Stentless Xenograft Aortic Valve Replacement: Subcoronary insertion of the Toronto SPV valve

A technique for the subcoronary implantation technique of the Toronto SPV is described.

Incision

A full median sternotomy or upper hemisternotomy may be used. The upper hemisternotomy extends from the sternal notch to the level of the fourth intercostal space. At the inferior aspect of the upper hemisternotomy, the sternum can be partially or fully transected (Figure 1).

This incision permits adequate visualization of the cardiac structures to allow central cannulation with standard equipment (Figure 2).

Cardiopulmonary Bypass

Transesophageal echocardiography (TEE) is employed. A single two-stage venous cannula is placed in the right atrial appendage. The arterial cannula is placed in the distal ascending aorta. Both cannulas are connected to the cardiopulmonary bypass circuit. A retrograde cardioplegia cannula is inserted into the coronary sinus through a stab incision in the right atrium. The antegrade cardioplegia cannula is placed in the proximal ascending aorta. The right superior pulmonary vein is used for placement of the left ventricular vent. Dissection of the ascending aorta away from the pulmonary artery is performed. Cardiopulmonary bypass is established, a crossclamp is applied to the ascending aorta for administration of antegrade and retrograde cold blood cardioplegia.

Replacement Technique

The aorta is opened transversely. It is essential to make this incision at least 1 cm above the sinotubular ridge. If the aorta is opened too close to the sinotubular ridge the valve posts will extend beyond the aortotomy, making proper commissural suspension difficult. The ascending aorta is completely transected (Figure 3).

Exposure is obtained by elevating the valve annulus with sutures at each commissure and pledgeted 4-0 polypropylene sutures in the right and non-coronary cusps (Figure 4).

The native aortic valve is excised. The aortic annulus and aortic wall of the distal suture line are thoroughly debrided. The diameters of the annulus and sinotubular junction are measured. The size of the replacement valve is the larger of these two measured diameters as long as the difference in the measured diameters is less than 10%. Undersizing will result in valvular incompetence. If the difference in measured diameters is > 10%, consider using a porcine stentless or homograft as a root replacement, or a stented valve.

The muscular portion of the stentless xenograft valve (porcine right cusp) should be aligned with the non-coronary cusp region. The proximal (lower) suture line is placed in the sub-annular position with interrupted 4-0 Ticron sutures or a running 4-0 polypropylene suture. We use the interrupted technique (Figure 5).

The lower suture line is placed in the sub-annular position as a single horizontal plane (Figure 6).

After tying the proximal suture line, each commissural post of the bioprosthesis is held in place with a single horizontal mattress 4-0 polypropylene suture. We do not tie these stay sutures until later. This maneuver ensures proper positioning of the commissural posts to achieve excellent coaptation of the aortic cusps and avoids occlusion of the coronary ostia. (Figure 7).

The distal suture line is a running 4-0 polypropylene suture that extends from the nadir of each cusp outward to the tip of each commissural post. It is this distal suture line that bears the stress of the valve closure. Care is taken to avoid obstruction of the coronary ostia. A full thickness of aortic wall is sutured to the bioprosthetic valve to prevent paravalvular leak. The aortic wall is lifted and kept on tension and the valve is pushed down while placing this suture line. This positions the valve to rest smoothly and firmly against the aortic wall, preventing gaps once the aorta is distended with blood (Figure 8).

The aortotomy is closed with two rows of a running 4-0 polypropylene suture (Figure 9).

De-airing is performed followed by removal of the aortic crossclamp. The patient is gradually wean off cardiopulmonary bypass, then decannulation is effected. Mean aortic transvavular gradient and coaptation of aortic cusps are documented with TEE. Atrial and ventricular wires are placed. After hemostasis is achieved, the sternum, fascia and skin are closed.