Tension measurement of artificial chordae tendinae implanted between the anterior mitral valve leaflet and the left ventricular apex: An in vitro study

OBJECTIVE: A newly developed surgical technique allows implantation of artificial chordae tendinae between a mitral valve leaflet and the left ventricular (LV) apex in a closed-chest, off-pump mitral valve repair operation. However, this orientation causes tension vectors on the mitral valve leaflet in a different direction than those of native chordae. The purpose of this study was to investigate the relationship between systolic LV pressure and the tension of artificial chordae secured at the ventricular apex to assess if the altered tension vectors on the mitral leaflet resulted in excessive stress on the chordae/leaflet system. METHODS: Freshly harvested porcine mitral valves were suspended in a mechanical LV simulator. Two 5-0 Gore-Tex sutures were secured to the free edge of the middle scallop of the anterior leaflet adjacent to the insertion point of two major native chordae. The native chordae were then cut. A simulator pump was activated at different pressure levels, and the tension of the artificial chordae was measured with a digital tensiometer during several cardiac cycles. RESULTS: The numerical relationship between chordal tension (in Newtons, N) and LV pressure (in mm Hg/100) averaged at 0.8 (range 0.6-1.05). This tension/pressure relationship was similar in order of magnitude and range to that measured in native chordae in previously published studies. CONCLUSIONS: In this in vitro model, orienting artificial chordae in a direction mimicking implantation between the valve and the LV apex does not result in excessive tension stress on either the chordae or the mitral leaflet.