We present MINOTAUR, a novel technique to mitigate neo-LVOT obstruction (LVOTO) risk in valve-in-valve (VIV) transcatheter mitral valve replacement (TMVR). Our transvenous transseptal approach combines prior methods, and involves precise leaflet penetration using an electrified wire, followed by sequential balloon dilatation and implantation of balloon expandable prostheses through the modified mitral intraleaflet tract to achieve maximal leaflet splaying.  

Patient 1 is a 47yo with NYHA class IV medically refractory pulmonary oedema with right heart failure and pulmonary hypertension due to stenotic degeneration of a 27mm Mosaic prosthesis. Patient 2 is a 48yo with NYHA class III heart failure and pulmonary hypertension due to stenotic degeneration of a 27mm Magna Ease prosthesis. Both had cardiac CT predicting extreme neo-LVOTO risk and deemed prohibitive risk for conventional redo surgeries by Heart Team consensus. See figure 1. 

Procedures were performed via femoral venous access under general anaesthesia. Under TEE guidance mid to low-posterior transeptal punctures were made. Penetration of the anteromedial prosthetic mitral leaflet was achieved via an antegrade approach for case 1 and retrograde for case 2 with an Astato XS 40 300cm 0.014” wire with cautery on 100W pure-cut mode, delivered via a telescopic system outlined in figure 2. Following fluoroscopic and TEE confirmation of leaflet traversal, a 330 cm RG3 wire was exchanged via the microcatheter.  Over this newly created veno-atrio-ventricular rail through the penetrated prosthetic mitral leaflet, sequential ballooning with coronary balloons was performed to achieve leaflet perforation.  A 110 cm 5F pigtail catheter was then exchanged over the RG3 into the LV and further exchanged for a Safari2 guidewire. Further sequential ballooning was then performed through the penetrated leaflet with vascular balloons for inside-out leaflet annihilation (figure 3 and 4).  Edwards Sapien 3 transcatheter heart valves were delivered through the intra-leaflet tract and deployed under rapid ventricular pacing to achieve VIV TMVR to complete the leaflet modification.  There were no neurological or vascular complications and both patients had marked symptomatic and echocardiographic improvement (figure 5). Our findings suggest that MINOTAUR is a viable option for patients at high risk of neo-LVOTO from ViV TMVR who otherwise would have limited treatment options.  

MINOTAUR is a feasible minimally invasive transcatheter percutaneous technique for the modification of degenerative mitral bioprosthetic valves being managed with VIV TMVR to mitigate the risk of neo-LVOTO. Investigation of the technique in larger patient cohorts is warranted.