Adult congenital heart disease: a review of the moderately complex lesions

The population of adults living with congenital heart disease (CHD) has expanded substantially over the last 40 years due to advances in diagnostic, transcatheter, and surgical techniques. Consequently, clinicians, regardless of their specialty, will encounter patients presenting with sequelae of both simple and complex CHD more frequently. Familiarisation with the pathophysiology and basic management of these conditions, including the role of adult congenital heart disease (ACHD) centres, is, therefore, vital. The moderately complex congenital heart defects that may present in adulthood include atrioventricular septal defects (AVSD), Ebstein’s anomaly (EA), tetralogy of Fallot (TOF) and transposition of the great arteries (TGA). Some of these defects are typically diagnosed and repaired in infancy, so clinicians must be aware of the possibility of adults presenting with post-repair complications, but some patients with unrepaired or undiagnosed defects remain asymptomatic until middle age, where they may present with heart failure, arrhythmia, endocarditis or even sudden cardiac death.

Introduction

As outlined by Prica et al.,¹ the number of children with congenital heart disease (CHD) surviving to, and thriving in, adulthood has increased dramatically since the 1980s due to earlier diagnosis and advances in transcatheter and surgical techniques. Consequently, the adult congenital heart disease (ACHD) population is larger than ever, and many patients will present to non-ACHD specialists with a variety of medical problems, cardiac or otherwise. Therefore, a working understanding of these lesions is key for all front-line physicians. However, ACHD remains a highly specialised subject with limited evidence-base. This review article is aimed at the general hospital cardiologist, with no specialist ACHD expertise, who may encounter patients with ACHD on the general cardiology take. It will outline the epidemiology, pathophysiology, clinical manifestations, management, sequelae and follow-up of moderately complex defects.

Atrioventricular septal defect

Atrioventricular septal defects (AVSDs) are characterised by a defect in the atrioventricular (AV) septum alongside a common AV junction. AVSDs make up 3.6% of cases of CHD,² most commonly in patients with trisomy 21.³

Pathophysiology

AVSDs arise due to failure of fusion of endocardial cushions during embryonic development. Partial AVSD (ostium primum atrial septal defect) describes a defect only at the atrial level, with two separate atrioventricular valve (AVV) orifices despite a common junction, due to a cleft of tissue connecting the superior and inferior bridging leaflets. Whereas, in complete AVSD there is a single-valve orifice (figure 1A).

Associated defects include left ventricular outflow tract obstruction (LVOTO), ventricular hypoplasia, and tetralogy of Fallot (TOF).⁴ Due to a deficient AV septum, the AV node, bundle of His and left-bundle branch are displaced, increasing the risk of conduction system disease.⁵

Clinical presentation

The exact morphology of the AVSD and lesions influence the degree and direction of shunting, and, therefore, the consequent presentation.

Partial AVSD

Symptoms may not become apparent until the fourth decade of life, when patients may develop dyspnoea, reduced exercise tolerance, palpitations, and fatigue.³ Left AVV regurgitation (LAVVR) may also result in heart failure (HF) in this cohort.

Clinical examination may reveal right ventricular (RV) heave, a fixed split-second heart sound with an increased pulmonic component, a pansystolic murmur due to LAVVR, and an ejection-systolic pulmonary flow murmur.

Complete AVSD

Patients with complete AVSDs with a large ventricular component, will either be surgically repaired in infancy, or will have established pulmonary vascular disease by the time they reach adulthood.

Complete AVSDs are not usually associated with a separate murmur, due to the large and unrestrictive ventricular defect.

Diagnosis

Electrocardiography (ECG) may demonstrate the characteristic finding of extreme right-axis deviation (RAD). First-degree heart block and a broad QRS complex are also common.⁴

Transthoracic echocardiography (TTE) is key in providing accurate evaluation of specific lesions, including direction and magnitude of shunting, severity of AVV regurgitation, LVOTO, and estimation of pulmonary arterial pressures (figure 1B). Cardiac magnetic resonance (CMR) imaging is utilised for additional evaluation of the above. Right heart catheterisation (RHC) can also be of benefit to measure pulmonary vascular resistance (PVR) and any reversibility, alongside exercise testing.

