What does 750ms rr-interval indicate including sinus arrythmia in an ecg, my age is 17 and my vent rate is 85bpm?is it dangerous? please reply doctor, it will be really helpful and relieving?

Normal range RR interval is 0.6-1.2 sec, sinus arrhythmia is a normally occurring irregularity in a regular baseline, or sinus rhythm - neither of these findings are dangerous, but to the contrary, are quite within normal limits…

These are normal range ECG findings. Sinus arrhythmia simply means the heart rate was a little faster or slower (generally due to breathing) when you had your ECG done; this is normal, particularly in younger healthy people. 750ms R-R cycle length interval means your heart rate was about 80 bpm during ECG calculations. Since ventricular rate was 85bpm, and sinus arrhythmia, sounds right.