Estimation of regurgitant volume and orifice in aortic regurgitation combining CW Doppler and parameter estimation in a Windkessel-like model

A method for noninvasive estimation of regurgitant orifice and volume in aortic regurgitation is proposed. The method was tested in anesthetized open-chested pigs. It can be used with noninvasive measurement of regurgitant jet velocity using continuous-wave ultrasound Doppler measurements together with cuff measurements of systolic and diastolic systemic pressure in the arm. These measurements are then used for parameter estimation in a Windkessel-like model which includes the regurgitant orifice as a parameter. The aortic volume compliance and the peripheral resistance are also included as parameters and estimated in the same process. Electromagnetic flow measurements in the ascending aorta and pulmonary artery are used for control. The correlation obtained between regurgitant volume derived from parameter estimation and from electromagnetic flow measurements is 0.95 over a range from 2.1 to 17.8 mL.