Pressure loss recovery in aortic valve stenosis: Contemporary relevance.

Pressure loss recovery (PLR) is a hydrodynamic phenomenon that occurs when blood flow encounters a narrowing typified by aortic valve stenosis (AS). Multiple factors contribute to the magnitude of PLR including the volumetric rate of flow, the geometry of the entrance to the vena contracta (VC) or point of minimum dimension, including that of the left ventricular outflow tract and valve orifice, and the geometry of the proximal aorta. In the majority of clinical circumstances, PLR results in echocardiographic Doppler gradient estimates that are modestly, but generally not clinically important, greater than those derived from rigorously performed catheter measurements. The contribution of PLR to the echocardiographically-measured gradient may not differ significantly between currently available valve prostheses and is likely to be small in patients with mild AS following TAVR.