Corrected Transposition of the Great Arteries

Fig. 10.1

10.2 Presentation in Adulthood

Adult patients with ccTGA and two functional ventricles tend to present to the surgeon after some interventional repair or palliative operation that results in pulmonary outflow tract obstruction, tricuspid (systemic) valve regurgitation, right ventricular (systemic ventricle) dysfunction, atrial baffle complications, or conduit stenosis/regurgitation. The presenting problems are largely based on the type of operative or non-operative strategy that was employed early in the patient’s life, usually one of three strategies:

  • Physiologic repair resulting in connections of the left ventricle to the pulmonary artery and the right ventricle to the aorta

  • Double switch operations resulting in connections of the right ventricle to the pulmonary artery and the left ventricle to the aorta

  • No initial surgical intervention because of an absence of atrial and ventricular shunts and non-obstructive pathways from the left ventricle to the pulmonary artery and the right ventricle to the aorta

Patients with remote physiologic repair by VSD closure and reconstruction of the left ventricular to pulmonary artery pathway (pulmonary valvotomy or left ventricle-pulmonary artery conduit) generally present with pulmonary outflow tract or conduit stenosis. They may or may not have accompanying tricuspid regurgitation, depending on the degree of right ventricular dysfunction.

Patients with remote physiologic and anatomic repair fall into two categories: double switch operation and atrial baffle/Rastelli operation. The preoperative conditions determine the type of anatomic repair that can be performed, and both have long-term complications originating from the original operation. For instance, patients who had the double switch operation (arterial switch and atrial baffle operations) may develop baffle leaks or obstructions, neoaortic regurgitation, supravalvar pulmonary stenosis, or coronary obstructions. Patients who had the atrial baffle/Rastelli operation may develop baffle leaks or obstructions, left ventricular outflow tract (LVOT) obstruction, and conduit stenosis/regurgitation that almost assuredly will require conduit replacement.

Patients who had a balanced ccTGA circulation without remote operations typically had no intracardiac shunts and mild or absent LVOT obstruction. These patients do well for many years into adulthood, with scattered reports of survival into the sixth and seventh decades, but some develop progressive significant pulmonary or subpulmonary valve stenosis that requires intervention to avoid coronary malperfusion, ventricular dysfunction, and severe cyanosis. Treatment options for these problems are controversial and not resolved.

To understand the pre-existing conditions that may require operative revision, a complete review of the surgical procedures will help the clinician unravel the problems that these patients experience in adulthood.

10.3 Classic Physiologic Repair for Congenitally Corrected Transposition of the Great Arteries and Ventricular Septal Defect without Pulmonary Stenosis

Figure 10.2 shows a patient with ccTGA, VSD, and situs solitus undergoing aortobicaval cardiopulmonary bypass with aortic cross-clamping and cardioplegic arrest. The relevant right atrial and morphological left ventricular anatomy is depicted with retraction of the mitral valve for transatrial perimembranous VSD closure. The location of the normally positioned atrioventricular node is included to emphasize the abnormal location of the aberrant atrioventricular node and the pathway of the bundle of His as it passes anterior to the pulmonary annulus along the morphologic left ventricular crest of the ventricular septum. The conduction system can be avoided during VSD closure by anchoring interrupted pledgeted sutures on the right ventricular side of the VSD over the course of the conduction system (Fig. 10.3). Sutures can be placed on the left ventricular side of the septum at the inferior margin of the VSD, which is safely away from the conduction system. The sutures can then be taken through a prosthetic patch and individually tied to effectively close the VSD.


Fig. 10.2


Fig. 10.3

10.4 Physiologic Classic Repair of Congenitally Corrected Transposition of the Great Arteries and Ventricular Septal Defect with Left Ventricular Outflow Tract Obstruction (Pulmonary Stenosis)

Before the introduction of the double switch procedures (arterial switch and atrial switch; Rastelli and atrial switch), it was common to perform physiologic repair that entailed simple VSD closure (as described above) or VSD closure and creation of a left ventricular to pulmonary artery conduit to address LVOT obstruction (pulmonary stenosis). Figure 10.4 shows a patient with ccTGA, VSD, and PS undergoing aortobicaval cardiopulmonary bypass with aortic cross-clamping and cardioplegic arrest. The pulmonary annulus is not favorably located for a transannular patch owing to the course of the right coronary artery, and the conduction system traverses this area en route to the interventricular septum and the bundle of His. Under these circumstances, surgeons have closed the VSD and reconstructed a conduit from the left ventricle to the pulmonary artery, allowing for a physiologic but not an anatomic correction (Fig. 10.5). The difficulty with this approach is that the right ventricle fails with time because of right ventricular dilatation, the resultant tricuspid regurgitation owing to papillary muscle stretching and arrhythmias. Interestingly, patients with acquired conduit stenosis and the resultant left ventricular hypertension tend to do better because the interventricular septum maintains its neutral position, and the cascade leading to right ventricular failure does not occur. That is, the interventricular septum does not bow into the left ventricle, the right ventricle does not correspondingly dilatate, and the tricuspid valve does not become regurgitant.


