ORIGINAL ARTICLES

CORRECTION OF PULMONARY ATRESIA WITH A HOMOGRAFT AORTIC VALVE

Ambient air pollution is a leading risk factor for cardiovascular diseases. No study has investigated the association between exposure to fine particulate matter <2.5 μm in aerodynamic diameter (PM_2.5) and the prognosis of patients undergoing surgery for the right ventricle–pulmonary artery (RV-PA) conduit.

From 2013 to 2020, patients with six complicated congenital heart defects who had undergone surgery for the RV–PA conduit were selected. Four conduit materials were used: bovine jugular vein graft (BJV), pulmonary homograft (PHG), aortic homograft (AHG), and handmade tri-leaflet expanded polytetrafluoroethylene (ePTFE) conduit. Telephone interviews were used to confirm the postoperative address of patients. The monthly average PM_2.5 concentration was obtained from the ChinaHighPM_2.5 dataset using the place of residence of patients. By comparing findings of echocardiography undertaken before patients' return to their residence and during re-examination, we defined an increase in the trans-conduit peak velocity of ≥1.5 m/s as the study endpoint.

We enrolled 232 patients. Compared with BJV conduits, homografts (AHGs and PHGs) (0.052 (95 % CI = 0.005–0.558), P = 0.015) and ePTFE conduits (0.009 (95 % CI = 0.002–0.054), P < 0.001) were protective factors. The cumulative monthly PM_2.5 concentration (10 μg/m³) was a risk factor (1.014 (95 % CI = 1.001–1.026), P = 0.028). Winter experience was a risk factor (1.971 (95 % CI: 1.021–3.804), P = 0.043). In the subgroup analysis, Spearman correlation analysis indicated BJV conduits (r = 0.680, P < 0.001), PHGs (r = 0.559, P = 0.020), and AHGs (r = 0.745, P = 0.021) had medium-to-high positive correlations between the cumulative PM_2.5 concentration and change in the conduit velocity. For ePTFE, the correlation was weak and not significant (r = 0.222, P = 0.073).

Postoperative exposure to PM_2.5 affects the patency of biologic prosthetic conduits (especially xenografts). The increase in the velocity of the ePTFE conduit is not associated with PM_2.5 exposure, and is a suitable material for patients living in areas with high pollutant concentrations.

Conduit longevity after right ventricular outflow tract (RVOT) reconstruction is determined by the interaction of different factors. We evaluated the relationship between conduit anatomic position and long-term durability among ≥18 mm polytetrafluoroethylene (PTFE) conduits.

A single-institution RVOT reconstructions using a PTFE conduit ≥18 mm were identified. Catheter-based interventions or the need for conduit replacement were comparatively assessed between orthotopic vs heterotopic conduit position. Time to the first reintervention, censored by death, was compared between the groups.

A total of 102 conduits were implanted in 99 patients, with a median age of 13.2 years (interquartile range [IQR] 8.9-17.8 years), median weight of 47 kg (IQR, 29-67 kg), and body surface area of 1.4 m² (IQR, 1-1.7 m²). Overall, 50.9% (n = 52) of conduits were placed in an orthotopic position after the Ross procedure in congenital aortic valve abnormalities (80% [n = 36]). Tetrology of Fallot in 39% (n = 18), followed by truncus arteriosus with 33% (n = 15), were the most common in the heterotopic position. Trileaflet configuration was similar (67% vs 69%; P = .32) between the groups. Survival free from reintervention was 91% (95% CI, 79-97) and 88% (95% CI, 71-95) in the orthotopic and the heterotopic group, respectively, at 5 years, without differences in the Kaplan Meier curves (log-rank >.05).

RVOT reconstruction with PTFE conduits ≥ 8 mm showed >90% conduit survival free from replacement in our cohort at 5 years. The anatomic position of the PTFE conduit does not seem to impact intermediate durability.

Appropriate conduit selection for right ventricle (RV)-to-pulmonary artery (PA) connection has been extensively studied, with older implantation age, pulmonary (vs aortic) homografts, and true sizing associated with increased longevity. Notably, patients with PA arborization abnormalities (ie, major aortopulmonary collateral arteries [MAPCAs]) are reported to require earlier and more frequent conduit interventions. We aim to understand the behavior of large-diameter aortic homografts in patients with MAPCAs, which are programmatically utilized at our institution.

