Pulmonary Artery Branch Stenosis in Patients with Congenital Heart Disease

Pediatric three-dimensional quantitative cardiovascular computed tomography

High-resolution, isotropic, 3-dimensional (D) data from pediatric cardiovascular computed tomography (CT) offer great potential for the accurate quantitative evaluation of pediatric cardiovascular and pulmonary vascular diseases. Recent pilot studies using pediatric 3-D cardiovascular CT have shown promising results in assessing cardiac function in conditions such as tetralogy of Fallot, cardiac defects with a hypoplastic ventricle, Ebstein anomaly, and in quantifying myocardial mass. In addition, the quantitative assessment of pulmonary vascularity is useful for evaluating differential right-to-left pulmonary vascular volume ratio, the effectiveness of pulmonary angioplasty, and predicting pulmonary hypertension. These initial experiences could broaden the role of pediatric cardiovascular CT in clinical practice. Furthermore, the current barriers to its widespread use, pertinent solutions to these problems, and new applications are discussed. In this review, the 3-D quantitative evaluations of cardiac function and pulmonary vascularity using high-resolution pediatric cardiovascular CT data are illustrated.

Patch Materials for Pulmonary Artery Arterioplasty and Right Ventricular Outflow Tract Augmentation: A Review

Patch augmentation of the right ventricular outflow tract (RVOT) and pulmonary artery (PA) arterioplasty are relatively common procedures in the surgical treatment of patients with congenital heart disease. To date, several patch materials have been applied with no agreed upon clinical standard. Each patch type has unique performance characteristics, cost, and availability. There are limited data describing the various advantages and disadvantages of different patch materials. We performed a review of studies describing the clinical performance of various RVOT and PA patch materials and found a limited but growing body of literature. Short-term clinical performance has been reported for a multitude of patch types, but comparisons are limited by inconsistent study design and scarce histologic data. Standard clinical criteria for assessment of patch efficacy and criteria for intervention need to be applied across patch types. The field is progressing with improvements in outcomes due to newer patch technologies focused on reducing antigenicity and promoting neotissue formation which may have the ability to grow, remodel, and repair.

Surgical repair of peripheral pulmonary artery stenosis: A 2-decade experience with 145 patients

BACKGROUND

Peripheral pulmonary artery stenosis (PPAS) is a relatively rare form of congenital heart disease often associated with Williams syndrome, Alagille syndrome, and elastin arteriopathy. This disease is characterized by stenoses at nearly all lobar and segmental ostia and results in systemic-level right ventricular pressures. The current study summarizes our experience with the surgical treatment of PPAS.

METHODS

This was a retrospective review of 145 patients who underwent surgical repair of PPAS. This included 43 patients with Williams syndrome, 39 with Alagille syndrome, and 21 with elastin arteriopathy. Other diagnoses include tetralogy of Fallot with PPAS (n = 21), truncus arteriosus (n = 5), transposition (n = 3), double-outlet right ventricle (n = 2), arterial tortuosity syndrome (n = 3), and other (n = 8).

RESULTS

The median preoperative right ventricle to aortic peak systolic pressure ratio was 1.01 (range, 0.50-1.60) which was reduced to 0.30 (range, 0.17-0.60) postoperatively. The median number of ostial repairs was 17 (range, 6-34) and median duration of cardiopulmonary bypass was 398 minutes (range, 92-844). There were 3 in-hospital deaths (2.1%). The median duration of follow-up was 26 months (range, 1-220) with 4 late deaths (2.9%). Eighty-two patients have subsequently undergone catheterization and 74 had a pressure ratio <0.50.

CONCLUSIONS

The surgical treatment of PPAS resulted in a 70% reduction in right ventricular pressures. At 3 years, freedom from death was 94% and 90% of those evaluated maintained low pressures. These results suggest that the surgical treatment of PPAS is highly effective in most patients.

Impact of liver dysfunction on outcomes in children with Alagille syndrome undergoing congenital heart surgery

OBJECTIVES

Children with Alagille syndrome often have complex forms of congenital heart defects with the majority having peripheral pulmonary artery stenosis (PPAS) and pulmonary valve atresia (PA) or pulmonary valve stenosis. Children with Alagille syndrome also have variable amounts of liver dysfunction. The purpose of this study was to evaluate the impact of liver dysfunction on outcomes in children with Alagille syndrome undergoing congenital heart surgery.

