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Annals of Biomedical Engineering

, Volume 44, Issue 7, pp 2240–2250 | Cite as

Quantitative Imaging Assessment of an Alternative Approach to Surgical Mitral Valve Leaflet Resection: An Acute Porcine Study

  • Steven M. Boronyak
  • Joseph L. Fredi
  • Michael N. Young
  • Douglas M. Dumont
  • Phillip E. Williams
  • Brett C. Byram
  • W. David MerrymanEmail author
Article
  • 258 Downloads

Abstract

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.

Keywords

Percutaneous mitral valve repair Mitral regurgitation Radiofrequency ablation Cryo-anchoring 

Abbreviations

MR

Mitral regurgitation

MV

Mitral valve

RF

Radiofrequency ablation

RFC

Radiofrequency ablation and cryo-anchoring

PM

Papillary muscle

AL

Anterior leaflet

PL

Posterior leaflet

Notes

Acknowledgments

The authors would like to acknowledge Dr. Michael Miga for use of the ultrasound machine in the ex vivo experiments.

Funding Sources

This work was funded by the Wallace H. Coulter Foundation and the American Heart Association (13PRE16340018).

Disclosures

None.

Supplementary material

10439_2015_1494_MOESM1_ESM.mov (4.7 mb)
Video 1 Cryo-anchoring shown in multiple leaflet locations on an excised MV, demonstrated in the left heart flow simulator. Also shown is an excised MV in the prolapse model and after treatment with the RFC catheter. MV leaflet size is significantly reduced following RFC catheter treatment. Supplementary material 1 (MOV 4823 kb)
10439_2015_1494_MOESM2_ESM.mov (1018 kb)
Video 2 Echocardiographic examination of excised MV leaflets at baseline, in the prolapse model, and after treatment with the RFC catheter. Supplementary material 2 (MOV 1018 kb)
Video 3

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)

Video 4

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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Copyright information

© Biomedical Engineering Society 2015

Authors and Affiliations

  • Steven M. Boronyak
    • 1
  • Joseph L. Fredi
    • 2
  • Michael N. Young
    • 2
  • Douglas M. Dumont
    • 1
  • Phillip E. Williams
    • 3
  • Brett C. Byram
    • 1
  • W. David Merryman
    • 1
    Email author
  1. 1.Department of Biomedical EngineeringVanderbilt UniversityNashvilleUSA
  2. 2.Division of Cardiovascular Medicine, Department of MedicineVanderbilt University Medical CenterNashvilleUSA
  3. 3.Division of Surgical Research, Department of SurgeryVanderbilt University Medical CenterNashvilleUSA

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