This is a single-center retrospective cohort study including all children less than 12 years of age who underwent RV-PA connection using an aortic homograft greater than or equal to 16 mm diameter between 2002 and 2019, with a primary outcome of freedom from any RV-PA reintervention and a secondary outcome of freedom from surgical reintervention. Patients were grouped by absolute and indexed conduit sizes for further analysis.

A total of 336 conduits were followed for a median of 3.0 years; transcatheter (n = 30) or surgical (n = 35) reintervention was performed on 64 conduits. Estimated freedom from reintervention and surgical replacement was 84% and 90% at 5 years. Younger age and smaller absolute conduit size were associated with earlier reintervention, but conduit Z-score (median 3.5) was not associated with outcome.

The programmatic use of oversized aortic homograft RV-PA conduits in the surgical repair of MAPCAs provides a focused experience that demonstrates similar longevity to reported best alternatives. Secondarily, conduit oversizing may improve durability and enables an increased likelihood of nonoperative reintervention.

Multiple congenital cardiac malformations require pulmonary valve replacement and/or right ventricular outflow (RVOT) reconstruction. Pulmonary valve replacement remains challenging in children owing to the limited growth potential of prosthetic valves. We evaluated outcomes in patients undergoing surgical implantation of a Melody valve in the RVOT.

Data were retrospectively collected for 23 patients undergoing surgical Melody valve implantation at Boston Children's Hospital between 2009 and 2019. We assessed postoperative valve function, reintervention rates, and mortality.

Median age was 1.7 years (range, 2 months to 6 years); 12 patients were aged greater than 2 years (52%). Diagnosis was tetralogy of Fallot in 15 patients (65%); 15 had a prior RVOT operation (65%). The Melody valve was dilated before surgery to a median diameter of 14 mm (range, 10-20 mm). No patients had acute pulmonary regurgitation. One required transcatheter RVOT reintervention before discharge. Median follow-up was 3.7 years (range, 0.02-8.7 years) with moderate or greater pulmonary regurgitation in 2 patients. Catheter-based interventions (mean, 0.83 ± 1.07/patient) occurred at a median of 1 year (range, 16 days to 5.4 years) and included valve expansion for somatic growth (n = 10) and subsequent valve-in-valve replacement (n = 3). Three patients (13%) required surgical valve explant or replacement at a median of 1.0 year (range, 0.6-3.7 years) for Melody-specific indications. One-, 3-, and 5-year freedom from Melody-driven reoperation was 90%, 90%, and 83%, respectively.

The Melody valve can be surgically implanted in the RVOT of young patients with acceptable early results. These valves can be successfully dilated through transcatheter reintervention to accommodate growth.

Right ventricular outflow tract continuity abnormalities are one of the most commonly encountered entities in the field of congenital cardiac surgery. Various strategies including homograft, valve conduit, Contegra are used to restore continuity between right ventricle and pulmonary artery. In countries like Pakistan these may not be easily available and affordable. We report the experience of our short observational study of using a handmade trileaflet valve conduit to reconstruct the right ventricular outflow tract.

From September 2015 to December 2016, a total of 15 patients with different congenital heart diseases underwent open-heart surgery at our institute. Restoration of right ventricular to pulmonary artery continuity was achieved using handmade valve conduit utilizing bovine pericardium and thin sheet PTFE sheets (0.1 mm) as conduit and valve respectively.

Patients ranged from 1 to 16 years. Seven patients had previous palliation including 4 blalock taussig (BT) Shunts and 3 pulmonary artery (PA) banding. Postoperative complications were observed in 4 patient including 2 in hospital deaths and 2 required interventions. One patient developed aneurysm at RV- conduit junction requiring surgical repair and the other underwent conduit dilatation for moderate to severe stenosis (gradient 60 mmHg). No significant regurgitation was observed in this series. Overall postoperative gradients were stable with mean gradient 25.3 mmHg (8 mmhg - 60 mmHg).

The use of handmade valve conduits has acceptable morbidity and mortality. These are cost effective alternatives in this part of the world, where well-established conduits have cost implications and uncertain availability.