Pulmonary artery remodeling in transposition of the great arteries: relevance for neoaortic root dilatation

Growth of the Neo-Aortic Root and Prognosis of Transposition of the Great Arteries

BACKGROUND

Neo-aortic root dilatation can lead to significant late morbidity after the arterial switch operation (ASO) for dextro-transposition of the great arteries (d-TGA).

OBJECTIVES

We sought to examine the growth of the neo-aortic root in d-TGA.

METHODS

A single-center, retrospective cohort study of patients who underwent the ASO between July 1, 1981 and September 30, 2022 was performed. Morphology was categorized as dextro-transposition of the great arteries with intact ventricular septum (d-TGA-IVS), dextro-transposition of the great arteries with ventricular septal defect (d-TGA-VSD), and double-outlet right ventricle-transposition of the great arteries type (DORV-TGA). Echocardiographically determined diameters and derived z scores were measured at the annulus, sinus of Valsalva, and sinotubular junction immediately before the ASO and throughout follow-up. Trends in root dimensions over time were assessed using linear mixed-effects models. The association between intrinsic morphology and the composite of moderate-severe aortic regurgitation (AR) and neo-aortic valve or root intervention was evaluated with univariable and multivariable Cox proportional hazards models.

RESULTS

Of 1,359 patients who underwent the ASO, 593 (44%), 666 (49%), and 100 (7%) patients had d-TGA-IVS, d-TGA-VSD, and DORV-TGA, respectively. Each patient underwent a median of 5 echocardiograms (Q1-Q3: 3-10 echocardiograms) over a median follow-up of 8.6 years (range: 0.1-39.3 years). At 30 years, patients with DORV-TGA demonstrated greater annular (P < 0.001), sinus of Valsalva (P = 0.039), and sinotubular junction (P = 0.041) dilatation relative to patients with d-TGA-IVS. On multivariable analysis, intrinsic anatomy, older age at ASO, at least mild AR at baseline, and high-risk root dilatation were associated with moderate-severe AR and neo-aortic valve or root intervention at late follow-up (all P < 0.05).

CONCLUSIONS

Longitudinal surveillance of the neo-aortic root is warranted long after the ASO.

Non-physiological Aortic Flow and Aortopathy in Adult Patients with Transposition of the Great Arteries after the Jatene Procedure: A Pilot Study Using Echo Planar 4D Flow MRI

Purpose

Dilated aortic root and ascending aorta (AAO) with progressive aortic regurgitation is a well-known sequela after arterial switch operation (ASO) in adults with transposition of the great arteries (TGA). We aimed to quantitatively assess aortic flow profiles in adults with TGA after ASO (Jatene procedure with LeCompte maneuver) using echo planar imaging (EPI) 4D flow MRI.

Methods

Prospectively, 9 consecutive adults (30.2 ± 6.6 years) after ASO (Jatene operation with LeCompte technique), 13 consecutive adults (34.3 ± 7.2 years) after the atrial switch operation with Senning procedure, and 8 age-matched control patients, who underwent turbo field echo (TFE) EPI 4D flow MRI (average scan time of approximately 4 min), were enrolled.

Results

TGA after ASO showed a markedly dilated sinus of Valsalva, compared to TGA after atrial switch operation (26.6. ± 4.9 vs. 18.6. ± 1.5 mm/cm²). Vorticity, helicity, wall share stress (WSS), and energy loss (EL) in the aortic root and the AAO in TGA were greater than in the controls. Vorticity, helicity, WSS, and EL in the aortic root and the AAO were also greater in TGA after ASO than after atrial switch operation. More acute aortic arch angle correlated with greater vorticity of the aortic root, and the significant diameter ratio of the sinus of Valsalva and the AAO was relevant to greater vorticity, helicity, and EL in TGA after ASO.

Conclusion

A non-physiological blood flow pattern of the aortic root was identified in TGA adults after the ASO (Jatene procedure with LeCompte maneuver). Missing spiral looping of the great arteries and the unique structure after the Jatene procedure may play an adjunctive role in promoting aortopathy. The evaluation of aortic flow profile using EPI 4D flow MRI may be useful for risk stratification for aortopathy in this population.

Neo-aortic posterior sinus of Valsalva reduction and closed coronary artery transfer as a method to approach aortopulmonary mismatch in transposition of great arteries

OBJECTIVE

In transposition of great arteries (TGA), aortopulmonary mismatch (APM) can determine postoperative neo-aortic insufficiency after arterial switch operation (ASO). The distortion of sinu-tubular junction may be the geometric mechanism responsible. We developed a strategy able to reduce the mismatch at the timing of ASO, and in this study, we aimed to describe our indications and results.

