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Abstract: Objective: To date, transfemoral and trans-apical valved stent implantation techniques are limited to the replacement of pulmonary and aortic valves in a strictly selected group of patients. The current study was designed to assess the short-term follow-up using a mitral valved stent in off-pump technique. Methods: A self-expanding, repositionable mitral valved stent was created for trans-apical implantation. Five pigs underwent successful trans-catheter implantation. Data were gathered to assess the animals’ haemodynamical stability after stent implantation (n =5), 6h (n =5) and 1 week (n =4). The valved stent function was assessed by trans-oesophageal echocardiography and ventriculogram. Cardiac computed tomography (CT) was used to evaluate positioning of the new implant. Results: Precise valved stent deployment and accurate subsequent adjustment of its intra-annular position allowed for reduction of paravalvular leakage in all animals. The deployment time ranged from 122 to 271s and blood loss from 65 to 245cc. Accurate positioning was established in all but one animal. The average mean transvalvular gradient and mean gradient across left ventricular outflow tract (LVOT) recorded immediately after deployment, 6h and 1 week were 1.9±0.9mmHg, 3.5±1.6mmHg, 4.1±02.3mmHg and 1.4±01.3mmHg, 1.5±0.7mmHg 1.9±0.7mmHg, respectively. Mild regurgitation was present after valved stent deployment in one out of five animals after 1h, one out of five animals at 6h, and two out of four animals at 1 week. All animals exhibited normal haemodynamics after mitral valved stent implantation and maintained stability for the period of monitoring (6h). One animal died of unrecognised imperfect valved stent positioning after 1 day. In the subsequent animals, valved stent migration, embolisation, systolic anterior movement or LVOT obstruction was not observed after 1 week follow-up. Conclusions: The new mitral valved stent can be deployed in a reproducible manner to achieve reliable stent stability, minimal gradients across the LVOT and adequate valved stent function in short-term follow-up. [Copyright &y& Elsevier]

Abstract: Objective: Percutaneous valve replacement was recently introduced, and reports of early clinical experience have already been published. To date, this technique is limited to the replacement of pulmonary and aortic valves in a strictly selected group of patients. The aim of this study was to analyse a self-expanding valved stent for minimally invasive replacement of the mitral valve in animals. Methods: A newly designed nitinol stent was specially designed for this experimental acute study. It comprised of a left ventricular tubular stent with star shaped left atrial anchoring springs and carried a trileaflet bovine pericardial valve. A polytetrafluoroethylene membrane was sutured to envelop the atrial springs and the outside of the ventricular stent. The ventricular anchoring system was the same as in our previously reported results with a similar mitral valved stent. Seven pigs underwent minimally invasive off-pump mitral valved stent implantation. This was performed through a lower mini-sternotomy and a standard transapical approach under transoesophageal echocardiographic (TEE) guidance was used. Results: The valved stent is fully retrievable and precise deployment and accurate adjustment of its intra-annular position is achievable to eliminate paravalvular leakage. The deployment time ranged from 127 to 255s and the blood loss from 70 to 220cc. One animal died of intractable ventricular fibrillation. Mitral regurgitation in all surviving animals was minimal (trace in 5/6 and mild in 1/6 during echo examination; on the contrast ventriculogram no mitral insufficiency was observed except in one documented as mild paravalvular regurgitation). These animals remained haemodynamically stable (6/6) and without TEE or ventriculographic changes for 1h. Conclusion: Implantation of a tricuspid bovine pericardial valved stent in the mitral position is feasible in pigs through a transcatheter approach. This was possible through a smaller delivery system than previously reported. Additional studies are required to demonstrate long-term feasibility, durability, and heart function. [Copyright &y& Elsevier]

