Abstract
The optimal treatment of Type-B aortic dissection (AD) is still a subject of debate, with up to 50% of the cases developing late-term complications requiring invasive intervention. A better understanding of the patient-specific haemodynamic features of AD can provide useful insights on disease progression and support clinical management. In this work, a novel in vitro and in silico framework to perform personalised studies of AD, informed by non-invasive clinical data, is presented. A Type-B AD was investigated in silico using computational fluid dynamics (CFD) and in vitro by means of a state-of-the-art mock circulatory loop and particle image velocimetry (PIV). Both models not only reproduced the anatomical features of the patient, but also imposed physiologically-accurate and personalised boundary conditions. Experimental flow rate and pressure waveforms, as well as detailed velocity fields acquired via PIV, are extensively compared against numerical predictions at different locations in the aorta, showing excellent agreement. This work demonstrates how experimental and numerical tools can be developed in synergy to accurately reproduce patient-specific AD blood flow. The combined platform presented herein constitutes a powerful tool for advanced haemodynamic studies for a range of vascular conditions, allowing not only the validation of CFD models, but also clinical decision support, surgical planning as well as medical device innovation.
Highlights
Aortic dissection (AD) is a life-threatening vascular condition in which an intramural tear results in blood flowing within the medial layer of the aortic wall leading to the development of an intimal flap (IF)
The experimental inlet flow rate was characterised by T = 0.82 s, corresponding to a heart frequency of 73 bpm, mean flow rate of 137.4 ± 5.4 mL/s, and SV of 106 ± 4.4 mL, closely matching the parameters extracted from the 2D phase-contrast magnetic resonance imaging (PC-MRI)
The clinical systolic/diastolic pressure values and mean flow rate at the outlets are within the experimental range with the only exception of brachiocephalic trunk (BT), where the clinical value exceeds the upper experimental bound by 1.5 mL/s, equivalent to an error of 6%
Summary
Aortic dissection (AD) is a life-threatening vascular condition in which an intramural tear results in blood flowing within the medial layer of the aortic wall leading to the development of an intimal flap (IF). The optimal treatment of Type-B dissections—those involving the arch and descending aorta—is still debated; when uncomplicated, they are commonly managed medically, but up to 50% of the cases will develop complications requiring invasive intervention. Some anatomical predictors of AD growth are used to customise the follow-up and treatment planning; haemodynamic information such as flow patterns, pressures, velocity and wall shear stress (WSS) indices can provide a more comprehensive understanding of the condition, adding prognostic value.[11]. Elevated time-averaged WSS (TAWSS) has been associated with retrograde Type-A dissections and tear initiation,[19] while low and oscillatory WSS and vortical flow have been correlated with FL shrinkage and thrombosis.[29]. Accurate haemodynamic measurements are difficult to obtain non-invasively in vivo
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