METHODS

Preoperative root circumferences at the level of the mid-portion of sinus of Valsalva and ascending aorta circumference were used to define APM. Indication to surgery was a neo-aortic root (NAR) to ascending aorta ratio ≥ 1.4. Along with standard ASO, posterior neo-aortic sinus inverted conal resection and punch technique for coronary reimplantation was used in all patients to re-establish the more geometric ratio possible between the two components. Hypoplastic aortic arch (HAA) and aortic coarctation (CA) were managed by aortic arch enlargement with an autologous pericardial patch.

RESULTS

Twenty patients (20 male), 19 with diagnoses TGA (17 with ventricular septal defect, 85%) and 1 with Taussig-Bing anomaly underwent ASO. HAA was present in three (15%) and CA in two (10%). The mean preoperative neo-aortic to ascending aorta ratio was 1.8 versus 1.1 postoperatively (p < .01). No moderate or severe neo-aortic insufficiency was observed before discharge and at a mean follow-up of 4.3 years (interquartile range = 0.5-12 years).

CONCLUSION

Neo-aortic reduction plasty with coronary reimplantation by punch technique is an effective strategy to approach preoperative APM in TGA. This technique confers a more harmonious geometry to NAR that can improve neo-aortic valve function.

Urgent neonatal balloon atrial septostomy in simple transposition of the great arteries: predictive value of fetal cardiac parameters

OBJECTIVES

To investigate the impact of abnormal perinatal loading conditions on cardiac geometry and function in term fetuses and neonates with transposition of the great arteries with intact interventricular septum (simple TGA), and to explore the predictive value of fetal cardiac parameters for an urgent balloon atrial septostomy (BAS) after birth.

METHODS

This was a prospective longitudinal follow-up study of women delivering at term, including both uncomplicated pregnancies with normal outcome and pregnancies affected by fetal simple TGA. Conventional, spectral-tissue Doppler and speckle-tracking echocardiographic parameters were obtained within 1 week before delivery and within the first few hours after delivery. Neonates with simple TGA that required urgent BAS were assessed after the procedure and before corrective arterial switch surgery. Cardiac parameters were normalized by cardiac cycle length, ventricular end-diastolic length or end-diastolic dimension, as appropriate. Fetal and neonatal cardiac parameters were compared between simple-TGA cases and controls, and perinatal changes in the simple-TGA group were assessed. Receiver-operating-characteristics (ROC)-curve analysis was used to assess the predictive value of fetal cardiac parameters for urgent BAS after birth in the simple-TGA group.

RESULTS

A total of 67 pregnant women delivering at term were included in the study (54 normal pregnancies and 13 with a diagnosis of fetal simple TGA). Compared with normal term fetuses, term fetuses with simple TGA exhibited more globular hypertrophied ventricles, increased biventricular systolic function and diastolic dysfunction (right ventricular (RV) sphericity index (SI), 0.58 vs 0.54; left ventricular (LV)-SI, 0.55 vs 0.49; combined cardiac output (CCO), 483 vs 406 mL/min/kg; LV torsion, 4.3 vs 3.0 deg/cm; RV isovolumetric relaxation time (IVRT'), 127 vs 102 ms; P < 0.01 for all). Compared with normal neonates, neonates with simple TGA demonstrated biventricular hypertrophy, a more spherical right ventricle and altered systolic and diastolic functional parameters (RV-SI, 0.61 vs 0.43; RV myocardial performance index, 0.47 vs 0.34; CCO, 697 vs 486 mL/min/kg; LV-IVRT', 100 vs 79 ms; RV-IVRT', 106 vs 71 ms; P < 0.001 for all). Paired comparison of neonatal and fetal cardiac indices in the simple-TGA group showed persistence of the fetal phenotype, increased biventricular systolic myocardial contractility and CCO, and diastolic dysfunction (RV systolic myocardial velocity (S'), 0.31 vs 0.24 cm/s; LV-S', 0.23 vs 0.18 cm/s; CCO, 697 vs 483 mL/min/kg; LV torsion, 1.1 vs 4.3 deg/cm; P < 0.001 for all). Several fetal cardiac parameters in term fetuses with simple TGA demonstrated high predictive value for an urgent BAS procedure after birth. Our proposed novel fetal cardiac index, LV rotation-to-shortening ratio, as a potential marker of subendocardial dysfunction, for a cut-off value of ≥ 0.23, had an area under the ROC curve (AUC) of 0.94, sensitivity of 100% and specificity of 83%. For RV/LV end-diastolic area ratio ≥ 1.33, pulmonary-valve-to-aortic-valve-dimension ratio ≤ 0.89, RV/LV cardiac output ratio ≥ 1.38 and foramen-ovale-dimension-to-total-interatrial-septal-length ratio ≤ 0.27, AUC was 0.93-0.98, sensitivity was 86% and specificity was 83-100% for all.

