Validation of a novel numerical model to predict regionalized blood flow in the coronary arteries

Abstract

Background Ischaemic heart disease results from insufficient coronary blood flow. Direct measurement of absolute flow (mL/min) is feasible, but has not entered routine clinical practice in most catheterisation laboratories. Interventional cardiologists therefore rely on surrogate markers of flow. Recently, we described a computational fluid dynamics (CFD) method for predicting flow that differentiates inlet, side branch and outlet flows during angiography. In the current study, we evaluate a new method that regionalises flow along the length of the artery. Methods and Results Three-dimensional coronary anatomy was reconstructed from angiograms from 20 patients with chronic coronary syndrome. All flows were computed using CFD by applying the pressure gradient to the reconstructed geometry. Side branch flow was modelled as a porous wall boundary. Side branch flow magnitude was based on morphometric scaling laws with two models: a homogenous model with flow loss along the entire arterial length; and a regionalised model with flow proportional to local taper. Flow results were validated against invasive measurements of flow by continuous infusion thermodilution (Coroventis™, Abbott). Both methods quantified flow relative to the invasive measures: homogenous (r 0.47, P 0.006; zero bias; 95% CI -168 to +168 mL/min); regionalised method (r 0.43, P 0.013; zero bias; 95% CI -175 to +175 mL/min). Conclusions During angiography and pressure-wire assessment, coronary flow can now be regionalised and differentiated at the inlet, outlet and side branches. The effect of epicardial disease on agreement suggests the model may be best targeted at cases with a stenosis close to side branches.

Sex differences in coronary microvascular resistance measured by a computational fluid dynamics model

“…This may also have influenced CMVR CFD results, but is unlikely to have influenced between-group differences. Although the CFD method has been validated in vitro , the physiological calculations may be subject to several sources of inaccuracies introduced from both invasive pressure measurements and the various stages of the CFD workflow, not least the in silico arterial reconstruction ( 15 , 16 ). Model sensitivity to these various sources of error is yet to be fully quantified and is likely to be case specific.…”

“…Model sensitivity to these various sources of error is yet to be fully quantified and is likely to be case specific. For example, in minimally-stenosed arteries, geometric error in the reference vessel is a dominant source of inaccuracy ( 16 ). In stenosed arteries, any error in the 3D reconstruction around the region of the stenosis will contribute significantly to overall model error ( 37 ).…”

“…In summary, two angiographic projections taken at least 30° apart were used to produce a 3D, axisymmetric, rigid reconstruction of the coronary artery of interest from an epipolar line method. Arteries with no appreciable stenosis were excluded, because the CFD method requires an epicardial pressure gradient to derive the flow and resistance values ( 13 , 16 ). The quality of arterial reconstructions was assessed by three cardiologists who were also expert users of the virtuQ software, all of whom were blinded to the CFD results.…”

Engineering innovations in medicine and biology: Revolutionizing patient care through mechanical solutions

“…Validating CFD models against real-world physiological measurements is challenging due to the invasive nature of acquiring detailed in-vivo flow data. Without rigorous validation, CFD predictions might remain speculative [ 174 ].…”