METHODS

This was a retrospective review of 69 patients with Alagille syndrome who underwent congenital heart surgery at our institution. The underlying diagnoses included PPAS (n = 29), tetralogy of Fallot with PPAS (n = 14), tetralogy with PA (n = 3), PA with ventricular septal defect and major aortopulmonary collateral arteries (n = 21) and one each with D-transposition and supravalvar aortic stenosis.

RESULTS

The median age at surgery was 16 months (range 0-228 months). Procedures performed included PPAS repair (n = 43), tetralogy with PA repair (n = 3), unifocalization procedures (n = 21) and other (n = 2). Forty-two (61%) patients had mild or no liver dysfunction, while 26 (38%) had moderate or severe liver dysfunction. The median cardiopulmonary bypass time was 345 min (341 with liver dysfunction, 345 without liver dysfunction). There were a total of 8 operative (12%) deaths and 3 late (4%) deaths. Six operative and 2 late deaths occurred in patients with liver dysfunction (combined 30.7%) versus 2 operative and 1 late death (combined 7.1%) for patients without liver dysfunction (P < 0.05).

CONCLUSIONS

These results suggest that liver dysfunction has a profound impact on survival in children with Alagille syndrome undergoing congenital heart surgery.

Late outcomes of surgical reconstruction of peripheral pulmonary arteries

OBJECTIVE

The ideal management of peripheral pulmonary artery stenosis is still controversial. We adopted a primary surgical approach to this complex lesion with excellent early outcomes. In this study, we analyzed our late outcomes.

METHODS

We performed a retrospective review of 91 patients with biventricular anatomy who underwent peripheral pulmonary artery reconstruction from March 2008 to July 2020. Our surgical approach included either a single-stage complete repair through median sternotomy or a 2-stage repair through sternotomy/left thoracotomy, depending on the degree of distal involvement of the left pulmonary artery branches.

RESULTS

Median age was 26 months. Syndromic etiology was established in 54 patients (59.3%) versus nonsyndromic etiology in 37 patients (40.7%). Single-stage repair was achieved in 68 patients (74.7%). There were 2 (2.2%) in-hospital mortalities. The mean right ventricular to aortic systolic pressure ratio decreased from 1.07 ± 0.20 preoperatively to 0.32 ± 0.07 immediately postoperatively (P < .001), representing a 70.1% reduction. At 1-year postoperative catheterization, the mean right ventricular to aortic systolic pressure ratio was 0.28 ± 0.05 (P < .001 compared with immediately postoperative value). With a median follow-up of 68 months (IQR, 39-117.5 months), there was no late mortality after discharge. All patients were active and asymptomatic on the most recent follow-up. There were no early or late reinterventions on pulmonary arteries.

CONCLUSIONS

Late outcomes of surgical reconstruction of peripheral pulmonary arteries are excellent and durable in various pathologies (syndromic and nonsyndromic) with a significant reduction in right ventricular to aortic systolic pressure ratio, low mortality, and no reintervention.

Pulmonary artery augmentation using decellularized equine pericardium (Matrix Patch™): initial single-centre experience

OBJECTIVES

The aim of this study was to report our initial experience when using Matrix Patch™ a cell-free equine-derived pericardium for the augmentation of branch pulmonary arteries (PAs) in children.

METHODS

Between September 2016 and September 2019, Matrix Patch was used for the augmentation of branch PAs in 96 patients and implanted in 147 separate locations. The median age at implantation was 3.2 years (interquartile range: 0.9-8.4), and 33% of patients were infants. The patch was used mainly in redo surgeries (89.6%). Intra-procedural feasibility and reinterventions were analysed. Primary end points were death or patch-related reoperation/stent implantation. Explanted patches were stained for recellularization/calcification, or to reveal proliferation/inflammation.

RESULTS

A total of 81 patients, who received patches in 119 separate locations, were followed within a median of 20 months (interquartile range: 10.2-30.2). Patients with early reoperation/stent implantation were excluded from follow-up. No patch-related death was noted. Survival at last follow-up was 88% (95% CI: 78.8-93.7%). Overall probability of freedom from reoperation/stent implantation per location, 12 and 24 months after initial surgery was 85.8% (95% CI: 76.2-91.7%) and 78.7 (95% CI: 65.9-87.2%), respectively. At 20 months, superficial proliferation with discrete macrophage activity was seen in explants; however, no signs of calcification are observed.

