The Role of Extra-Coronary Vascular Conditions that Affect Coronary Fractional Flow Reserve Estimation

The treatment of coronary stenosis relies on invasive high risk surgical assessment to generate the fractional flow reserve, a ratio of distal to proximal pressures in respect of the stenosis. Non-invasive methods are therefore desirable. Non-invasive imaging-computational methodologies call for robust and calibrated mathematical descriptions of the coronary vasculature that can be personalized. In addition, it is important to understand extra-coronary co-morbidities that may affect fractional flow estimates. In this preliminary theoretical work, a 0D human coronary vasculature model was implemented, and used to demonstrate the distinct roles of focal and extended stenosis (intra-coronary), as well as microvascular disease and atrial fibrillation (extra-coronary) on fractional flow reserve estimation. It was found that the right coronary artery is maximally affected by diffuse stenosis and microvascular disease. The model predicts that the presence, rather than severity, of both microvascular disease and atrial fibrillation affect coronary flow deleteriously. The model provides a computationally inexpensive instrument for future in silico coronary blood flow investigations as well as clinical-imaging decision making. The framework provided is extensible as well as can be personalized. Furthermore, it provides a starting point and crucial boundary conditions for future 3D computational hemodynamics flow estimation.