Neoaortic Arch Research Articles

Hypoplastic Left Heart Syndrome: Definition, Morphology, and Classification.

This manuscript will provide information about hypoplastic left heart syndrome (HLHS) and related malformations, including definitions, morphology, and classification, based on the 2021 International Paediatric and Congenital Cardiac Code (IPCCC) and the Eleventh Revision of the International Classification of Diseases (ICD-11). HLHS is defined as "a spectrum of congenital cardiovascular malformations with normally aligned great arteries without a common atrioventricular junction, characterized by underdevelopment of the left heart with significant hypoplasia of the left ventricle including atresia, stenosis, or hypoplasia of the aortic or mitral valve, or both valves, and hypoplasia of the ascending aorta and aortic arch." Functionally univentricular heart is defined as "a spectrum of congenital cardiac malformations in which the ventricular mass may not readily lend itself to partitioning that commits one ventricular pump to the systemic circulation, and another to the pulmonary circulation." The Norwood operation is synonymous with the term "Norwood (Stage 1)" and is defined as (1) creation of an aortopulmonary connection and neoaortic arch construction resulting in univentricular physiology and (2) creation of a controlled source of pulmonary blood flow with a calibrated systemic-to-pulmonary artery shunt, a right ventricle to pulmonary artery conduit, or rarely, a cavopulmonary connection. The goals of the Norwood (Stage 1) Operation are creation of (1) unobstructed systemic blood flow via aortopulmonary connection and neoaortic arch construction, (2) unobstructed coronary blood flow, (3) unobstructed flow across the atrial septum, and (4) controlled pulmonary blood flow.

Surgical reintervention on the neo-aorta after the Norwood operation.

We sought to identify the prevalence of surgical reintervention on the neo-aorta after Norwood procedure and its impact on long-term outcomes. We reviewed the medical records of all patients who underwent Norwood procedure. The impacts of surgical neoaortic reintervention on outcomes were analysed in each stage of palliation. A total of 335 patients were included in this study. Thirty patients underwent surgical reintervention on the neo-aorta after Norwood procedure. The timing of initial reintervention was before stage II in 13 patients, at stage II in 7, between stage II and stage III in 5, at stage III in 3 and after stage III in 2. A reintervention before stage II was significantly associated with mortality (HR 14.4, 95% confidence interval 6.00-34.6, P < 0.001). In patients who underwent stage II (n = 251), reintervention had no significant impact on mortality. In patients who underwent stage III (n = 188), the previous reintervention was significantly associated with higher mean pulmonary pressure (P = 0.05) and a higher rate of reduced ventricular function (P = 0.002). Greater than mild atrioventricular valve regurgitation was significantly associated with the development of a neoaortic arch stenosis after stage II (P = 0.03). Surgical reinterventions on the neo-aorta were required in each inter-stage phase. A surgical neoaortic reintervention was not related to increased mortality after stage II but significantly associated with a higher rate of reduced ventricular function and elevated mean pulmonary artery pressure.

Aortic arch reconstruction in the Norwood procedure using a curved polytetrafluorethylene patch.

The aortic arch enlargement in the Norwood procedure is classically carried out using a curved homograft patch on the inner curvature of the neoaortic arch. The study investigates the outcome of a newly used artificial patch from a vascular prosthesis as an alternative to a homograft patch. Since April 2007, we used curved polytetrafluorethylene (PTFE) patches cut out of a prosthesis as an alternative to homograft patches for the aortic arch reconstruction. The decision for either patch material was made due to anatomic reasons, preferring PTFE patches in larger aortas. In this study, 224 Norwood patients, operated between April 2007 and April 2018, were analysed. A total of 104 patients received a PTFE patch (group PTFE), and 120 patients got a pulmonary homograft patch (group homograft). A single-centre retrospective analysis was carried out concerning postoperative course and long-term follow-up regarding aortic arch interventions and reoperations and comparing the 2 material groups. There were no material associated operative or postoperative complications. In-hospital mortality was 13% in group PTFE. Six children died late during follow-up (6%). One aortic isthmus dilatation (1%) was carried out 12 months after the Norwood procedure in this group, no arch reoperation was necessary during the complete follow-up. The curved PTFE patch showed good qualities in operative technical demands and excellent long-term results. In selected cases of hypoplastic left heart syndrome, it can be well used as alternative to the pulmonary homograft.

