A 3D printed pulmonary mock loop for hemodynamic studies in congenital heart disease.

Background. With the increasing survival of the congenital heart disease population, there is a growing need for in-depth understanding of blood circulation in these patients. Mock loops provide the opportunity for comprehensive hemodynamic studies without burden and risks for patients. This study aimed to evaluate the ability of the presented mock loop to mimic the hemodynamics of the pulmonary circulation with and without stenosis and the MR compatibility of the system.Methods. A pulsatile pump with two chambers, separated by a flexible membrane, was designed and 3D printed. A cough assist device applied an alternating positive and negative pressure on the membrane. One adult, and three pediatric pulmonary bifurcations were 3D printed and incorporated in the setup. Two pediatric models had a 50% stenosis of the left branch. Bilateral compliance chambers allowed for individual compliance tuning. A reservoir determined the diastolic pressure. Two carbon heart valves guaranteed unidirectional flow. The positive pressure on the cough assist device was tuned until an adequate stroke volume was reached with a frequency of 60 bpm. Flow and pressure measurements were performed on the main pulmonary artery and the two branches. The MR compatibility of the setup was evaluated.Results. A stroke volume with a cardiac index of 2 l min-1m-2was achieved in all models. Physiological pressure curves were generated in both normal and stenotic models. The mock loop was MR compatible.Conclusion.This MR compatible mock loop, closely resembles the pulmonary circulation thereby providing a controllable environment for hemodynamic studies.

Computational Analysis of the Pulmonary Arteries in Congenital Heart Disease: A Review of the Methods and Results.

With the help of computational fluid dynamics (CFD), hemodynamics of the pulmonary arteries (PA's) can be studied in detail and varying physiological circumstances and treatment options can be simulated. This offers the opportunity to improve the diagnostics and treatment of PA stenosis in biventricular congenital heart disease (CHD). The aim of this review was to evaluate the methods of computational studies for PA's in biventricular CHD and the level of validation of the numerical outcomes. A total of 34 original research papers were selected. The literature showed a great variety in the used methods for (re) construction of the geometry as well as definition of the boundary conditions and numerical setup. There were 10 different methods identified to define inlet boundary conditions and 17 for outlet boundary conditions. A total of nine papers verified their CFD outcomes by comparing results to clinical data or by an experimental mock loop. The diversity in used methods and the low level of validation of the outcomes result in uncertainties regarding the reliability of numerical studies. This limits the current clinical utility of CFD for the study of PA flow in CHD. Standardization and validation of the methods are therefore recommended.

Safety and efficacy of stenting for aortic arch hypoplasia in patients with coarctation of the aorta.

BACKGROUND: Despite a successful repair procedure for coarctation of the aorta (CoA), up to two-thirds of patients remain hypertensive. CoA is often seen in combination with abnormal aortic arch anatomy and morphology. This might be a substrate for persistent hypertension. Therefore, we performed endovascular aortic arch stent placement in patients with CoA and concomitant aortic arch hypoplasia or gothic arch morphology. The goal of this retrospective analysis was to investigate the safety and efficacy of aortic arch stenting. METHODS: A retrospective analysis was performed in patients who underwent stenting of the aortic arch at the University Medical Center Utrecht. Measurements collected included office blood pressure, use of antihypertensive medication, invasive peak-to-peak systolic pressure over the arch, and aortic diameters on three-dimensional angiography. Data on follow-up were obtained at the date of most recent outpatient visit. RESULTS: Twelve patients underwent stenting of the aortic arch. Mean follow-up duration was 14 ± 11 months. Mean peak-to-peak gradient across the arch decreased from 39 ± 13 mm Hg to 7 ± 8 mm Hg directly after stenting (p < 0.001). There were no major procedural complications. Mean systolic blood pressure decreased from 145 ± 16 mm Hg at baseline to 128 ± 9 mm Hg at latest follow-up (p = 0.014). CONCLUSION: This retrospective study shows that stenting of the aortic arch is successful when carried out in a state-of-the-art manner. A direct optimal angiographic and haemodynamic result was shown. No major complications occurred during or after the procedure. At short- to medium-term follow-up a decrease in mean systolic blood pressure was observed.

Three-dimensional rotational angiography in children with an aortic coarctation.

BACKGROUND: Children with aortic coarctations (CoA) are increasingly percutaneously treated. Good visualisation of the CoA is mandatory and can be obtained with three-dimensional rotational angiography (3DRA). This study aims to compare the diagnostic and therapeutic additional value of 3DRA with conventional biplane angiography (CA) in children with a CoA. METHODS: Patients undergoing percutaneous treatment of CoA with balloon angioplasty (BA) or stent between 2003 and 2015, were retrospectively reviewed on success rate, complications, radiation and technical settings. Diagnostic quality of CA and 3DRA and additional value of 3DRA were scored. RESULTS: In total, 134 patients underwent 183 catheterisations, 121 CA and 62 3DRA-guided. Median age was 0.52 years in the BA group and 11.19 years in the stent group. 3DRA was superior to CA in displaying the left ventricle (p = 0.008), ascending aorta (p < 0.001), aortic arch (p = 0.005) and coronary arteries (p < 0.001). In the BA group, 3DRA had a significantly higher success rate than CA (100.0 % versus 68.9 %, p = 0.016). All stent interventions were successful. Complication rates did not differ significantly. The median total dose area product did not significantly differ between CA and 3DRA in the BA (27.88 µGym2/kg versus 15.81 µGym2/kg, p = 0.275) or stent group (37.34 µGym2/kg versus 45.24 µGym2/kg, p = 0.090). 3DRA was of additional value in 96.8 % of the interventions. CONCLUSIONS: 3DRA is superior to CA in diagnostic quality and not associated with increased radiation exposure. It provides high additional value in guiding CoA related interventions.