gms | German Medical Science

Introduction: Minimally invasive off-pump procedures become more important in cardiac valve surgery. In focus of research is the implantation of valved stents into mitral position. In this study we outline the experimental experiences with our most recent stent design implanted in a porcine model, guided by Real Time 3D transesophageal echocradiography (TEE).

Material and methods: Transapical mitral valved stent implantation in the beating heart was performed in eleven pigs under 3D TEE and 2D TEE evaluation. The nitinol self expandable stents consist of a tube shaped ventricular element carrying a bioprosthetic valve, a crownshaped atrial element and an apical fixation system. A full TEE examination was conducted before and after implantation as well as a follow-up at one month (n= 7) to assess valved stent position and performance.

Results: 3D TEE proved beneficial during the implant procedure as well as for the detection and analysis of paravalvular leakages (PVL), whereas for the estimation of stent function 2D TEE evaluation was indispensable. Implantation was successful in nine of eleven pigs, two pigs died of ventricular fibrillation during the procedure. Seven Pigs were followed up for one month. Dependable spatial visualization of the left heart, the mitral apparatus, the delivery system and the valved stent was provided with 3D TEE (Figure 1 [Fig. 1]). After successful implantation echocardiographic evaluation showed mild mitral regurgitation (MR) in four cases and none in five cases, no PVLs were detected. After one month three animals suffered from mild MR, mild PVLs were found in two, two pigs showed neither. No clinical significant gradients across the valve and a normal ejection fraction were recorded (Table 1 [Tab. 1]).

Conclusion: Transapical mitral valved stent implantation is reproducably feasable under 3D TEE guidance. The latter supplemented common 2D TEE in the evaluation of stent performance. RT 3D TEE guided procedures could pose as a good alternative to angiographically guided interventions.