Management

Surgery aims to close the septal defect and separate the common AV valve into two separate and competent valves, with low operative mortality.⁶ For patients with complete AVSD, the European Society of Cardiology (ESC) does not recommend surgical repair in the presence of Eisenmenger physiology or those with pulmonary arterial hypertension (PAH) who desaturate on exercise.³

Follow-up

The ESC recommends lifelong regular follow-up of all with an AVSD, whether corrected or uncorrected. Patients with surgically repaired defects without residual abnormalities should be seen at least every two to three years. Shorter intervals should be considered for those with residual abnormalities, such as LAVVR, LVOTO, and arrhythmia.³

Sequelae

Mortality is significantly higher in individuals with unrepaired AVSD compared with repaired.^7,8 Overall, post-operative long-term outcomes for both complete and partial repair are excellent, though the most common indications for re-operation are LAVVR, LVOTO, and complete heart block (CHB).⁶ Due to anatomical challenges, consequent repair of LAVVR can result in symptomatic stenosis, requiring intervention.

Ebstein’s anomaly

Ebstein’s anomaly (EA) is a rare abnormality of the tricuspid valve (TV), accounting for under 1% of all cases of CHD.⁹

Pathophysiology

Failure of delamination of the TV results in the leaflets (most commonly the posterior and septal) becoming tethered to the septum or RV free wall, along with apical displacement of the TV and annular dilatation (figure 2A). The anterior leaflet is typically deformed and described as ‘sail-like’. This results in a large right atrium (RA), and a RV that is separated into two distinct portions: the ‘atrialised’ and ‘functional’ RV. The atrialised RV is a thin-walled, dilated chamber between the anatomical tricuspid annulus and the functional RV (the ‘inlet’ portion) (figure 2A).⁹ The functional RV may be small, and in severe cases, may only consist of the RV outflow tract (RVOT). RVOT obstruction (RVOTO) may occur secondary to mobile leaflet tissue or the sail-like anterior leaflet.^9,10 Due to valve incompetency, patients develop tricuspid regurgitation (TR). The RV is often functionally impaired, which alongside RVOTO culminates in right HF.

Associated defects include a co-existent secundum atrial septal defect (ASD) or patent foramen ovale (PFO) in approximately 80%,¹¹ and Wolff-Parkinson-White (WPW) syndrome with multiple accessory pathways present in 20% of EA patients, respectively.

Clinical presentation

Clinical presentation varies with age, the severity of the lesion and the presence of a right-to-left shunt.¹²

Symptoms include fatigue, decreased exercise tolerance, shortness of breath and, rarely, progressive cyanosis. The most frequent presentation in adults is arrhythmia, occurring in up to 30–40% of patients,¹³ of which AV re-entrant tachycardia (AVRT) is the most common.³ 

On examination, the pansystolic murmur of TR is heard. AV conduction is often prolonged resulting in audible atrial and ventricular filling sounds producing a ‘gallop’ (a widely split S1 and S2 with a loud S3 and/or S4). The JVP may demonstrate a prominent V-wave due to significant TR.

Diagnosis

ECG can detect accessory pathways and classify arrhythmias.¹⁴ P pulmonale is common due to RA dilation. The displaced location of the TV and atrialised RV results in intra-atrial and intra-ventricular conduction delay, respectively, producing a prolonged PR interval and broad QRS with right-bundle branch block (RBBB) pattern.¹⁵

TTE permits visualisation of all four cardiac chambers, and specifically the size and function of the large RA and the functional RV (figure 2B). The degree of tricuspid displacement is important in EA, the septal leaflet of the TV is displaced by at least 8 mm/m² from the insertion of the anterior mitral valve (MV) leaflet.³ The more septal leaflet tissue present, the greater the likelihood of successful repair. However, significant tethering or presence of mobile leaflets within the RVOT increases the repair complexity.¹⁰

