How do you calculate ECG RR value?

Answer 1

There are different short-cut methods that can be used to calculate rate, all of which assume a recording speed of 25 mm/sec. One method is to divide 1500 by the number of small squares between two R waves. For example, the rate between beats 1 and 2 in the above tracing is 1500/22, which equals 68 beats/min. Alternatively, one can divide 300 by the number of large squares (red boxes in this diagram), which is 300/4.4 (68 beats/min). Another method, which gives a rough approximation, is the "count off" method. Simply count the number of large squares between R waves with the following rates: 300 - 150 - 100 - 75 - 60. For example, if there are three large boxes between R waves, then the rate is 100 beats/min. One must extrapolate, however, between boxes. Atrial rate can be determined like the ventricular rate, but using the P waves. Remember, if the heart in in sinus rhythm and there is a one-to-one correspondence between P waves and QRS completes, then the atrial rate will be the same as ventricular rate.

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Answer 2

You will need to know the QT interval. The QT interval can then be measured on a ECG by seconds, milliseconds, and small squares.

Answer 3

On an ECG the PR interval measures the conduction time from the atria to the ventricles

Answer 4

Bazett's formula

QT/sqrt(RR)