This site puts the heart rate at 130-325 beats per minute, which is a wide range
Another site says normal is 250
If you can, try to determine what the rate is. You might feel her pulse at the wrist. I doubt she'll sit still for a full minute like that, so try 15 seconds and multiply by 4. If it is above 250, you may want to have her seen by a vet. Has she been recently for a check-up? Ever had a vet listen to her heart?