Today I had a 2nd screening but they didn't do it. The ultrasound…

Today I had a 2nd screening but they didn't do it. The ultrasound technician says I have hypertonus, because of that the screening won't work, she says. So is this really true? My heart rate is 160, but she says my heartbeat is weak ?. I was so upset, I have to take medication for 10 days and then come back. But she says hypertonus can lead to miscarriage, how true is that? I am very worried ???