Background: Fetal and neonatal atrioventricular (AV) reentrant tachycardias can be life-threatening but resolve in most cases during the first year of life.

• 背景：胎儿和新生儿房室（AV）折返性心动过速可危及生命，但在大多数情况下生命中第一年这种危险得到解决。