Related Experiment Videos
Pulsatile velocity measurements in a model of the human abdominal aorta under resting conditions
1George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332-0405.
Insights
Near-wall velocity oscillations in the abdominal aorta, particularly retrograde flow at the posterior wall, correlate with atherosclerotic plaque localization. This study quantifies these hemodynamic differences, suggesting a link to disease distribution.
Area of Science:
- Cardiovascular Science
- Biomedical Engineering
- Fluid Dynamics
Background:
- Atherosclerosis localization is linked to near-wall velocity oscillations in the carotid artery.
- The role of hemodynamic factors in abdominal aortic atherosclerosis remains unclear.
Purpose of the Study:
- To quantify the abdominal aorta's velocity field.
- To determine if hemodynamic velocity differences contribute to atherosclerotic plaque localization in this region.
Main Methods:
- Utilized Magnetic Resonance Imaging velocimetry.
- Measured pulsatile velocity profiles in an anatomically accurate in vitro model of the abdominal aorta.
Main Results:
- Suprarenal aorta velocities were largely laminar, closely matching Womersley flow solutions.
- Infrarenal aorta exhibited skewed maximal velocities anteriorly, with significant retrograde flow (82% of cardiac cycle) at the posterior wall.
- Time-averaged velocity near the posterior wall was -12.5 cm/s, contrasting with +3.0 cm/s anteriorly.
Conclusions:
- Quantified low and oscillatory velocities in the abdominal aorta.
- Demonstrated a strong relationship between retrograde flow and atherosclerotic plaque distribution.
- Suggests hemodynamic velocity patterns are key factors in abdominal aortic atherosclerosis localization.
Abstract:
Oscillations in near-wall velocity direction have been found to correlate with atherosclerotic plaque localization in the carotid sinus bifurcation. However, it remains unproven whether these conditions could account for the localization of the disease at other sites where atherosclerosis forms. The abdominal aorta is an important site of clinical disease in a relatively straight segment of artery. This study was initiated to quantify the velocity field in the abdominal aorta in order to determine if local differences in hemodynamic velocity directions could account for the localization of disease in this segment. Magnetic Resonance Imaging velocimetry was used to measure the pulsatile velocity profiles in an anatomically accurate in vitro model of the abdominal aorta. Velocities measured in the suprarenal aorta were laminar and reversed minimally, comparing well with theoretical solutions of Womersley flow (r = 0.96). The time-averaged velocity was +3.0 cm/s near-wall at a distance of 1 mm away from the wall. In the infrarenal aorta, the maximal velocities were skewed toward the anterior wall. At the posterior wall, velocity oscillated in direction and was retrograde for 82 percent of the cardiac cycle. The time-averaged velocity near the posterior wall was -12.5 cm/s as compared to +3.00 cm/s near the anterior wall. At the aortic bifurcation, the locations of maximal and minimal velocities in this slice were concentrated near the lateral posterior walls. This study quantifies the magnitude of low and oscillatory velocity that may exist in the abdominal aorta and suggests that there is a strong relationship between the velocities in the retrograde direction under resting conditions and the distribution of atherosclerotic plaque.