In vitro models demonstrate that pressure recovery distal to a stenosis can cause apparent Doppler overestimation of pressure gradients compared to downstream catheter measurements.
Does pressure recovery distal to a stenosis cause apparent overestimation of pressure gradients by Doppler echocardiography compared to invasive catheterization?
Doppler echocardiography provides the maximal pressure gradient at the vena contracta, which may appear as an overestimation compared to distal catheter measurements due to pressure recovery.
Doppler ultrasound is currently being widely applied to measure intracardiac pressure gradients noninvasively. In comparative invasive studies, it is generally assumed that pressure is effectively uniform distal to the stenosis. As the poststenotic jet expands, however, its velocity decreases, and pressure is recovered to the extent permitted by turbulence, so that the measured gradient will be lower if the distal catheter is positioned downstream from the vena contracta. This can lead to apparent Doppler "overestimation" of the pressure gradient because of this phenomenon of pressure recovery. This study demonstrates that pressure recovery can be important in a variety of clinical settings studied by in vitro models. Although most prominent in streamlined tunnels modeled after the obstruction in patients with hypertrophic cardiomyopathy, these effects are important even for central stenoses at physiologic flow rates. Because precise catheter position is not always known or controlled, these findings suggest an important advantage for Doppler gradient estimation, because it provides the maximal gradient at the vena contracta, which determines the load on the proximal chamber.
Levine et al. (1989) studied Stenosis / Hypertrophic cardiomyopathy. Doppler ultrasound gradient estimation vs. Invasive catheter measurement was evaluated on Pressure gradient measurement. In vitro models demonstrate that pressure recovery distal to a stenosis can cause apparent Doppler overestimation of pressure gradients compared to downstream catheter measurements.