CMR is an important pre-surgical imaging modality, as it provides a greater understanding of RA, RV and TV size and function.³

Management

Observation alone may be appropriate, initially, for those with mild symptoms and normal exercise tolerance. Those with symptomatic HF who are not yet surgical candidates, are treated with standard HF therapies, including diuretics. In the presence of paradoxical emboli, anticoagulation is recommended, and should also be considered for those with a right-to-left shunt.³ For symptomatic treatment of AVRT, ablation of accessory pathways is typically offered, where feasible.

The ESC recommend repair, such as the cone procedure, when there is severe TR, reduction in exercise capacity or progression of symptoms. However, if there is evidence of right heart dilatation and reduced RV systolic function, then surgical intervention should be considered, regardless of symptoms. In some cases, the RV dysfunction is too severe, and transplantation should be considered. Valve repair is technically challenging, but over 90% of patients who undergo intervention survive over 10 years. However, the timing of repair is complex, and procedures should only be performed by operators with experience in EA repairs in specialised ACHD centres.³ ASD or PFO closure can be performed simultaneously.

Follow-up

The ESC recommends annual follow-up for all EA patients in a specialised ACHD centre.³ Follow-up TTE assesses for post-operative complications, valvular and RV systolic dysfunction. Both exercise prescription and endocarditis prophylaxis should be counselled. EA patients who are asymptomatic, with only mild TR, or who have had a successful operation without remaining anomalies, can exercise without restriction.³

Sequelae

Morbidity in EA is often related to arrhythmia or paradoxical emboli with potential haemodynamic compromise. Development of RV failure is likely, with additional risk of liver cirrhosis and sudden cardiac death (SCD). Post-operatively, typical complications of valve replacement may occur, including recurrence of TR and prosthetic valve failure. Atrial tachycardia is still problematic despite repair, therefore, control of arrhythmia may improve durability of valve repair and subsequent quality of life.¹⁰

Tetralogy of Fallot

TOF is the most common cyanotic heart defect, and accounts for around 10% of CHD.¹⁶ It is characterised by four structural features; ventricular septal defect (VSD), overriding aorta, pulmonary stenosis (PS) and right ventricular hypertrophy (RVH) (figure 3A).

Pathophysiology

TOF results from abnormal formation of the ventricular chambers and development of the great arteries, with rightward displacement of the outlet septum.¹⁷ Deoxygenated blood flow entering the right side of the heart is divided between the pulmonary circulation, across an obstructed outflow tract, and the systemic circulation, across the VSD and into the aorta. Depending upon the level of resistance across each lesion, this often results in right-to-left shunting and subsequent cyanosis. RVH is a consequence of the above mechanisms.

TOF is also often associated with other lesions, such as abnormalities of the aortic arch and branch pulmonary arteries, or syndromes including trisomy 21 and 22q11.2 deletion.

Clinical presentation

Most patients will have surgical repair in infancy, therefore, adult patients presenting with unrepaired TOF are rare, but do occur. However, in those having undergone successful repair, symptoms are likely to be related to post-surgical complications, most commonly; exertional dyspnoea or palpitations and presyncope secondary to atrial or ventricular arrhythmia.

Clinical findings include a split-second heart sound along with ejection systolic or early diastolic murmur due to residual PS or progressive pulmonary regurgitation (PR). There will be evidence of previous surgical scars (sternotomy and possible thoracotomy scar), parasternal heave relating to RVH and an absent radial pulse on the ipsilateral arm in patients who have had a classical Blalock-Thomas Taussig (BT) shunt performed, although this is now a rare finding.

Diagnosis

ECG usually shows RAD and RBBB. TTE can identify residual lesions and assess ventricular function (figure 3B). CMR is frequently used to gather more quantitative measurements of ventricular size and function, as well as haemodynamic assessment of specific lesions.

