Influence of Fractional Flow Reserve Setting on the Procedure Precision

Coronary artery disease is the progressive narrowing (stenosis) of the heart supply arteries. Heart attack could occur as a consequence of severe blockage in the artery. A definitive diagnosis of its severity is of great importance for physicians to decide the best treatment plan. Fractional flow reserve (FFR) is a procedure that adopts a sensor tipped guidewire to measure upstream and downstream pressures of the stenosis. It is considered the most accurate method to pinpoint the stenosis severity. In this procedure, the centerlines of the guidewire and blood vessel should be aligned together. Due to the long distance between its insertion point and the stenosis, a possible inclination of the guidewire can occur. The aim of the present study is to investigate the effect of guidewire inclination on pressure measurements. Three different degrees of severity are modeled with placing the guidewire at different inclination angles. Continuity and momentum equations of blood flow are stated and computationally simulated. Comparisons between calculated and available measured values show a good agreement. The ratios between pressure drop and distal dynamic pressure (CDP), and between pressure recovery coefficient and the area blockage (η) are calculated. The predicted results for each case are compared with the control case (without guidewire) and analyzed. The results aid in improving the FFR accuracy in diagnosis of stenosis severity.