Why do ulcerated atherosclerotic carotid artery plaques embolize? A flow dynamics study

Area of Science:

• Cardiovascular Science
• Biomedical Engineering
• Fluid Dynamics

Background:

• Atherosclerosis in the carotid artery can lead to stroke.
• Ulcerated plaques are particularly associated with embolic events.
• Understanding the hemodynamics of ulcerated plaques is crucial for stroke prevention.

Purpose of the Study:

• To analyze flow dynamics and pressure relationships in a replica of an ulcerated human carotid bulb.
• To investigate the hemodynamic factors contributing to thrombus formation and embolism from carotid plaques.

Main Methods:

• Created replicas of an ulcerated atherosclerotic human carotid bulb using the lost wax technique.
• Simulated human physiological flow profiles using pulsating non-Newtonian fluid.
• Recorded flow patterns and measured pressures within the carotid bulb replica.

Main Results:

• The replica exhibited significant stenosis (59% diameter, 88% area) with a shallow ulcer.
• Flow accelerated through the narrowed bulb, creating disturbed, helical, but nonturbulent flow patterns.
• Lower radial pressure and vortex circulation were observed at the ulcer site during peak systole.

Conclusions:

• The combination of slow swirling flow within the ulcer and the Bernoulli effect may promote platelet aggregate formation.
• These aggregates can be dislodged into the main flow, potentially causing embolic stroke.
• Hemodynamic analysis of ulcerated carotid plaques provides insights into stroke mechanisms.