Management

Traditionally, before significant advancements were made in surgical correction, palliative shunts were performed to bypass blood flow from the aorta to the pulmonary arteries to facilitate increased pulmonary blood flow, such as the BT shunt (subclavian artery to pulmonary artery). Primary repair in infancy is now more common.

Complete repair typically involves patch closure of the VSD and relieving RVOTO, which can be achieved by a number of means including; resection of obstructing muscle, pulmonary valvotomy or through widening the pathway with transannular patching.³ Following this, medical management focuses on treating symptoms, typically beta blockers to treat atrial arrhythmia and diuretics to manage fluid overload from RV dysfunction. Transcatheter or surgical pulmonary valve replacement is used for severe PR and RV dilation.

Follow-up

Most patients will require lifelong annual follow-up in specialist ACHD centres with regular TTE and CMR, due to ongoing high risk of developing ventricular impairment, progressive PR and significant arrhythmia.¹⁸

Sequelae

Advances in surgical repair have produced excellent long-term survival rates,¹⁹ however, still falling below that of the general population and patients with more simple congenital lesions.²⁰ Complications following repair in the adult population can include PR, which is often well tolerated, but can eventually lead to RV dilation and dysfunction. Residual RVOTO can recur at any level, often needing repeat interventions.²¹ Residual VSD can lead to left ventricular (LV) volume loading. Late complications include aortic dilatation and aortic regurgitation (AR). Atrial arrhythmia is common and, in some circumstances, ventricular arrhythmia, usually in conjunction with biventricular impairment, can be a cause of SCD.¹⁸ This population also has higher risk of endocarditis, especially where prosthetic valve material is used.³

Transposition of the great arteries

Transposition of the great arteries (TGA) is a cyanotic CHD characterised by the aorta (Ao) arising from the morphological RV, and the pulmonary artery (PA) from the morphological LV (figure 4A). TGA accounts for around 3% of CHD.²²

Pathophysiology

In unrepaired TGA, the systemic and pulmonary circulations run in parallel, and survival is, therefore, only possible with a patent ductus arteriosus (PDA) or septal defect, and is very much the exception in adults. Two main surgical techniques have been used to treat TGA; the atrial switch and the arterial switch, the latter being the modern and preferred method.²³

Atrial switch

The atrial switch involves creating a baffle to direct systemic venous return from the RA to the sub-pulmonary LV, and a baffle to direct pulmonary venous return from the left atrium (LA) to the sub-systemic RV (Mustard or Senning procedure).²⁴ The morphologic RV remains in the systemic position and is prone to early failure.

Clinical presentation

HF symptoms are common, along with palpitations and presyncope or syncope. Examination may reveal a RV parasternal heave, elevated JVP, peripheral oedema and a holosystolic murmur indicating systemic AVVR (SAVVR).

Diagnosis

ECG will typically demonstrate RVH and sinus bradycardia or junctional rhythm. TTE provides an assessment of ventricular size and function, and the presence of SAVVR, baffle leaks or stenosis. CMR provides a more reliable assessment of the sub-systemic RV function, the size of the great arteries and baffle leaks or stenoses.

Cardiopulmonary exercise testing (CPET) is helpful for long-term follow-up of exercise capacity and chronotropic incompetence. Holter monitoring or electrophysiological studies (EPS) can be performed if there is suspicion of brady- or tachyarrhythmias, respectively.

Management

The use of diuretics relieves symptoms in patients with systemic RV failure. Conventional HF pharmacotherapies, sacubitril/valsartan and sodium-glucose cotransporter type 2 inhibitors (SGLT2i) are safe to use in this population, although their long-term benefits remain unclear.^25,26 Patients that are symptomatic of baffle leaks or stenosis are recommended to undergo catheter intervention, or maybe surgical repair. The presence of isolated severe SAVVR should prompt consideration of valve repair or replacement.³

Follow-up

All patients with TGA, regardless of the type of operation, should be seen in a specialist ACHD quaternary centre.

