Development of systemic to pulmonary collateral arteries in premature infants.

Infants with congenital heart disease and chronic lung disease are at risk for development of systemic-to-pulmonary collateral arteries (SPCA). This study characterizes associated clinical findings in 20 premature infants without CHD who were diagnosed as having SPCA with echocardiography. SPCA can occur in premature infants without chronic lung disease and may represent a transient phenomenon.

Pediatric echocardiography: current role and a review of technical advances.

Advances in echocardiography have enhanced our diagnostic imaging capabilities for congenital heart defects. In addition to improved resolution of two-dimensional images, cardiac hemodynamic assessment is possible with the use of Doppler, color Doppler, and stress echocardiography. Transesophageal echocardiography has allowed intraoperative assessment of cardiac repairs, and fetal echocardiography has allowed development of the field of fetal cardiology. The developing areas of intravascular ultrasonography and three-dimensional echocardiography show promise for the future. Echocardiography continues to revolutionize our ability to diagnose congenital heart defects accurately.

Review of studies evaluating ductal patency in the premature infant.

A series of investigations has been performed to assess the timing of physiologic closure of the ductus arteriosus in premature infants with and without respiratory distress syndrome. The data from these studies emphasize the concept of physiologic ductal patency and give normative data for expected closure rates through the fourth day of life. On the basis of these data, patency on or beyond the fourth day of life is abnormal irrespective of gestational age, and prematurity, in the absence of respiratory distress syndrome, is not a risk factor for persistent patent ductus arteriosus. We also found that persistent patent ductus arteriosus in larger premature infants (> or = 30 weeks of gestation) with respiratory distress syndrome is relatively uncommon. Last, ductal patency was evaluated in a group of low birth weight infants with severe respiratory distress syndrome in a randomized, double-blind trial of exogenous surfactant administration. We concluded that the beneficial effects of exogenous surfactant are not associated with either a greater clinical need for indomethacin or any increased risk of delayed closure of the ductus arteriosus.

Duration of ductal shunting in healthy preterm infants: an echocardiographic color flow Doppler study.

The purpose of this investigation was to assess the duration of ductal shunting after birth in healthy preterm infants (30 to 37 weeks gestational age) without evidence of respiratory distress. Thirty-six infants were evaluated in the first 12 hours of life by means of two-dimensional echocardiography and color flow Doppler techniques, and then once daily until no ductal flow was detected (defined as functional closure). Preterm infants were subdivided into two groups by gestational age: group 1 = 30 to 33 weeks (n = 12); group 2 = 34 to 37 weeks (n = 24). Sixteen full-term infants (38 to 41 weeks) were similarly evaluated as control subjects (Group 3). One infant from each group had a closed ductus at the time of the first study (performed at a mean of 7.7 +/- 3.2 hours). Subsequent studies for the entire group were performed at a mean of 31.3 +/- 5.4 hours (day 2), 55.0 +/- 4.5 hours (day 3), and 80.3 +/- 6.1 hours (day 4). For the three groups, the rates of ductal closure ranged from 50.0% to 58.3% on day 2 and 81.3% to 87.5% on day 3. For the entire group, all but one infant had demonstrated closure of the ductus arteriosus by day 4. Within the range of gestational ages studied, we conclude that prematurity, in the absence of respiratory distress syndrome, does not prolong the initial duration of physiologic ductal shunting.

Tricuspid regurgitation in newborn infants with respiratory distress: echo-Doppler study.

The purpose of this investigation was to use Doppler echocardiography to evaluate respiratory problems significant enough to warrant supplemental oxygenation in newborn infants. Of 17 infants (mean gestational age 37.5 weeks, mean birth weight 3070 g) 14 (82%) had detectable tricuspid regurgitation. By modified Bernoulli equation, all infants had right ventricular pressure greater than 60% of systemic pressure, and nine of 14 had estimated right ventricular pressure at or near systemic pressures. In eight infants for whom sequential evaluations could be obtained, right ventricular pressure as a percentage of systemic pressure gradually decreased, and corresponded to decreasing needs for supplemental oxygenation. Tricuspid regurgitation could no longer be detected between 3 and 16 days after the first study, and was associated with decreased right ventricular pressures (less than 50% systemic) and weaning from supplemental oxygenation. We conclude that in the near-term infant with early respiratory difficulties, tricuspid regurgitation is common and is associated with increased right ventricular pressure.