Computational modeling and ovine data reveal spontaneous reversal of early tissue-engineered vascular graft stenosis, with clinical implications.

Background: Tissue-engineered vascular grafts (TEVGs) have the potential to advance the surgical management of infants and children requiring congenital heart surgery by creating functional vascular conduits with growth capacity. Methods: Herein, we used an integrative computational-experimental approach to elucidate the natural history of neovessel formation in a large animal preclinical model; combining an in vitro accelerated degradation study with mechanical testing, large animal implantation studies with in vivo imaging and histology, and data-informed computational growth and remodeling models. Results: Our findings demonstrate that the structural integrity of the polymeric scaffold is lost over the first 26 weeks in vivo, while polymeric fragments persist for up to 52 weeks. Our models predict that early neotissue accumulation is driven primarily by inflammatory processes in response to the implanted polymeric scaffold, but that turnover becomes progressively mechano-mediated as the scaffold degrades. Using a lamb model, we confirm that early neotissue formation results primarily from the foreign body reaction induced by the scaffold, resulting in an early period of dynamic remodeling characterized by transient TEVG narrowing. As the scaffold degrades, mechano-mediated neotissue remodeling becomes dominant around 26 weeks. After the scaffold degrades completely, the resulting neovessel undergoes growth and remodeling that mimicks native vessel behavior, including biological growth capacity, further supported by fluid–structure interaction simulations providing detailed hemodynamic and wall stress information. Conclusions: These findings provide insights into TEVG remodeling, and have important implications for clinical use and future development of TEVGs for children with congenital heart disease.

Background: Stent implantation (SI) is more effective than balloon angioplasty for the treatment of coarctation of the aorta (CoA). Due to technical factors, balloon angioplasty is more commonly performed in small patients. We sought to evaluate outcomes of percutaneous adult sized SI for the treatment of CoA in small patients. Methods: A single-center retrospective review of all patients ≤20 kg who underwent percutaneous adult sized SI for native or recurrent CoA from 2004 to 2015 was performed. Results: Thirty-nine patients (20 patients ≤10 kg) were identified, with 28 (71.8%) having recurrent CoA and 22 (56.4%) previously failed balloon angioplasty. At the time of SI, the median (range) patient age and weight were 1.1 (0.3–7.9) years and 10 (5.5–20.4) kg, respectively. SI resulted in significant improvements in the median gradient (26 mm Hg [interquartile range (IQR), 18–42] to 0 mm Hg [IQR, 0–2]; P < 0.05) and median minimum diameter (3.6 mm [IQR, 2.4–4.8] to 7.7 mm [IQR, 6.5–9.4]; P <0.05). Seven patients (18%) had procedural adverse events. Twenty-seven (69%) patients underwent elective reintervention at a median time of 49.3 (IQR, 26.5–63.2) months from SI, with 8 (21%) stents requiring repeat SI for stent fracture. Over a median follow-up of 67.2 (IQR, 33.8–116.1) months, 25 patients (69%) were without hypertension or blood pressure gradient. Three (11%) patients developed femoral arterial occlusion. Conclusions: Adult sized SI is an alternative to surgical intervention for small patients with CoA. SI carries a risk of access-related complications, which may improve with the development of lower profile stents with adult sized maximum diameters.

We aimed to evaluate the utility of computed tomography angiography (CTA) for coronary compression (CC) prediction in patients with congenital heart disease undergoing balloon-expandable transcatheter pulmonary valve replacement (TPVR). Coronary compression is a serious complication of TPVR, but the value of preprocedural CTAs to assess CC risk is largely unexplored. In all, 586 patients underwent TPVR between January 2009 and July 2018. Adults with a pre-TPVR CTA and children with a CTA performed less than one year prior to TPVR were included. Patients with poor CTA image quality or with aborted cases due to reasons other than CC were excluded. Sixty-six patients were finally included. Cardiac anatomy was assessed via multiplanar reconstruction of CTAs. Coronary compression occurred in 9 (14%) of the 66 patients who underwent TPVR. Most CC cases (seven of nine) occurred in patients with conduits. Proximity of the right ventricular outflow tract (RVOT) landing zone to the coronary arteries and to the chest wall was a significant risk factor for compression (P < .001 and P = .019, respectively). Compression risk increased significantly if patients had an RVOT to coronary artery distance of ≤3 mm (P < .001) and an RVOT to chest wall distance of ≤8 mm (P = .026). Anomalous course of coronary arteries was another significant univariate risk factor (P = .003). Right ventricular outflow tract landing zone distance of ≤3 mm to a coronary artery, landing zone distance of ≤8 mm to the chest wall, and anomalous coronary arteries are associated with increased CC risk. Electrocardiogram gating may not be necessary if coronary arteries are opacified on CTAs. Larger studies are needed to explore and confirm these coronary artery compression risk factors.