Long-term outcome after the arterial switch operation: 43 years of experience

Decreased clinical performance in TGA-ASO patients after RVOT interventions; a multicenter European collaboration

BACKGROUND

In patients with transposition of the great arteries and an arterial switch operation (TGA-ASO) right ventricular outflow tract (RVOT) obstruction is a common complication requiring one or more RVOT interventions.

OBJECTIVES

We aimed to assess cardiopulmonary exercise capacity and right ventricular function in patients stratified for type of RVOT intervention.

METHODS

TGA-ASO patients (≥16 years) were stratified by type of RVOT intervention. The following outcome parameters were included: predicted (%) peak oxygen uptake (peak VO2), tricuspid annular plane systolic excursion (TAPSE), tricuspid Lateral Annular Systolic Velocity (TV S'), right ventricle (RV)-arterial coupling (defined as TAPSE/RV systolic pressure ratio), and N-terminal proBNP (NT-proBNP).

RESULTS

447 TGA patients with a mean age of 25.0 (interquartile range (IQR) 21-29) years were included. Patients without previous RVOT intervention (n = 338, 76%) had a significantly higher predicted peak VO2 (78.0 ± 17.4%) compared to patients with single approach catheter-based RVOT intervention (73.7 ± 12.7%), single approach surgical RVOT intervention (73.8 ± 28.1%), and patients with multiple approach RVOT intervention (66.2 ± 14.0%, p = 0.021). RV-arterial coupling was found to be significantly lower in patients with prior catheter-based and/or surgical RVOT intervention compared to patients without any RVOT intervention (p = 0.029).

CONCLUSIONS

TGA patients after a successful arterial switch repair have a decreased exercise capacity. A considerable amount of TGA patients with either catheter or surgical RVOT intervention perform significantly worse compared to patients without RVOT interventions.

The impact of unilateral pulmonary artery stenosis on right ventricular to pulmonary arterial coupling in patients with transposition of the great arteries

BACKGROUND

Unilateral pulmonary artery (PA) stenosis is common in the transposition of the great arteries (TGA) after arterial switch operation (ASO) but the effects on the right ventricle (RV) remain unclear.

AIMS

To assess the effects of unilateral PA stenosis on RV afterload and function in pediatric patients with TGA-ASO.

METHODS

In this retrospective study, eight TGA patients with unilateral PA stenosis underwent heart catheterization and cardiac magnetic resonance (CMR) imaging. RV pressures, RV afterload (arterial elastance [Ea]), PA compliance, RV contractility (end-systolic elastance [Ees]), RV-to-PA (RV-PA) coupling (Ees/Ea), and RV diastolic stiffness (end-diastolic elastance [Eed]) were analyzed and compared to normal values from the literature.

RESULTS

In all TGA patients (mean age 12 ± 3 years), RV afterload (Ea) and RV pressures were increased whereas PA compliance was reduced. RV contractility (Ees) was decreased resulting in RV-PA uncoupling. RV diastolic stiffness (Eed) was increased. CMR-derived RV volumes, mass, and ejection fraction were preserved.

CONCLUSION

Unilateral PA stenosis results in an increased RV afterload in TGA patients after ASO. RV remodeling and function remain within normal limits when analyzed by CMR but RV pressure-volume loop analysis shows impaired RV diastolic stiffness and RV contractility leading to RV-PA uncoupling.

Outcomes of neo-aortic valve and root surgery late after arterial switch operation

BACKGROUND

Neo-aortic root dilatation and valve regurgitation are emerging problems late after arterial switch operation (ASO). We sought to evaluate the prevalence and outcomes of neo-aortic root or valve reoperation after ASO.

METHODS

All patients with biventricular circulation who underwent an ASO between 1983 and 2015 were included at a single institution.

