Spontaneous closure of muscular ventricular septal defect identified by echocardiography in neonates.

Muscular ventricular septal defects were diagnosed by echocardiography in 97 neonates within 7 days of birth. In 82 of the neonates (84.5%), the defect was solitary, while 15 had multiple defects. The solitary defects was located at mid-septal, apical, anterior and inlet locations in 42 (51.2%), 21 (25.6%), 14 (17.1%) and 5 (6.1%) neonates, respectively. Multiple defects occurred in the apical, anterior and mid-septal areas. The diameter of the solitary defects ranged from 1 to 6 mm (2.3 +/- 0.8 mm), while the multiple lesions were 1 to 4 mm in diameter (2.1 +/- 0.8 mm) in 28 instances in which they could measured. It proved possible to follow 79 of the patients for period of 10 to 13 months. The defects closed spontaneously in 56 (84.8%) of 66 patients with a single defect, and in 7 (53.8%) of 13 of those with multiple defects (P<0.05). For the solitary defects, the position and size were factors determining the likelihood and speed of closure. Defects located at the apical septum, or defects larger than 4 mm in diameter, closed slowly and at a later stage. Echocardiography is an useful technique in establishing of natural history of muscular ventricular septal defects encountered in neonates.