Cardiovascular changes in children with coarctation of the aorta treated by endovascular stenting

Computational Modelling of Cerebral Blood Flow Rate at Different Stages of Moyamoya Disease in Adults and Children

Moyamoya disease is a cerebrovascular disorder which causes a decrease in the cerebral blood flow rate. In this study, a lumped parameter model describing the pressures and flow rates in the heart chambers, circulatory system, and cerebral circulation with the main arteries in the circle of Willis, pial circulation, cerebral capillaries, and veins was used to simulate Moyamoya disease with and without coarctation of the aorta in adults and children. Cerebral blood flow rates were 724 mL/min and 1072 mL/min in the healthy adult and child cardiovascular system models. The cerebral blood flow rates in the adult and child cardiovascular system models simulating Moyamoya disease were 676 mL/min and 1007 mL/min in stage 1, 627 mL/min and 892 mL/min in stage 2, 571 mL/min and 831 in stage 3, and 444 and 537 mL/min in stage 4. The cerebral blood flow rates were 926 mL/min and 1421 mL/min in the adult and child cardiovascular system models simulating coarctation of the aorta. Furthermore, the cerebral blood flow rates in the adult and child cardiovascular system model simulating Moyamoya disease with coarctation of the aorta were 867 mL/min and 1341 mL/min in stage 1, 806 mL/min and 1197 mL/min in stage 2, 735 mL/min and 1121 in stage 3, and 576 and 741 mL/min in stage 4. The numerical model utilised in this study can simulate the advancing stages of Moyamoya disease and evaluate the associated risks with Moyamoya disease.

Endovascular Stent Repair of Aortic Coarctation in a Developing Country: A Single-Center Experience

BACKGROUND/PURPOSE

CoA remains one of the most common congenital heart diseases and is associated with significant morbidity and mortality and if untreated. We aim to evaluate the safety, feasibility, and outcomes of endovascular stenting of Coarctation of the aorta (CoA) in a developing country with limited resources and compare it to available benchmarks.

MATERIALS/METHODS

A retrospectively review of all patients who underwent endovascular stent repair of aortic coarctation at our tertiary center since 2009 was done.

RESULTS

18 patients were identified, sixteen had native CoA, while two had recurrent CoA. mean age at the time of procedure was 21.2 ± 9.8 years (range 10-45 years), and 12(66%) patients were males. The mean follow-up duration was 4 ± 2.8 years. Post stenting, the average ascending-to-descending aorta systolic gradient decreased by 42.9 ± 20.4 mmHg (p < 0.001). After the intervention, 13(72.2%) patients achieved normal BP while 5(27.8%) had residual hypertension. Fourteen patients received bare-metal stents, and four had covered stents. Attempted stent implantation was successful in all patients. Our procedural success rate was 94%. On follow-up, no dissections or aneurysmal changes were detected, four patients underwent re-expansion of the stent, one patient with suboptimal stenting result required surgery 6 months after stenting, and two patients had minor post-operative complications.

CONCLUSIONS

Endovascular stenting for de-novo or recurrent CoA in children and adults at a tertiary center in a developing country is feasible and safe with outcomes comparable to developed countries. A multidisciplinary team approach is paramount in achieving good results and low complication rates in limited-resource settings.

Prediction of post-stenting biomechanics in coarcted aortas: A pilot finite element study

Endovascular stenting has recently become a standard treatment for native coarctation of the aorta (CoA) in children and young adults, given the efficacy in relieving vessel obstruction with a low incidence of adverse events. Yet, despite the short-term success of the technique, late hypertension remains an endemic risk. To assess the impact of the percutaneous procedure on the aortic wall biomechanics, we designed a novel finite element (FE) protocol for the simulation of endovascular stenting in three patient-specific CoA anatomies, developing a remeshing procedure that allows for coping with different CoA severities. Our FE protocol was able to yield numerical results on stent distortions and stresses, as well as on changes in aortic wall stresses and distensibility. These results were consistent with intraprocedural in-vivo evidences and with previous findings from the literature, and they suggest that our numerical approach could be used to understand the role of patient specific anatomical features (CoA severity and arch type) on the post-stenting aortic biomechanics. If soundly validated on a vast cohort of patients, our approach could support patient selection for the procedure.

Aortic stenting in the growing sheep causes aortic endothelial dysfunction but not hypertension: Clinical implications for coarctation repair

BACKGROUND

Stent implantation is the treatment of choice for adolescents and adults with aortic coarctation (CoAo). Despite excellent short-term results, 20%-40% of the patients develop arterial hypertension later in life, which was attributed to inappropriate response of the aortic baroreceptors to increased stiffness of the ascending aorta (ASAO), either congenital or induced by CoAo repair. In particular, it has been hypothesized that stent itself may cause or sustain hypertension. Therefore, we aimed to study the hemodynamic and structural impact following stent implantation in the normal aorta of a growing animal.

METHODS

Eight female sheep completed the study and a stent was implanted in four. Every 3 mo we measured blood pressure of the anterior and posterior limbs and left ventricular function by echocardiography. Twelve months later invasive pressure was measured under baseline and simulated stress conditions. Expression of genes indicating oxidative stress (OS), endothelial dysfunction (ED) and stiffness, as well as pathological examination were performed in ascending (ASAO) and descending aorta (DSAO).

RESULTS

SOD1 and MMP9 gene expression were higher in ASAO of the stented animals, compared to DSAO and controls, while NOS3 was decreased. No differences were found in blood pressure and echocardiographic parameters. No histological differences were found in the aorta of the two groups of animals.

CONCLUSIONS

Stent does not affect central and peripheral hemodynamics, cardiac structure and function even in the long term. However, the finding of markers of OS and increased stiffness of ASAO, proximal to the stent, points to molecular mechanisms for increased cardiovascular risk of patients with stented CoAo.