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Hemodynamic stress in lateral saccular aneurysms.
D W Liepsch1, H J Steiger, A Poll
1Hal B. Wallis Research Facility, Eisenhower Medical Center, Rancho Mirage, CA 92270.
Biorheology
|January 1, 1987
Summary
Pulsatile blood flow significantly increases intra-aneurysmal velocities and shear stress, influencing thrombosis risk. Blood
Area of Science:
- Biomedical Engineering
- Fluid Dynamics
- Cardiovascular Research
Background:
- Saccular aneurysms pose a significant risk of rupture and hemorrhage.
- Understanding intra-aneurysmal hemodynamics is crucial for predicting aneurysm progression and thrombosis.
- Previous studies have explored aneurysm models, but the combined effects of wall elasticity, pulsatility, and blood properties require further investigation.
Purpose of the Study:
- To quantitatively measure intra-aneurysmal flow velocities in glass and silastic aneurysm models.
- To investigate the influence of wall elasticity, pulsatile flow, and perfusion medium properties on intra-aneurysmal circulation.
- To estimate shear stresses at critical locations within the aneurysm and correlate them with flow dynamics.
Main Methods:
- Utilized a non-invasive laser Doppler method for quantitative flow velocity measurements.
- Employed standardized glass and silastic lateral aneurysm models.
- Investigated both non-pulsatile and pulsatile perfusion conditions using glycerol/water solutions and blood-mimicking polymer suspensions.
Main Results:
- Intra-aneurysmal flow velocities were significantly higher under pulsatile perfusion (8-13% of parent vessel velocity) compared to non-pulsatile flow (0.4-2%).
- Flow velocities were lower with a blood-like polymer suspension than with a glycerol/water solution.
- Maximum shear stresses at the downstream lip were comparable to those at arterial bifurcation flow dividers.
- Intra-aneurysmal flow and shear stress are directly related to perfusion pulsatility (systolic/diastolic pressure difference).
Conclusions:
- Pulsatility of perfusion is a key factor in determining intra-aneurysmal flow dynamics and shear stress.
- The viscoelastic properties of blood, specifically hematocrit, likely influence the tendency for spontaneous thrombosis.
- Findings suggest a direct link between hemodynamic forces and thrombosis potential in saccular aneurysms.