CONCLUSIONS

The initial experience with the Matrix Patch in PAs showed comparable results to other xenogeneic patch materials. Long-term follow-up data are needed to prove the desired durability of the patch in different locations.

Non-invasive MRI Derived Hemodynamic Simulation to Predict Successful vs. Unsuccessful Catheter Interventions for Branch Pulmonary Artery Stenosis: Proof-of-Concept and Experimental Validation in Swine

OBJECTIVE

This study assessed the ability of hemodynamic simulations to predict the success of catheter interventions in a swine model of branch pulmonary artery stenosis (bPAS).

BACKGROUND

bPAS commonly occurs in congenital heart disease and is often managed with catheter based interventions. However, despite technical success, bPAS interventions do not lead to improved distal pulmonary blood flow (PBF) distribution in approximately 1/3rd of patients. New tools are needed to better identify which patients with bPAS would most benefit from catheter interventions.

METHODS

For 13 catheter intervention cases in swine with surgically created left PAS (LPAS), PA pressures from right heart catheterization (RHC) and PBF distributions from MRI were measured before and after catheter interventions. Hemodynamic simulations with a reduced order computational fluid dynamics (CFD) model were performed using non-invasive PBF measurements derived from MRI, and then correlated with changes in invasive measures of hemodynamics and PBF distributions before and after catheter intervention to relieve bPAS.

RESULTS

Compared to experimentally measured changes in left PBF distribution, simulations had a small bias (3.4 ± 11.1%), moderate agreement (ICC = 0.69 [0.24-0.90], 0.71 [0.23-0.91]), and good diagnostic capability to predict successful interventions (> 20% PBF increase) (AUC 0.83 [0.59-1.0]). Simulations had poorer prediction of changes in stenotic pressure gradient (ICC = 0.28 [- 0.33 to 0.73], r = 0.57 [- 0.04 to 0.87]) and MPA systolic pressure (ICC = 0.00 [- 0.52 to 0.53], r = 0.29 [- 0.32 to 0.72]).

CONCLUSION

While there was only weak to moderate agreement between predicted and measured changes in PA pressures and pulmonary blood flow distributions, hemodynamic simulations did show good diagnostic value for predicting successful versus unsuccessful catheter based interventions to relieve bPAS. The results of this proof of concept study are promising and should encourage future development for using hemodynamic models in planning interventions for patients with bPAS.

Accelerated Estimation of Pulmonary Artery Stenosis Pressure Gradients with Distributed Lumped Parameter Modeling vs. 3D CFD with Instantaneous Adaptive Mesh Refinement: Experimental Validation in Swine

Branch pulmonary artery stenosis (PAS) commonly occurs in congenital heart disease and the pressure gradient over a stenotic PA lesion is an important marker for re-intervention. Image based computational fluid dynamics (CFD) has shown promise for non-invasively estimating pressure gradients but one limitation of CFD is long simulation times. The goal of this study was to compare accelerated predictions of PAS pressure gradients from 3D CFD with instantaneous adaptive mesh refinement (AMR) versus a recently developed 0D distributed lumped parameter CFD model. Predictions were then experimentally validated using a swine PAS model (n = 13). 3D CFD simulations with AMR improved efficiency by 5 times compared to fixed grid CFD simulations. 0D simulations further improved efficiency by 6 times compared to the 3D simulations with AMR. Both 0D and 3D simulations underestimated the pressure gradients measured by catheterization (- 1.87 ± 4.20 and - 1.78 ± 3.70 mmHg respectively). This was partially due to simulations neglecting the effects of a catheter in the stenosis. There was good agreement between 0D and 3D simulations (ICC 0.88 [0.66-0.96]) but only moderate agreement between simulations and experimental measurements (0D ICC 0.60 [0.11-0.86] and 3D ICC 0.66 [0.21-0.88]). Uncertainty assessment indicates that this was likely due to limited medical imaging resolution causing uncertainty in the segmented stenosis diameter in addition to uncertainty in the outlet resistances. This study showed that 0D lumped parameter models and 3D CFD with instantaneous AMR both improve the efficiency of hemodynamic modeling, but uncertainty from medical imaging resolution will limit the accuracy of pressure gradient estimations.

