quantifying-inferior-vena-cava-compliance-distensibility-an-vivo

Quantifying Inferior Vena Cava Compliance and Distensibility in an <i>In Vivo</i> Ovine Model Using 3D Angiography

Synthetic vascular grafts overcome some challenges of allografts, autografts, and xenografts but are often more rigid and less compliant than the native ...

Nationwide Children's Hospital

Patients who undergo implantation of a tissue-engineered vascular graft (TEVG) for congenital cardiac anomalies are monitored with echocardiography, followed by magnetic resonance imaging or angiography when indicated. While these methods provide data regarding the lumen, minimal information regarding neotissue formation is obtained. Intravascular ultrasound (IVUS) has previously been used in a variety of conditions to evaluate the vessel wall. The purpose of this study was to evaluate the utility of IVUS for evaluation of TEVGs in our ovine model. Eight sheep underwent implantation of TEVGs either unseeded or seeded with bone marrow-derived mononuclear cells. Angiography, IVUS, and histology were directly compared. Endothelium, tunica media, and graft were identifiable on IVUS and histology at multiple time points. There was strong agreement between IVUS and angiography for evaluation of luminal diameter. IVUS offers a valuable tool to evaluate the changes within TEVGs, and clinical translation of this application is warranted.

Intravascular Ultrasound Characterization of a Tissue-Engineered Vascular Graft in an Ovine Model.

We developed a tissue-engineered vascular graft (TEVG) for use in children and present results of a U.S. Food and Drug Administration (FDA)-approved clinical trial evaluating this graft in patients with single-ventricle cardiac anomalies. The TEVG was used as a Fontan conduit to connect the inferior vena cava and pulmonary artery, but a high incidence of graft narrowing manifested within the first 6 months, which was treated successfully with angioplasty. To elucidate mechanisms underlying this early stenosis, we used a data-informed, computational model to perform in silico parametric studies of TEVG development. The simulations predicted early stenosis as observed in our clinical trial but suggested further that such narrowing could reverse spontaneously through an inflammation-driven, mechano-mediated mechanism. We tested this unexpected, model-generated hypothesis by implanting TEVGs in an ovine inferior vena cava interposition graft model, which confirmed the prediction that TEVG stenosis resolved spontaneously and was typically well tolerated. These findings have important implications for our translational research because they suggest that angioplasty may be safely avoided in patients with asymptomatic early stenosis, although there will remain a need for appropriate medical monitoring. The simulations further predicted that the degree of reversible narrowing can be mitigated by altering the scaffold design to attenuate early inflammation and increase mechano-sensing by the synthetic cells, thus suggesting a new paradigm for optimizing next-generation TEVGs. We submit that there is considerable translational advantage to combined computational-experimental studies when designing cutting-edge technologies and their clinical management.

Article	Year
Intravascular Ultrasound Characterization of a Tissue-Engineered Vascular Graft in an Ovine Model. Journal of cardiovascular translational research\| PubMed ID: 28097523	2017
Spontaneous reversal of stenosis in tissue-engineered vascular grafts. Science translational medicine\| PubMed ID: 32238576	2020

Eric D. Heuer

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