Echo-phonocardiographic determination of left atrial and left ventricular filling pressures with and without mitral stenosis.

In mitral stenosis (MS) the interval between the second sound and the opening snap (A2-OS) is known to shorten, while the interval between the onset of the QRS and the first sound (Q-M1) lengthens with smaller mitral valve orifice size and higher left atrial pressures. Because M1 and OS are temporally related to the C and E points on the mitral valve echogram, respectively, the ratio of Q-C to A2-E may relate to left atrial pressure in MS and to left ventricular filling pressures (LVFP) in the absence of MS. To test this hypothesis the Q-C/A2-E ratio was measured in 22 patients without MS from simultaneous mitral valve echogram, ECG and phonocardiogram at cardiac catheterization. An excellent correlation between Q-C/A2-E and left ventricular end-diastolic pressure (LVEDP) was observed (r = 0.93; SEE = 2.6 mm Hg; LVEDP range 5-28 mm Hg). The resulting regression equation: LVEDP = 21.6 (Q-C/A2-E) + 1.1, was prospectively evaluated in a second group of 32 patients without MS and with echo-phonocardiograms performed at left-heart catheterization (25 patients) or right-heart catheterization with flow-directed, balloon-tip catheters for measurement of