Mitral valve hemodynamics after repair of acute posterior leaflet prolapse: quadrangular resection versus triangular resection versus neochordoplasty

Abstract

Objective: Leaflet prolapse resulting from acute chordal rupture is one presentation of fibroelastic deficiency that is associated with minimal leaflet changes in the prolapsing segment. Minimizing resection and preserving leaflet tissue may be an optimal surgical strategy. We examined the importance of the leaflet preservation concept by comparing resective and nonresective surgical procedures in practice today.

Methods: Eight porcine mitral valves were evaluated in an in vitro heart simulator before surgical manipulation. Mitral regurgitation was created in these valves by transecting the posterior marginal chordae resulting in severe P2 prolapse. After confirmation of mitral regurgiation via regurgitant flow measurement (mL/beat), regurgitation was corrected by three repairs: neochordoplasty with polytetrafluoroethylene sutures (Gore-Tex; W. L. Gore & Associates, Inc, Flagstaff, Ariz), triangular resection, and quadrangular resection with annular compression. Postrepair valve hemodynamics were quantified under pulsatile conditions of 120 mm Hg peak transmitral pressure and 5 L/min cardiac output at 70 beats/min. Furthermore, hemodynamic, geometric, and echocardiographic indices were measured.

Results: Transecting the marginal chordae resulted in severe P2 prolapse and significant mitral regurgiation (19.3 +/- 4.3 mL/beat). Regurgitant volume was significantly reduced after any of the three surgical approaches (quadrangular, 4.38 +/- 1.6 mL/beat; triangular, 2.56 +/- 1.0 mL/beat; neochordal, 2.86 +/- 1.24 mL/beat). In comparison with the baseline normal valves, leaflet coaptation length and posterior leaflet mobility were significantly reduced in the quadrangular resection group, whereas they were partially restored in the triangular resection and fully preserved in the neochordoplasty group.

Conclusions: Although the three repair procedures are hemodynamically comparable, valve function and leaflet kinematics were significantly better after a nonresection or limited resective correction of leaflet prolapse in this experimental model of acute chordal rupture with otherwise normal leaflet geometry.

FIGURE 1

A, Schematic of the in vitro left heart simulator with a native porcine mitral valve. B, Atrial view of the mitral valve showing the anterior and the posterior leaflets. C, Ventricular view of the valve showing the chordae tendineae and the papillary muscles.

FIGURE 2

A, The top left image is a 2-dimensional echocardiograph that shows the prolapsing P2 scallop of the posterior leaflet resulting from chordal transection, and the bottom left image is a 3-dimensional reconstruction of the prolapsing leaflet as seen from the left atrium. The 3-dimensional reconstruction clearly shows the leaflet prolapse and the loss of leaflet coaptation. B, The 3-dimensional eccentric regurgitation jet recorded by 3-dimensional echocardiography from the top view and isometric views. A regurgitation jet directed toward the anterior annulus can be clearly seen with the posterior leaflet prolapse.

FIGURE 3

A, Sequential steps to replace the ruptured posterior chordae tendineae with loops of 5-0 ePTFE sutures. B, Sequential steps to perform triangular resection and approximation of the resected region. C, Protocol to perform quadrangular resection and annular plication with a compression stitch.

FIGURE 4

A, Variation in regurgitation volume per heart beat for the control, prolapse, and the three repair procedures. B, Variation in peak systolic leaflet coaptation length between the different experimental conditions.

FIGURE 5

Geometric endpoints measured from 2-dimensional echocardiographs to quantify leaflet mobility.