| As the rapid development of interventional technology, transcatheter aorticvalve implantation（TAVI） therapy has become an alternative method tosurgical aortic valve replacement (AVR) because of its lower risk and fasterrecovery in high-risk patients. With accumulation of experience andadvancement of TAVI devices, nearly30000TAVI procedures were performedworldwide to date. In China, TAVI had not been prevalent. This situation is notconsistent with the large population and ageing society of China. To promoteanti-calcification ability of transcatheter valves is also a critical problem to besolved before TAVI is applied to younger patients or lower risk patients. In viewof previous achievement we got in new generation of no stent porcine valve andanti-calcification of biological heart valves, we designed a new anti-calcificationtranscatheter valve for TAVI. We need find a proper way to perform the TAVIexperiment and establish an animal model for TAVI, and evaluate the feasibilityand function of the new anti-calcification transcatheter valve for TAVI inexperimental animals. ⅠAnimal model establishment for TAVIObjective To establish an animal experimental model of transcatheter aorticvalve implantation (TAVI) and to determine the optimal projecting position foraortic root angiography. Methods Fifteen healthy adult sheep were selected.From the lower1/3neck to the suprasternal fossa, the diameter of aortic annulusand carotid artery were measured by echocardiography and vascular ultrasoundrespectively. Then, common carotid artery was dissected and measured underdirect vision. Left ventriculography via the same carotid artery using a pigtailcatheter was performed and the best projecting position for demonstrating theaortic root was evaluated.20F (French) and24F catheter delivery sheaths wereinserted through the dissected carotid artery. The main hemodynamic data wereevaluated preoperatively and postoperatively by cardiac catheter technology andtransthoracic echocardiography（TTE）.Results Echocardiography showed thatthe diameter of systolic aortic annulus and diastolic aortic annulus atsuprasternal fossa was (24.98±2.41) mm and (19.82±2.14) mm, and vascularultrasound showed that the diameter of carotid artery at the lower1/3neck andthoracic entrance was (9.16±0.84)mm and (5.61±0.50)mm respectively. Bydirect vision, the diameter of carotid artery was (5.90±0.64) mm. The20Fcatheter delivery sheaths were easily inserted through the carotid arteries of allsheep and the24F catheter delivery sheaths were successfully inserted throughthe carotid arteries of13sheep. The ostia of left and right coronary artery andthe aortic root were well demonstrated in the position of right anterior oblique2.5°±3°plus cranial7.1°±6°. No significant difference was observed betweenthe postoperative and preoperative measurements of the effective orifice area(EOA), reflux percentage, aortic systolic pressure (ASP), diastolic aorticpressure (DAP), mean aortic pressure (MAP), left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP) and heart rate.Ⅱ The feasibility and function study of the new anti-calcificationtranscatheter valve for TAVI in sheepObjective To evaluate the feasibility of transcatheter aortic valveimplantation(TAVI) using a new anti-calcification transcatheter valve andobserve its short-term results. Methods Twenty healthy adult sheep wereselected as subjects. Under general anesthesia and the guidance of X-ray andtransthoracic echocardiography（TTE）, the new anti-calcification transcathetervalve was released from delivery system and implanted at the level of nativeaortic annulus. Position and function of the new anti-calcification transcathetervalve were evaluated by angiography and TTE immediately after intervention.Hemodynamic data were also recorded and evaluated peri-operatively. Thirtyday survival rate of animals was observed. Results Five sheep died afterTAVI within30days, including one fatal ventricular fibrillation occurredimmediately after releasing the transcatheter valve and another sheep died ofacute myocardial infarction due to left main coronary artery occlusion, whichwas also evidenced by angiography. Two sheep died of severe mitralregurgitation8and12hours post-operatively and one died of infectiveendocarditis26days after intervention. Fifteen sheep survived andpost-operative examination showed that the transcatheter valve was in optimalposition without migration and mitral valve impingement. The native coronaryartery was clear and patent, but slight paravalvular leak existed in5sheep.Postoperative echocardiography showed reflux percentage was significantlyhigher（p<0.05) compared with that of pre-intervention. There was no statisticaldifference in the data of effective orifice area (EOA),aortic systolic pressure(ASP), diastolic aortic pressure (DAP), mean aortic pressure (MAP), left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure(LVEDP) and heart rate. Thirty-day animal survival rate was75%.Conclusion1. In this study, the deliver catheter system has good flexibility and elasticity.The18F delivery sheath can be easily inserted into sheep carotid artery toreach the desired location. In particular, vascular injury might be avoidedowing to the improved front-end design of delivery sheath. Two-stagedesigned delivery catheter system admits back and repositioning oftranscatheter valve before waist of stent valve released. The safety andprecise positioning were achieved.2. Echocardiographic and left ventricular angiography of survived animalsafter TAVI showed the new anti-calcification transcatheter valve had goodhemodynamic results in vivo.30-day animal survival rate was75%.Ourpreliminary animal experiment showed that it was feasible to perform TAVIusing the new anti-calcification transcatheter valve. Precise positioning ofthe new anti-calcification transcatheter valve was the crucial point of theprocedure.3. Transcatheter aortic valve prosthesis is implanted via the carotid artery ofadult sheep by retrograde approach. This model meets the requirements ofanimal study for TAVI, and founds the basic of making the new TAVIsystem in the future. |
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