Tetralogy of Fallot correction with transannular patch reconstruction in a patient with an anomalous right coronary artery and an unusual course of the right ventricular branch

Abstract

Anomalous coronary arteries occur in as many as 12% of patients with tetralogy of Fallot (TOF). In patients with this condition, pulmonary hypoplasia can be prohibitive in performing a valve-sparing repair, subsequently resulting in various techniques to preserve the anomalous coronary artery. The management strategy is often complex in such a situation. We report on a case of TOF with an anomalous right coronary artery crossing the right ventricular outflow tract, with an unusual course of the right ventricular (RV) branch, which precluded placement of a valved conduit. In this case, we performed a successful repair with mobilization of the anomalous coronary artery and reconstruction of the right ventricular outflow tract with a limited transannular patch.

Introduction

Anomalous coronary arteries occur in as many as 12% of patients with tetralogy of Fallot (TOF). When the anomalous coronary artery crosses the infundibular area, adequate relief of right ventricular outflow tract (RVOT) obstruction can be quite a challenge, especially in patients with small pulmonary annuli. In these instances, the usual treatment involves implantation of a valved conduit between the right ventricle to the pulmonary artery. However, in this patient, there was an unusual course of the right ventricular branch, which made it impossible to place a conduit. Hence, a limited transannular patch was performed by extensive mobilization of the right coronary artery, which was crossing the right ventricular outflow tract.

Case report

An 11-month-old boy, who was a known case of TOF, presented with moderate oxygen saturations of 85% on room air. Two-dimensional echocardiography showed dilated right atrium and ventricle, a doubly committed sub-arterial defect with overriding of the aorta, and severe RVOT obstruction. The pulmonary annulus was noted to be small (6 mm; z-score − 3.13), and there was an anomalous course of the coronary artery across the right ventricular outflow tract. Cardiac catheterization showed severe pulmonary stenosis (pressure gradient 40 mmHg), a small pulmonary valve annulus (5.9 mm, z-score − 3.65), and a single coronary artery, with the right coronary artery (RCA) arising from the left coronary artery (LCA). On further review, there was note of the coronary crossing the RVOT (Fig. 1).

Fig. 1.

Cardiac catheterization showing the anomalous course of the right coronary artery (arising from the left coronary artery, turning anteriorly, crossing the infundibulum)

Given that the pulmonary valve is small, we could not preserve the valve for this case. Our original preoperative surgical plan was to place a right ventricle-to-pulmonary artery (RV-to-PA) conduit. During bypass, we noted the anomalous right coronary artery coming from the left coronary artery, with a dominant right ventricular (RV) branch coursing along diagonally across the RVOT at approximately 1 cm below the pulmonary valve annulus (Fig. 2). Because of the position of the coronary artery, and since there was a short distance from the anomalous coronary branch to the pulmonary valve annulus, it would have been difficult to place an adequate-sized conduit without compromising the coronary artery. The anomalous right coronary artery was extensively mobilized from the right ventricular outflow tract. The surgery was performed through a combined transatrial and transpulmonary approach. The doubly committed sub-arterial ventricular septal defect was repaired using a 0.4-mm polytetrafluoroethylene patch. The pulmonary artery was opened longitudinally extending 7 mm beyond the pulmonary annulus. The pulmonary valve was bicuspid and dysplastic, which was incised to widen the outflow tract. The right ventricular outflow tract was reconstructed with glutaraldehyde-treated autologous pericardium, with the patch extending below the mobilized right coronary artery, keeping the coronary artery above the patch (Fig. 3).

Fig. 2.

a Illustration showing the patient’s anatomy, with a cross section of the anomalous coronary anatomy. b Post-repair illustration depicting the placement of the transannular patch. RA, right atrium; LA, left atrium; PA, pulmonary artery; Ao, aorta; LV, left ventricle; RV, right ventricle; TAP, transannular patch; RCA, right coronary artery; LAD, left anterior descending artery; Cx, left circumflex artery

Fig. 3.

(Left) Intraoperative photo showing the mobilized branch of the right coronary artery (yellow vessel loop), crossing the right ventricular outflow tract. (Right) Post-repair photo showing the limited transannular patch beneath the anomalous coronary artery

The patient had an uneventful postoperative course. He was extubated on the 2nd postoperative day and was discharged improved on the 8th postoperative day. Postoperative echo showed a mild residual RVOT gradient (max 24 mmHg) with free flow pulmonary regurgitation and good flow to both pulmonary artery branches. Postoperative electrocardiogram showed no evidence of coronary ischemia.

Discussion

The incidence of coronary anomalies in patients with TOF occurs anywhere from 2 to 12% of cases [1–4]. In many of these patients, there is note of an artery crossing the ventricular infundibulum. Based on various surgical and angiographic series, the most common anomalous coronary artery pattern in TOF patients is a single left anterior descending artery (LAD) coming from the RCA. Other common anatomies include a significant conal branch crossing the RVOT, which was seen in our patient; the RCA coming from the LAD; and paired anterior descending arteries [2–4].

