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DOI: 10.1055/s-0036-1571535
Off-pump Transfemoral Pulmonary Polycarbonate Urethane Valved Stent Implantation in Sheep: One-, Three- and Six- Month Follow-up
Objectives: Catheter-based heart valve implantation is getting an accepted treatment option in selected patient groups and special indications. In this study a novel low-profile polycarbonate urethane valved stent transfemorally implanted in sheep is evaluated.
Methods: Percutaneous off-pump transfemoral implantation into the pulmonary valve position was evaluated in 12 sheep (35 - 51 kg). Four animals were followed up for 1 month, four sheep for up to 3 months and four up to six months.
The polycarbonate urethane (PU) tricuspid valve leaflets were sewn into a conical self-expanding nitinol stent frame. The implantation procedure is catheter based (14 Fr). Implantation was fluoroscopically guided. Post implantation and after one, three and six month's transthoracic echocardiography was performed. Angiography was re-performed at the end of the study. Histological analysis focused on inflammation and calcification was performed.
Results: Implantation was successful in all animals as demonstrated in fluoroscopy and echocardiography. The native pulmonary valve annulus was 19.3 ± 2.2 mm (range 17 - 23 mm). During the deployment procedure, rhythm disturbances occurred in all animals. Follow up echocardiography showed good result without any paravalvular leakages and low transvalvular gradients. The mean systolic internal diameter of the valved nitinol stents was 16.5 ± 1.5 mm and the mean internal diastolic diameter was 19.6 ± 0.7 mm. The peak-to-peak gradient across the valved stent was 1.94 ± 1.92 mm Hg initially, and 1.5 ± 0.82 mm Hg at six months follow-up.
Postmortem investigation demonstrated macroscopically low calcification with good opening and closure characteristics. Histological analysis showed calcification and signs of inflammation as a rare complication in a small number.
Conclusion: Good result after 6 months of pulmonary polycarbonate urethane valved stent implantation in sheep was demonstrated. The very small delivery system of 14 Fr. will be an alternative, particularly in children.