Sequelae

The common complications of the procedure include sub-systemic RV dysfunction, HF and progressive SAVVR, e.g. TR and arrhythmia.

Arterial switch

The arterial switch procedure involves the removal of the right and left coronary arteries from the aorta; the ascending aorta and pulmonary artery are divided and reversed, with the aorta being placed posteriorly to the pulmonary artery, commonly referred to as the LeCompte manoeuvre. The coronary arteries are then re-implanted.²⁷

Clinical presentation

Clinical presentations vary depending on the complications listed below, but most patients will remain asymptomatic.

Diagnosis

TTE provides information on the size of the neo-aortic root, presence of AR, supravalvular and branch PA stenosis and LV/RV systolic function. CMR is used for reliable quantitative assessment of the above. Cardiac computed tomography (CT) is the preferred method for non-invasive coronary assessment.

Management

Coronary intervention or surgery is recommended in cases of coronary artery stenosis causing ischaemia. Severe AR or root dilatation over 55 mm should prompt consideration of neo-aortic valve or root replacement, respectively. Stenting for branch pulmonary artery stenosis should be considered when there is either over 50% narrowing in diameter and RVSP over 50 mmHg and/or related reduced lung perfusion. Intervention for severe supravalvular PS should be considered, regardless of symptoms, if the peak Doppler gradient exceeds 64 mmHg, provided no valve replacement is required.

Sequelae

The most common complications encountered are neo-aortic root dilatation causing AR, supravalvular PS and branch PA stenosis. Current data suggest survival up to at least 30 years, and most patients will remain free from re-intervention.²⁸

Follow-up

All patients with TGA, regardless of the type of operation, should be seen in a specialist ACHD quaternary centre.

Congenitally corrected TGA

Congenitally corrected TGA (ccTGA) is characterised by AV and ventriculoarterial (VA) discordance. The right atrium connects to the left ventricle (AV discordance), while the right ventricle connects to the aorta (VA discordance) resulting in a sub-systemic RV (figure 4B). ccTGA accounts for 0.05% of all CHD. Dextrocardia, conduction abnormalities and other associated lesions are common.²⁹

Clinical presentation

Up to two-thirds of patients with unoperated ccTGA with no associated lesions will present in adulthood.

Pathophysiology

The pathophysiology, presentation, complications and management are similar to that of an atrial switch, due to the sub-systemic RV and systemic TV.³⁰

Diagnosis

ECG may demonstrate a prolonged PR-interval or heart block.³ TTE is key for monitoring the SAVVR and function of the sub-systemic RV. CMR is used to quantify the volume and function of the sub-systemic RV. Holter monitoring or EPS could be indicated for assessment of arrhythmias.

Management

Diuretic therapy is useful for symptom relief, but the long-term benefits of conventional HF therapies remain unclear. ESC guidelines suggest that TV replacement is indicated with severe TR and preserved or mildly impaired RV systolic function.³ The ESC also recommends consideration of biventricular pacing in cases of CHB, or if ventricular pacing is expected to be over 40%.

Sequelae

The most common complications include systemic RV dysfunction and HF, progressive TR and heart block.

Follow-up

Patients with ccTGA should be seen annually in a specialist ACHD quaternary centre.

Conclusion

The population of adults living with CHD is increasing due to advances in surgical and catheter-based interventions. A basic understanding of moderately complex ACHD lesions is important for both acute and general physicians. These previously asymptomatic patients may not present with an established diagnosis of ACHD on the general cardiology take, but, even when they do, can still bewilder the non-ACHD specialist. With this article, the authors hope to instil confidence in all cardiologists managing patients with moderately complex lesions, by providing a good foundation in the anatomy and pathophysiology, and familiarising readers with the often-impenetrable nomenclature and abbreviations.

