Real-time observation of blood flow velocity profiles in the right ventricular inflow tract by a newly-developed instantaneous B-mode and multi-channel Doppler echocardiography

We observed the blood flow profile in the right ventricular inflow tract through the tricuspid valve using the newly-developed equipment which images by instantaneous B-mode and multi-channel Doppler echocardiography. The Doppler system had 64 sampling gates in an ultrasonic beam within a depth of 13 cm. A cursor line was set at an angle of 45 degrees to the tricuspid annulus on two-dimensional echocardiography in a parasternal long-axis view of the right atrium and right ventricle. The blood flow velocity was displayed on the vertical line on the left-side of the CRT image. All Doppler-shifted frequencies of the 64 channels were analyzed using a fast Fourier transform formula by a built-in processor. The Doppler-shifted frequency was displayed at 30 frames per sec. The study subjects consisted of 20 children without cardiac anomalies. Their ages ranged from 2 to 18 years. A typical blood velocity profile at the tricuspid valve ring during the rapid filling phase had an "M" shape, i.e., the velocity was greater at both margins than in the central portion, followed by a flat profile. A small retrograde flow was observed behind the posterior tricuspid leaflet at this time. The flow velocity decreased in mid-diastole, then increased again during the atrial contraction period, with either flat or parabolic profile. During inspiration, the velocity was greater and the shape of the flow profile throughout diastole tended to be flat. In systole, a slow antegrade flow was observed in the tricuspid valve ring area, and its flow profile was parabolic.(ABSTRACT TRUNCATED AT 250 WORDS)