Does the size of pulmonary artery impact on recoarctation of the aorta after the Norwood procedure without patch?

This study aimed to evaluate whether recoarctation of the aorta (reCoA) after the Norwood procedure for hypoplastic left heart syndrome correlates with pre- and postoperative anatomic factors. This retrospective study included 48 patients who underwent Norwood procedure with right ventricle-to-pulmonary artery conduit between 2009 and 2017. Anatomical factors such as preoperative length, diameter of the main pulmonary artery (MPA), and postoperative neoaortic arch angle stratified by arch reconstruction technique were analysed using the receiver operating characteristic analysis. Eleven patients needed surgical intervention for reCoA at stage 2. Out of the 30 patients who underwent direct anastomosis during arch reconstruction, 7 developed reCoA. Seven patients received the full patch augmentation (patch augmentation for both lesser and greater curvatures) and were all spared from reCoA. Among the patients who had direct anastomosis, the preoperative MPA length was correlated with the postoperative arch angle (P = 0.021) and was associated with the occurrence of reCoA (P = 0.002) and the best cutoff value for MPA length was 10 mm. The postoperative arch angle was also correlated with the incidence of reCoA (P < 0.001) and was larger in patients who underwent the full patch augmentation than in patients who had direct anastomosis (126° vs 112°, P = 0.005) despite comparable MPA length. ReCoA after the Norwood procedure correlates with MPA length when a direct anastomosis was used. Direct anastomosis can be considered in patients with a longer preoperative MPA. In other cases, the full patch augmentation should be considered for obtaining a large and smooth neoaortic arch.

Chimney reconstruction provides a wider subaortic space and reduces the risk of pulmonary artery compression in the Norwood-type aortic arch reconstruction without patch supplementation.

Pulmonary artery (PA) compression by the neoaorta is a serious complication after the Norwood-type palliation (NP) for hypoplastic left heart syndrome. Either excess patch tailoring or limited use of autologous tissue may cause narrowing of the subaortic space. The chimney technique could theoretically provide a wide subaortic space. Twenty-nine patients with both pre- and post-NP computed tomography data available of the 37 consecutive patients who underwent NP in our institution were reviewed. Arch height, arch width, sinus of Valsalva diameter, area under the neoaortic arch and arch angle were measured. These patients were divided according to the neo-arch reconstruction technique, chimney reconstruction technique (CR) or conventional direct reconstruction technique (DR). Median age and weight at NP were 2.1 months and 3.5 kg, respectively. Twenty-two patients underwent previous bilateral PA banding. During NP, 17 CR and 12 DR were performed. Four patients in the DR group developed PA compression. No neoaortic arch dilatation was found in either group. Post-NP arch width, area under the neo-arch and the arch angle were significantly larger in the CR group. Pre-NP arch height was significantly smaller in DR patients with PA compression than in those without. The chimney technique decreased the risk of PA compression and provided a wider subaortic space and a less acute arch angle. This technique had no short-term effect on the neoaortic root. Small preoperative arch height is a potential risk factor for PA compression in DR, and the chimney technique could be an effective solution.

High-degree Norwood neoaortic tapering is associated with abnormal flow conduction and elevated flow-mediated energy loss

