Exploring the effect of different exercise intensities on hemodynamics of abdominal aortic aneurysm based on multiscale computational fluid dynamics simulations

Exercise has been shown to provide cardiovascular benefits for patients with abdominal aortic aneurysms (AAA). However, the relationship between AAA hemodynamics and exercise intensities is unclear. The present study aims to use multiscale computational fluid dynamics (CFD) simulations to investigate how different intensities affect the AAA hemodynamics, hoping to help patients' daily exercise management. A patient-specific AAA model was established based on magnetic resonance angiography. The hemodynamic environment under resting and five intensity exercise states was obtained using multiscale CFD simulations. The required heart rate, cardiac output, and blood pressure were calculated from the metabolic equivalent (MET). The results show that: (1) The shape of the AAA flow waveform during exercise is different from that at rest. (2) The reverse velocity vectors are always concentrated on one side of the AAA. Exercise increases the flow velocity, but the systolic flow patterns become chaotic during moderate- and high-intensity exercises. (3) As the intensity increases, the proportions of time-averaged wall shear stress (TAWSS) <0.4 Pa area are 34.58, 6.81, 2.68, 0.53, 0.25, and 0.07%, and those of TAWSS >4 Pa are 0, 0.21, 2.40, 9.53, 14.84, and 31.56%. Compared with the resting state, the proportions of oscillatory shear index >0.3 area decrease 1.50, 2.23, 2.29, 2.33, and 3.65 times. For this patient, the recommended exercise plan maintains 1.75–2.5 METs with a heart rate of 75–83 bpm. Multiscale CFD simulations can effectively display the hemodynamic environment within AAA during exercise. It has the potential to provide concrete insights into vague exercise intensity, benefiting specific AAA patients.