Context: Aortic stenosis (AS) is characterized by a narrowing of the aortic valve opening, which induces a left ventricle (LV) pressure overload. LV pressure curve is essential for the estimation of pressure-strain loops (PSL), which could be a potential novel tool to provide prognostic information in patients with AS. However, measurement of intraventricular pressure, by invasive procedures, is particularly difficult in AS and is rarely done routinely.
Methods: In this paper, a model-based estimation of left ventricular pressure, adapted to AS, is proposed. The model of the cardiovascular system is composed of: i) cardiac electrical activity, ii) elastance-based cardiac cavities, iii) systemic and pulmonary circulations and iv) cardiac valves. The experimental dataset includes echocardiography and invasive pressures measured from 4 patients with severe aortic stenosis. An identification strategy was implemented using a leave-one-out cross validation approach in order to provide patient-specific simulated LV pressure of the 4 AS patients, from aortic valve area, systolic and diastolic pressures.
Results and Discussion: A close match was observed between LV experimental and simulated pressures since, for all patients, root mean square error (RMSE) is equal to 20.34 (+/- 5.34) mmHg. The mean RMSE for diastolic and systolic pressures are respectively 0.89 (+/- 0.79) and 0.2370 (+/- 0.18) mmHg. The mean PSL areas calculated for experimental and model-based pressures are respectively 1965.6 (+/-206.77) cm2 and 2206.4 (+/-289.64) cm2. The main contributions of this study concern the proposition of an integrated model of cardiovascular system model and the parameter identification approach able to reproduce LV pressure specifically to each patient.
Conclusion: Assessment of LV pressure and PSL, for patients with severe AS, can be improved by using patient-specific models of the cardiovascular system. Future works will be dedicated to more extensive evaluations including a greater population of patients.