RESULTS

In our cohort of 782 late ASO survivors, the median duration of follow-up was 18.1 years (interquartile range [IQR], 11.3-25.6 years). During follow-up, 47 patients (6.0%) underwent 60 reoperations on the neo-aortic valve/root. The first neo-aortic valve/root reoperation occurred at a median of 15.2 years (IQR, 7.8-18.4 years) after ASO. Operations included mechanical Bentall (31.9%; n = 15), aortic valve repair (25.5%; n = 12), mechanical aortic valve replacement (AVR) (21.3%; n = 10), valve-sparing root replacement (19.1%; n = 9), and the Ross procedure (2.1%; n = 1). There was 1 late death (2.1%). Multivariable predictors of neo-aortic valve/root reoperation were bicuspid valve (hazard ratio [HR], 4.8; 95% confidence interval [CI], 2.1-10.7; P < .001), Taussig-Bing anomaly (HR, 3.0; 95% CI, 1.2-7.4; P < .02), previous pulmonary artery band (HR, 2.8; 95% CI, 1.2-6.3; P < .01) and left ventricular outflow tract obstruction before ASO (HR, 2.4; 95% CI, 1.0-5.8; P < .04). Freedom from neo-aortic valve or root reoperation was 98.0% (95% CI, 96.7%-98.8%) at 10 years, 93.3% (95% CI, 90.8%-95.2%) at 20 years, and 88.5% (95% CI, 84.1%-91.8%) at 30 years after ASO. Among the 47 patients who underwent neo-aortic reoperation, freedom from AVR was 82.3% (95% CI, 67.7%-90.7%) at 10 years, 58.0% (95% CI, 41.8%-71.2%) at 20 years, and 43.2% (95% CI, 27.0%-58.3%) at 25 years after ASO.

CONCLUSIONS

The need for neo-aortic valve or root reoperation surpasses 10% by 30 years post-ASO. Evolving understanding of the mechanisms of neo-aortic valve insufficiency and techniques of neo-aortic valve repair may decrease the need for AVR.

The effects of percutaneous branch pulmonary artery interventions on exercise capacity, lung perfusion, and right ventricular function in biventricular CHD: a systematic review

BACKGROUND

Branch pulmonary artery stenosis is common after surgical repair in patients with biventricular CHD and often requires reinterventions. However, (long-term) effects of percutaneous branch pulmonary artery interventions on exercise capacity, right ventricular function, and lung perfusion remain unclear. This review describes the (long-term) effects of percutaneous branch pulmonary artery interventions on exercise capacity, right ventricular function, and lung perfusion following PRISMA guidelines.

METHODS

We performed a systematic search in PubMed, Embase, and Cochrane including studies about right ventricular function, exercise capacity, and lung perfusion after percutaneous branch pulmonary artery interventions. Study selection, data extraction, and quality assessment were performed by two researchers independently.

RESULTS

In total, 7 eligible studies with low (n = 2) and moderate (n = 5) risk of bias with in total 330 patients reported on right ventricular function (n = 1), exercise capacity (n = 2), and lung perfusion (n = 7). Exercise capacity and lung perfusion seem to improve after a percutaneous intervention for branch pulmonary artery stenosis. No conclusions about right ventricular function or remodelling, differences between balloon and stent angioplasty or specific CHD populations could be made.

CONCLUSION

Although pulmonary artery interventions are frequently performed in biventricular CHD, data on relevant outcome parameters such as exercise capacity, lung perfusion, and right ventricular function are largely lacking. An increase in exercise capacity and improvement of lung perfusion to the affected lung has been described in case of mild to more severe pulmonary artery stenosis during relatively short follow-up. However, there is need for future studies to evaluate the effect of pulmonary artery interventions in various CHD populations.

Persistent neo-aortic root dilatation and aortic valve insufficiency after arterial switch operation following prior pulmonary artery banding

Although there have been great improvements in the short- and medium-term outcomes of the arterial switch operation (ASO) for transposition of the great arteries (TGA), some complications including pulmonary artery stenosis, aortic valve insufficiency, and aortic root dilatation have also been reported. After ASO, the original pulmonary root and valve, which function in the systemic position as the neo-aortic root and valve respectively, are exposed to the systemic blood pressure, resulting in aortic root dilatation and valve insufficiency in some patients. One of the risk factors for these complications is a history of prior pulmonary artery banding (PAB). Complex TGA anatomy, including transposition of the great arteries and ventricular septal defect (TGA-VSD) or double outlet right ventricle and ventricular septal defect (DORV-VSD), is also an independent risk factor for neo-aortic dilatation and aortic valve regurgitation. Aortic valve and root replacement is sometime necessary for the patients with these pathologies long-term after ASO. Here, we present a patient who had persistent aortic sinus dilatation and aortic valve insufficiency since ASO and necessitating aortic root and valve replacement 15 years after ASO preceded by PAB. The patient underwent Bentall operation and his clinical course was favorable. Histological findings after root replacement revealed no remarkable structural difference between neo-aortic wall (originally pulmonary artery) and original aortic wall.