ObjectiveThe Norwood neoaortic arch biomechanical properties are abnormal due to reduced vessel wall compliance and abnormal geometry. Others have previously described neoaortic geometric distortion by the degree of diameter reduction (tapering) and associated this with mismatched ventricular-neoaortic coupling, abnormal flow hemodynamic parameters, and worse patient outcome. Our purposes were to investigate the influence of neoaortic tapering (ie, diameter reduction) on flow-mediated viscous energy loss (EL′) in post-Norwood palliated hypoplastic left heart syndrome patients, and correlate flow-geometry with single ventricle power generation. MethodsTwenty-six palliated hypoplastic left heart syndrome patients underwent comprehensive cardiac evaluation with 4-dimensional-flow magnetic resonance imaging. Patients were grouped into high- (group H, n = 13) and low- (group L, n = 13) degree neoaortic tapering using the median cutoff value of neoaortic diameter variance. EL′ was calculated along standardized segments using 4-dimensional-flow magnetic resonance imaging. Flow-mediated power loss as a percentage of total power generated by the single ventricle was determined. ResultsGroup H had a higher prevalence of abnormal recirculating flow in the neoaorta and elevated neoaortic EL′ in the ascending aorta (1.0 vs 0.6 mW; P = .004). Group H EL′ was increased across the entire thoracic aorta (2.6 vs 1.3 mW; P = .002) and accounted for 0.7% of generated ventricular power versus 0.3% in group L (P = .024). EL′ directly correlated with the degree of ascending aortic dilation (R = 0.49; P = .012). ConclusionsPatients with high degree neoaortic tapering have more perturbed flow through the neoaorta and increased EL′. Flow-mediated energy loss due to abnormal flow represents irreversibly wasted power generated by the single right ventricle. In patients with high-degree neoaortic tapering, EL′ was more than 2-fold greater than low-degree tapering patients. These data suggest that oversizing the Norwood neoaortic reconstruction should be avoided and that patients with distorted neoaortic geometry may warrant increased surveillance for single-ventricle deterioration.

How to Reconstruct Neo-Aortic Arch Without Patch at Norwood-Sano Procedure

The Norwood procedure consists of a complex reconstruction resulting in: (1) unobstructed systemic outflow from the right ventricle to neo-aorta, (2) creation of large atrial septal defect, and (3) a controlled source of pulmonary blood flow (PBF) from the systemic circulation. The Sano modification provides the source of PBF from the right ventricle. Both procedures have advantages and disadvantages, therefore, there have been many debates regarding which procedure is better as a first stage palliation. Another ongoing debate of first stage palliation is the method of reconstruction of the neo-aorta. Aortic arch obstruction increases afterload and leads to ventricular dysfunction and tricuspid regurgitation. Recent SVR Trial identified recurrent coarctation requiring intervention in 18% of patients. We believe that another important point regarding reconstruction of the neo-aorta is the use of only native tissue and minimizing the use of inelastic patch material. Because elastic properties of the arterial tree are known to have a profound influence on ventricular function, arterial elasticity may therefore be of particular importance to those patients with hypoplastic left heart syndrome. During the past 20 years, we have modified our original technique of aortic arch reconstruction. Proximal arch plication and creation of elongated flaps of the main pulmonary artery are 2 of our recent modifications which facilitate neo-aortic reconstruction with native tissue. We describe a technique where direct anastomosis of neo-aorta is achieved with avoidance of foreign material in a majority of our patients.

Suboptimal neoaortic arch geometry correlates with inefficient flow patterns in hypoplastic left heart syndrome

Suboptimal neoaortic arch geometry correlates with inefficient flow patterns in hypoplastic left heart syndrome

Porcine Small Intestinal Submucosa May Be a Suitable Material for Norwood Arch Reconstruction

Norwood palliation typically requires patch augmentation of the ascending aorta and aortic arch. Patients having undergone Norwood palliation are at risk of recurrent arch obstruction, the risk of which may be affected by the type of patch material used at the time of Norwood palliation. We sought to determine the freedom from neoaortic arch reintervention and overall survival in patients who underwent Norwood palliation utilizing porcine small intestinal submucosa (PSIS) as the patch material. Retrospective chart review was performed to identify patients who underwent a Norwood operation utilizing PSIS material at our institution. Cardiac diagnosis, age at surgery, shunt type, need for reintervention, and outcome (survival, transplant, and death) were evaluated. Forty-four patients had PSIS material utilized for arch reconstruction at the time of Norwood palliation. There were only five neoaortic arch reinterventions in 4 patients (11.4%). An additional 10 reinterventions, unrelated to the PSIS patch, were performed, including five shunt revisions and five branch pulmonary artery interventions. There were 3 deaths, and 5 patients underwent transplantation. Median follow-up was 387.5 days (range, 4 to 1,513). Freedom from neoaortic arch reintervention and survival after Norwood palliation with PSIS patch material is promising. The PSIS appears noninferior and may be an appropriate tissue choice for Norwood palliation. Studies with longer follow-up are needed to determine the rate of neoaortic reintervention over time.

