Effects of Patent Ductus Arteriosus on Right Ventricle inPremature Infants : by M-mode and Doppler Echocardiography

Purpose : Patent ductus arteriosus, derived left to right shunt flows, elevate the pulmonary artery pressure in infants and children and may alter right ventricular afterload thereby right ventricular function. Therefore, we examined the effects of patent ductus arteriosus on the right ventricular systolic time interval in premature infants by non-invasive Doppler echocardiography. Methods : Tweleve premature infants with patent ductus arteriosus were studied by M-mode and Doppler echocardiography before and after treatment with mefenamic acid. Heart rate(HR), ratio of left atrium/aorta(LA/AO), right ventricular preejection period (RVPEP), right ventricular ejection time(RVET) and right ventricular systolic time interval(RVSTI : ratio of RVPEP/RVET), both corrected or uncorrected for heart rate were measured. Results : After mefenamic acid treatment, in infants showing clinical response, right ventricular preejection period(RVPEP) and right ventricular systolic time intetrval(RVSTI), both corrected or uncorrected for heart rate, decreased significantly following ductal closure(RVPEP : 70.3msecc±14.5 vs 54.3msec±10.9, P<0.01, RVPEPc : 129.2msec±13.5 vs 111.7msec±8.4, P<0.01, RVSTI : 0.38±0.09 vs 0.28±0.05, P<0.05, RVSTIc : 0.31±0.04 vs 0.27±0.03, P<0.01). Conclusion : Premature infants with patent ductus arteriosus exhibit echocardiographic evidence of increased RVSTI as a result of increased right ventricular afterload. This results suggest that we have to make every effort to prevent the ductal reopening or early closure of ductus arteriosus in premature infants. (J Korean Pediatr Soc 1998;41:734-740)