Outcomes of coronary artery obstructions after the arterial switch operation for transposition of the great arteries

OBJECTIVE

Coronary obstruction is a rare but common complication of the arterial switch operation for transposition of the great arteries. The majority of patients remain asymptomatic and no risk factors allow targeting for reinforced surveillance. We aim to review the natural history of patients diagnosed with coronary obstruction after arterial switch operation for transposition of the great arteries and occurrence of coronary-related outcomes.

METHODS

We retrospectively reviewed medical records of the 102 patients diagnosed with coronary obstruction after arterial switch operation for transposition of the great arteries in our institution from 1981 to 2022. Outcomes were anti-ischemic treatment introduction, revascularization (surgical or percutaneous angioplasty), and death; investigations that motivated revascularization were also reviewed.

RESULTS

Twenty-eight out of 102 patients presented with myocardial ischemia during the immediate postoperative phase, 31 were diagnosed when symptomatic, and 43 were identified at the presymptomatic stage, according to our screening policy in preschool-aged children. Stenosis-related event occurrence was, respectively, 29 out of 31 and 32 out of 43 in the latter 2 subgroups. Coronary-related mortality reached 10% in patients diagnosed when symptomatic; no patients died in the presymptomatic subgroup. Of the 28 low-risk patients with no signs of ischemia at diagnosis, 10 developed obstruction warranting reintervention during follow-up. Revascularization was motivated by appearance of symptoms in patients with severe stenosis in normal coronary dispositions, and by clinical symptoms or documented silent ischemia in abnormal coronary patterns.

CONCLUSIONS

Occurrence of stenosis-related events remains significant in patients after arterial switch operation, underlining the importance of early diagnosis for timely intervention. Initial anatomical evaluation identifies stenotic and at-risk patients; this will require periodical function testing. Follow-up modalities can be tailored to a patient's individual anatomic characteristics.

Paediatric quality of life in toddlers and children who underwent arterial switch operation beyond early neonatal period

OBJECTIVES

The aim of this study was to evaluate the quality of life (QOL) of children who underwent the arterial switch operation (ASO) for Transposition of Great Arteries in our population and, specifically, to explore early modifiable factors and the influence of parental and socioeconomic factors on the QOL of these children.

METHODS

Cross-sectional study using Paediatric Quality of Life Inventory™ 3.0 Cardiac Module was carried out on 3- to 12-year-old children who had undergone ASO between the years 2012-2018. Socioeconomic status was calculated using the modified Kuppuswamy scale (2019). Other clinical factors with possible bearing on the outcome were also analysed.

RESULTS

Immediate survival after surgery was 196 out of 208 (94.2%) with an attrition of 19 patients (9.6%) over the follow-up period. Most surviving children (98.9%) had started formal schooling in age-appropriate classes. Two children had severe neuromotor impairment. The median cumulative health-related QOL score of the children was 97.9 (interquartile range 4.2) at 5.6 ± 1.27 years of life. The median scores each of the health-related QOL parameters, viz, heart problem symptoms, treatment compliance, perceived physical appearance, treatment-related anxiety, cognitive problems, and communication was 100 with negative skewing.

CONCLUSIONS

Excellent QOL was observed in most children after ASO with the median total paediatric QOL scores in all domains of 97.9. Social factors did not show a statistically significant influence on the QOL parameters in the current cohort. The gradually declining trend across the age groups emphasizes the need for continued follow-up for early identification of possible correctable factors and initiating intervention to ensure good QOL into teenage and adulthood.

