Invasive assessment of aortic stenosis in contemporary practice

Abstract

The authors review the current role of cardiac catheterization in the characterization of aortic stenosis, its main clinical applications, its pitfalls, and its additional value to the information provided by echocardiography. Discrepancies that may arise between these two modalities are discussed and further explained. Hemodynamic variables besides transvalvular pressure drop are described, and emphasis is given to an integrative approach to aortic stenosis assessment, that includes invasive and noninvasive evaluation.

Keywords: aortic stenosis; echocardiography/catheterization discrepancies; integrative approach; invasive assessment; low-flow; pressure drop.

FIGURE 1

Echocardiographic and invasive characterization of aortic stenosis. Panel (A) The geometric orifice area (GOA) is the true anatomical area of the aortic valve and the area of the flow jet at the vena contracta, which occurs downstream of the valve orifice, is the effective orifice area (EOA), and corresponds to the calculated AVA by the continuity equation. GOA is always larger than EOA (they will be equal if GOA has the same size as LVOT). The pressure difference between the LVOT and EOA is known as ΔP_max. The pressure difference between the ascending aorta and LVOT is ΔP_net, as it is recorded after the occurrence of pressure recovery, and corresponds to the measured pressure drop in the catheterization laboratory. In the presence of the pressure recovery phenomenon, ΔP_max is higher than ΔP_net, which partially explains the discrepancies between Doppler and invasive metrics. Panel (B) The shaded area represents the mean transaortic pressure drop (ΔP_mean); peak-to-peak pressure drop (ΔP_P–P) is the difference between the peak LV pressure and the peak aortic pressure at two different points in time; maximum instantaneous pressure drop (ΔP_peak) is the maximum recorded difference between the LV and aortic pressure at the same point in time. Ao indicates aortic pressure; Asc Ao, ascending aorta; LV, left ventricle pressure; LVOT, left ventricular outflow tract.