Flow disturbances in stent-related coronary evaginations: a computational fluid-dynamic simulation study

Area of Science:

• Cardiovascular research
• Biomedical engineering
• Medical imaging analysis

Background:

• Late stent thrombosis is linked to angiographic ectasias and aneurysms in stented segments.
• Optical coherence tomography (OCT) can detect coronary evaginations, which resemble ectasias, in stented areas.

Purpose of the Study:

• To investigate if OCT-detected coronary evaginations can alter local blood flow dynamics.
• To utilize computational fluid-dynamic (CFD) simulations to explore the impact of evaginations on blood flow.

Main Methods:

• Modeled 3-D coronary evaginations of varying sizes (depth 0.2-1.0 mm, length 1-9 mm) with an ellipsoid shape.
• Employed CFD simulations using average coronary artery flow velocity data.
• Assessed flow changes via particle tracing, comparing transit times in evaginated segments versus control vessels.

Main Results:

• OCT-detected evaginations are outward bulges between stent struts, deeper than strut thickness.
• The presence of evaginations caused delayed particle transit times, increasing with evagination size.
• Simulations revealed local flow recirculation within evaginations and flow deceleration due to lumen changes.

Conclusions:

• CFD simulations indicate that coronary evaginations significantly impact local blood flow.
• The degree of flow disturbance is directly proportional to the size of the evagination.