Simultaneous Double Balloon Dilatation for Supravalvar Pulmonary Obstruction After Arterial Switch Operation

The optimal approach for supravalvar right ventricular outflow tract obstruction(RVOTO) after arterial switch operation(ASO) is unclear. The results of percutaneous balloon dilatation have been variable. We report the results of simultaneous double balloon dilation for RVOTO after ASO. Sixteen patients (1.3(0.7-3.8) years; 9.8(8.1-15.1) kgs underwent the procedure at 14(8-44.5) months after ASO. Salient technical features included placement of balloons over stiff guide-wires positioned in both branch pulmonary arteries to enable dilation of the distal-most main pulmonary artery (MPA) with high inflation pressures (~ 12-14 atmospheres) and short inflation-deflation cycles. Effective balloon size was based on the PA annulus or MPA distal to the narrowing. The final balloon: narrowest segment diameter ratio was 2.7. Following dilation, the right ventricle to systemic systolic pressure ratio decreased from 0.9 ± 0.18 to 0.52 ± 0.16 (p  < 0.001) and mean RVOT gradient from 78 ± 18 to 34 ± 13.9 mmHg (p < 0.001). Narrowest diameter improved from 5.4 ± 2.2 to 9.2 ± 2.2 mm. There were no major complications. Two patients with inadequate relief (final RV-systemic ratios: 1.03 and 0.7) were referred for surgery. At median follow up of 9 months, IQR 7-22, range 5-73, others are free of re interventions with median RVOT gradient of 42, IQR 27-49, range 21-55 mmHg. The immediate and short-term follow up results of double balloon dilatation for supravalvar RVOTO is encouraging and may avoid the need for repeat surgery in the majority of patients. Further follow up is needed to determine the long-term durability of the results.

30 years' experience with the arterial switch operation: risk of pulmonary stenosis and its impact on post-operative prognosis

Pulmonary stenosis is one of the most common complications in patients with transposition of the great arteries after the arterial switch operation. The reason for this is multifactorial and related to the anterior shift of the pulmonary trunk during the LeCompte manoeuvre, the complex suture line required to fill the gaps after harvesting the coronary arteries, and the need for patch implantation to maintain a tensionless anastomosis.We reviewed all patients with transposition of the great arteries operated on at our institute between 1991 and 2020 to establish the frequency of pulmonary stenosis during post-operative follow-up, reinterventions, and reoperations related to pulmonary stenosis and its potential risk factors.During the analysed period, we performed 848 arterial switch operations for simple and complex cases of transposition of the great arteries. The overall early mortality was 6.96%, and the late mortality was 2.53%. Among all study groups, 243 (28.66%) patients developed mild pulmonary stenosis, 43 patients (5.07%) developed moderate, and 45 patients (5.31%) developed severe pulmonary stenosis. During follow-up, 21 patients required interventions related to pulmonary stenosis. Pulmonary reconstruction with patches, aortic arch anomalies, and ventricular septal defects associated with transposition of the great arteries were significant risk factors. Nine patients required reoperation because of pulmonary artery stenosis with patch reconstruction of the pulmonary artery, aortic arch anomalies, and aortic cross-clamping time, increasing the risk of reoperation.Pulmonary stenosis in patients with transposition of the great arteries after the arterial switch operation is a common complication. If significant, it occurs early after surgery and is the most frequent reason for post-operative interventions and reoperations.

A new predictor of the optimal pulmonary artery reconstruction method during the arterial switch operation

OBJECTIVES

The aim of this study was to more accurately predict the optimal pulmonary artery (PA) reconstruction procedure (Lecompte manoeuvre or original Jatene procedure) during the arterial switch operation, we focused on the horizontal sectioning (HS) angle between the left hilum PA and the great arteries using preoperative computed tomography imaging.

METHODS

We defined the HS angle α (β) as the angle between the tangential line from the posterior (anterior) wall of the left PA at the hilum to the left anterior (right posterior) surface of the main PA and the tangential line from the left surface of the ascending aorta to the left anterior (right posterior) surface of the main PA. We identified 14 consecutive patients diagnosed with transposition of the great arteries or transposition of the great artery-type double-outlet right ventricle who underwent preoperative computed tomography imaging. The original Jatene or Lecompte procedure was used for 9 (OJ group) and 5 (L group) patients. Relationships of the great arteries of the OJ and L groups were side by side in 8 and 2 patients, oblique in 1 and 1 patient and anteroposterior in 0 and 2 patients, respectively.

RESULTS

In the OJ group, β was greater than α in all patients. The median α/β value was 0.618. In group L, α was greater than β in all patients. The median α/β was 1.307. Left PA stenosis caused by stretching was not observed in the L group. Coronary obstruction was not identified in the OJ group. Left PA stenosis behind the neo-ascending aorta was observed in 1 patient in the OJ group and required reoperation.

CONCLUSIONS

The HS angle may be a useful predictor of optimal intraoperative PA reconstruction during arterial switch operation, especially for side-by-side or oblique relationships.

