A predictive patient-specific computational model of coronary artery bypass grafts for potential use by cardiac surgeons to guide selection of graft configurations

Abstract

Cardiac surgeons face a significant degree of uncertainty when deciding upon coronary artery bypass graft configurations for patients with coronary artery disease. This leads to significant variation in preferred configuration between different surgeons for a particular patient. Additionally, for the majority of cases, there is no consensus regarding the optimal grafting strategy. This situation results in the tendency for individual surgeons to opt for a “one size fits all” approach and use the same grafting configuration for the majority of their patients neglecting the patient-specific nature of the diseased coronary circulation. Quantitative metrics to assess the adequacy of coronary bypass graft flows have recently been advocated for routine intraoperative use by cardiac surgeons. In this work, a novel patient-specific 1D-0D computational model called “COMCAB” is developed to provide the predictive haemodynamic parameters of functional graft performance that can aid surgeons to avoid configurations with grafts that have poor flow and thus poor patency. This model has significant potential for future expanded applications.

Personalized surgical planning for coronary bypass graft configurations using patient-specific computational modeling to avoid flow competition in arterial grafts

“… * RCA lesions were > 90% in this study whereas Onorati et al ( 46 ) had >80%. ++ Affected by head of pressure from aorta ( 25 ). Values are presented as mean ± standard deviation.…”

“…The limitations arising from computational modeling have been described previously ( 25 ). With more invasive clinical patient data available, the idealized generic parameters of aortic root pressure, LV pressure, heart rate, CO, total arterial compliance and systemic arterial branch dimensions could be made more patient-specific.…”

“…The chosen meshgrid size, Δ x , was set at Δ x ≈ 0.1cm and the timestep, Δ t , was chosen to be the largest value possible whilst ensuring stability of the numerical scheme with Δ t ≈ 2.95 × 10 −5 . The methodology for the creation of the CFD models has previously been described in detail in the literature ( 25 ). The vessel segment data and vessel segment relations used for all network simulations for the five patients are provided in Supplementary material 1 – 5 .…”

“…Approximately 4.5% of CO was assigned to myocardial blood flow with this flow distributed to the three main coronary territories: LAD, CIRC, and RCA, as dictated by distribution of vessels on the CTCA. Total arterial compliance was estimated at 1.15 cm 3 /mmHg from the aortic pressure waveform and a 3-element Windkessel resistance-capacitance-resistance (RCR) model was applied at the outlets of the terminal vessels to represent the distal microcirculation ( 25 ). iFR was chosen as the metric for functional stenosis severity as it is measured at rest like TTFM graft measurements, not at hyperemia which is used for FFR.…”

“…Future studies could also be streamlined by including more surgeons who perform anaortic total arterial OPCABG revascularisation using BIMA or even CABG involving more composite and sequential grafts. The limitations arising from computational modeling have been described previously (25). With more invasive clinical patient data available, the idealized generic parameters of aortic root pressure, LV pressure, heart rate, CO, total arterial compliance and systemic arterial branch dimensions could be made more patient-specific.…”