Quantitative Imaging Assessment of an Alternative Approach to Surgical Mitral Valve Leaflet Resection: An Acute Porcine Study
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This study reports the initial in vivo use of a combined radiofrequency ablation and cryo-anchoring (RFC) catheter as an alternative to surgical mitral valve (MV) leaflet resection. Radiofrequency ablation thermally shrinks enlarged collagenous tissues, providing an alternative to leaflet resection, and cryo-anchoring provides reversible attachment of a catheter to freely mobile MV leaflets. Excised porcine MVs (n = 9) were tested in a left heart flow simulator to establish treatment efficacy criteria. Resected leaflet area was quantified by tracking markers on the leaflet surface, and leaflet length reductions were directly measured on echocardiography. Leaflet area decreased by 38 ± 2.7%, and leaflet length decreased by 9.2 ± 1.8% following RFC catheter treatment. The RFC catheter was then tested acutely in healthy pigs (n = 5) under epicardial echocardiographic guidance, open-chest without cardiopulmonary bypass, using mid-ventricular free wall access. Leaflet length was quantified using echocardiography. Quantitative assessment of MV leaflet length revealed that leaflet resection was successful in 4 of 5 pigs, with a leaflet length reduction of 13.3 ± 4.6%. Histological, mechanical, and gross pathological findings also confirmed that RFC catheter treatment was efficacious. The RFC catheter significantly reduces MV leaflet size in an acute animal model, providing a possible percutaneous alternative to surgical leaflet resection.
KeywordsPercutaneous mitral valve repair Mitral regurgitation Radiofrequency ablation Cryo-anchoring
Radiofrequency ablation and cryo-anchoring
The authors would like to acknowledge Dr. Michael Miga for use of the ultrasound machine in the ex vivo experiments.
This work was funded by the Wallace H. Coulter Foundation and the American Heart Association (13PRE16340018).
Cryo-anchoring demonstrated on the AL and PL, separately, in the in vivo study. Note the free motion of the leaflets not targeted for cryo-anchoring. Supplementary material 3 (MOV 4245 kb)
AL motion before and after treatment with the RFC catheter. Also shown are the corresponding leaflet length measurements. Supplementary material 4 (MOV 4598 kb)
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