Correction of Ischemic Mitral Regurgitation

Carpentier classification of mitral regurgitation. (I) Normal leaflet motion. (II) Increased leaflet motion. (III) Restricted leaflet motion. (A) Diastolic and systolic restriction. (B) Systolic restriction. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

Intraoperative transesophageal echocardiography (TEE) is performed as conduits are being harvested. The anatomy of the valve and subvalvular apparatus is carefully assessed, and the mechanism of the MR is confirmed. A “normal” valvular and subvalvular apparatus characterizes ischemic MR. Most commonly, a central or posterior jet is noted, but careful study of the jet will reveal a larger jet arising from the P2/P3 region and a smaller jet comes from the anterolateral commissure. Our practice has evolved to the routine repair of 2+ or greater MR. If lesser degrees of MR are noted, we will pharmacologically increase the blood pressure to a mean of 90 to 100 mm Hg and then reassess the MR. If the MR increases to 2+ or greater, we repair the mitral valve. Most patients require concomitant coronary artery revascularization and mitral valve repair. A full median sternotomy is used. Standard aortic and bicaval cannulation is performed. We have found that vacuum-assisted venous drainage allows us to use smaller venous cannulae and still have a bloodless field. Normothermic bypass is established, and the heart is arrested with a combination of antegrade and retrograde cold blood–modified Buckberg cardioplegia (4°C). Distal vein or radial artery anastomoses are completed and then connected to the cardioplegia manifold. Cardioplegia is administered retrograde and down grafts at least every 15 minutes to maintain myocardial protection. Caval isolation is achieved, and a standard left atriotomy is performed after developing the interatrial groove. The atriotomy is extended under the superior vena cava and inferior vena cava. Placing traction on the caval tourniquets, which are subsequently attached to the operative drape, can facilitate additional exposure. Left-side pericardial well sutures are removed. We use a self-retaining mitral retractor for all cases. The table is rotated away from the surgeon. If the view is still inadequate, a sponge on a ring forceps can be placed on top of the heart to depress the medial commissure. A small, metal-tip basket suction is placed in the left superior pulmonary vein to scavenge blood returning through the pulmonary bed. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

Although intraoperative TEE is always performed, direct inspection of the mitral valve is necessary to confirm pathology. Cold saline solution is infused into the ventricle under pressure to demonstrate the leak. The valve and the subvavular apparatus are carefully studied. With type IIIb ischemic MR, typically the posteromedial papillary muscle is tethered and the annulus is asymmetrically deformed at the P3 region. Findings may be subtle depending on the amount of tethering present. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

We generally start placing nonpledgeted sutures of 2-0 braided suture in the middle of the posterior annulus. Traction on these sutures sets up exposure of the entire valve. Generally, 8 sutures are placed in the posterior annulus and 6 sutures are placed in the anterior annulus. We size the ring to the surface area of the anterior leaflet. Unlike myxomatous disease, the leaflets are not elongated. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

The 26-mm or 28-mm Carpentier-McCarthy-Adams IMR ETLogix ring is typically used. Sutures are passed through the ring with appropriate spacing, and then the ring is lowered into the annulus after moistening the sutures with saline solution. The ring is sized to the anterior leaflet. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

We usually tie the sutures along the anterior annulus first and tie the sutures over P3 last to allow for as much remodeling as possible. The left atrial appendage is excluded with an over and over or purse string stitch of 4-0 polypropolene. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

The ventricle is pressurized with cold saline solution to test for a residual leak. Occasionally, an edge-to-edge repair with 4-0 braided suture may be required if a residual leak is noted, usually at the medial commissure. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

De-airing maneuvers are performed as the atrium is closed. The left internal mammary artery to left anterior descending coronary artery anastomosis is constructed, and proximal anastomoses are fashioned (Fig 8). Further de-airing maneuvers are performed. The cross clamp is released with flow diminished and the aortic vent on suction. If indicated, left ventricular reconstruction (modified Dor procedure) and tricuspid repair are performed while the heart reperfuses. After weaning from bypass, TEE is used to assess the adequacy of repair. MR greater that 1+ is not accepted and is dealt with by additional repair or choral sparing mitral valve replacement. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

For mitral valve replacement, the exposure and setup are the same as for mitral valve repair. The anterior leaflet usually is split at its midpoint. The midportion of the anterior leaflet can be removed if it is bulky, but this is rare in ischemic MR. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

Pledgetted 2-0 braided sutures are placed with the pledgets on the atrial side. Sutures are placed so as to incorporate annulus and the leaflet, and act to plicate the chords to the annulus. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

A dental mirror is useful to determine the midpoint of the left ventricular outflow tract. The landmark for this is the left and noncoronary commissural post of the aortic valve. The struts of the bioprosthesis are oriented so that they straddle the outflow tract and do not impinge on it. This is accomplished by passing the sutures that lie in the middle of the left ventricular outflow tract between the struts on the valve. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

The bioprosthetic valve (bovine Carpentier-Edwards PERIMOUNT pericardial bioprosthesis [Edwards Lifesciences, Irvine, CA]) is carefully seated. Sutures are tied first at each of the struts, and then over the circumference of the valve. The holder is not removed until all sutures are tied. The atrium is closed and de-aired in the standard fashion. We avoid lifting the heart if a valve has been placed, especially in frail elderly patients. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)

Completed valve replacement with struts straddling the left ventricular outflow tract. Note the position of the black marks on the valve sewing ring at 1230 and 0800 that mark the position of the valve struts and aid in orientation of the valve. (Color version of figure is available online at http://www.us.elsevierhealth.com/optechstcvs/.)