Abdominal aortic hemodynamics in young healthy adults at rest and during lower limb exercise: quantification using...

Area of Science:

• Cardiovascular Physiology
• Biomechanical Engineering
• Medical Imaging

Background:

• Atherosclerotic lesions in the abdominal aorta are linked to adverse hemodynamic conditions like low wall shear stress and flow recirculation.
• Exercise offers systemic benefits and is proposed to provide local vascular advantages by altering regional blood flow patterns.

Purpose of the Study:

• To investigate the effects of exercise on hemodynamic conditions in the human abdominal aorta.
• To determine if exercise alters regional flow patterns, mean wall shear stress (WSS), and oscillatory shear index (OSI).

Main Methods:

• Subject-specific computational models of the abdominal aorta were created from magnetic resonance angiograms of five healthy individuals.
• Computer simulations were conducted under resting and exercise (50% heart rate increase) pulsatile flow conditions.
• Analysis of velocity fields, WSS, and OSI was performed across different aortic regions.

Main Results:

• Averaged across subjects, mean wall shear stress (WSS) increased from 4.8 to 31.6 dyn/cm2, and oscillatory shear index (OSI) decreased from 0.22 to 0.03 in the infrarenal aorta during exercise.
• Significant increases in WSS and decreases in OSI were observed at the supraceliac, infrarenal, and suprabifurcation levels during exercise.
• Distinct spatial variations in WSS were noted between anterior and posterior aortic sections.

Conclusions:

• Exercise acutely alters hemodynamic forces within the abdominal aorta, characterized by increased WSS and reduced OSI.
• These exercise-induced mechanical stimuli are hypothesized to trigger biological processes that protect against atherosclerosis development and progression.
• The findings support exercise as a localized protective intervention for cardiovascular health.