I am very tired and I have very rapid heart rate up to 250 bpm?

The ER can evaluate. A heart rate over 200 beats per minute is way too fast. If having no other symptoms, one's cardiologist or the ER doctor can evaluate for the cause, to see if an adult truly has heart rate over 200. Heart rates close to 200 may be SVT (supraventricular tachycardia). If feeling any ill symptoms, and one's heart rate is near 200, the wisest thing to do would be to call 911 for the paramedics.