Predicting the Need for Neoaortic Arch Intervention in Infants with Hypoplastic Left Heart Syndrome Through the Glenn Procedure.

Neoaortic recoarctation is present in up to over one-third of patients having undergone the Norwood procedure for hypoplastic left heart syndrome. Some of these patients will require reintervention by catheterization or surgery through the time of the Glenn procedure. Echocardiography and catheterization are often utilized in this period to assess hemodynamics although no specific criteria have been identified to predict whether and when neoaortic arch reintervention will be needed. We sought to identify predictors, including but not limited to echocardiographic and catheterization gradients, to predict such intervention. A retrospective analysis was conducted including patients with hypoplastic left heart syndrome. Patients with significantly comorbid lesions such as isomerism, anomalous pulmonary venous connections, and significant atrioventricular valve insufficiency were excluded as were patients without interstage echocardiographic and catheterization data. Receiver operator curve analysis was performed to establish peak-value gradients by echocardiography and catheterization that were predictive of neoaortic reintervention from the time of the Norwood through the time of the Glenn. These values were then entered into a multivariate regression with several other factors to determine what factors were predictive of need for such intervention. Bland-Altman analysis was conducted to compare echocardiographic and catheterization gradients. A peak echocardiographic gradient of 26mmHg (100% sensitivity, 85% specificity) and a peak-to-peak catheterization gradient of 8.5mm Hg (83% sensitivity, 86% specificity) were found to be predictive of need for neoaortic arch reintervention after multivariate analysis. Echocardiographic and catheterization gradients were found to have poor correlation with one another. A peak gradient of 26mmHg or greater by echocardiography and a peak-to-peak gradient of 8.5mmHg or greater by catheterization after the Norwood but prior to the Glenn are predictive of need for neoaortic reintervention through the time of the Glenn hospitalization.

Modified Norwood Procedure for Tricuspid Atresia, Transposition of Great Arteries, and Hypoplastic Right Arch With Complete Vascular Ring

We report a modified Norwood stage I procedure for tricuspid atresia, transposition of great arteries, and hypoplastic right aortic arch with complete vascular ring. In this technique, we applied dual arterial cannulation to avoid circulation arrest during neoaortic reconstruction, and also corrected the arch laterality during the Norwood stage I palliation procedure. Pulmonary flow was supplied by the Blalock-Taussig shunt. Postoperative imaging revealed the patent left neoaortic arch, and the vascular ring was relieved with a patent tracheobronchial tree.

Aortic arch geometry after the Norwood procedure: The value of arch angle augmentation

ObjectiveAortic arch reconstruction in the Norwood procedure is occasionally associated with postoperative airway and branch pulmonary artery stenosis, as well as recoarctation. This study investigated geometric changes in the aortic arch after the Norwood procedure and evaluated the efficacy of arch angle augmentation with glutaraldehyde-treated autologous pericardium in aortic arch reconstruction. MethodsOf 52 consecutive patients who underwent the Norwood procedure between 1998 and 2013, a total of 36 patients who underwent postoperative multidetector-row computed tomographic angiography were reviewed retrospectively, and divided into 2 groups according to whether arch angle augmentation with glutaraldehyde-treated autologous pericardium was performed (AAA group, 26 patients) or not (NA group, 10 patients). ResultsThe neoaortic arch in the Norwood procedure was characterized by having a significantly smaller angle, being lower in height, and being narrower than that in age-matched control patients with a normal aortic arch. Moreover, all of these arch geometric measurements were significantly larger in the AAA group than in the NA group. Freedom from reintervention and reoperation for bronchomalacia or branch pulmonary artery stenosis, caused by extrinsic compression of the neoaorta, was significantly better at 1 year in the AAA group than in the NA group. Recoarctation of the neoaorta was documented in only 1 (3.8%) patient in the AAA group versus 3 patients (30%) in the NA group. ConclusionsArch angle augmentation with glutaraldehyde-treated autologous pericardium in the Norwood procedure creates more aortopulmonary space with a smoother arch angle and diminished incidence of postoperative recoarctation, bronchial compression, or branch pulmonary artery compression.

