Influence of Heart Rate and Contractility on Coronary Diagnostic Parameters With Normal Microvasculature in Porcine Model

Invasive guide-wire measurements are used to assess coronary lesion severity under clinical settings. The objective of the present research is to determine the influence of heart rate (HR) and contractility (CY) on fractional flow reserve (FFR; the ratio of distal pressure to proximal pressure at a stenotic section) and pressure drop coefficient (CDPe; the ratio of trans-stenotic pressure drop to distal dynamic pressure). In-vivo experiments were performed on eight Yorkshire pigs, to evaluate the diagnostic parameters for the conditions “CY<1100 mmHg/sec” and “CY>1100 mmHg/sec,” and for the conditions “HR<110 bpm” and “HR>110 bpm”. It was found that in the presence of normal microvasculature the measured coronary diagnostic parameters (FFR and CDPe) have a significant mean difference for variation in contractility (0.59±0.04 to 0.89±0.045 for FFR and 121.63±18 to 23.53±18 for CDPe). The variation in HR has no significant effect on FFR and CDPe (0.72±0.048 to 0.74±0.048 and 54±20 to 53±20 respectively).