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Recent studies have demonstrated the benefits of using fractional derivatives to simulate a blood pressure profile. In this work we propose to combine a one-dimensional model of coronary blood flow with fractional-order Windkessel boundary conditions. This allows us to obtain a greater variety of blood pressure profiles for better model personalization An algorithm of parameter identification is described, which is used to fit the measured mean value of arterial pressure and estimate the fractional flow reserve (FFR) for a given patient. The proposed framework is used to investigate sensitivity of mean blood pressure and fractional flow reserve to fractional order. We demonstrate that the fractional derivative order significantly affects the fractional flow reserve (FFR), which is used as an indicator of stenosis significance. [ABSTRACT FROM AUTHOR]

Recent studies have demonstrated the benefits of using fractional derivatives to simulate a blood pressure profile. In this work we propose to combine a one-dimensional model of coronary blood flow with fractional-order Windkessel boundary conditions. This allows us to obtain a greater variety of blood pressure profiles for better model personalization An algorithm of parameter identification is described, which is used to fit the measured mean value of arterial pressure and estimate the fractional flow reserve (FFR) for a given patient. The proposed framework is used to investigate sensitivity of mean blood pressure and fractional flow reserve to fractional order. We demonstrate that the fractional derivative order significantly affects the fractional flow reserve (FFR), which is used as an indicator of stenosis significance.

Background As younger patients are being considered for transcatheter aortic valve implantation (TAVI), the assessment and treatment of concomitant coronary artery disease is taking on increased importance. Methods and Results Thirteen contemporary lower‐risk patients with TAVI with severe aortic stenosis (AS) and moderate‐severe coronary lesions were included. Patients underwent assessment of coronary hemodynamics in the presence of severe AS (pre‐TAVI), in the absence of severe AS (immediately post‐TAVI), and at longer‐term follow‐up (6 months post‐TAVI). Fractional flow reserve decreased from 0.85 (0.76–0.88) pre‐TAVI to 0.79 (0.74–0.83) post‐TAVI, and then to 0.71 (0.65–0.77) at 6‐month follow‐up (P

Background As younger patients are being considered for transcatheter aortic valve implantation (TAVI), the assessment and treatment of concomitant coronary artery disease is taking on increased importance. Methods and Results Thirteen contemporary lower-risk patients with TAVI with severe aortic stenosis (AS) and moderate-severe coronary lesions were included. Patients underwent assessment of coronary hemodynamics in the presence of severe AS (pre-TAVI), in the absence of severe AS (immediately post-TAVI), and at longer-term follow-up (6 months post-TAVI). Fractional flow reserve decreased from 0.85 (0.76-0.88) pre-TAVI to 0.79 (0.74-0.83) post-TAVI, and then to 0.71 (0.65-0.77) at 6-month follow-up ( P <0.001 for all comparisons). Conversely, instantaneous wave-free ratio was not significantly different: 0.82 (0.80-0.90) pre-TAVI, 0.83 (0.77-0.88) post-TAVI, and 0.83 (0.73-0.89) at 6 months ( P =0.735). These changes are explained by the underlying coronary flow. Hyperemic whole-cycle coronary flow (fractional flow reserve flow) increased from 26.36 cm/s (23.82-31.82 cm/s) pre-TAVI to 30.78 cm/s (29.70-34.68 cm/s) post-TAVI ( P =0.012), to 40.20 cm/s (32.14-50.00 cm/s) at 6-month follow-up ( P <0.001 for both comparisons). Resting flow during the wave-free period of diastole was not significantly different: 25.48 cm/s (21.12-33.65 cm/s) pre-TAVI, 24.54 cm/s (20.74-27.88 cm/s) post-TAVI, and 25.89 cm/s (22.57-28.96 cm/s) at 6 months ( P =0.500). Conclusions TAVI acutely improves whole-cycle hyperemic coronary flow, with ongoing sustained improvements at longer-term follow-up. This enhanced response to hyperemic stimuli appears to make fractional flow reserve assessment less suitable for patients with severe AS. Conversely, resting diastolic flow is not significantly influenced by the presence of severe AS. Resting indices of coronary stenosis severity, therefore, appear to be more appropriate for this patient population, although large-scale prospective randomized trials will be required to determine the role of coronary physiology in patients with severe AS.