Longitudinal Evolution of Pulmonary Artery Wall Shear Stress in a Swine Model of Pulmonary Artery Stenosis and Stent Interventions

Branch pulmonary artery stenosis (PAS) commonly occurs in congenital heart disease and it has previously been hypothesized that in branch PAS the pulmonary arteries (PAs) remodel their lumen diameter to maintain constant wall shear stress (WSS). We quantified the longitudinal progression of PA WSS in a swine model of unilateral PAS and two different intervention time courses to test this hypothesis. To quantify WSS in the entire pulmonary tree we used 4D Flow MRI for the large-proximal PAs and a structured tree model for the small-distal PAs. Our results only partially supported the hypothesis that in branch PAS the PAs remodel their lumen diameter to maintain WSS homeostasis. Proximal PA WSS was similar between groups at the final study time-point but WSS of mid-sized (5 mm to 500 μm) PA segments was found to be different between the sham and LPAS groups. This suggests that WSS homeostasis may only be achieved for the large-proximal PAs. Additionally, our results do not show WSS homeostasis being achieved over shorter periods of time suggesting that any potential WSS dependent changes in PA lumen diameter were a long-term remodeling response rather than a short-term vasodilation response. Future studies should confirm if these findings hold true in humans and investigate the impacts of WSS at different levels of the pulmonary tree on growth.

Pulmonary artery and lung parenchymal growth following early versus delayed stent interventions in a swine pulmonary artery stenosis model

OBJECTIVES

Compare lung parenchymal and pulmonary artery (PA) growth and hemodynamics following early and delayed PA stent interventions for treatment of unilateral branch PA stenosis (PAS) in swine.

BACKGROUND

How the pulmonary circulation remodels in response to different durations of hypoperfusion and how much growth and function can be recovered with catheter directed interventions at differing time periods of lung development is not understood.

METHODS

A total of 18 swine were assigned to four groups: Sham (n = 4), untreated left PAS (LPAS) (n = 4), early intervention (EI) (n = 5), and delayed intervention (DI) (n = 5). EI had left pulmonary artery (LPA) stenting at 5 weeks (6 kg) with redilation at 10 weeks. DI had stenting at 10 weeks. All underwent right heart catheterization, computed tomography, magnetic resonance imaging, and histology at 20 weeks (55 kg).

RESULTS

EI decreased the extent of histologic changes in the left lung as DI had marked alveolar septal and bronchovascular abnormalities (p = .05 and p < .05 vs. sham) that were less prevalent in EI. EI also increased left lung volumes and alveolar counts compared to DI. EI and DI equally restored LPA pulsatility, R heart pressures, and distal LPA growth. EI and DI improved, but did not normalize LPA stenosis diameter (LPA/DAo ratio: Sham 1.27 ± 0.11 mm/mm, DI 0.88 ± 0.10 mm/mm, EI 1.01 ± 0.09 mm/mm) and pulmonary blood flow distributions (LPA-flow%: Sham 52 ± 5%, LPAS 7 ± 2%, DI 44 ± 3%, EI 40 ± 2%).

CONCLUSION

In this surgically created PAS model, EI was associated with improved lung parenchymal development compared to DI. Longer durations of L lung hypoperfusion did not detrimentally affect PA growth and R heart hemodynamics. Functional and anatomical discrepancies persist despite successful stent interventions that warrant additional investigation.

Computed Tomography Pulmonary Vascular Volume Ratio Can Be Used to Evaluate the Effectiveness of Pulmonary Angioplasty in Peripheral Pulmonary Artery Stenosis

OBJECTIVE

To explore whether computed tomography (CT) pulmonary vascular volume ratio can be used to evaluate the effectiveness of pulmonary artery angioplasty in patients with peripheral pulmonary artery stenosis.

MATERIALS AND METHODS

Changes in CT pulmonary vascular volume ratio between serial cardiothoracic CT examinations were calculated in 38 patients. Fifteen patients underwent interim pulmonary artery angioplasty (group 1), while 23 did not (group 2). According to the effectiveness of pulmonary artery angioplasty, patients in group 1 were further divided into group 1A (improved or aggravated) and group 1B (ineffective). Changes in the pulmonary vascular volume percentages among the three groups (group 1A, group 1B, and group 2) on serial CT examinations were compared.

RESULTS

Pulmonary artery angioplasty on serial CT examinations was successful in seven patients, ineffective in seven patients, and aggravated in one patient. As a result, eight patients were included in group 1A and seven were included in group 1B. Changes in the CT pulmonary vascular volume percentages in group 1A were statistically significantly greater than those in group 1B (11.6 ± 5.6% vs. 2.7 ± 1.6%, p < 0.003) and group 2 (11.6 ± 5.6% vs. 1.9 ± 1.4%, p < 0.002), while no statistically significant difference was found between group 1B and group 2 (2.7 ± 1.6% vs. 1.9 ± 1.4%, p > 0.1).

