Intro4u2u

Ten years ago, Alfieri and colleagues from Milan introduced a simple and revolutionary method for mitral valve repair in patients with complex valve pathology requiring demanding surgical techniques for reconstruction or, when an unsuccessful result was expected, as in cases with prolapse of both leaflets, massive chordal elongation of the anterior leaflet, commissural lesions, endocarditis lesions, and leaflet prolapse associated with severe annular calcification (1). Initially, this still controversial operation was received with active criticism from those who believe that mitral valve anatomy should be respected and considered as a composite apparatus where every element (annulus, leaflets, chordae, papillary muscles and left ventricle) plays an important role in this complex valve mechanism. However, the “Alfieri stitch”, or more appropriately the “edge-to-edge” or “double orifice” technique, is gaining the attention of many surgeons who are now using this simple and innovative technique to extend the indications for mitral valve repair, after the satisfactory mid-term results and the stability of this method has been demonstrated (2). From the original paper in 1995, where Fucci et al.(1) reported using this technique in 12% of their mitral valve repairs, a few years later this group was performing the edge-to-edge plasty in 75% of cases (2).

Alfieri et al. (2) recommend a running 4-0 polypropylene suture to fix the free edges of the leaflets at the site of regurgitation, instead of a simple pledgeted supported stitch as the technique was initially reported. In patients with Barlow´s disease, this suture must plicate the leaflet redundancy to restore competence and prevent postoperative left ventricular outflow obstruction due to systolic anterior movement (SAM) of the anterior leaflet. This running suture also reduces the risk of rupture or tearing of the leaflets causing early failure, particularly in the presence of a friable leaflet, by adding two mattress sutures with pericardial pledgets to reinforce the repair. The major drawback is that suture length causes restrictive constraint of the leaflets movements. Long-term anticoagulation is not required with this operation, unless atrial fibrillation is present. Since most patients also receive a prosthetic annuloplasty ring, a 3-month anticoagulation is strongly recommended.

Since minimally invasive approach with the Heartport system is demanded by young patients, and robotic surgery is being performed in an increasing number of institutions, thus providing the opportunity for performing mitral valve repair percutaneously, the “edge-to-edge technique” is an attractive operation for surgeons, invasive cardiologists, and also for the industry which is trying to develop a device to staple the two mitral leaflets. Preliminary results and prospects for percutaneous approach were part of the program of the recent Cardiothoracic Techniques & Technologies meeting (9th Annual CTT Meeting 2003). However, this simple technique requires a concomitant annuloplasty to avoid repair failure and to reduce the risk of tissue degeneration; freedom from reoperation at 5 years in patients who underwent an annuloplasty procedure was 92 ± 3.4%, compared with 70 ± 15.0% in those without it (2). Localized fibrotic degeneration of the leaflets at the site of suture line was not reported but it should be expected, as with any fixed valve tissue. Votta et al. (5) has recently demonstrated that annular dilatation represents the most important influence on stress distribution in the region close to the suture, both in systole and diastole; the presence of an annuloplasty ring significantly reduces stresses acting on this critical area, as it was previously reported by Nielsen et al. (8) in an experimental model. Maximal stress was evidenced in marginal chordae inserted in the central region of the anterior leaflet, close to the suture line, as shown by a 3-D finite element model that simulated the stress pattern following the Alfieri´s operation. This elegant study also demonstrated that this technique produces a two fold increase in maximum stress with respect to the mechanics of a normal mitral valve. This computational analysis should be taken in consideration until long-term durability of this mitral reconstructive technique is established.

As Alfieri et al. (2) reported, the overall freedom from reoperation at 5 years was 90 ± 3.3%; significantly lower in patients with rheumatic disease (72 ± 14.5%) when compared with patients with degenerative disease (91 ± 3.7%). This finding is comparable to what is observed with every mitral reconstructive technique. Since rheumatic disease is frequently associated with relatively smaller effective orifices, this etiology is now considered a relative contraindication for the edge-to-edge operation. The cause of reoperation was recurrent severe mitral regurgitation (due, in most cases, or to leaflet prolapse, disruption of the suture), or severe hemolysis. Whether this technique should be used in cases of ischemic mitral disease, where geometric changes in the annulus, subvalvular apparatus and left ventricle are the causes of regurgitation, is still controversial (2), since the tethering effect may not be corrected with a central approximation of the leaflets.

A considerable reduction in the mitral valve effective orifice is the most important drawback with this procedure; however, no patient required reoperation for mitral valve stenosis in Alfieri´s experience (2). As Maisano et al. (4) have reported, the hemodynamic behavior of a double orifice mitral valve is not penalized by the new configuration of the valve after repair, with pressure drops and flow velocities across the leaflets similar to a single orifice valve. Timek et al. (7) have confirmed that the edge-to-edge mitral valve repair was not associated with substantial transvalvular obstruction during high flow conditions induced with dobutamine. However, a redundant subvalvular apparatus, as in Barlow´s disease, may decrease the pressure recovery within the left ventricle by generating vortexes, as these authors pointed out. Echo Doppler calculation of the maximum velocities is a consistent method for transvalvular pressure gradient estimation after “edge-to-edge” mitral valve repair.

Although long-term clinical results will be the ultimate test, a judicious use of this innovative and simple technique for complex mitral valve regurgitation, particularly in the degenerative disease, will prevent the mitral valve replacement in a significant number of patients. Furthermore, this operation will have a beneficial effect increasing the confidence of many surgeons and cardiologists and widening the indications of valve repair when a difficult mitral anatomy is present.