The Usefulness of Doppler Echocardiography for the Evaluation of Hemodynamics in Tetralogy of Fallot: Comparison of the Patients with Pre‐ and Post‐Corrective Surgery and Control Healthy Children

Abstract

AbstractTwodimensional Doppler echocardiographic examinations were performed in 61 patients (39 boys and 22 girls) with tetralogy of Fallot (TOF). The patients were examined at the Department of Pediatrics, University of Tokyo, and at the Department of Pediatrics, Ohta General Hospital, in Koriyama city, Fukushima Prefecture.One hundred and eighteen healthy children (59 boys and 59 girls) were also examined at the Waseda housing complex in Misato city, Saitama Prefecture.By short axis view of aorta, samples were collected from both the right ventricular outflow tract below the pulmonary valve and in the main pulmonary artery. On the other hand, the apex four chamber view was used to collect samples at the right and left atrial outflows.Right ventricular systolic time intervals were measured both at the main pulmonary artery (PA) and at the outflow tract below the pulmonary valve (RVO).The right ventricular systolic pre‐ejection period (PAPEP) and acceleration time (PAACT), measured at the supra‐valvular site, were shorter before surgery as compared to after surgery and normals. The ratio of right ventricular pre‐ejection period to ejection time (PAPEP/ET) and the ratio of acceleration time to ejection time (PAACT/ET) were both significantly lower before surgery compared to after surgery and controls.The mean main pulmonary artery peak velocity before surgery was 369 cm/sec and the peak pressure gradient calculated with the modified Bernoulli formula was 55 mmHg.Before surgery, peak velocity of right ventricular rapid filling (R‐wave) was low, while peak velocity of atrial contraction (A‐wave) was high. After surgery, however, R‐wave increased and A‐wave decreased in velocity. The peak velocity of left ventricular filling R‐wave was also low before surgery and increased after surgery, while peak velocity of left atrial contraction A‐wave was increased before surgery and decreased to almost normal values after surgery. The left ventricular A/R ratio before surgery was also high as a result of low R‐wave velocity. The measured time interval between aortic valve closing sound and left ventricular rapid filling wave (IIA‐R time), and the measured time interval between pulmo nary valve closing sound and ventricular filling wave (IIP‐R time) were both longer before surgery than those after surgery and controls. Consequently, the measured time intervals between rapid ventricular filling flow wave and atrial contraction wave (R‐A time) for both right and left atrial were shorter before surgery than after surgery and controls. A new method for estimation of pulmonary‐to‐systemic blood flow ratio (Qp/Qs) was successfully applied to TOF, and a good correlation was obtained between Qp/Qs determined by this method and that by the Fick method.