Validation of a Novel, Non-Dimensional Approach for Estimation of Pressure Gradients in Aortic Stenosis
Validation of a Novel, Non-Dimensional Approach for Estimation of Pressure Gradients in Aortic Stenosis
A novel, image-based model for estimation of the pressure gradient across stenosed aortic
 valves is compared against invasively measured pressure gradients from clinical routine.
Using temporally resolved computed tomography images, the patient-specific geometry of the
 stenosed aortic valve during peak systole is reconstructed. Using this geometry, the
 projected area of the aortic valve's orifice (AVA) is calculated. Additionally, the left
 ventricular geometry is reconstructed for the complete heart cycle. Using the information of
 the left ventricular volume change, the patient-specific flow profile and peak-systolic flow
 (Q)is calculated. Using this information, the pressure gradient is calculated using a power
 law estimation of the form PG = a * AVA^b * Q^c. The model generation and parameter fit is
 described in [1].

 To validate this model, retrospective data of patients receiving a catheter-based replacement
 of the aortic valve (TAVI) is collected. For those patients, CT images are already acquired
 for treatment planning and the invasive pressure measurements are performed during
 replacement of the aortic valve. Therefore, no additionally steps are required. Using the CT
 images the patient-specific aortic valve area ad flow rate are calculated. This information
 is then used for estimation of the pressure gradient using the power law model. The
 catheter-based pressure gradient is calculated as the difference between the peak-systolic
 pressure in the left ventricle and the ascending aorta before implantation of the prosthesis.

 [1] Franke et al.; Towards improving the accuracy of aortic transvalvular pressure gradients:
 rethinking Bernoulli; Medical & Biological Engineering & Computing (2020);
 https://doi.org/10.1007/s11517-020-02186-w
Inclusion Criteria:

 -  aortic valve stenosis

 -  treatment via TAVI