Comparison of Instantaneous Wave-Free Ratio (iFR) and Fractional Flow Reserve (FFR) with respect to Their Sensitivities to Cardiovascular Factors: A Computational Model-Based Study

Figure 4

Percentage changes of iFR and FFR relative to their reference values upon the variations of each model parameter. The variations of all parameters except for EOA_dia and EOA_sys are expressed in normalized form relative to their reference values to facilitate the comparisons of the effects on iFR/FFR among different parameters. The stenosis is present in mid-LAD with its stenosis rate being set at 50% and 70%, respectively, and the corresponding reference values (computed with all model parameters being fixed at their reference states) of iFR/FFR are 0.920/0.813 and 0.677/0.534, respectively. (a) EOA_dia. (b) EOA_sys. (c) E_lva. (d) E_lvb. (e) HR. (f) aPWV. (g) R_sys. (h) R_cmv. Notations: EOA_dia/EOA_sys, effective orifice area of aortic valve during diastole/systole (an increase in EOA_dia represents an increase in the severity of aortic valve regurgitation, whereas a decrease in EOA_sys represents an increase in the severity of aortic valve stenosis); E_lva/E_lvb, peak systolic elastance/baseline diastolic elastance of the left ventricle; HR, heart rate; aPWV, aortic pulse wave velocity; R_sys, total systemic vascular resistance; R_cmv, total coronary microvascular resistance.

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