Cardiac Fibrosis and Innervation State in Uncorrected and Corrected Transposition of the Great Arteries: A Postmortem Histological Analysis and Systematic Review

In the transposition of the great arteries (TGA), alterations in hemodynamics and oxygen saturation could result in fibrotic remodeling, but histological studies are scarce. We aimed to investigate fibrosis and innervation state in the full spectrum of TGA and correlate findings to clinical literature. Twenty-two human postmortem TGA hearts, including TGA without surgical correction (n = 8), after Mustard/Senning (n = 6), and arterial switch operation (ASO, n = 8), were studied. In newborn uncorrected TGA specimens (1 day-1.5 months), significantly more interstitial fibrosis (8.6% ± 3.0) was observed compared to control hearts (5.4% ± 0.8, p = 0.016). After the Mustard/Senning procedure, the amount of interstitial fibrosis was significantly higher (19.8% ± 5.1, p = 0.002), remarkably more in the subpulmonary left ventricle (LV) than in the systemic right ventricle (RV). In TGA-ASO, an increased amount of fibrosis was found in one adult specimen. The amount of innervation was diminished from 3 days after ASO (0.034% ± 0.017) compared to uncorrected TGA (0.082% ± 0.026, p = 0.036). In conclusion, in these selected postmortem TGA specimens, diffuse interstitial fibrosis was already present in newborn hearts, suggesting that altered oxygen saturations may already impact myocardial structure in the fetal phase. TGA-Mustard/Senning specimens showed diffuse myocardial fibrosis in the systemic RV and, remarkably, in the LV. Post-ASO, decreased uptake of nerve staining was observed, implicating (partial) myocardial denervation after ASO.

Right Ventricular Systolic Dysfunction in Adults With Anatomic Repair of d-Transposition of Great Arteries

The purpose of this study was to assess the prevalence of right ventricular (RV) systolic dysfunction in adults with anatomic repair of dextro-transposition of great arteries (d-TGAs), and to determine its relation to clinical outcomes across multiple domains (functional status, peak oxygen consumption, N-terminal pro-brain natriuretic peptide, and heart failure hospitalization). Adults with anatomic repair for d-TGA and with echocardiographic images for strain analysis were divided into 2 groups: (1) d-TGA status after an arterial switch operation (d-TGA-ASO group) and (2) d-TGA status after a Rastelli operation (d-TGA-Rastelli group). RV systolic function was assessed using RV global longitudinal strain (RVGLS), and RV systolic dysfunction was defined as RVGLS >-18%. We identified 151 patients (median age 21 years [19 to 28]; d-TGA-ASO group 89 [59%], and d-TGA-Rastelli group 62 [41%]). The mean RVGLS was -22 ± 4%, and 47 patients (31%) had RV systolic dysfunction. The d-TGA-Rastelli group had lower (less negative) RVGLS than that of the d-TGA-ASO group (-19 ± 3% vs -25 ± 3%, p <0.001) and higher prevalence of RV systolic dysfunction (48% vs 19%, p <0.001). RVGLS (absolute value) was associated with peak oxygen consumption (r = 0.58, p <0.001; adjusted R2 = 0.28), log-N-terminal pro-brain natriuretic peptide (r = -0.41, p = 0.004; adjusted R2 = 0.21), New York Heart Association class III/IV (odds ratio 2.29, 1.56 to 3.19, p = 0.01), and heart failure hospitalization (hazard ratio 0.93, 0.88 to 0.98, p = 0.009). RV systolic dysfunction was common in adults with d-TGA and anatomic repair and was associated with clinical outcomes. Longitudinal studies are required to determine the risk factors for progressive RV systolic dysfunction and to identify strategies for preventing RV systolic dysfunction in this population.

Anesthetic Considerations for Adult Patients With Both Down Syndrome and Congenital Heart Disease Undergoing Noncardiac Surgery: A Review Article

The population of adult patients with both Down syndrome and congenital heart disease is increasing due to better medical and surgical care. This cohort presents with multiple unique comorbidities, secondary to both progressions of health conditions associated with the aging of patients with Down syndrome, as well as due to pathophysiologic effects of uncorrected, corrected, or palliated congenital heart disease. These patients need frequent medical care and interventions requiring multiple anesthetics. This review focuses on the various factors relevant to the perioperative medical care of adult patients with both Down syndrome and congenital heart disease, founded on existing literature. Various anesthetic considerations for the different patterns of noncardiac and cardiac comorbidities are reviewed, and a systematic approach for the perioperative anesthetic management of these patients is presented.

