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Background: In recent years, some experimental and clinical studies on transcatheter aortic valve implantation (TAVI) have been conducted. TAVI is indicated in patients with calcified pure or predominant aortic stenosis. The risk of this technique is still high. Aortic valved stent implantation above the coronary ostia might avoid blocking the coronary ostia., Methods and Results: Twenty healthy dogs were selected to establish a canine model of acute aortic valve rupture. The dogs were randomly divided into 2 groups: the rupture model group without any treatment and the valved stent group with percutaneous valved stent implantation above the coronary ostia. The 2 groups of animals were followed up for 3 months. Echocardiography and other tests were performed to assess aortic regurgitation and ventricular function. Acute aortic valve rupture models were successfully established in 16 of 20 dogs. In the rupture model group, the mean aortic regurgitation was 6.8 ± 1.9 ml/s; only 3 of 8 animals survived for 3 months. In the valved stent group, the mean aortic regurgitation was 7.0 ± 2.1 ml/s; valved stents were successfully implanted in 8 animals. Instant post-implantation anatomy showed that the stents were located appropriately. Seven dogs survived for 3 months., Conclusions: Percutaneous valved stent implantation above the coronary ostia is feasible and effective as a transitional treatment for acute aortic valve rupture.

Background: Pulmonary regurgitation leads to progressive right ventricular dysfunction, susceptibility to arrhythmias, and sudden cardiac death. Percutaneous valve replacement has been developed in recent years, providing patients with an alternative option. Percutaneous pulmonary valve replacement has been recently introduced into clinical practice. The goal of this study was to evaluate the feasibility of percutaneous valve stent insertion to correct the pulmonary regurgitation in sheep using a cup-shaped valve stent., Methods: Pulmonary regurgitation was created by percutaneous cylindrical stent insertion in native pulmonary annulus of 8 sheep. One month after the initial procedure, the sheep with previous cylindrical stent implanted underwent the same implantation procedure of pulmonary valve stent. The valve stent consisted of a cup-shaped stent and pericardial valves. Hemodynamic assessments of the bioprosthetic pulmonary valve were obtained by echocardiography at immediately post-implant and at 2 months follow up., Results: Successful transcatheter cylindrical stent insertion was performed in 7 sheep but failed in 1 sheep because the cylindrical stent was released to right ventricle outflow tract. After one month the 7 sheep with pulmonary regurgitation underwent valve stent implantation successfully. Echocardiography confirmed the stents were in desired position during the follow-up. No evidence of pulmonary valve insufficiency occurred in any animals. Echocardiography showed all heart function markers were normal., Conclusions: Percutaneous cylindrical stent insertion to induce significant pulmonary regurgitation in sheep was feasible, simple and reproducible. Percutaneous pulmonary valve stent implantation can reduce pulmonary regurgitation in a sheep model. Further development of animal model and clinical trials are warranted.

Background: Various percutaneous valve replacement approaches have been reported in animals to replace the aortic and pulmonary valve. To broaden the indications of percutaneous approach to atrioventricular valves replacement, we developed a novel valved stent and evaluated the feasibility and safety of percutaneous implantation of the device in the tricuspid position., Materials and Methods: A unidirectional semilunar valve of porcine pericardium was sutured to a valvular ring. Then the ring with pericardial valve was mounted on a double-edge nitinol stent to construct the tricuspid valved stent. Transcatheter tricuspid valved stent implantation was performed on 10 healthy sheep. These sheep were followed up shortly after procedure with echocardiography evaluation and 64-slice CT imaging examination during the periodical follow-up at 1 mo and at 6 mo post-implantation. Additionally, two sheep were sacrificed after the procedure for anatomic and histological evaluation one at 1 h and the other at 1 mo, respectively., Results: Percutaneous valve implantation was successful in eight of 10 sheep. Two sheep died during the procedure due to migration of stent and fatal arrhythmia. The pressure of right heart did not significantly change after the procedure. Further echocardiography and imaging confirmed the stents were in desired position during the follow-up. The remaining six sheep with normal valvular and cardiac functionality survived for 6 mo after implantation., Conclusions: The tricuspid stent with a valvular ring and pericardial valve can be implanted in tricuspid annulus percutaneous. The double-edge stent could substitute the native tricuspid valve chronically., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

Objective: Percutaneous pulmonary valve replacement has been recently introduced into clinical practice. Patients with transcatheter pulmonary valve replacement will definitely face the problems of valve degeneration. In addition to surgical re-replacement of the degenerated bioprosthetic valves, we studied the replacement of degenerated bioprosthetic valves with transcatheter reimplantation of stent-mounted pulmonary valves., Methods: Percutaneous pulmonary valve replacement was first performed in 6 sheep used a homemade valved stent. Two months after the initial procedure, the 6 sheep previously implanted with a valved stent underwent the same implantation procedure of a pulmonary valved stent. Hemodynamic assessment of the bioprosthetic pulmonary valve was obtained by echocardiography immediately post-implant and at 2 months follow-up., Results: All 6 sheep had successful transcatheter stent-mounted pulmonary valve replacement in the first experiment. After 2 months, reimplantation was successful in 5 sheep but failed in 1 sheep because the first valved stent was pushed to the bifurcation of the pulmonary artery by the delivery sheath. Echocardiography confirmed the stents were in the desired position during the follow-up. The remaining 5 sheep with normal valvular and cardiac functionality survived for 3 months after implantation., Conclusion: Transcatheter stent-mounted bioprosthetic pulmonary valve reimplantation is feasible in an animal model and more convenient than open chest reimplantation.