Mitral Valve Hemodynamics Following Repair of Acute Posterior Leaflet Prolapse: Quadrangular Resection vs. Triangular Resection vs. Neo-chordoplasty
Muralidhar Padala1, Laura R. Croft1, Scott Powell1, Vinod H. Thourani2, Ajit P. Yoganathan1, David H. Adams3; 1Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA; 2Emory University, Atlanta, GA; 3Mt.Sinai School of Medicine, New York, NY
Comment on this Abstract
Objective: Fibro-elastic deficiency is a dominant form of degenerative mitral valve disease, and may present with acute chordal rupture, minimal leaflet distension and severe segmental prolapse. In this study, we compare the hemodynamics and functional efficacy of three techniques used for degenerative mitral valve repair: quadrangular resection with annular compression, limited triangular resection and Gortex neo-chordoplasty.
Methods: Twenty-four porcine mitral valves (size 36mm) were evaluated in an in-vitro left heart simulator prior to surgical manipulation (Control). Severe mitral regurgitation (MR) was created in these valves by transecting marginal chordae resulting in severe P2 prolapse. MR was corrected using 3 surgical techniques: quadrangular resection with compression (n=8), limited triangular resection (n=8), and chordal replacement without leaflet resection (n=8). A custom rigid annuloplasty ring was used to reinforce the repairs. All valves were tested at 120mmHg peak trans-mitral pressure, 5L/min cardiac output, and a heart rate of 70 beats/min. Mitral regurgitant fraction, peak systolic leaflet coaptation length (mm), and the posterior leaflet mobility index (mm) were measured. P<0.05 was considered statistically significant.
Results: Transection of the marginal chordae resulted in severe P2 prolapse and significant mitral regurgitation (19.7±17.7 ml/beat, Fig A).The mitral regurgitant volume was significantly decreased using all 3 surgical approaches (Quadrangular: 2.6±1.6 ml/beat, Triangular: 3.2±4.4 ml/beat, and Neochordae: 4.9±5.0 ml/beat, Fig A).While the Quadrangular (9.8±0.9mm) group had significantly smaller leaflet coaptation lengths compared to the Control valves (12.5± 0.7mm), the Triangular (11.3±1mm)and Neochordae groups(13.4±1mm) restored better peak systolic coaptation (Fig B).Posterior leaflet mobility was reduced in the Quadrangular resection (7.0±2.1mm) group, while it was higher in the Triangular (11.8±2.1 mm) and Neochordae (17.2±1.9 mm) groups, when compared to the Control valves (14.3±1.6mm) (Fig C).
Conclusion: All three reparative techniques evaluated proved successful in treating mitral regurgitation. However, triangular resection and neo-chordoplasty were associated with better coaptation length and preserved posterior leaflet mobility in this experimental model of fibroelastic deficiency with acute leaflet prolapse and minimal leaflet distension.
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