Hemodynamic changes during simulation of Valsalva-derived cardiovascular conditions in small basilar tip aneurysms: A computational fluid dynamics and one-way fluid-structure interaction analysis.

The Valsalva Maneuver (VM) produces complex oscillations in arterial blood and intracranial pressure. Herein, we aim to analyze the hemodynamics of basilar tip aneurysms (BTAs) with changes in cardiovascular parameters and intracranial pressure reported during the onset of the VM. Computational fluid dynamics (CFD) and one-way fluid-structure interaction (FSI) simulations were completed in resting conditions and hemodynamic conditions approximating phases I and IV of the VM. Time averaged wall shear stress, principal stress, Hencky strain, and wall displacement were quantified and statistically compared at the defined physiological states. Five unruptured (mean diameter 5.57 mm) and two ruptured (mean diameter 3.58 mm) BTAs from patients with a mean age of 60.9 ± 4.3 years were analyzed. Ruptured aneurysms had higher values of LSAR (4.5 vs. 0 %; p = 0.0445). In unruptured aneurysms, simulating cardiovascular changes during the VM increased the TAWSSan (Stage I + 41.78 %, p = 0.0008; Stage IV + 135.11 %, p = 0.0012), TAWSSpa (Stage I + 36.25 %, p = 0.0019; Stage IV + 98.73 %, p = 0.0021), and the TAWSSR (Stage I + 41.78 %, p = 0.0431; Stage IV + 135.11 %, p = 0.0431). RRT decreased from 0.42 at rest to 0.29 m2/N in Stage I (-30.93 %, p = 0.0001) and to 0.18 in Stage IV (-57.39 %, p = 0.0001), while HSAR increased from 14.3 % at baseline to 31.7 % in Stage I and 72.1 % in Stage IV (both p = 0.0431). Maximum principal stress increased by + 8.53 % (p = 0.0026) in Stage I and + 33.19 % (p = 0.0081) in Stage IV, and maximum strain rose by + 4.63 % (p = 0.0014) and + 16.27 % (p = 0.0018), respectively. Wall displacement augmented from 0.30 mm to 0.35 mm in Stage I (+6.10 %, p = 0.0422) and to 0.46 mm in Stage IV (+22.12 %, p = 0.0422). Similar trends were seen in ruptured aneurysms with significant increases in Stage I for TAWSSan (+41.2 %, p = 0.048), maximum principal strain (+4.40 %, p = 0.0425), and average strain (+5.62 %, p = 0.0317). Virtually simulating cardiovascular conditions of the VM in unruptured BTAs led to higher aneurysmal wall shear stress, increased HSAR, elevated wall stress, strain, and wall displacement, with a greater accentuation during the simulated stage IV.