PubMed1985
To assess the patho-physiological severity of hypertrophic obstructive cardiomyopathy (HOCM), the systolic pressure differences caused by the functional stenosis across the outflow tract of the left ventricle must be evaluated. The present study explored and proposed a non-invasive method predicting the pressure difference across the intraventricular obstruction and the pressure proximal to the obstruction by using pulsed Doppler technique, guided by simultaneous two-dimensional echocardiography. The ultrasonic equipment recently developed in our laboratory was used. It consisted of a 3.0 MHz pulsed ultrasonic transducer with a 4.4 KHz repetition rate and a mechanical sector scanner equipped with a single concave transducer 1.3 cm in diameter having a 70 mm radius of curvature. The sample volume was approximately 3 X 3 X 3 mm. Doppler signals obtained were subjected to a real-time analyzer with a fast Fourier transformer, and were simultaneously recorded on a thermal recorder as a spectral display together with an M-mode echocardiogram, lead II ECG, phonocardiogram and mechanocardiogram. Ten adults with HOCM were the subjects in the present study. For six of the 10, good pressure tracings were obtained. The pressure differences estimated by the maximum velocity as measured from the Doppler signals at the left ventricular (LV) outflow tract and the pressure gradients as obtained by cardiac catheterization were subjected to correlative analysis. Prior to investigating the pressure differences, the site and mechanism of the outflow obstruction in HOCM were studied in two cases using two-dimensional echocardiography in the longitudinal- and short-axis views. The obstruction was produced during systole by posteroinferior displacement of the hypertrophied interventricular septum and by abnormal anterosuperior movement of the hypertrophied, and elongated anterior or posterior papillary muscles. Thus, a concentric and centripetal narrowing was formed at the midportion of the outflow tract. In some cases, a bottle-shaped chamber was clearly observed in the apical area. Ultrasonic Doppler examinations were performed by the apical approach. Flow velocity patterns in the apical region or proximal to the obstruction had two peaks with a narrow spectrum in systole. At the distal portion or downstream the obstruction had a pattern with a narrow spectrum and a sharp single peak. To measure the maximum flow velocity, Doppler velocity patterns recorded immediately distal to the obstruction were used.(ABSTRACT TRUNCATED AT 400 WORDS)