CONCLUSIONS

Simple-TGA fetuses exhibited cardiac remodeling at term with more profound alterations in these cardiac parameters after birth, suggestive of adaptation to abnormal loading conditions and possible adaptive responses to hypoxemia. Perinatal adaptation in simple TGA might reflect persistence of the abnormal parallel arrangement of cardiovascular circulation and the presence of widely patent fetal shunts imposing volume load on the neonatal heart. The fetal cardiac parameters that showed high predictive value for urgent BAS after birth might reflect the impact of late-gestation pathophysiology and progressive hypoxemia on fetal cardiac geometry and function in simple TGA. If these findings are validated in larger prospective studies, detailed cardiac assessment of fetuses with simple TGA near term could facilitate improvements in perinatal management and refinement of the timing of postnatal intervention strategies to prevent adverse pregnancy outcomes. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

The Development of the Ascending Aortic Wall in Tricuspid and Bicuspid Aortic Valve: A Process from Maturation to Degeneration

Background: Patients with a bicuspid aortic valve (BAV) have an increased risk for aortic dilation and dissection. In this study, we provide a histological stratification of the developing aorta in the tricuspid aortic valve (TAV) and the BAV populations as a reference for future studies on aortopathy and related syndromes. Methods: Non-dilated TAV and BAV ascending aortic wall samples were collected, including 60 TAV (embryonic–70 years) and 32 BAV specimens (fetal–72 years, categorized in eight age groups. Results: In TAV, intimal development starts in the neonatal phase. After birth, the thickness of the medial layer increases significantly by increase of elastic lamellae up to and including the “young child” phase stabilizing afterwards. The BAV shows already prenatal intimal thickening becoming significantly thinner after birth subsequently stabilizing. In BAV, increase in elastic lamellae is seen between the young child and the adolescent phases, stabilizing afterwards. Conclusions: Vascular development in TAV is described in three phases: maturation, stabilization, and degeneration. For BAV, the development can be described in two phases: maturation (already prenatally) and degeneration. After birth, the development of the aorta is characterized by degeneration, leading to weakening of the ascending aortic wall and increasing the risk of aortopathy.

Mechano-biological adaptation of the pulmonary artery exposed to systemic conditions

Cardiac surgeries may expose pulmonary arterial tissue to systemic conditions, potentially resulting in failure of that tissue. Our goal was to quantitatively assess pulmonary artery adaptation due to changes in mechanical environment. In 17 sheep, we placed a pulmonary autograft in aortic position, with or without macroporous mesh reinforcement. It was exposed to systemic conditions for 6 months. All sheep underwent 3 ECG-gated MRI’s. Explanted tissue was subjected to mechanical and histological analysis. Results showed progressive dilatation of the unreinforced autograft, while reinforced autografts stabilized after two months. Some unreinforced pulmonary autograft samples displayed more aorta-like mechanical behavior with increased collagen deposition. The mechanical behavior of reinforced autografts was dominated by the mesh. The decrease in media thickness and loss of vascular smooth muscle cells was more pronounced in reinforced than in unreinforced autografts. In conclusion, altering the mechanical environment of a pulmonary artery causes changes in its mechano-biological properties.

Neoaortic Regurgitation in Patients with Transposition Long Term After an Arterial Switch Operation and Its Relation to the Root Diameters and Surgical Technique Used

Neoaortic regurgitation and root dilatation are common findings in patients with transposition after an arterial switch operation. The aim of this study was to describe the relation between neoaortic regurgitation long term after an arterial switch procedure, aortic root diameters, and surgical technique used. We also assessed the agreement of the neoaortic regurgitation grade and root diameters in different imaging modalities. For this retrospective study, we qualified 56 consecutive patients who, according to our institutional protocol, had a routine postoperative evaluation of more than 16 years with multimodality imaging studies. Neoaortic regurgitation was assessed by both transthoracic echocardiography and magnetic resonance imaging, and the root diameters obtained by echocardiography and tomography were compared to the reference values and associated with the presence of neoaortic insufficiency. Neoaortic insufficiency was present in 75% of examined patients; the vast majority of them had trace or mild regurgitation, and its qualitative evaluation was significantly different between echocardiography and magnetic resonance imaging. In our study group, the neoaortic valve and aortic sinus were larger in relation to the normal values, and they were significantly correlated with the presence of neoaortic insufficiency, but not with the surgical technique used. Values obtained by echocardiography and tomography correlated well but were significantly different. Transthoracic echocardiography has a tendency to overestimate the severity of regurgitation compared to magnetic resonance imaging. Neoaortic valve and sinus dilatation are significantly correlated with valve insufficiency, but in most cases of root dilatation, the valve remains competent.

