[A new noninvasive method for calculating pulmonary to systemic flow ratio (Qp/Qs) in patients with atrial septal...

The number of patients with atrial septal defect (ASD) who undergo intracardiac repair without cardiac catheterization has been increasing. A noninvasive quantitative method to estimate the Qp/Qs ratio in this disease is therefore needed, but no simple, accurate method has yet been reported. The purpose of this study was to devise a new clinically useful method. Study materials consisted of 15 patients with ASD who were catheterized and five post-operative patients. For this study a multigated Doppler echocardiographic instrument (Fujitsu ME 120A) was used, which allowed us to ascertain Doppler shift frequency at 64 consecutive sampling volumes up to 13 cm in depth simultaneously. In the parasternal four-chamber view, the cursor was set so as to cross obliquely the right ventricular inflow tract just below the tricuspid valve and the left atrium, just above the mitral valve. Two blood flow profiles were obtained from the flow crossing the tricuspid and mitral valves. The multigated Doppler echocardiogram was recorded on videotape and then analyzed. (1) The encircling area between the profile and the base line was measured for tricuspid and mitral flow independently throughout diastole. After summing up each area of tricuspid (TA) and mitral (MA) flow profiles, the ratio TA/MA was obtained (area calculation method). (2) The flow volume passing through each tricuspid (TF) and mitral valve (MF) was calculated from the flow profile using the "ring approach" reported by Jenni, and the ratio TF/MF was obtained (flow calculation method).(ABSTRACT TRUNCATED AT 250 WORDS)