Gianluca Rigatelli, Marco Zuin, Fabio Dell’Avvocata, Aravinda Nanjundappa, Ramesh Daggubati and Thach Nguyen
To non-invasively evaluate by computational fluid dynamic (CFD) analysis the physiology and rheology of aortoiliac bifurcation disease at different angles and different stent configurations.
Material and methods
For the analysis, we considered a physiologic model of abdominal aorta with an iliac bifurcation set at 30°, 45° and 70° without stenosis. Subsequently, a bilateral ostial common iliac stenosis of 80% was considered for each type of bifurcation. For the stent simulation, we reconstructed Zilver vascular self-expanding (Zilver; Cook, Bloomington, MN) and Palmaz Genesis Peripheral (Cordis, Miami, FL) stents.
The physiologic model, across the different angles, static pressure, Reynolds number and stream function, were lower for the 30° bifurcation angle with a gradient from 70° to 30° angles, whereas all the other parameters were inversely higher. After stenting, all the fluid parameters decreased homogenously independent of the stent type, maintaining a gradient in favour of 30° compared to 45° and 70° angles. The absolute greater deviation from physiology was observed for low kissing when self-expandable stents were used across all angles; in particular, the wall shear stress was high at at 45° angle.
Bifurcation angle deeply impacts the physiology of aortoiliac bifurcations, which are used to predict the fluid dynamic profile after stenting. CFD, having the potential to be derived both from computed tomography scan or invasive angiography, appears to be an ideal tool to predict fluid dynamic profile before and after stenting in aortoiliac bifurcation.
Gianluca Rigatelli, Marco Zuin, Tra T. Ngo, Hung T. Nguyen, Aravinda Nanjundappa, Ernest Talarico, Le Cao Phuong Duy and Thach Nguyen
Background and Objectives
Significant rather than moderate coronary artery stenosis has been postulated to be the main substrate of plaque rupture in acute myocardial infarction (AMI). We evaluate if cavitation could influence the coronary artery plaque rupture contributing to the progression of thrombotic process.
We reconstructed a 3D model of the left anterior descending coronary artery (LAD) after reviewing the intravascular ultrasound (IVUS) data of 30 consecutive patients with mild to severe coronary artery disease.
Turbulent flow or cavitation occurs in both concentric and eccentric coronary artery stenosis (≥ 75% for the former and ≥ 50% for the latter). The analysis of vapor phase demonstrated that cavitation propagated downstream, creating microbubbles, which exploded when the fluid pressure was lower than the vapor pressure at a local thermodynamic state. The relative higher vorticity magnitude (as turbulent flow in vivo angiogram) observed on the distal cap of the atherosclerotic plaque created a higher turbulence, probably able to destabilize the plaque through a micro-erosion process.
Cavitation seems to be able to promote the thrombotic occlusion within the coronary vessels due the ‘constant injuries’ created by the micro-explosion of bubbles.