Fig. 10.4


Fig. 10.5

When the time comes for conduit replacement, two issues become important. The first is that the left ventricle becomes decompressed, thereby allowing the interventricular septum to bow to the left and cause tricuspid regurgitation. The second is unwanted coronary artery injury owing to left ventricular free wall incision for the larger conduit. This problem usually does not happen in the right ventricle, because the right anterior ventricular wall is not rich with large coronary arteries. The left ventricular free wall is a different issue, however, as it contains many branches arising from the course of the right coronary artery. Interruption of these vessels during conduit replacement can have an additive negative effect on ventricular interaction and overall ventricular function. Cardiac transplantation may be the only solution for this unfortunate series of events.

10.5 Physiologic Repair by Ventricular Septal Defect Closure, Pulmonary Valvotomy, and Bidirectional Glenn Shunt for Congenitally Corrected Transposition of the Great Arteries, Ventricular Septal Defect, and Moderate Pulmonary Stenosis

Ventricular interaction in patients with ccTGA, VSD, and moderate PS has been shown to be an important element in preventing tricuspid regurgitation and right ventricular failure. It is well known that patients treated by atrial switch for simple transposition of the great arteries can develop right ventricular dilatation and tricuspid regurgitation owing to papillary muscle stretching caused by septal deviation toward the left ventricle. During the era of left ventricular training by pulmonary artery banding in preparation for atrial switch takedown and late arterial switch, it was found that tricuspid regurgitation improved significantly with pulmonary artery band placement. This improvement was owing to increased left ventricular pressure caused by the increased afterload (pulmonary artery band), interventricular septal shift, and relief of papillary muscle stretching, resulting in tricuspid competency and improved right ventricular function. These physiologic determinants were applied to a small number of patients with ccTGA, VSD, and moderate PS in whom the PS could be improved, the VSD could be closed, and the left ventricle could be unloaded by a bidirectional Glenn shunt (one and one-half ventricular repair) that resulted in a left ventricular pressure of 60–70% of the right ventricular pressure. Presumably, these pressure conditions with favorable interventricular interactions could maintain right ventricular function over the long term without applying the complex double switch operations or the physiologic repairs requiring left ventricular to pulmonary artery conduits. Figure 10.6 shows a patient with ccTGA, VSD, and moderate PS who has undergone aortobicaval cardiopulmonary bypass, transatrial VSD closure, infundibular resection (subpulmonic resection) away from the conduction system, and bidirectional Glenn shunt. This operative drawing shows the localized sharp pulmonary valvotomy. The bidirectional Glenn shunt functions to unload the left ventricle to lower the developed pressure to sub-systemic levels, but high enough to maintain the favorable interventricular interactions. Figure 10.7 shows the completed repair, which has been successful in a handful of patients over a 10-year period. This operation can be applied only to a minority of patients who must have the right constellation of lesions with moderate PS and may benefit from this type of procedure.


Fig. 10.6


Fig. 10.7

10.6 Double Switch Operation for Congenitally Corrected Transposition of the Great Arteries, Ventricular Septal Defect, and no Pulmonary Stenosis

The atrial switch-arterial operation was introduced to create an anatomic and physiologic repair of ccTGA in circumstances where there is no valvar PS, with or without an associated VSD. The physiologic considerations that are necessary for this operation to be successful are largely the same as for arterial switch as applied to transposition of the great arteries. Patients with ccTGA, VSD, and no PS may have their operation delayed for a few months, assuming that the VSD is large enough to affect left ventricular systemic pressure. Those patients with ccTGA and no PS may require a neonatal double switch or two-stage repair using preparatory pulmonary artery banding for left ventricular training before the double switch operation. The drawbacks of this preparatory approach center around the neoaortic valve, which is subject to valvar regurgitation after preparatory pulmonary artery banding. The long-term results with these clinical strategies are yet to be determined. Nevertheless, the concept of double switch to accomplish physiologic and anatomic repair is very appealing despite the long-term possibilities of atrial pathway obstructions, atrial arrhythmias, neoaortic regurgitation, and coronary artery problems.

