Abstract
Objective: To investigate the effect of the blood flow direction and afflux location of emissary veins (EVs) on the hemodynamics of the transverse-sigmoid sinus (TS-SS) junction.Methods: A patient-specific geometric model was constructed using computed tomography venography (CTV) and 4D flow MR data from a venous pulsatile tinnitus (PT) patient. New EV models were assembled with the afflux at the superior, middle and inferior portions of the SS from the original model, and inlet and outlet directions were applied. Computational fluid dynamics (CFD) simulation was performed to analyze the wall pressure and flow pattern of the TS-SS junction in each condition.Results: Compared to the model without EVs, the wall pressure was greatly increased in models with inlet flow and greatly decreased in models with outlet flow. The more closely the EV approached the TS-SS, the larger the pressure in models with inlet flow, and the smaller the pressure in models with outlet flow. The flow streamline in the lateral part of the TS-SS junction was smooth in all models. The streamlines in the medial part were regular spirals in outlet models and chaotic in inlet models. The streamlines showed no obvious changes regardless of afflux location. The velocity at the TS-SS junction of inlet models were uniform, medium-low flow rate, while in control and outlet models were the lateral high flow rate and the central low flow rate.Conclusion: The flow direction and afflux location of EVs affect the hemodynamics of the TS-SS junction, which may influence the severity of PT.
Highlights
Pulsatile tinnitus (PT) is a bothersome and not infrequent condition with vascular origins; this condition, mostly occurs in childbearing women
Comparing the velocity streamline of the real 4D flow MR postprocessing model of the patient collected in this study with the streamline model obtained by Computational fluid dynamics (CFD) simulation, it was found that the blood flow pattern and velocity were consistent (Figure 2), which confirmed the accuracy of CFD simulation in vivo blood flow state
A specific-patient hemodynamic analysis implies that the flow direction and afflux location of Emissary veins (EVs) affect the hemodynamics of the transverse-sigmoid sinus (TS-SS) junction and the severity of PT
Summary
Pulsatile tinnitus (PT) is a bothersome and not infrequent condition with vascular origins; this condition, mostly occurs in childbearing women. Venous origins are most commonly found (Lyu et al, 2018). The transverse-sigmoid sinus (TS-SS) junction has been reported as the most commonly involved site in venous PT. Recent studies have implied that venous PT may be generated by a combination of multiple vascular, skeletal and pressure factors (Eisenman et al, 2018). Increased wall pressure and a turbulent flow pattern at the TS-SS junction are thought to be associated with venous PT (Amans et al, 2018; Li et al, 2018; Mu et al, 2020), which implies that any procedure changing the hemodynamics in this area may alleviate or worsen the sound
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