Fig. 2From: Variable open-end wave reflection in the pulmonary arteries of anesthetized sheepA pressure–velocity (PU) loop for a single resting cardiac cycle with the velocity signal delay reduced by 20 ms. In early systole (arrow), there is now a linear relationship between P and U as predicted by the water hammer equation, and wave speed can now be accurately determined and compares favourably to the independent single-point techniqueBack to article page