Fetal heartbeat has an echo

So I'm 19 weeks 3 days. We had the anatomy scan today. My blood test for Down syndrome came back normal, and he's measuring correctly anatomically. The doctor said he looks really good in that aspect. He did however, notice that his heartbeat had a bit of an echo. He said we shouldn't worry, and we'll just do another ultrasound at 32 weeks. Has anyone else had something similar? I tried to find out if Down syndrome is still possible even with a normal blood test, but I'm paranoid to venture to google. 😩