Order of authorship in the original paper: Hatle, Brubakk, Tromsdal, Angelsen. "Hatle (born 1936) was the pioneer of continuous wave Doppler echocardiography. "Today, Doppler echocardiography is central to our ability to determine cardiovascular hemodynamics, especially in valvular heart diseases, noninvasively. Continuous-wave Doppler (CWD) plays a central diagnostic role in the diagnosis and management of patients with aortic stenosis. The development and use of CWD in aortic stenosis was due to the pioneering work of Dr. Liv Hatle and her outstanding medical and engineering colleagues in Norway. The author was fortunate to be the first to use the early CWD instruments in North America" (Randolph Martin, "Clinic implementation of continuous-wave Doppler: It made all the difference," J. Am. Soc. Echocardiogr. ,12 (2018) 1323-1329).