Transposition of the great arteries: Fetal pulmonary valve growth and postoperative neo-aortic root dilatation

Objectives

Documentation of semilunar valve growth in fetal transposition of the great arteries (TGA) and the relationship between neo‐aortic root (NAoR) dilatation, a cause for postoperative reinterventions after the arterial switch operation (ASO), and pulmonary valve (PV) annulus dimensions prenatally.

Methods

This retrospective multicenter observational study included TGA fetuses suitable for ASO. Semilunar valve annuli pre‐ASO and NAoR diameters (post‐ASO) were measured. Trends in annulus diameters were analyzed using a linear mixed‐effects model and compared with normal values. Prenatal semilunar valve Z‐scores were correlated with NAoR diameters post‐ASO.

Results

We included 137 TGA fetuses (35.8% with significant ventricular septal defects [VSDs]). One hundred twenty‐one underwent ASO. Fetal TGA‐PV diameters were significantly larger than control aortic valve (AoV) and PV annuli from 23 and 27 weeks, respectively, especially when a VSD was present. Fetal TGA‐AoV annuli were significantly larger than control AoV and PV annuli from 26 and 30 weeks, respectively.

Z‐scores of fetal TGA‐PV and NAoR diameter at last follow‐up correlated significantly (P < .001 at 26‐30 wk).

Conclusion

Fetal TGA semilunar valve annuli are larger than control annuli, especially when there is a significant VSD. Factors besides postoperative hemodynamics, including fetal anatomy, PV Z‐score, prenatal flow, connective tissue properties, and genetics, may influence the risk for late reintervention in these fetuses.

Does Coronary Reimplantation After Neoaortic Reconstruction Increase Aortic Regurgitation?

Coronary reimplantation after neoaortic reconstruction (CRANR) in the arterial switch operation (ASO) allows easy selection of accurate coronary transfer sites in the distended neoaorta. However, neoaortic valve injury may occur during coronary reimplantation. We determined whether the CRANR procedure increased the incidence of aortic valve regurgitation (AR) after ASO. Between March 1994 and August 2017, 227 patients underwent ASO. Since September 2000 CRANR has been performed on 155 patients and open coronary reimplantation (OCR) on 72. Patients who had undergone aortocoronary flaps procedures (n = 13), had early or late mortality (n = 27), or lacked data (n = 11) were excluded. We enrolled and retrospectively reviewed the medical records of 176 patients who were followed up for postoperative AR: 38 underwent OCR and 138 underwent CRANR. We compared the incidences of early and late postoperative AR in both groups. We defined mild or greater AR as "significant AR." The groups did not differ in body weight at operation, great artery relationship, and coronary artery anatomy. The incidences of significant AR at discharge were 21.1% (8/38) in the OCR group and 16.6% (23/138) in the CRANR group (p = 0.53). The freedom from significant AR at 5 years was 59.9% in the OCR group and 62.4% in the CRANR group with no difference between the two groups (p = 0.73). Moderate AR occurred in one patient in the CRANR group. No surgical intervention was required for the aortic valve in either group. ASO using the CRANR technique did not increase the incidence of postoperative early and late AR.

Validation of aortic valve 4D flow analysis and myocardial deformation by cardiovascular magnetic resonance in patients after the arterial switch operation

BACKGROUND

Aortic regurgitation (AR) and subclinical left ventricular (LV) dysfunction expressed by myocardial deformation imaging are common in patients with transposition of the great arteries after the arterial switch operation (ASO). Echocardiographic evaluation is often hampered by reduced acoustic window settings. Cardiovascular magnetic resonance (CMR) imaging provides a robust alternative as it allows for comprehensive assessment of degree of AR and LV function. The purpose of this study is to validate CMR based 4-dimensional flow quantification (4D flow) for degree of AR and feature tracking strain measurements for LV deformation assessment in ASO patients.

METHODS

A total of 81 ASO patients (median 20.6 years, IQR 13.5-28.4) underwent CMR for 4D and 2D flow analysis. CMR global longitudinal strain (GLS) feature tracking was compared to echocardiographic (echo) speckle tracking. Agreements between and within tests were expressed as intra-class correlation coefficients (ICC).

RESULTS

Eleven ASO patients (13.6%) showed AR > 5% by 4D flow, with good correlation to 2D flow assessment (ICC = 0.85). 4D flow stroke volume of the aortic valve demonstrated good agreement to 2D stroke volume over the mitral valve (internal validation, ICC = 0.85) and multi-slice planimetric LV stroke volume (external validation, ICC = 0.95). 2D flow stroke volume showed slightly less, though still good agreement with 4D flow (ICC = 0.78) and planimetric LV stroke volume (ICC = 0.87). GLS by CMR was normal (- 18.8 ± 4.4%) and demonstrated good agreement with GLS and segmental analysis by echocardiographic speckle tracking (GLS = - 17.3 ± 3.1%, ICC of 0.80).

