Congenital Aortic Valve Repair When the Options aren’t Good: Truncus Arteriosus and Transposition of the Great Arteries

https://doi.org/10.1053/j.pcsu.2022.12.004Get rights and content

Patients with truncus arteriosus and transposition of great arteries are prone to neo-aortic valve insufficiency. Although presenting at opposite ends of the age spectrum, both conditions tend to be commonly associated with neo aortic root dilatation. In patients with truncus arteriosus there is an additional complexity of quadricuspid valve morphology, which make up the majority of valves requiring repair. A unified approach to all these patients would include reduction and stabilization of the annulus and sinotubular junction, as well as achieving equal and symmetrical coaptation of the valve leaflets. By systematically employing these techniques, valve replacement should be avoidable in most children.

Introduction

Children with conotruncal anomalies, particularly truncus arteriosus (TA) and transposition of the great arteries (TGA) are prone to neo-aortic root dilatation and neo-aortic valve insufficiency. In those with TA, 20% of patients require truncal valve surgery by 20-years follow-up, especially affecting children with quadricuspid truncal valves.1, 2, 3 Frequently, truncal valve surgery is required in early childhood, often at the time of the initial repair.1,3 In children with TGA the rate of moderate neo-aortic regurgitation (AR) or surgery is 15%-20% at 25-years.4,5 These patients often present with AR in late childhood or adulthood. Typically, the neo-aortic valve in both of these conditions fails by regurgitation, rendering surgery the only option for correction. Although presenting at different ends of the age spectrum, in both TA and TGA, neo-aortic dilatation is a major contributor to AR. As in all children with valve pathology, repair is preferred to replacement.6 In TA patients especially, repair is important as there is no option of a Ross procedure, which remains the best technique for valve replacement in children.6,7 We discuss our approach to repair of the neo-aortic valve in patients with TA and TGA with a focus on the systematic application techniques to achieve a stabilized annulus and sino-tubular junction, and symmetrical equal sized leaflets.

The long-term rate of reoperation on the truncal valve is consistently reported as approximately 20% at 20 years1, 2, 3,8 in large series. The majority of these children undergo truncal valve repair during infancy, either as a concomitant surgery with their TA repair, or as a reoperation.[1] The risk factors identified for truncal valve reoperation are presence of truncal valve regurgitation at the time of initial repair, as well as diagnosis of quadricuspid truncal valve.3 Freedom from truncal valve surgery at 20 years was 74% in patients with a quadricuspid valve, compared to 90% in those without a quadricuspid valve.3 In fact, truncal valve surgery is required in approximately one third of patients with quadricuspid valves.1,8 Thus, if one operates on a truncal valve, the valve is most likely quadricuspid. Another important contributor to truncal valve regurgitation is annular dilation which is usually very pronounced in patients with TA.9

Typically, repair of the truncal valve has been achieved by one or more of the following techniques: subcommissural annuloplasty, suture valvuloplasty or cusp resection and annular reduction (Fig. 1). In patients with quadricuspid valves it appears that tricuspidization is the technique, which achieves the greatest freedom from reoperation.9,10 Tricuspidization may be achieved by simple approximation of leaflets, or alternatively by excision of a rudimentary cusp and its adjacent neo-aortic wall and part of the annulus (Fig. 2). In some cases, partial cusp excision and reconstruction may be required due to a juxtacommissural coronary artery, or due to deficiency of leaflet tissue (Fig. 2). The advantage of cusp excision is it allows simultaneous reduction of the truncal annulus and root. We have previously demonstrated10 that tricuspidization technique appeared to be superior to all other techniques of non-tricuspidization, including valve replacement (Fig. 2).

Although reduction of the root at the annulus and sino-tubular (ST) – junction can be achieved to some degree by cusp approximation and plication of both the interleaflet triangles and ST-junction, such reduction of the root can be achieved to a much greater degree by resection of the wall of neo-aortic root (Fig. 3).

