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 ven- tricular 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 catheteriza- tion (25 patients) or right-heart catheterization with flow-directed, balloon-tip catheters for measurement of mean pulmonary capillary wedge pressure (PCWP) (seven patients); LVFP ranged from 5-40 mm Hg. Calculated LVFP correlated well with measured LVFP (r = 0.81; SEE = 4 mm Hg). Ten of 11 patients (91%) with LVFP > 14 mm Hg were correctly separated from 19 of 21 patients (90%) with LVFP 18 mm Hg from nine of 11 patients (87%) with PCWP < 18 mm Hg. Thus, the Q-C/A2-E ratio and left atrial pressure correlate closely. This relationship allows one to closely estimate LVFP in patients with various types of heart disease and to judge severity of MS noninvasively.