CONCLUSIONS

Aortic 4D flow and CMR feature tracking GLS analysis demonstrate good to excellent agreement with 2D flow assessment and echocardiographic speckle tracking, respectively, and can therefore reliably be used for an integrated and comprehensive CMR analysis of aortic valve competence and LV deformation analysis in ASO patients.

Long-Term Results of Bay Window Technique for Coronary Translocation in the Arterial Switch Operation

BACKGROUND

Accurate coronary translocation is very important for a successful arterial switch operation (ASO) for transposition of the great arteries (TGA) and to provide good long-term outcomes. We have previously reported the "bay window" technique as a useful option for coronary translocation with excellent midterm results. However, the long-term results of this technique and the morphological changes in the coronary channel have not yet been reported.

PATIENTS AND METHODS

Between September 2001 and December 2012, 33 patients with TGA underwent coronary translocation using the bay window technique concomitantly with ASO. The diagnoses were TGA with intact ventricular septum in 21, TGA with ventricular septal defect in 7, and Taussig-Bing anomaly in 5. The median age of the patients at operation was 12 days, and their median body weight was 2.93 kg. Coronary artery patterns were as follows: Shaher and Puddu's type 1 in 23, single coronary artery in 4, intramural type in 1, and others in 5.

RESULTS

The median follow-up period was 4.5 years. There were no operative deaths, but there was one late death because of sepsis 13 months after ASO. Coronary artery evaluation with angiography, computed tomography, or myocardial scintigraphy was performed in 22 patients. There was no abnormal coronary morphology or perfusion. Coronary channel dilatation was not observed. Three patients underwent reoperation for pulmonary stenosis.

CONCLUSIONS

The bay window technique provides excellent long-term results in ASO for TGA. Three-dimensional computed tomography revealed no aneurysmal changes in the bay window channel at nine-year follow-up examination.

Aortic dilatation in complex congenital heart disease

A bicuspid aortic valve and/or coarctation of the aorta (COA) are often associated with dilatation of the ascending aorta and para-coarctation. Congenital heart diseases (CHD), such as truncus arteriosus, transposition of the great arteries (TGA), tetralogy of Fallot (TOF), hypoplastic left heart syndrome (HLHS), single ventricle with pulmonary stenosis/atresia and the Fontan procedure, are also associated with aortic root dilatation, aneurysm and rarely, dissection, which can be fatal and require aortic valve and root surgery. A significant subset of adults with complex CHD exhibit progressive dilatation of the aortic root even after repair due to aortic medial degeneration. Medial degeneration in the ascending aorta is prevalent among the above CHD. In Marfan syndrome, bicuspid aortic valve and COA, medial degeneration is more extensive and severe than in another complex CHD. Accordingly, the incidence of ascending aortic dilatation, dissection and rupture is higher in the former. This aortic medial degeneration in CHD may either be intrinsic or secondary to the increased volume overload of the aortic root due to right-to-left shunting, or a combination of both. The association of aortic pathophysiological abnormalities, aortic dilatation and aorto-ventricular interaction is clinically referred to as "aortopathy". The major purpose of medical treatment for aortopathy is to reduce the structural changes within the aortic wall and slow down the progression of aortic dilatation to reduce the risk of cardiovascular events. Several medications have been studied, including β-blockers, angiotensin II type I (AT1) receptor blockers (ARBs) and Ca-antagonists. However, the results, except for Marfan syndrome, are limited. In aortopathy, concomitant aortic valve and aortic root repair/replacement is required. The Bentall operation comprises root replacement with an aortic tube graft and mechanical valve, and has been widely applied. On the other hand, valve-sparing operations have been developed in order to preserve the aortic valve.

Is the Lecompte technique the last word on transposition of the great arteries repair for all patients? A magnetic resonance imaging study including a spiral technique two decades postoperatively

OBJECTIVES

To compare the Lecompte technique and the spiral anastomosis (complete anatomic correction) two decades after arterial switch operation (ASO).

METHODS

Nine patients after primary ASO with Lecompte and 6 selected patients after spiral anastomosis were evaluated 20.8 ± 2.1 years after ASO versus matched controls. Blood flow dynamics and flow profiles (e.g. vorticity, helicity) in the great arteries were quantified from time-resolved 3D magnetic resonance imaging (MRI) phase contrast flow measurements (4D flow MR) in addition to a comprehensive anatomical and functional cardiovascular MRI analysis.

RESULTS

Compared with spiral reconstruction, patients with Lecompte showed more vortex formation, supranatural helical blood flow (relative helicity in aorta: 0.036 vs 0.089; P < 0.01), a reduced indexed cross-sectional area of the left pulmonary artery (155 vs 85 mm²/m²; P < 0.001) and more semilunar valve dysfunctions (n = 5 vs 1). There was no difference in elastic aortic wall properties, ventricular function, myocardial perfusion and myocardial fibrosis between the two groups. Cross-sectional area of the aortic sinus was larger in patients than in controls (669 vs 411 mm²/m²; P < 0.01). In the spiral group, the pulmonary root was rotated after ASO more towards the normal left position (P < 0.01).