CONCLUSION

CT pulmonary vascular volume ratio can be used to evaluate the effectiveness of pulmonary artery angioplasty in patients with peripheral pulmonary artery stenosis.

Computed tomography pulmonary vascular volume ratio in children and young adults with congenital heart disease: the effect of cardiac phase

BACKGROUND

The effect of cardiac phase on CT pulmonary vascular volumetry is unknown.

OBJECTIVE

To evaluate the effect of cardiac phase on CT pulmonary vascular volume ratio in children and young adults with congenital heart disease.

MATERIALS AND METHODS

Thirty-one children and young adults (median age 14 years) with congenital heart disease underwent electrocardiography-synchronized cardiothoracic CT at the end-systolic and end-diastolic phases as well as lung perfusion scintigraphy (n=20) or cardiac MRI (n=11). The author calculated right and left pulmonary vascular volumes by using threshold-based CT volumetry. Right pulmonary vascular volume percentages measured by CT obtained at the end-systolic and end-diastolic phases were compared with corresponding values measured by the reference method (lung perfusion scintigraphy or phase-contrast MRI) by using paired t-test and Bland-Altman analysis.

RESULTS

The right pulmonary vascular volume percentages measured by CT were significantly greater at the end-systolic phase than at the end-diastolic phase (64.0±14.1% vs. 61.9±10.7%; P<0.01). The end-systolic CT right pulmonary vascular volume percentages were not significantly different from the corresponding values measured by the reference method (64.0±14.1% vs. 65.3±13.6%; P>0.05), while the end-diastolic vascular volume percentages were significantly smaller than the corresponding values measured by the reference method (61.9±10.7% vs. 65.3±13.6%; P=0.01). Bland-Altman analysis showed a mean difference of 1.4±7.2% for the end-systolic CT, which was significantly smaller than that for the end-diastolic CT (3.4±7.0%; P<0.01).

CONCLUSION

The CT pulmonary vascular volume ratio is significantly influenced by the cardiac phase of cardiothoracic CT. The end-systolic phase offers more accurate CT pulmonary vascular volumes than the end-diastolic phase.

Consequences of an early catheter-based intervention on pulmonary artery growth and right ventricular myocardial function in a pig model of pulmonary artery stenosis

OBJECTIVE

To determine the consequences of an early catheter-based intervention on pulmonary artery (PA) growth and right ventricular (RV) myocardial function in an animal model of branch PA stenosis.

BACKGROUND

Acute results and safety profiles of deliberate stent fracture within the pulmonary vasculature have been demonstrated. The long-term impact of early stent intervention and deliberate stent fracture on PA growth and myocardial function is not understood.

METHODS

Implantation of small diameter stents was performed in a pig model of left PA stenosis at 6 weeks (10 kg) followed by dilations at 10 (35 kg) and 18 weeks (65 kg) with intent to fracture and implant large diameter stents. Hemodynamics, RV contractility, and 2D/3D angiography were performed with each intervention. The heart and pulmonary vasculature were histologically assessed.

RESULTS

Stent fracture occurred in 9/12 and implantation of large diameter stents was successful in 10/12 animals with no PA aneurysms or dissections. The final stented PA segment and distal left PA branch origins equaled the corresponding PA diameters of sham controls. Growth of left PA immediately beyond the stent was limited and there was diffuse fibro-intimal proliferation within the distal left and right PA. RV contractility was diminished in the intervention group and the response to dobutamine occurred uniquely via increases in heart rate.

CONCLUSIONS

Early stent intervention in this surgically created PA stenosis model was associated with improved growth of the distal PA vasculature but additional investigation of PA vessel physiology and impact on the developing heart are needed.

Pulmonary vascular volume ratio measured by cardiac computed tomography in children and young adults with congenital heart disease: comparison with lung perfusion scintigraphy

BACKGROUND

Lung perfusion scintigraphy is regarded as the gold standard for evaluating differential lung perfusion ratio in congenital heart disease.

OBJECTIVE

To compare cardiac CT with lung perfusion scintigraphy for estimated pulmonary vascular volume ratio in patients with congenital heart disease.