Comprehensive outcomes after primary arterial switch operation

OBJECTIVE

To report the long-term outcomes of the arterial switch operation for transposition of the great arteries.

METHODS

The data of 35 patients who underwent an arterial switch operation between April 2006 and May 2021 were retrospectively examined; five had double-outlet right ventricles, three had side-by-side transposition, and 27 had d-transposition. The punch-out technique was the basic method for coronary transplantation; however, if coronary artery kinking after additional peeling was a concern, the trap-door technique was used. In aortic reconstruction, the caliber difference between the neoascending aorta and the native pulmonary artery was fixed using the pulmonary artery flap. In pulmonary reconstruction, the pulmonary artery was bilaterally exposed over the second branch.

RESULTS

The median age at operation and follow-up duration were 10.0 (8.0-12.5) days and 72.9 (40.7-139.5) months, respectively. Thirty-four patients survived, and one was lost to follow-up ([coronary transplantation]: right coronary artery, punch-out = 31, trap-door = 2; left coronary artery, punch-out = 28, trap-door = 7; [aortic regurgitation]: no-slight = 27, mild = 6, moderate = 1; [pulmonary regurgitation]: no-slight = 22, mild = 11, moderate = 1). Slight coronary bending occurred in two patients; ischemia was not observed. Catheter stent placement was performed in one of three patients with stenosis at the pulmonary artery bifurcation. Catheter balloon dilation was performed in one patient with supravalvular pulmonary stenosis. There were no cases of coronary, aortic, or pulmonary artery reoperations. The 15-year cumulative reintervention avoidance rate was 91.0%.

CONCLUSIONS

There were no deaths or reoperations during the long-term follow-up period, and arterial switch operation outcomes at our hospital were satisfactory.

Anomalous connection of the circumflex coronary artery to the pulmonary trunk in a patient with Taussig–Bing anomaly: a case report

Background

Coronary anomalies are present in one-third of all patients with transposition of the great arteries (TGA) and have been associated with increased risk of adverse outcomes after the arterial switch operation. Therefore, knowledge about coronary anatomy remains key.

Case summary

A 5-day-old girl with prenatal diagnosis of Taussig–Bing anomaly (double outlet right ventricle with TGA and large subpulmonary ventricular septal defect) along with aortic arch hypoplasia and coarctation of the aorta underwent the arterial switch operation with closure of the ventricular septal defect and aortic arch repair. On preoperative echocardiography, the right (R) and left coronary artery (LCx) connected both to aortic sinus 1, suggesting 1RLCx coronary anatomy according to the Leiden Convention coronary coding system. However, intraoperative inspection led to a reclassification of the coronary anatomy: the right coronary artery and left anterior descending coronary artery connected to aortic sinus 1 (1RL) as had been observed on echocardiography, but—remarkably—the circumflex coronary artery (Cx) connected to the posterior sinus of the pulmonary trunk. As a consequence, cardioplegia was administered into both the aortic and pulmonary roots, and the circumflex coronary artery could stay in its native position without having to be transferred during the arterial switch operation.

Discussion

Various disruptions during embryological development can lead to unusual coronary anatomy in TGA patients. While anomalous connection of a coronary artery to the pulmonary trunk remains exceedingly rare, care should be taken to identify this pattern when present as failure to do so may result in adverse outcomes.

Myocardial fibrosis in congenital heart disease

Myocardial fibrosis resulting from the excessive deposition of collagen fibers through the myocardium is a common histopathologic finding in a wide range of cardiovascular diseases, including congenital anomalies. Interstitial fibrosis has been identified as a major cause of myocardial dysfunction since it distorts the normal architecture of the myocardium and impairs the biological function and properties of the interstitium. This review summarizes current knowledge on the mechanisms and detrimental consequences of myocardial fibrosis in heart failure and arrhythmias, discusses the usefulness of available imaging techniques and circulating biomarkers to assess this entity and reviews the current body of evidence regarding myocardial fibrosis in the different subsets of congenital heart diseases with implications in research and treatment.