CONCLUSIONS

In this study, selected patients with spiral anastomoses showed, two decades after ASO, better physiologically adapted blood flow dynamics, and attained a closer to normal anatomical position of their great arteries, as well as less valve dysfunction. Considering the limitations related to the small number of patients and the novel MRI imaging techniques, these data may provoke reconsidering the optimal surgical approaches to transposition of the great arteries repair.

Recurrent neoaortic insufficiency after the switch back operation with previous repair of transposition with ventricular septal defect and aortic arch hypoplasia

Neoaortic insufficiency is not uncommon after the arterial switch operation (ASO) for d-Transposition, yet surgery is rarely required. In a patient with worsening neoaortic regurgitation post-arterial switch and ventricular septal defect (VSD) closure, we performed a successful "switch back" operation with documented aortic valve competence on discharge echocardiography. However, recurrent severe aortic insufficiency required valve replacement, and histopathology of the excised valve indicated abnormal leaflet/vascular wall structure. We question whether the switch back operation is a viable option for neoaortic insufficiency after an ASO in patients with previous d-Transposition and VSD, when the native pulmonary valve may have structural deficiencies.

Aortic dilatation and aortopathies in congenital heart disease

PURPOSE OF REVIEW

The objective of this review is to summarize the recent data pertaining to aortic dilatation in congenital heart disease (CHD) and to discuss the current understanding of the pathophysiology and management of this disease.

RECENT FINDINGS

Aortic dilatation is a common finding in CHD. However, acute aortic complications appear to be relatively rare. Multiple factors predispose this population to aortic dilatation, including underlying genetics, cellular-based mechanisms, and abnormalities in aortic mechanics and valve morphology.

SUMMARY

Although aortic dilatation is common in CHD, data about adverse long-term outcomes are limited. Optimal disease-specific management strategies have yet to be developed, and further research is needed to guide care in this population.

Great vessel root and artery dimensions in transposition of the great arteries repaired with atrial switch operation

To describe great-vessel dimensions in patients with D-loop transposition of the great arteries (TGA) who have undergone atrial switch operation (ATSO). Patients who have undergone arterial switch operation for TGA have a high incidence of dilation of the neoaortic root. The incidence and degree of great artery dilation in patients who have undergone ATSO for TGA has not previously been described. A retrospective database review identified patients with TGA and intact ventricular septum who underwent ATSO at <1 year of age with cardiac magnetic resonance (CMR) within the previous 5 years (n = 39). A control group of patients referred for CMR with normal findings was identified for comparison (n = 40). Measurements of the annulus, root, sinotubular junction, and great vessels were performed, and interobserver/intraobserver variability was assessed. Median age of subjects at ATSO was 3 months (range 1-12) with median age at CMR of 29 years (range 18-40). For aortic measurements, mean z scores (± SDs) for patients relative to body surface area (BSA)-adjusted normal controls were as follows: annulus 1.41 (0.80), root 2.04 (1.48), sinotubular junction 2.16 (1.26), and great vessel 1.86 (1.53). For pulmonary measurements, similar values were as follows: annulus 1.82 (1.42), root 3.25 (2.01), sinotubular junction 2.47 (1.79), and great vessel 3.96 (3.08). In all cases, the p value was <0.001, and no confidence interval included the value 0. Adult patients with TGA repaired with ATSO in infancy have a greater incidence of dilation of both great vessels, particularly the pulmonary artery. These results may indicate abnormalities in the vascular structure of both great arteries in TGA that may predispose to progressive arterial dilation.

Arterial mechanics at rest and during exercise in adolescents and young adults after arterial switch operation for complete transposition of the great arteries

We sought to determine the arterial mechanics at rest and during exercise in adolescents and young adults with complete transposition of the great arteries after arterial switch operation and their relations with neoaortic complications. Thirty patients (22 men) aged 16.2 ± 2.1 years and 22 controls (15 men) were studied. Central and peripheral arterial pulse wave velocities, carotid and radial augmentation indices, and central systolic blood pressure (cSBP) were determined by oscillometry and applanation tonometry, whereas arterial dimensions were measured by 2-dimensional echocardiography. Arterial strain, distensibility, and stiffness were determined at rest and during supine bicycle exercise testing. At rest, patients had significantly higher heart-carotid pulse wave velocity, carotid and radial augmentation indices, and cSBP than controls. At rest and during submaximal exercise, patients had significantly lower aortic strain and distensibility, greater aortic and carotid stiffness, and higher SBP than controls. Dilated aortic sinus found in 23 (76.7%) patients was associated with lower aortic distensibility, greater aortic stiffness, and higher cSBP at rest and lower aortic distensibility and strain at submaximal exercise. Significant aortic regurgitation found in 20% (6 of 30) of patients was associated with significantly higher neoaortic z scores. Multivariate analysis identified aortic stiffness at rest (β = 0.46, p = 0.003) and age at operation (β = 0.44, p = 0.004) as significant determinants of aortic sinus z scores. In conclusion, altered mechanics of the central arteries are present at rest and during exercise in adolescents and young adults after arterial switch operation. These findings may have important implications on progression of neoaortic root dilation, exercise recommendations, and medical therapy.

