheter delivery sheaths were easily inserted through the carotid arteries of all sheep and the 24F catheter delivery sheaths were successfully inserted through the carotid arteries of 13 sheep.The ostia of left and right coronary arteries and aortic root were well demonstrated in the position of right anterior oblique 2.5°±3° plus cranial 7.1°±6°.No significant difference was observed between pre-and postoperative measurements of EOA,reflux percentage,heart rate,ASP,DAP,MAP,LVSP,and LVEDP.CONCLUSION:Transcatheter aortic valve prosthesis is implanted via the carotid artery of adult sheep by retrograde approach.Using angiography,the optimal projecting position to visualize the aortic root and coronary ostia is right anterior oblique 2.5°±3 plus cranial 7.1°±6°.This model meets the requirements of animal study for the TAVR system.
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