Abstract: Background and objective: Endovascular procedures for heart valve replacement provide an alternative to open surgery. It might be necessary to remove the native valve before implantation of a new valve mounted in a collapsible stent. The aim of this study was to evaluate the feasibility of using an Er:YAG laser for the resection of human calcified valves and to quantify this process. Materials and methods: A commercially available Er:YAG laser with a specially designed fiber coupling device and fiber tip was used to cut calcified aortic and mitral valve leaflets (n=12) in vitro. Light and electron microscopic analyses of the debris were performed. Results: Cutting velocities of up to 15.3mm per minute were achieved with an average of 7.67±4.28mm per minute. The cutting efficiency depended on the rate of tissue calcification. The debris particle size ranged from smaller than 10μm to 1mm. Conclusions: Calcified heart valves can be cut using an Er:YAG laser system in vitro. Nonetheless, cutting times were rather long considering a future in vivo use of this technique. [Copyright &y& Elsevier]

Abstract: Introduction: Percutaneous techniques to replace the pulmonary valve are emerging as an alternative to congenital cardiac surgical procedures. Promising experimental and early clinical results have been reported so far, focusing on technical feasibility and valved stent function. The present study aimed to describe the micropathology after experimental percutaneous valve replacement. Methods: Self-expanding nitinol stents carrying a valved bovine jugular vein were transfemorally implanted into the pulmonary position of nine sheep. After 3 months of survival, macro- and micropathological examinations were carried out using standard staining techniques and immunohistochemistry. Additionally, calcification characteristics were determined by X-ray examinations and von Kossa stainings. Results: Six of nine animals survived the 3-month study time with good angiographic and echocardiographic function. All valves were grossly functional at the time of explantation. Slight fibrous overgrowth was seen at the inflow portions of two valved stents. No cuspal perforations or intracuspal hematomas were observed. Light microscopy proved the absence of cellular inflammatory infiltrates in any tissue samples. The myocardium directly proximal to the stent appeared structurally normal without calcification. The overall structure of the native pulmonary artery was well preserved with few mineral deposits spread diffusely throughout the wall distal to the stent. Massive calcification appeared in the bovine jugular-vein wall together with increased numbers of T lymphocytes. Neither calcific deposits in the cusps nor extrinsic mineralization was noted. Conclusion: For the first time, micropathologic evaluation of percutaneously implanted heart valves is described. The results demonstrate that calcification of valved stents occurs in the wall portions without affecting the cusps. The cardiac structures in the vicinity had normal histology without inflammation. [Copyright &y& Elsevier]

Abstract: 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 1200μm in one case, and an average of 580±145μm 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. [Copyright &y& Elsevier]

Abstract: Objective: Valvuloplasty of the aortic valve is currently used in selected patients for severe calcified aortic valve disease, but clinical effectiveness is low and complication rate remains high. In this study, the total particle load after valvuloplasty and the embolization risk of calcific debris into the coronary arteries was analyzed in an in vitro model. Methods: Three highly calcified human aortic leaflets have been sutured into a porcine annulus (N =9). Both coronary arteries were separated and each was anastomized to a silicon line, which was drained off into a measuring beaker. Then valvuloplasty was performed (Thyshak II, 20mm, 1.5atm). After removal of the balloon, 100ml of sodium chloride solution irrigated the ascending aorta. After passing through the separated coronary arteries, the solution was filtered (filter size 0.45μm), dried, and the total amount of particles was analyzed microscopically. Results: Nine experiments were analyzed. After valvuloplasty, all hearts showed a median of 18 particles larger than 1mm in the coronary arteries (range 0–307). The amount of particles smaller than 1mm was 6574 (median, range 2207–14200). In five cases, coronary arteries were completely occluded by bulky particles. Conclusion: This study demonstrated a large amount of calcific particles after valvuloplasty with a consequently high risk for coronary embolic events in case of highly calcified aortic valves. In times of valvuloplasty rediscovering as part of transcatheter valve implantation, the risk of embolization should be taken into consideration and filtering techniques have to be developed. [Copyright &y& Elsevier]