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Updated: Jun 25, 2026
A Minimally Invasive Model of Aortic Stenosis in Swine
Published on: October 20, 2023
Treatment of aortic stenosis with aortic valve bypass (apicoaortic conduit) surgery: an assessment using
Elias Balaras1, K S Cha, Bartley P Griffith
1Department of Mechanical Engineering, University of Maryland Medical Center, Baltimore, MD 21201, USA.
Insights
Aortic valve bypass surgery effectively relieves left ventricular outflow tract obstruction in aortic valve stenosis. Computational modeling shows even small conduits maintain cerebral blood flow via the native valve, potentially reducing thromboembolism risk.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Computational Fluid Dynamics
Background:
- Aortic valve stenosis (AVS) is treated with aortic valve bypass (AVB) surgery, creating a conduit from the left ventricle to the aorta.
- Post-AVB, blood flows through both the native stenotic valve and the new conduit.
- The study investigates AVB's impact on aortic and cerebral blood flow, and conduit size effects.
Purpose of the Study:
- To determine the effects of AVB on aortic and cerebral blood flow using computational modeling.
- To assess how different conduit sizes influence blood flow distribution between the native valve and the bypass conduit.
Main Methods:
- A hybrid Eulerian-Lagrangian formulation was employed for blood flow modeling.
- The finite element method was coupled with an immersed boundary approach to simulate vascular interactions.
Main Results:
- Native valve to conduit flow ratios varied with conduit size: 45:55 (20mm), 52:48 (16mm), and 60:40 (10mm).
- Mean aortic valve gradients were 12.5, 13.8, and 17.6 mm Hg for the respective conduit sizes.
- Cerebral blood flow remained unchanged post-AVB and was consistently supplied by the native valve across all modeled conduit sizes.
Conclusions:
- AVB conduits as small as 10 mm effectively relieve left ventricular outflow tract obstruction in critical AVS.
- AVB does not alter cerebral blood flow, which is entirely supplied by antegrade flow through the native valve.
- This native valve flow pattern may reduce the long-term risk of cerebral thromboembolism.
Background:
Aortic valve bypass surgery treats aortic valve stenosis with a valve-containing conduit that connects the left ventricular apex to the descending thoracic aorta. After aortic valve bypass, blood is ejected from the left ventricle via both the native stenotic aortic valve and the conduit. We performed computational modeling to determine the effects of aortic valve bypass on aortic and cerebral blood flow, as well as the effect of conduit size on relative blood flow through the conduit and the native valve.
Methods:
The interaction of blood flow with the vascular boundary was modeled using a hybrid Eurelian-Lagrangian formulation, where an unstructured Galerkin finite element method was coupled with an immersed boundary approach.
Results:
Our model predicted native (stenotic) valve to conduit flow ratios of 45:55, 52:48, and 60:40 for conduits with diameters of 20, 16, and 10 mm, respectively. Mean gradients across the native aortic valve were calculated to be 12.5, 13.8, and 17.6 mm Hg, respectively. Post-aortic valve bypass cerebral blood flow was unchanged from preoperative aortic valve stenosis configurations and was constant across all conduit sizes. In all cases modeled, cerebral blood flow was completely supplied by blood ejected across the native aortic valve.
Conclusions:
An aortic valve bypass conduit as small as 10 mm results in excellent relief of left ventricular outflow tract obstruction in critical aortic valve stenosis. The presence of an aortic valve bypass conduit has no effect on cerebral blood flow. All blood flow to the brain occurs via antegrade flow across the native stenotic valve; this configuration may decrease the long-term risk of cerebral thromboembolism.
