Mitral ring annuloplasty relieves tension of the secondary but not primary chordae tendineae in the anterior mitral leaflet.
OBJECTIVE
Mitral ring annuloplasty is routinely applied as an adjunct procedure in reconstructive surgery on the mitral valve leaflets or chordae tendineae. It is assumed that mitral ring annuloplasty relieves tensile stress on the repaired valve tissue and thereby improves the durability of the procedure, but the indication is disputable. We sought to study the effect of mitral ring annuloplasty on the tension of the primary and secondary chordae tendineae of the anterior mitral valve leaflet in vivo.


METHODS
In 17 adult pigs miniature chordal force transducers were sutured to the 2 major fixing primary chordae and the 2 strut secondary chordae of the anterior leaflet. Baseline measurements were accomplished. After randomization, one group (n = 10) underwent a mitral ring annuloplasty (Carpentier-Edwards Classic, 28 mm; Edwards Lifesciences, Irvine, Calif), and the second group (n = 7) served as controls and underwent a sham operation. Simultaneous recordings of chordae tendineae tension and hemodynamics and echocardiographic assessment of anterior leaflet occlusion area were acquired at baseline and after the mitral ring annuloplasty/sham operation.


RESULTS
Mitral ring annuloplasty caused a significant reduction of the anterior leaflet occlusion area (1.85 ± 0.16 vs 4.63 ± 0.37 cm(2)) and the tension of the secondary chordae (0.33 ± 0.06 vs 0.67 ± 0.12 N) but did not affect the tension of the primary chordae (0.24 ± 0.07 vs 0.17 ± 0.06 N). The sham procedure had no effect on these variables.


CONCLUSIONS
In normal porcine hearts mitral ring annuloplasty primarily relieves stress on the anterior leaflet belly rather than the leading edge. Mitral ring annuloplasty might therefore protect repairs of the central portion of the anterior leaflet and secondary chordae but not repairs that solely involve the anterior leaflet's leading edge and adjacent chordae.
Nielsen
Sten Lyager
SL
Department of Cardiothoracic and Vascular Surgery and the Institute of Experimental Clinical Research, Aarhus University Hospital-Skejby, Aarhus, Denmark. lyager@ki.au.dk
Lomholt
Mads
M
Johansen
Peter
P
Hansen
Soeren B
SB
Andersen
Niels Trolle
NT
Hasenkam
John Michael
JM
D000818:Animals; D001696:Biomechanical Phenomena; D002815:Chordae Tendineae / Q000000981:diagnostic imaging / Q000601:surgery*; D018618:Echocardiography, Doppler, Color; D004867:Equipment Design; D019918:Heart Valve Prosthesis Implantation; D006439:Hemodynamics; D008904:Miniaturization; D008943:Mitral Valve / Q000000981:diagnostic imaging / Q000601:surgery*; D058386:Mitral Valve Annuloplasty; D013314:Stress, Mechanical; D013318:Stroke Volume; D013552:Swine; D014160:Transducers, Pressure; D016277:Ventricular Function, Left