The Norwood Operation With Innominate Artery and Descending Aortic Cannulation, Performed With Continuous Mildly Hypothermic Bypass

Conventional perfusion technique for the Norwood operation relies on deep hypothermia for protection of the body during construction of the neoaortic arch, with or without the provision of cold antegrade perfusion into the cerebral circulation. Bypass time required for cooling and warming, the exposure of the lower body to prolonged ischemia, and the effects of hypothermia itself, may contribute to postoperative oliguria and third-space fluid gain, and may prolong recovery. In this article, a technique is presented for exposure and cannulation of the descending aorta. This, combined with direct cannulation of the innominate artery, allows continuation of full-flow bypass to the entire body throughout repair, and obviates the use of deep hypothermia. Modifications of the conduct of operation are presented which take advantage of the absence of cardiopulmonary bypass time spent cooling and warming to reduce the overall duration of bypass and myocardial ischemia.

Risk Factors for a Positive Neoaortic Arch Gradient After Stage I Palliation for Hypoplastic Left Heart Syndrome

Providing unobstructed systemic blood flow is one goal of stage I palliation for hypoplastic left heart syndrome. Although clinically significant obstruction is defined when the arch gradient exceeds 15 mm Hg, any positive gradient constitutes obstruction, which may impair ventricular function. We sought to identify risk factors before stage I palliation that result in a positive neoaortic arch gradient before bidirectional Glenn. Reviewed were 51 neonates who underwent stage I palliation and subsequent bidirectional cavopulmonary anastomosis procedures for hypoplastic left heart syndrome. Echocardiograms before stage I palliation were reviewed for aortic dimensions. Cardiac catheterization before bidirectional cavopulmonary anastomosis determined the aortic arch gradient and degree of right ventricular dysfunction. Of the 51 patients, 24 (47%) had a negative or absent arch gradient. Patients with a positive gradient had a median gradient of 5 mm Hg (range, 1 to 60 mm Hg). The diameter of the ascending aorta and proximal transverse arch indexed to the descending thoracic aorta (0.5 ± 0.2 vs 0.7 ± 0.4 and 0.4 ± 0.2 vs 0.6 ± 0.2 mm, p = 0.02 and p = 0.01) and lower birth weight (3.1 ± 0.5 vs 3.4 ± 0.4 kg, p = 0.03) were risk factors of a positive neoaortic arch gradient. Further, the degree of arch obstruction was inversely related to the degree of right ventricular function (odds ratio, 1.08; p < 0.01). Lower birth weight and a smaller aortic diameter confer a higher risk of developing a positive neoaortic arch gradient, resulting in reduced right ventricular function.

Right-Ventricular Global Longitudinal Strain May Predict Neo-Aortic Arch Obstruction After Norwood/Sano Procedure in Children With Hypoplastic Left Heart Syndrome

Neo-aortic arch obstruction (NAAO) is a common complication following the Norwood/Sano procedure (NP) for hypoplastic left heart syndrome (HLHS) and is associated with increased morbidity and mortality. However, there is currently no objective method for predicting which patients will develop NAAO. This study was designed to test the hypothesis that hemodynamic changes from development of NAAO after NP in patients with HLHS will lead to changes in myocardial dynamics that could be detected before clinical symptoms develop with strain analysis using velocity vector imaging. Patients with HLHS who had at least one cardiac catheterization after NP were identified retrospectively. Strain analysis was performed on all echocardiograms preceding the first catheterization and any subsequent catheterization performed for intervention on NAAO. Twelve patients developed NAAO and 30 patients never developed NAAO. Right ventricular strain was worse in the group that developed NAAO (-6.2 vs. -8.6 %, p = 0.040) at a median of 59 days prior to diagnosis of NAAO. Those patients that developed NAAO following NP were significantly younger at the time of first catheterization than those that did not develop NAAO (92 ± 50 vs. 140 ± 36 days, p = 0.001). This study demonstrates that right ventricular GLS is abnormal in HLHS patients following NP and worsening right ventricular strain may be predictive of the future development of NAAO.

