Baby has an ectopic heartbeat

I went in to have my 20 weeks anatomy scan yesterday and after my doctor looked over the scans he told me that my baby has an ectopic heartbeat. He said not to worry because it usually fixes itself after the baby is born, but they are still sending me to a specialist to have a ultrasound done just for her heart. I was wondering if anyone else had gone through this and what was the outcome. I can't help but worry!! This is my second pregnancy and I never had anything like this happen with my first.