The operation is rather complex, requiring close attention to its pace, order, and execution. It is best visualized in steps, with myocardial preservation strategies that include antegrade, retrograde, and direct coronary administration of cardioplegia. There are basically three steps: the VSD closure, the atrial switch procedure, and the arterial switch portion, performed more or less in that order. Figure 10.8 shows the epicardial anatomic details of ccTGA with VSD and no PS. The coronary arteries generally require more dissection, mobilization, and modified implantation techniques to accomplish a tension-free anastomosis. When this operation was being conceived, anatomic dissections were performed in ccTGA cadaver specimens to determine whether coronary transfer could be accomplished safely. The initial assessment was not supportive, perhaps because the specimens were fixed and not amenable to mobilization. The operation was subsequently performed successfully in the clinical setting, making the operation feasible and applicable to this group of patients. Figure 10.9 shows a coronal view of the left ventricle with the noted landmarks. The VSD is highlighted in the subpulmonic area. The right coronary artery traverses the anterior margin of the pulmonary artery. The same VSD is visualized through a coronal section of the right ventricle in Figs. 10.10 and 10.11. Sometimes the tricuspid valve apparatus can be overriding, as in these figures. These anatomic details are rather subtle and require careful consideration before this operation is performed. Some surgeons have reimplanted the papillary muscle and chordal apparatus onto the right side of the VSD patch. Others find this approach too risky and opt for the univentricular Fontan approach. If there are no impediments to VSD closure, the surgeon can opt for several exposure techniques; the right atrial approach through the mitral valve is now most often used. The path of the conduction system and the correct suture placement were noted in the previous section. Alternatively, a right ventriculotomy can be performed for optimal exposure (Fig. 10.12), or the transaortic root can be elected at the beginning of the arterial switch operation (Fig. 10.13). Once the VSD closure is accomplished, right atrial exposure for the atrial switch operation is commenced. In the next several figures, we elected to show the Mustard operation, although most surgeons now prefer the Senning operation for reasons expressed in the next section. Figure 10.14 shows the patient undergoing aortobicaval cardiopulmonary bypass, aortic cross-clamping, and cardioplegic arrest. The anatomic details are shown with the dotted lines projecting the suture line that will be necessary to implant the pericardial baffle. Note that the coronary sinus is incised into the left atrium to ensure drainage. The baffle therefore serves to direct systemic venous blood flow toward the tricuspid valve and into the right ventricle. In Fig. 10.15, the baffle is in the process of being sewn into place, leaving space for the pulmonary venous return to flow unimpeded toward the mitral valve and into the left ventricle. Once the baffle is completed, there is no access to the coronary sinus for the administration of retrograde cardioplegia. Because the arterial switch operation is the next part of the operation that must be completed, preparations should be made for administration of direct intracoronary cardioplegia, should it be necessary. Figure 10.16 shows the epicardial anatomy of the same patient after the Mustard operation. Note that the right atrium does not show patch augmentation, which is usually accomplished. Also, the aortic cross-clamp is not shown, though it is generally left in place in preparation for the arterial switch operation. The dotted lines represent the paths of great artery transection, coronary artery button formation, and reimplantation sites on the pulmonary artery (neoaorta). Figure 10.17 shows the proper placement of the aortic cross-clamp, with great artery transection and coronary artery mobilization. The linear incisions in the pulmonary artery are made in preparation for a “trap door” type of implantation technique, as shown in Fig. 10.18. The “trap door” technique is used to optimize the coronary flow pattern, as the coronary arteries need to be mobilized for a considerable distance for this operation—more than for the usual pattern used for arterial switch for simple TGA. The neopulmonary artery reconstruction can then be accomplished by separate pericardial patches (Fig. 10.19), or by a pantaloon pericardial patch, as described in Chap. 9. Figure 10.19 shows the completed arterial switch operation after the maneuver of Lecompte was performed before great artery reconstruction. Some surgeons prefer not to perform the maneuver of Lecompte if the expectant anatomic configuration is not favorable. This is a personal choice, best left to the surgeon who is performing the operation.


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Apr 27, 2020 | Posted by in CARDIAC SURGERY | Comments Off on Corrected Transposition of the Great Arteries
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