Key messages

• Patients with moderately complex adult congenital heart disease (ACHD) should be followed-up in specialised quaternary surgical centres
• Complications are common in all ACHD lesions, including arrhythmia, endocarditis, valvular regurgitation and ventricular dysfunction
• Somewhat surprisingly, patients with lesions, such as partial atrioventricular septal defect (AVSD), Ebstein’s and congenitally corrected transposition of the great arteries (ccTGA), can present for the first time in middle age
• Associated lesions are common in moderately complex ACHD, both cardiac and non-cardiac, which may influence presentation and management
• A common complication following repair of a regurgitant valve, e.g. mitral, is stenosis, and a common complication following repair of a stenotic valve, e.g. pulmonary, is regurgitation

Conflicts of interest

None declared.

Funding

None.

References

1. Prica M, Kamalathasan S, Gopaul K, Warriner D. Adult congenital heart disease: a review of the simple lesions. Br J Hosp Med (Lond) 2022;83:1–12. https://doi.org/10.12968/hmed.2021.0302

2. Liu Y, Chen S, Zühlke L et al. Global birth prevalence of congenital heart defects 1970-2017: updated systematic review and meta-analysis of 260 studies. Int J Epidemiol 2019;48:455–63. https://doi.org/10.1093/ije/dyz009

3. Baumgartner H, De Backer J, Babu-Narayan SV et al. 2020 ESC guidelines for the management of adult congenital heart disease. Eur Heart J 2021;42:563–645. https://doi.org/10.1093/eurheartj/ehaa554

4. Craig B. Atrioventricular septal defect: from fetus to adult. Heart 2006;92:1879–85. https://doi.org/10.1136/hrt.2006.093344

5. Feld RH, Du Shane JW, Titus JL. The atrioventricular conduction system in persistent common atrioventricular canal defect: correlations with electrocardiogram. Circulation 1970;42:437–44. https://doi.org/10.1161/01.CIR.42.3.437

6. Ramgren JJ, Nozohoor S, Zindovic I et al. Long-term outcome after early repair of complete atrioventricular septal defect in young infants. J ThoracCardiovasc Surg 2021;161:2145–53. https://doi.org/10.1016/j.jtcvs.2020.08.015

7. Daene M, De Pauw L, De Meester P et al. Outcome of Down patients with repaired versus unrepaired atrioventricular septal defect. Int J Cardiol Congenit Heart Dis 2023;12:100452. https://doi.org/10.1016/j.ijcchd.2023.100452

8. El-Najdawi EK, Driscoll DJ, Puga FJ et al. Operation for partial atrioventricular septal defect: a forty-year review. J Thorac Cardiovasc Surg 2000;119:880–90. https://doi.org/10.1016/S0022-5223(00)70082-1

9. Attenhofer Jost CH, Connolly HM, Dearani JA et al. Ebstein’s anomaly. Circulation 2007;115:277–85. https://doi.org/10.1161/CIRCULATIONAHA.106.619338

10. Gatzoulis MA, Webb GD, Daubeney PEF. Diagnosis and Management of Adult Congenital Heart Disease. Philadelphia, PA: Elsevier, 2018. https://doi.org/10.1016/C2015-0-01488-5

11. Brickner ME, Hillis LD, Lange RA. Congenital heart disease in adults (second of two parts). N Engl J Med 2000;342:334–42. https://doi.org/10.1056/NEJM200002033420507

12. Giuliani ER, Fuster V, Brandenburg RO, Mair DD. Ebstein’s anomaly: the clinical features and natural history of Ebstein’s anomaly of the tricuspid valve. Mayo Clin Proc 1979;54:163–73. https://doi.org/10.1016/S0025-6196(25)19026-5

13. Hebe J. Ebstein’s anomaly in adults. Arrhythmias: diagnosis and therapeutic approach. Thorac Cardiovasc Surg 2000;48:214–19. https://doi.org/10.1055/s-2000-6897

14. Khairy P, Marelli AJ. Clinical use of electrocardiography in adults with congenital heart disease. Circulation 2007;116:2734–46. https://doi.org/10.1161/CIRCULATIONAHA.107.691568