In rare cases where the truncal valve cannot be repaired, replacement can be achieved either with a mechanical prosthesis or homograft.11 The dilated nature of the truncal annulus can usually accommodate an adult sized prosthesis even in young patients. However, it should be kept in mind that valve replacement is associated with a higher rate of reoperation.10 Recently some groups have described using the Ozaki technique for truncal valve replacement, however, long-term results have yet to be reported.12, 13, 14, 15

Progressive AR is a common problem following the arterial switch operation in patients with TGA, with 15%-20% of patient having moderate neo-aortic AR or neo-aortic valve surgery at 25-years follow-up.4,5 Factors contributing to progressive neo-aortic AR include enlargement of the ST-junction due to coronary transfer,16 aortic root dilatation, ventricular septal defect, prior pulmonary artery banding,17 presence of arch obstruction18,19 and structural abnormalities of the neo-aortic valve, such as the presence of bicuspid anatomy. Bicuspid valves occur in 2.5%-7%20,23 of patients with TGA, and are associated with a higher rate of aortic root dilatation, regurgitation, and reoperation20, 21, 22, 23.

Just as in TA, the repair must be targeted to the mechanism of valvular dysfunction. Whereas in normal aortic root anatomy, the aortic root is positioned centrally (Fig. 4A) and well supported by the adjacent structures and fibrous skeleton of the heart, in patients who underwent arterial switch operation for TGA (Fig. 4B) or Taussig-Bing anomaly (Fig. 4C), the non-coronary cusp appears to be less supported. Thus, in contrast to normal aortic root (Fig. 5A), the unsupported non-coronary sinus often dilates, pulls away from the rest of the annulus with resulting in prolapse of the non-coronary cusp (Fig. 5B). This phenomenon led us to coin the term “run-away sinus.” It is difficult to bring the “run-away sinus” back and, as such, these valves are challenging to repair. The patient with side-by-side arrangement, inverted coronary artery pattern exemplifies the challenge24 (Fig. 6A and B). The left coronary artery was in close contact with the annulus of the non-facing sinus, suggesting it would be difficult to safely achieve annuloplasty and reduction of this dilated sinus. This patient underwent Ross operation, however, after detaching coronary arteries it became apparent that repair, in fact was feasible (Fig. 6C) by circumferential band annuloplasty, after detachment and mobilization of the coronary where it contacted the annulus. The technique for annuloplasty is detailed in Figure 7. Good exposure of the neo-aortic valve is key. The right pulmonary artery must be divided to achieve such exposure (Fig. 7A). A stich is placed at the nodules of Arantius of the coronary cusps first (Fig. 7B) to determine the extent of the non-coronary cusp prolapse. The redundant part of the non-coronary cusp is identified (Fig. 7C) and plicated (Fig. 7D). Once such plication is completed, the enlarged wall of the adjacent sinus is partially resected (Fig. 7E). The wall of the sinus is reconstructed and pledgetted sutures are placed circumferentially (Fig. 7F) and anchored to a Gore-Tex strip (WL Gore and Associates, Newark, DE) to achieve effective reduction of the annulus (Fig. 7G). and prevent subsequent dilatation. The size of the annuloplasty band is determined by the predicted aortic size for the patient's weight determined from standardized tables25. The annuloplasty strip is left open to allow growth when the patient has not yet achieved adult size. Annuloplasty sutures should be spaced to achieve 3 equal sized sinuses.

In cases of symmetric aortic root dilatation, a valve sparing root replacement may be the preferred technique, allowing the annulus, sinuses and ST-junction to be stabilised.26 Recently the Personalized External Aortic Root Support (PEARS)27 has become available as an alternative to valve-sparing aortic root replacement in patients with mild to moderate central neo-aortic valve infifficiency and symmetrical aortic root dilatation, however, so far this has been adopted prophylactically prior to the development of significant neo-aortic AR. Long term-results of this approach are yet to be reported. An alternative technique is the Ross procedure,28 which has sometimes been referred to as the “switch back procedure”. As the autograft performs particularly well in the redo setting7, this may be the optimal option when the valve cannot be repaired.

Section snippets

Conclusions

Neo-aortic valve regurgitation is a common complication in patients with TA and TGA. Although these patients present at opposite ends of the age spectrum, repair principles are the same, and founded on the reduction of the dilated annulus and restoration of normal trileaflet anatomy. Using these techniques, valve replacement can be avoided in most patients.

Funding

Nil

References (28)

Cited by (0)

A/Prof Christian Brizard serves on the advisory board of Admedus. No other disclosures.

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