A new noninvasive method for estimation of pulmonary arterial pressure in mitral stenosis

Abstract

The appearance of an increased pulmonary artery (PA) pressure is an important moment in the clinical history of mitral stenosis. A direct measurement of PA pressure levels is possible only with rightsided cardiac catheterization. This technique, being invasive is not risk-free and, consequently, many noninvasive methods for the evaluation of PA pressure have been proposed.¹ These procedures usually lack sensitivity and are limited in their ability to detect and quantify mild to moderate modifications of PA pressure. The introduction of Doppler echocardiography allowed the development of new procedures.^2–6 Unfortunately this method is not applicable in the absence of Doppler-detectable tricuspid regurgitation.⁷ Furthermore, the computed systolic PA pressure value is approximate because a clinical estimation of the right atrial pressure is necessary. Moreover, a good acoustic window and satisfactory flow tracings are indispensable. To avoid the aforementioned drawbacks we attempted a different approach to the noninvasive estimation of PA pressure, devising a method based on the modifications induced by an increased PA pressure on the power spectrum of the pulmonary component of the second heart sound. We used fast-Fourier analysis to examine the acoustic characteristics of this heart sound and to define its frequency distribution in patients with normal and increased PA pressure to search for a relation between the PA pressure level and the spectral characteristics of the pulmonary component of the second heart sound.