15. He B, Merriman A, Cakulev I et al. Ebstein’s anomaly: review of arrhythmia types and morphogenesis of the anomaly. J Am Coll Cardiol EP 2021;7:1198–206. https://doi.org/10.1016/j.jacep.2021.05.008

16. Villafañe J, Feinstein JA, Jenkins KJ et al. Hot topics in tetralogy of Fallot. J Am Coll Cardiol 2013;62:2155–66. https://doi.org/10.1016/j.jacc.2013.07.100

17. Sommer RJ, Hijazi ZM, Rhodes JF. Pathophysiology of congenital heart disease in the adult. Part III: complex congenital heart disease. Circulation 2018;117:1340–50. https://doi.org/10.1161/CIRCULATIONAHA.107.714428

18. Wu MH, Lu CW, Chen HC, Kao FY, Huang SK. Adult congenital heart disease in a nationwide population 2000–2014: epidemiological trends, arrhythmia, and standardized mortality ratio. J Am Heart Assoc 2018;7:e007907. https://doi.org/10.1161/JAHA.117.007907

19. Smith CA, McCracken C, Thomas AS et al. Long-term outcomes of tetralogy of Fallot: a study from the Pediatric Cardiac Care Consortium. JAMA Cardiol 2019;4:34–41. https://doi.org/10.1001/jamacardio.2018.4255

20. Diller G-P, Kempny A, Alonso-Gonzalez R et al. Survival prospects and circumstances of death in contemporary adult congenital heart disease patients under follow-up at a large tertiary centre. Circulation 2015;132:2118–25. https://doi.org/10.1161/CIRCULATIONAHA.115.017202

21. Hirsch JC, Mosca RS, Bove EL. Complete repair of tetralogy of Fallot in the neonate: results in the modern era. Ann Surg 2000;232:508–14. https://doi.org/10.1097/00000658-200010000-00006

22. Martins P, Castela E. Transposition of the great arteries. Orphanet J Rare Dis 2008;3:27. https://doi.org/10.1186/1750-1172-3-27

23. Kiener A, Kelleman M, McCracken C et al. Long-term survival following arterial vs. atrial switch in d-transposition of the great arteries. Ann Thorac Surg 2018;106:1827–33. https://doi.org/10.1016/j.athoracsur.2018.06.084

24. Haeffele C, Lui G. Dextro-transposition of the great arteries: long-term sequelae of atrial and arterial switch. Cardiol Clin 2015;33:543–58. https://doi.org/10.1016/j.ccl.2015.07.012

25. Fusco F, Scognamiglio G, Merola A et al. Safety and efficacy of sacubitril/valsartan in patients with a failing systemic right ventricle: a prospective single-center study. Circ Heart Fail 2023;16:e009848. https://doi.org/10.1161/CIRCHEARTFAILURE.122.009848

26. Neijenhuis RML, MacDonald ST, Zemrak F et al. Effect of sodium-glucose cotransporter 2 inhibitors in adults with congenital heart disease. J Am Coll Cardiol 2023;83:1403–14. https://doi.org/10.1016/j.jacc.2024.02.017

27. Jonas RA. The arterial switch operation in 2019: how to do it and how to teach it. World J Pediatr Congenit Heart Surg 2019;10:90–7. https://doi.org/10.1177/2150135118811115

28. Breinholt JP, John S. Management of the adult with arterial switch. Methodist Debakey Cardiovasc J 2019;15:133–7. https://doi.org/10.14797/mdcj-15-2-133

29. Wallis GA, Debich-Spicer D, Anderson RH. Congenitally corrected transposition. Orphanet J Rare Dis 2011;6:22. https://doi.org/10.1186/1750-1172-6-22

30. Beauchesne LM, Warnes CA, Connolly HM. Outcome of the unoperated adult who presents with congenitally corrected transposition of the great arteries. J Am Coll Cardiol 2002;40:285–90. https://doi.org/10.1016/S0735-1097(02)01952-6