Double root switch: a complete anatomical correction for transposition of the great arteries

We report the cases of two neonates with transposition of the great arteries, whose surgical correction consisted of translocation of the aortic root with the aortic valve and coronary arteries to the left ventricle and translocation of the pulmonary root with the pulmonary valve to the right ventricle. We believe that the aortic translocation may reduce the likelihood of dilatation of the neoaorta, aortic regurgitation, and changes in the endothelium of coronary arteries which have occasionally been seen following arterial switch operations.

Similarities and differences of the aortic root after arterial switch and ross operation in children

Pulmonary root dilation and valve regurgitation if translocated into the aortic position is frequently seen in children with transposition of the great arteries (TGA) after an arterial switch operation, as well as in patients after the Ross procedure. Many mechanisms are thought to be responsible for the progressive dilation. Despite the differences between the 2 groups, the similarity of having the pulmonary valve and its adjacent tissue working in the systemic circulation might have a comparable effect on the neoaortic root dimensions and elasticity. We prospectively recruited 52 patients with TGA, 23 Ross patients, and 48 healthy subjects for echocardiographic assessment of their aortic valve, root, sinutubular junction, and ascending aortic dimensions and elasticity. The data were compared, stratified by patient age at investigation and the duration of follow-up postoperatively. In relation to the healthy subjects, the neoaortic root dimensions were significantly larger and the tissue stiffer and less distensible in those with TGA and those who had undergone the Ross procedure. Although the pulmonary valve of the Ross patients had been under systemic pressure load for a significantly shorter period (4.4 ± 3.6 vs 10.1 ± 5.5 years), the dimensions and elasticity values had deteriorated more. These differences could neither be clearly attributed to the age differences at surgery or to an auxiliary congenital ventricular septal defect in those with TGA or the aortic valve phenotype before the Ross operation. In conclusion, the worse outcome of the neoaortic root dimensions and elasticity in the Ross patients should at least be partly related to the different predefined pulmonary artery structures and the different development of the normal and transposed pulmonary arteries.

Long-term outcomes of the neoaorta after arterial switch operation for transposition of the great arteries

BACKGROUND

After the arterial switch operation (ASO) for transposition of the great arteries (TGA), the native pulmonary root and valve function in the systemic position, and the long-term risk for neoaortic root dilation and valve regurgitation is currently undefined. The aim of this study was to determine the prevalence and progression of neoaortic root dilation and neoaortic valve regurgitation in patients with TGA repaired with the ASO.

METHODS

Measurements of the neoaortic annulus, neoaortic root at the level of the sinuses of Valsalva, and the degree of neoaortic regurgitation were assessed by serial transthoracic echocardiograms on 124 patients with TGA at a median follow-up of 7.2 years (range, 1 to 23 years) after the ASO at our institution.

RESULTS

Neoaortic root dilation with z scores of 2.5 or greater was identified in 66%, and the root diameter z score increased at an average rate of 0.08 per year over time after ASO. Freedom from neoaortic root dilation at 1, 5, 10, and 15 years after ASO was 84%, 67%, 47%, and 32%, respectively. Risk factors for root dilation include history of double-outlet right ventricle (p = 0.003), previous pulmonary artery banding (p = 0.01), and length of follow-up (p = 0.04). Neoaortic valve regurgitation of at least moderate degree was present in 14%. Neoaortic root dilation was a significant risk factor for neoaortic valve regurgitation (p < 0.0001). No patient required reintervention on the neoaorta or neoaortic valve during follow-up.

CONCLUSIONS

Progressive neoaortic root dilation is common in patients with TGA after the ASO. Continued surveillance of this population is required.

