Percutaneous aortic valve replacement: resection before implantation☆

OBJECTIVE: After transluminal endovascular implantation of a new valved stent, the aim of this study was to evaluate the feasibility of using a high-pressure water stream to endovascularly resect human calcified aortic valves. METHODS: First, human calcified aortic valves were excised and then resected in vitro to determine optimal water jet parameters. Second, healthy porcine aortic valves were ablated in vitro to evaluate possible destruction to the surrounding anatomy. Third, resection was performed endoluminally by introducing microsystemic tools into the descending aorta, passing them through the arch and ascending aorta to the aortic valve in an in vitro porcine model. Macro- and micropathology of specimens were analyzed. RESULTS: First, resection of human calcified valves took a mean of 6.0+/-2.4min per three leaflets at 150bar (n=17). The maximum size of the cut leaflets was 7.1+/-1.7mm. Second, resection of healthy porcine aortic valves at 60bar took 2.3+/-0.3min per three leaflets (n=10). Only the aortic annulus was moderately affected in six cases. Third, endoluminal resection via the descending aorta took 12.2+/-0.8min per three leaflets at 60bar (n=10). The aortic wall was affected in four cases, the aortic annulus and the coronary ostia only once. Microscopic analysis also revealed superficial lesions with a maximum lesion depth of 1200microm in one case, and an average of 580+/-145microm in subsequent lesions. The mitral valve and the left ventricular outflow tract were not affected. CONCLUSIONS: Percutaneous resection of heart valves is emerging as a promising auxiliary method for the resection of calcified aortic heart valves because they can be cut endoscopically. Nonetheless, before this resection tool can be clinically applied by surgeons to perform a true percutaneous valve replacement, an additional aortic valve resection chamber (already at the prototype stage) designed for capturing all debris, has to be established.