In TOF patients with a pulmonary annulus of decent size, an anomalous coronary artery (ACA) crossing the RVOT will generally not be a problem. Complete repair can be performed satisfactorily, preserving the pulmonary valve (PV) annulus and the RVOT, without resulting in significant residual pulmonary stenosis. ACAs, however, become a significant issue in TOF patients with small or hypoplastic pulmonary annuli. In this particular situation, several techniques of repair have been proposed. In the past, the presence of a coronary artery crossing the RVOT has resulted in delay in primary repair, typically prompting surgeons to perform initial palliation with a systemic-to-pulmonary shunt, and as such, allowing growth. In more recent times, definitive repair is preferred. Instead of performing a transannular patch, as one would do in uncomplicated cases of TOF with pulmonary valve hypoplasia, many surgeons opt to address the RVOT by implantation of a right ventricle-to-pulmonary artery valved conduit. In our patient, we initially planned to place a conduit. However, the large right ventricular branch, which was crossing the RVOT, made it impossible for us to do so.

The major disadvantage to conduit placement is the inevitable need for reoperation and valve replacement in the future. In order to minimize this risk, several more conservative techniques have been developed to successfully reconstruct the RVOT in these instances. Brizard et al., in a series of 36 TOF patients with ACA, suggested that the transatrial-transpulmonary approach with a limited transannular patch and infundibulotomy is sufficient to relieve the RVOT obstruction in these cases [2]. Meanwhile, Kalfa et al., in the biggest series of TOF patients with ACAs involving 72 patients, advocated the use of a “tailored” ventriculotomy and patch reconstruction, with the infundibulotomy performed in parallel to the course of the abnormal coronary artery [3]. These reports have shown fairly acceptable outcomes, with 10-year and 15-year reoperation rates of 96% [2] and 77% [3], respectively. Still others have suggested unique techniques, such as patching two separate RV and PA incisions, patch enlargement of the annulus via a ventriculotomy distal to the coronary, and translocation of the main pulmonary artery in front of the ACA [1–5].

Newer surgical techniques to augment the RVOT while avoiding the ACA, specifically in patients with hypoplastic pulmonary annuli, have also been performed in smaller case series or in case reports. One such technique is a doublebarrel technique, wherein a double-barrel outflow of the right ventricle to the pulmonary artery is established, with the ACA situated in between the tracts. The original technique uses the anterior pulmonary arterial wall, which is flapped and sutured to the right ventricle over the coronary artery; modifications have been made in recent years, using pericardial patches instead [1, 6]. The main advantage of this technique is the lower risk of late pulmonic stenosis in these patients, which is attributed to maintenance of the growth potential when using native tissue.

One of the least commonly executed repairs in this situation is that first reported by Bonchek in 1976 [7], performed on an 11-year-old girl. This technique involves mobilization of the anomalous coronary artery, and placement of a transannular patch underneath it. Reviewing the other options, a mere transatrial-transpulmonary approach without crossing the annulus would have produced a significant residual RVOT gradient in this case, as the patient’s pulmonary annulus is hypoplastic, and performing a separate RV incision would not be of much benefit, as the obstruction is at the valvar level. It would not be suitable to perform a tailored ventriculotomy in this case, as the abnormal course of the RV branch of the RCA makes it difficult to do so. Given that only a limited infundibular incision had to be done in our patient to adequately relieve the RVOT obstruction based on intraoperative assessment, we decided to perform mobilization of the coronary artery and place a limited transannular patch on the RVOT. To date, this subcoronary patching technique of TOF repair has only been reported by five authors, including the original report. In 2000, Tchervenkov et al. [5] reported on the use of this technique in 2 of 20 patients with ACAs. The coronary artery was mobilized, together with the epicardium and underlying myocardium, and the transannular patch was slightly undersized to prevent stretching of the coronary artery. This was performed successfully in a neonate and an infant, with good outcomes over a 5-year period. Oshima et al. [8] in 2003 likewise reported using this technique on a 7-year-old who developed progressive stenosis after initial repair, while Ozkara et al. [9] used it in 2005 on an adult TOF patient. Most recently, the use of this technique was reported by Benjaout et al. [10] in 2020. They performed RVOT augmentation under a mobilized coronary artery in 14 patients, with no coronary injuries and only one patient requiring an extracardiac conduit. There were also no reinterventions nor in hospital mortality in their case series.

Some authors have been quick to point out issues with this technique, which involve the possibility of damage or compression to the anomalous coronary artery, resulting in myocardial ischemia. Another concern is the possibility of sacrificing the outcomes of the procedure by performing an unsatisfactory repair with minimal pulmonary artery enlargement, resulting in residual RVOT obstruction. Our patient did not develop myocardial ischemia postoperatively, and there was only mild residual RVOT obstruction noted postoperatively. The patient was discharged improved, and has been doing well on last follow-up. Risks of coronary artery spasm and late stenosis can occur with this technique, and we plan to closely follow-up this patient to prevent these dreaded complications. Longer follow-up would have to be performed to determine any long-term effects associated with the procedure.

Conclusion

We report the successful repair of TOF with an anomalous coronary artery having a dominant RV branch that crosses the RVOT using a limited subcoronary transannular patch. It is important to recognize and evaluate the presence of coronary artery anomalies in TOF patients, particularly those with pulmonary hypoplasia, in order to allow for proper operative planning of the most ideal approach to relieve the RVOT obstruction. It is likewise crucial to be aware of the various surgical options for managing these complicated cases.

Authors’ contributions

Both authors contributed equally to the preparation and writing of the manuscript, and approved the final manuscript.

Funding

Nil.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethics approval

This case report was conducted in a retrospective manner, from data obtained clinically. This case report was conducted in accordance with the ethical standards of the institutional and national research committees, and with the 1964 Declaration of Helsinki and its later amendments.

Informed consent

Informed consent was taken from the patient’s legal guardians.