MATERIALS AND METHODS

We included 52 children and young adults (median age 4 years, range 2 months to 28 years; 31 males) with congenital heart disease who underwent cardiac CT and lung perfusion scintigraphy without an interim surgical or transcatheter intervention and within 1 year. We calculated the right and left pulmonary vascular volumes using threshold-based CT volumetry. Then we compared right pulmonary vascular volume percentages at cardiac CT with right lung perfusion percentages at lung perfusion scintigraphy by using paired t-test and Bland-Altman analysis.

RESULTS

The right pulmonary vascular volume percentages at cardiac CT (66.3 ± 14.0%) were significantly smaller than the right lung perfusion percentages at lung perfusion scintigraphy (69.1 ± 15.0%; P=0.001). Bland-Altman analysis showed a mean difference of -2.8 ± 5.8% and 95% limits of agreement (-14.1%, 8.5%) between these two variables.

CONCLUSION

Cardiac CT, in a single examination, can offer pulmonary vascular volume ratio in addition to pulmonary artery anatomy essential for evaluating peripheral pulmonary artery stenosis in patients with congenital heart disease. However there is a wide range of agreement between cardiac CT and lung perfusion scintigraphy.

Twenty years of experience with intraoperative pulmonary artery stenting

OBJECTIVES

To describe our 20-year experience with intraoperative pulmonary artery (PA) stent placement and evaluate long-term patient outcomes, specifically the need and risk factors for reintervention.

BACKGROUND

Intraoperative PA stent placement is an alternative to surgical patch arterioplasty and percutaneous angioplasty or stent placement to treat branch PA stenosis.

METHODS

We performed a retrospective review of all intraoperative PA stents placed at our institution from 1994-2013. Patient and stent characteristics and outcome data were collected. Risk factors associated with reintervention were identified using univariate cox regression analysis.

RESULTS

Eighty-one PA stents were placed in 68 patients. The procedural complication rate was 4.4%. During a median follow-up period of 6 years (interquartile range [IQR] 0.9-12.7), 30 patients (44%) underwent reintervention on the stented PA with a median time to first reintervention of 2.6 years (IQR 0.7-4.4 years). The first reintervention was surgical in 30% and catheter-based in 70%. Risk factors for reintervention included age < 18 months (Hazard ratio [HR] 2.97, P = 0.005) and body surface area < 0.47 m² (HR 3.20, P = 0.003) at the time of stent implantation, and the presence of multiple aortopulmonary collaterals in patients with tetralogy of Fallot (HR 4.61, P = 0.003).

CONCLUSIONS

Intraoperative PA stent implantation is a safe and effective alternative to percutaneous stent implantation and offers several advantages, including the ability to implant adult-size stents in small patients while avoiding injury to peripheral vessels, to position stents to facilitate future percutaneous stent redilation, and to access the PAs directly, which eliminates radiation exposure. © 2017 Wiley Periodicals, Inc.

Combined Surgical and Interventional Approaches for Treating Patients with Congenital Heart Disease

AIMS

During the last decade the cooperation between surgeons and cardiologists has further expanded by combining surgical and interventional techniques (CCBSI) performed in the operating room, without the use of fluoroscopy. We sought to evaluate the results of our experience with CCBSI.

METHODS

All children with congenital heart disease (CHD) who underwent a CCBSI in the operating room between June 2007 and January 2014 were enrolled.

RESULTS

Sixty-eight patients were included. Median age at CCBSI was five months (range 1-48 months). The three main diagnoses leading to surgery included: (1) tetralogy of Fallot (TOF) (n = 40), (2) muscular ventricular septal defects (VSD) (n = 12), (3) single ventricle with pulmonary artery branch stenosis (n = 4). There were 72 catheter-based procedures associated with surgical maneuvres, including: (1) transatrial balloon dilation (BD) of the pulmonary valve (n = 45), (2) transinfundibular BD of the main pulmonary artery trunk (n = 12), (3) perventricular VSD closure with septal occluder (n = 8), (4) BD of pulmonary artery branches (n = 5), and other less common procedures (n = 2). There were no procedure-related complications and no hospital deaths. Median follow-up time was four years (range 0.95-7.9 years). There was one late death for respiratory distress after transapical balloon dilation of the aortic valve. One patient required BD and stenting of the left pulmonary artery branch 3.6 years after intraoperative BD for residual stenosis.

CONCLUSIONS

The CCBSI represents a safe and effective treatment for selected patients with complex CHD. It will be helpful in minimizing patients' surgical trauma and in shortening or avoiding the use of cardiopulmonary bypass.