Reconstruction of the Bicuspid Aortic Valve

In 40% of patients, we have found pathologic dilation of the ascending aorta involving the root. Preoperative angiograms in these patients clearly delineate the dilation of both aorta and root; there is no sinutubular narrowing. These patients clearly need an operation that includes root replacement, and we have had excellent results applying modified root remodeling to this setting (A).

There is a considerable proportion of individuals with a BAV (in our experience 25 to 30%) that have no or only mild dilation of the root, and the maximum dilation of the aorta is above the sinutubular junction. Angiograms or echocardiography images typically show sinutubular narrowing in these patients. The operation must address both aortic regurgitation and aortic dilation, but probably root replacement is not necessary. We have chosen separate valve repair plus supracommissural aortic replacement for this setting (B).

Although the current discussion gives the impression that the aorta is often or always abnormal in the presence of bicuspid aortic valve anatomy, clinical data indicate that this is not correct. We have seen normal aortic configuration and normal diameters in 30 to 40% of patients with a BAV. In these, the operative procedure should remain confined to the valve, and based on current evidence, there is no need to perform aortic replacement (C).

The anatomy of a BAV includes different variations. In approximately 95% of regurgitant valves, we have seen a consistent morphology with fusion of rudimentary right and left coronary cusps. The noncoronary cusp is unusually large and high. The space between its two commissures takes up approximately 45% of the circumference of the root as compared with the normal 33%. Almost always there is a rudimentary commissure between the two fused cusps, which is lower in height than the commissures of the noncoronary cusp. The thickened tissue of the rudimentary commissure extends as a median raphe onto the central portion of the fused or “conjoint” cusp in more than 80%. Cusp tissue and free margins are frequently thickened, but the pliability of the cusp tissue is preserved.

Different patterns are rare. Congenital fusion may be present between right and noncoronary cusps, which we have seen in 1%, or fusion may be present between left and noncoronary (1%). The remaining cusp is always larger than normal. We have observed true symmetry of a BAV in 2% of individuals, in which there was no third (rudimentary) commissure, and each of the two cusps took up 50% of the circumference.

Exposure is an important prerequisite for successful repair, even more than for valve replacement. A horizontal incision approximately 1 cm above the commissures (sinutubular narrowing) gives good exposure and avoids distortion of root geometry. We place three stay sutures in the area of the commissures and tie them under tension to the skin of the patient, carefully maintaining the direction of each commissure. The remainder of the ascending aorta is kept out of the way with another stay suture.

The first step of repair is assessment of cusp geometry. Prolapse is almost always present on the fused cusp, but also the noncoronary cusp may be deformed and prolapsing after long-standing regurgitation. Because the valve is only seen from its outflow and cannot be inspected in a filled condition (unlike the mitral valve), the relationship between free margin and aortic insertion serves as the best indicator of prolapse. It is helpful to assess the noncoronary cusp first; once this is correct, its free margin serves as reference for repair of the fused cusp.

The free margin of the noncoronary cusp is held with a forceps and pushed into the left ventricular outflow tract. With the cusp in an open position, the free margin should be at least 5 mm higher than its aortic insertion. In the last 2 years we have employed a caliper to provide a more quantifiable indicator of prolapse.⁷ With the cusp in a closed position, the height difference between aortic insertion and free margin can be measured in millimeters, and a height difference of ≥10 mm has reproducibly resulted in good configuration of the noncoronary cusp.

If prolapse of the noncoronary cusp is present, it can easily be corrected using simple plication sutures (Prolene 5-0 or 6-0) in the central part of the free margin. After each suture, the geometric result is reassessed. If necessary, additional sutures are placed. Sutures can also be removed if prolapse has been overcorrected. It is important not to overcorrect to avoid restrictive cusp dysfunction, which will also lead to regurgitation.

Once normal geometry of the noncoronary cusp has been confirmed or achieved, the relative geometry of the fused cusp is determined. The most reproducible approach has been the use of stay sutures on the free margins. One commissure is held with a forceps, corresponding lengths of both cusps are fixed with a 6-0 suture, ideally placed close to the center of the noncoronary cusp (A). The same procedure is repeated on the other half of the cusp margins. Both stay sutures are placed on radial tension, and the difference in length of the free cusp margins becomes readily visible (B).

