In Vivo Validation of Computational Fluid Dynamics for Determining the Pressure Gradient for Multi-segmental Femoropopliteal Disease

PURPOSE: In peripheral arterial disease, the presence of multi-segmental (adjacent) stenotic lesions is common. The application of anatomic grading and duplex ultrasound for defining the significance of multi-segmental lesions is limited. This study aimed to validate computational fluid dynamics (CFD) simulations for estimating the pressure gradient in patients with multi-segmental femoropopliteal disease. MATERIALS AND METHODS: Fifteen patients scheduled for angiography with multiple lesions in the femoropopliteal artery were prospectively enrolled. Pressures were recorded in rest and after papaverine administration using sheath and pressure-wire measurements. The resting pressure gradient of the full segment and the fractional flow reserve (FFR) of the full segment and individual lesions were calculated. These metrics were noninvasively replicated by CTA-based CFD using a reference flow rate (CFDm) and a duplex ultrasound-derived flow rate (CFDi). The agreement and diagnostic accuracy of CFD for identifying hemodynamic significance was assessed. RESULTS: CFDm underestimated the pressure gradient by - 4.0 ± 6.2 mmHg (mean ± SD). CFDi closely approximated the measured gradient with a 0.1 ± 3.1 mmHg difference. The full-segment FFR had a - 0.02 ± 0.06 difference and the individual-lesion FFR had a 0.01 ± 0.06 difference relative to the measured FFR. The diagnostic accuracy of CFD for the resting pressure gradient was 73% (CFDi) and 80% (CFDm). CFD demonstrated a diagnostic accuracy of 89% for full-vessel FFR and 83% for individual-lesion FFR. CONCLUSION: The results provide proof-of-concept validation for the use of CFD for noninvasive assessment of multi-segmental femoropopliteal disease. This could guide the treatment plan of multi-segmental PAD. LEVEL OF EVIDENCE: Level 3b, Individual case-control study.