Natural closing time of patent foramen ovale in newborns

Objectives To investigate the closing time of patent foramen ovale in newborns and infants in order to provide appropriate follow-up time points. Methods From September 1, 2010 to April 30, 2011, 131 of 1 202 full-term infants with patent foramen ovale were finished follow up at 3, 6 and 12 months of age in Beijing Children's Hospital, Capital Medical University. If the foramen ovale was not closed at 12 months of age, the patients were followed up until two years of age. The closing time and the effects of complicated patent ductus arteriosus (PDA) were analyzed statistically using two-independent t test, Chi-square and trend Chi-square tests. Results Of the 131 full-term infants with patent foramen ovale, 72 were males, and 59 were females. The foramen ovale size in neonatal period was not statistically different between males and females [(2.94 ±0.86) vs (2.95±0.92) mm, t=0.641, P=0.964]. The foramen ovale closing rate at 3 months was 21.4% (28/131), 67.9% (89/131) at 6 months, and 95.4% (125/131) at 12 months. The rate of foramen ovale closing decreased with larger foramen ovale at 3, 6 and 12 months of age (χ2trend were 42.930, 101.050 and 63.260, all P 0.05). In the simple patent foramen ovale group, the closing rate at 3 months was less than that at 6 months and 12 months (χ2 were 10.410 and 62.515, both P 0.05). Conclusions Asymptomatic patent foramen ovale with a foramen ovale <5.0 mm may not require follow-up. But patients with a foramen ovale ≥ 5.0 mm, even asymptomatic, should be followed up using thoracic echocardiography at 2 years, and further follow-up is required if unclosed. Key words: Foramen ovale, patent; Foramen ovale; Echocardiography; Infant, newborn; Follow-up studies