A theory for water and macromolecular transport in the pulmonary artery wall with a detailed comparison to the aorta

The pulmonary artery (PA) wall, which has much higher hydraulic conductivity and albumin void space and approximately one-sixth the normal transmural pressure of systemic arteries (e.g, aorta, carotid arteries), is rarely atherosclerotic, except under pulmonary hypertension. This study constructs a detailed, two-dimensional, wall-structure-based filtration and macromolecular transport model for the PA to investigate differences in prelesion transport processes between the disease-susceptible aorta and the relatively resistant PA. The PA and aorta models are similar in wall structure, but very different in parameter values, many of which have been measured (and therefore modified) since the original aorta model of Huang et al. (23). Both PA and aortic model simulations fit experimental data on transwall LDL concentration profiles and on the growth of isolated endothelial (horseradish peroxidase) tracer spots with circulation time very well. They reveal that lipid entering the aorta attains a much higher intima than media concentration but distributes better between these regions in the PA than aorta and that tracer in both regions contributes to observed tracer spots. Solutions show why both the overall transmural water flow and spot growth rates are similar in these vessels despite very different material transport parameters. Since early lipid accumulation occurs in the subendothelial intima and since (matrix binding) reaction kinetics depend on reactant concentrations, the lower intima lipid concentrations in the PA vs. aorta likely lead to slower accumulation of bound lipid in the PA. These findings may be relevant to understanding the different atherosusceptibilities of these vessels.

Neoaortic Valve Function 10 to 18 Years After Arterial Switch Operation

Anatomical correction is a procedure of choice for transposition of the great arteries (TGA) in neonates. During surgery, the aorta and pulmonary artery are switched—the native pulmonary valve becomes the neoaortic valve. The fate of this valve remains uncertain. Many reports suggest that its ability to function worsens with time after surgery. Of 519 patients with TGA operated on between 1991 and 2008, 161 met inclusion criteria for this retrospective study and were followed 10 years or more to assess neoaortic valve regurgitation (NeoAR) occurrence and development and to estimate potential risk factors. The subjects were divided into 2 groups: group 1 (simple TGA) and group 2 (TGA + ventricle septal defect). Within the analyzed group, the frequency of significant regurgitation increased from 9% 1 year after the operation to 47% at the most recent follow-up. No severe regurgitation necessitating reoperation was observed. Analysis of potential risk factors revealed that pulmonary/aortic valve diameter discrepancy and nonfacing commissures were associated with increased risk of development of neoaortic insufficiency. NeoAR arises and develops over time after correction of the defect. No hemodynamic repercussions necessitating cardiac surgical interventions were observed. The majority of insufficiencies are detected between 2 and 6 years after surgery. The degree of incompetence is usually mild and increases during follow-up by about 0.5 or 1 degree. The risk factors for NeoAR appearance are pulmonary artery/aortic annulus discrepancy and nonfacing commissures.

Follow-up outcomes 10 years after arterial switch operation for transposition of the great arteries: comparison of cardiological health status and health-related quality of life to those of the a normal reference population

The purpose of this study was to investigate the cardiological health status and health-related quality of life after the arterial switch operation (ASO) for transposition of the great arteries (TGA) in comparison with a normative reference group. Chart review and cross-sectional systematic follow-up, including echocardiography, exercise testing, and electrocardiography, were performed on all survivors of ASO for TGA between 1990 and 1995. Health-related quality of life (HRQOL) was assessed using a standardized questionnaire. A normative reference group was included. Forty-nine survivors [median age at operation 13 days, mean age at follow-up 11 +/- 2 years (37/49 with intact ventricular septum] were identified. Thirty-three of 49 patients (67%) [22/33 TGA with intact ventricular septum (IVS)] participated in cross-sectional follow-up. Cumulative 10-year event-free survival was 88% and the re-intervention rate 6%. Aortic root dilatation occurred in 70% of patients; none had severe aortic regurgitation. Left ventricular function was normal. Exercise performance (85% of reference capacity, p = 0.02), maximal oxygen uptake (85%, p < 0.01) and peak heart rate (95%, p < 0.01) were decreased. Exercise electrocardiogram was normal as was rhythm status. Unfavourable outcomes on HRQOL were found for motor functioning and positive emotional functioning. Overall there were no significant differences between TGA/IVS and TGA/VSD. We conclude that at mid- to long-term follow-up after ASO, major events and re-interventions (6%) occur infrequently. Exercise capacity and maximal oxygen uptake are lower than those in a reference population, which could not be related to diminished ventricular function. Aortic root dilatation is frequent, irrespective of the anatomical subgroup. Severe aortic regurgitation or left ventricular dilatation was not found. The unfavourable health-related quality of life deserves further attention.

Is the Ross procedure as good as we thought it would be?

For patients requiring intervention because of progressive disease of the aortic valve, the perfect palliation will provide a valve that produces normal dynamics of flow, will not require anti-coagulation, will grow with the patient, and have long term durability. Current surgical interventions include aortic valvoplasty, or replacement with either a mechanical or tissue prosthesis. Options for tissue valves include insertion of a pulmonary autograft in the Ross procedure, a cadaveric homograft, or porcine or bovine xenograft valves. The optimal option is still debated.