The technique of repair depends on the morphology of the fused cusp. If the fused cusp is relatively thin and pliable, simple plication of its free margin will be sufficient (A). Frequently the tissues of cusp margin and raphe are thickened and fibrosed; there may also be localized calcium deposits in the central portion of the cusp. This interferes with direct approximation of redundant cusp tissue by plication, and triangular excision of this stiff tissue is necessary (B). With tension on the stay sutures, the extent of necessary resection is readily apparent. The remaining parts of the fused cusp are readapted. Interrupted monofilament sutures (Prolene 5-0 or 6-0) exert minimal trauma on the tissue and avoid retraction of the cusp (C). Even in the presence of more extensive calcification, repair is possible. The calcified portion of the fused cusp is excised. Autologous pericardium is prepared by fixing it to a piece of cardboard and keeping it immersed in glutaraldehyde (0.5%) for 2 to 3 minutes. The necessary size can easily be judged using the stay sutures for extension of the remnants of the fused cusp (D). The pericardium is sutured into the defect with a running monofilament suture (Prolene 6-0).

The technique of repair depends on the morphology of the fused cusp. If the fused cusp is relatively thin and pliable, simple plication of its free margin will be sufficient (A). Frequently the tissues of cusp margin and raphe are thickened and fibrosed; there may also be localized calcium deposits in the central portion of the cusp. This interferes with direct approximation of redundant cusp tissue by plication, and triangular excision of this stiff tissue is necessary (B). With tension on the stay sutures, the extent of necessary resection is readily apparent. The remaining parts of the fused cusp are readapted. Interrupted monofilament sutures (Prolene 5-0 or 6-0) exert minimal trauma on the tissue and avoid retraction of the cusp (C). Even in the presence of more extensive calcification, repair is possible. The calcified portion of the fused cusp is excised. Autologous pericardium is prepared by fixing it to a piece of cardboard and keeping it immersed in glutaraldehyde (0.5%) for 2 to 3 minutes. The necessary size can easily be judged using the stay sutures for extension of the remnants of the fused cusp (D). The pericardium is sutured into the defect with a running monofilament suture (Prolene 6-0).

The adequacy of the cusp repair is judged by applying radial tension on the two commissures (A). Both free margins should be at identical height. Subcommissural plication of the root is helpful to improve coaptation surface further. Tension is applied on the cusps with a forceps for easy identification of insertion margins close to the commissure. A Teflon-pledgetted suture is placed through the insertion lines of the two cusps 1 to 1.5 cm beneath the top of the commissure (B). The suture is tied firmly, bringing the paracommissural cusp bases closer together.

Patients with aortic dilation need aortic replacement in addition to valve repair. We chose separate treatment of valve and aorta if root diameters are preserved and a sinutubular narrowing is present. Although ideal cutoff value will have to be determined, we have found a sinutubular diameter of less than 33 mm as a reasonable size (intraoperative measurement on the flaccid aorta). This corresponds to the transesophageal echocardiogram (TEE) determination of a sinutubular diameter of less than 40 mm and a maximum sinus diameter of no more than 45 mm. In determining the sequence of operative steps, it is important to recognize that any alteration of the intercommissural distances may change cusp geometry, eg, create prolapse. Any cusp repair should be done after anastomosing the graft to the aorta and thus creation of the final sinutubular junction. As a first step, the aortic root is transected 5 mm above the commissures, and a Dacron graft is sutured to the root as supracommissural replacement (A). This suture line should remain in a horizontal level at the top of the commissures of the noncoronary cusp (B).

The graft is shortened to a maximum of 2 to 3 cm (A). The final configuration of the aortic root including the valve can now be assessed. The sequence of steps on the valve then follows those of isolated valve repair. The configuration of the large cusp is determined, and any cusp prolapse (frequent!) is corrected. If more extensive aortic replacement is required, a second graft is anastomosed to the ascending aorta or arch and the two graft segments are connected (B).

In many patients with a BAV and aortic aneurysm, aortic dilation clearly involves the root. The patients commonly have maximum sinus diameters of more than 45 to 50 mm (TEE), and the average intraoperative sinotubular diameter (flaccid aorta) measures 40 mm. Complete elimination of aortic pathology requires root replacement, which may also serve as stabilization of the valve repair. We always use root remodeling as operative strategy, as it probably carries less risk of distortion of root and valve geometry compared with valve reimplantation.

After administration of cardioplegia, the aorta is divided; the root is mobilized, and the sinuses are excised, leaving approximately 5 mm of aortic wall adjacent to the cusp insertion lines. For tailoring of the vascular graft, the geometry of the aortic root has to be considered with the noncoronary sinus being the largest and deepest. The two commissures of the large cusp are higher than the rudimentary commissure. Correspondingly, the graft is configured with one large and two small tongues.

The graft is sutured to the cusp insertion lines in all three sinuses and then shortened to 1 to 2 cm above the commissures. Only at this time, the valve is inspected for cusp geometry and coaptation, and any necessary cusp repairs are then performed as in isolated valve repair. In keeping to this sequence, the exposure of the cusps is slightly limited, but not only preexistent malformation but also prolapse induced by the reduction of root diameters can be detected and corrected. If the extent of dilation requires it, aortic replacement is completed with a second vascular graft.