AATS: American Association for Thoracic Surgery.
Watch the AATS Leadership Video
 
3D Geometry of the Mitral Valve Determines the Success of Secondary Chordal Cutting in Alleviating Ischemic Mitral Regurgitation
Muralidhar Padala1, Katherine L. Bell1, Vinod H. Thourani3, David H. Adams2, Ajit P. Yoganathan1; 1Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA; 2Mt.Sinai Hospital, New York, NY; 3Emory University, Atlanta, GA
READER COMMENTS
Objective: Mitral annuloplasty often fails in patients with dilated left ventricles due to ischemic heart disease or cardiomyopathies, resulting in recurrence of mitral regurgitation (MR). Sub-valvular repair using secondary chordal cutting (CT-cut) is proposed as a solution to prevent recurrent MR by relieving leaflet tethering. However, current clinical literature is divided on the efficacy of this technique with some studies supporting its efficacy while others challenging it. In this study, we sought to investigate if the 3D geometry of the mitral valve (ie, spatial location of the papillary muscles in the ventricle, and extent of leaflet tethering) impacts the outcomes of the chordal cutting technique.
Methods: Eight porcine mitral valves (N =8) of sizes 28 were studied in an in-vitro pulsatile left heart simulator at 120mm Hg peak transmitral pressure, 5L/min cardiac output at 70bpm. Each valve was first tested with its physiological geometry to obtain the baseline conditions. MR was induced by dilating the annulus (to size 34) and selectively displacing the PMs first by 10mm apically only, followed by 10mm apically, laterally & posteriorly. MR was repaired in both cases by implanting an annuloplasty ring (size 28) first and then by transecting the secondary chordae on the anterior leaflet. At each step, MR volume (ml/beat), and tenting area (mm2) were measured and compared to the baseline.
Results: At baseline conditions none of the valves had MR, but annular dilatation and PM displacement induced significant MR (Fig 1A). Annuloplasty alone decreased MR, but did not eliminate it completely at both PM locations (Fig 1A). CT-cut technique reduced residual MR to trace levels only when the PMs were apically displaced, but did not have a positive effect when the PMs were apically-laterally-posteriorly displaced from their physiological positions (Fig 1A). Tenting area was reduced to the baseline conditions after CT-cutting in the apical-displacement case but not in the apical-lateral-posterior displacement case (Fig 1B).
Conclusion: This study demonstrates that the location of the PMs and the extent of leaflet tethering impact the outcomes of the secondary chordal cutting subvalvular repair technique, explaining the variability seen in clinical studies. Therefore, pre-operative assessment of the 3D mitral valve geometry is imperative for appropriate patient selection for the procedure, optimal surgical planning and improved outcomes of this procedure.


Fig1A: depicts the MR volume before and after chordal cutting for the two PM positions; Fig 1B: depicts the reduction in tenting area with chordal cutting for the two PM positions;
Back to 2009 Annual Meeting
Back to Program Outline
Back to Main Program
Policies | Find a Surgeon | About | Contact
We Model Excellence
 Follow AATS on Facebook
Copyright © American Association for Thoracic Surgery. All rights reserved.
Read the Privacy Policy.
IMPORTANT REMINDER: The preceding information is intended only to provide
general guidance and not as a definitive basis for diagnosis or treatment in any particular case.
It is very important that you consult a doctor about any specific medical problem or question.