Spontaneous Obstruction of Interatrial Communication in Infants with Atrioventricular Valve Atresia or Stenosis in the Neonatal Period: Serial Echocardiographic-Doppler Study.

BACKGROUND AND METHODS: The objective of this serial echocardiographic study was to document the critical size of the interatrial communication in infants with atrioventricular valve atresia, with which spontaneous obstruction is most likely to occur. Spontaneous obstruction of interatrial communication (patent foramen ovale) has been reported to occur in infants with atrioventricular valve atresia or severe stenosis. Atrial septostomy or septectomy therefore may be considered during initial palliation of these infants. Serial two-dimensional Doppler echocardiographic examinations were performed on 11 newborn infants with complex cyanotic congenital cardiac lesions for whom Fontan procedure was contemplated. These newborn infants had either mitral or tricuspid valve atresia or severe stenosis other than hypoplastic left heart syndrome. The size of the foramen ovale was measured from the subcostal frontal, long-axis oblique, and parasagittal views. Conventional Doppler and color flow mapping of the interatrial shunt also was obtained on each patient. RESULTS: The size of the foramen ovale was 5 mm in nine patients at birth. Five of these patients underwent Blalock-Taussig shunt in the neonatal period for severely restricted pulmonary blood flow. In three patients, surgery was postponed due to severe systemic (noncardiac) disease. One patient underwent the hemi-Fontan procedure without a previous shunt. In all nine patients, the foramen ovale remained the same size or became progressively smaller beyond the neonatal period, and atrial septectomy was performed in five patients after initial palliation. In the remaining two patients (who underwent Blalock-Taussig shunt as initial palliation), the foramen ovale measured >/=10 mm at birth and became progressively larger on subsequent follow-up studies. Atrial septectomy was not necessary in these patients. In the first nine patients, Doppler technique did not detect any obstructive pattern during the first 2-4 weeks of life, after which it became progressively obstructive (i.e., >2 m/sec and nonphasic). CONCLUSIONS: In newborn infants with either atrioventricular valve atresia or severe stenosis, the interatrial communication, which may not appear restrictive by Doppler at birth, becomes progressively obstructed beyond the neonatal period. If the size of the communication is <10 mm in diameter, as measured by two-dimensional echocardiography, atrial septectomy should be performed as an integral part of any initial palliation to protect the pulmonary vascular bed for subsequent successful Fontan repair.