Algorithm for estimation of left ventricular filling pressures in patients with normal ejection fraction. See text for details. Ar, duration of reverse pulmonary venous wave; A, duration of transmitral A wave; LA, left atrium; PAS, systolic pulmonary artery pressure (estimated from tricuspid regurgitation). Modified and reproduced with permission from Nagueh SF, Appleton CP, Gillebert TC, et al. Recommendations for the evaluation of left ventricular diastolic function by echocardiography. Eur J Echocardiogr 2009; 10: 165–93