Mitral valved stent implantation

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 271 s and blood loss from 65 to 245 cc. 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, 6 h and 1 week were 1.9 + or - 0.9 mmHg, 3.5 + or - 1.6 mmHg, 4.1 + or - 02.3 mmHg and 1.4 + or - 01.3 mmHg, 1.5 + or - 0.7 mmHg 1.9 + or - 0.7 mmHg, 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.