RESUMO
Color Doppler echocardiography of tricuspid valve regurgitation (TR) is a valid, noninvasive method of determining systolic pulmonary artery pressure (SPAP). In a prospective study the authors examined 56 healthy full-term newborns (group I), 36 healthy preterm newborns (group II), and 10 preterm newborns with severe respiratory distress syndrome requiring surfactant replacement therapy (group III). Doppler studies were repeated until the transtricuspid gradient was < 20 mm Hg. In 83.3% of children a reproducible spectral curve was recorded at least once. The authors estimated the transtricuspid gradient delta p (RV-RA) by using the modified Bernoulli equation. Within the first twenty-four hours delta p (RV-RA) was < 20 mm Hg in 72.7%, 50%, and 25% of children with measurable TR in groups I, II, and III, respectively, increasing to 91.1%, 78.6%, and 55.6% within forty-eight hours. There was no significant correlation between SPAP and gestational age, birth weight, mode of delivery, and ductal closing time. Continuous holosystolic envelope tracing of TR was recorded in 16.6%. In these patients delta p (RV-RA) was measured markedly higher (mean of 30.1 mm Hg) than in the others (mean 17.3 mm Hg). The authors conclude that there is a high prevalence of TR in neonates, which allows estimation of SPAP in > 80% of newborns without considerable impairment. Normalization of SPAP takes place within four days in most patients, but there is a delay in preterm infants with severe respiratory distress syndrome.