Outcomes of swing-back aortic arch repair in arterial switch and Norwood operations

The outcomes of the swing-back technique for aortic arch repair during the arterial switch and Norwood operations are not well reported. Between May 2004 and January 2011, we performed this technique during the arterial switch and Norwood operations in 2 and 4 patients, respectively. The median (range) patient age and body weight were 17 (12-147) days and 3.4 (2.2-6.1) kg, respectively. All patients survived the procedures. The median follow-up duration was 4 (1-8) years. One patient showed recoarctation in the early postoperative period, which was successfully repaired by a single-catheter intervention. The latest median pressure gradient across the neoaortic arch was 0 (0-6) mmHg. Neoaortic valve regurgitation was found to be minimal by echocardiography. During the follow-up period, the Fontan operation was performed in all the patients who underwent the Norwood operation. These results suggest that the swing-back technique yields satisfactory mid-term outcomes.

Novel use of an Amplatzer Vascular Occluder II to close an acquired fistula between a reconstructed aortic arch and the left atrial appendage in a patient with hypoplastic left heart syndrome

An 8-month-old female with hypoplastic left heart syndrome had undergone bidirectional cavopulmonary anastomosis at the age of 4.5 months and presented with a new continuous flow murmur on routine follow-up. Diagnostic catheterization demonstrated a fistula between the left atrial appendage and the neo-aortic arch. The fistula was sealed with an Amplatzer Vascular Occluder II device without complications.

Aortic Atresia Combined with Right Aortic Arch

We present a case of an aortic atresia and a persistent right aortic arch with a retro-aortic brachiocephalic vein. A left neo-aortic arch was constructed using a reversed subclavian flap and a standard Norwood-type patch enlargement to provide systemic outflow. The intercarotid section of the aortic arch was hypoplastic. Therefore, we maintained the patency of the right arch, thus creating a vascular ring.

Balloon angioplasty of recoarctation of the neoaortic arch after the norwood operation: Factors affecting outcome and recurrence

Balloon angioplasty (BA) is effective in relieving neoaorta recoarctation (reCoa) after the Norwood procedure. However, recurrence is not uncommon and risk factors for success and recurrence require further elucidation. We report the results of BA for reCoa following the Norwood procedure. We examine acute results and risk factors associated with success and recurrence after BA. Patients who underwent BA between November 2000 and June 2010 were studied. Factors for immediate success and recurrence after BA were determined using logistic regression. Recurrence-free survival was evaluated using the Kaplan-Meier curve. Forty-seven angioplasties were performed in 39 patients. Mean age at catheterization was 5.0 ± 4.1 months. BA was successful in 40 angioplasties (85.1%). A higher preprocedure gradient across the coarctation (P = 0.04) and a higher ratio of balloon to descending aorta (P = 0.01) were associated with success. Six patients required redilation. Risk factors for recurrence included older age at Norwood (P = 0.02), younger age (P = 0.03), lower weight (P = 0.04) and smaller body surface area at balloon angioplasty (BA) (P = 0.04), and shorter duration between surgery and angioplasty (P = 0.03). Freedom from recurrence from the first catheterization was 82% after 6 months and 78% after 1 year. There were no neurologic sequelae or deaths. BA is effective acutely and long term with limited morbidity and mortality. Recurrence occurs usually within the first year. Delay in performing the initial angioplasty may be beneficial in reducing the risk of recurrence, but further study is needed.

Pseudoaneurysm following percutaneous balloon angioplasty for aortic arch recoarctation after the Norwood procedure

We experienced a rare case of 5-month-old male infant presenting with a pseudoaneurysm following percutaneous balloon angioplasty for aortic arch recoarctation after undergoing the Norwood procedure. The pseudoaneurysm, which measured 1 cm in diameter, was located between the left carotid artery and the left subclavian artery. Under deep hypothermic circulatory arrest, resection of the pseudoaneurysm and reconstruction of the neoaortic arch were performed successfully.