Q-I-IIA-OS formula for predicting left atrial pressure in mitral stenosis

The relation of the phonocardiographic time intervals (Q-I) and (IIA-OS) and the use of two formulas (Q-I, IIA-OS difference versus their ratio) for estimation of left atrial pressure were investigated in 70 cases of pure mitral stenosis. It was noted that, in cases with normal blood pressure and pluse rate, there was a fair correlation of the two intervals to left atrial pressure. In our studies the best correlation was obtained by using the ratio of these two intervals (Q-I)/(IIA-OS). These results indicate that it is possible to use a new formula and equation that are dependable for phonocardiographic evaluation of left atrial pressure.