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Normal Cardiac Cycle and Measurements

R
QRS T
P P

Q S
P-R interval
0.04 sec
0.20 sec
Normal Rate → 60 to 100 bpm
Normal PR → 0.12–0.20 sec
Normal QRS → 0.08–0.12 sec
P wave → atrial depolarization; QRS → ventricular depolarization; T wave →
ventricular repolarization
Quick Guide to Analyzing the ECG
■ Determine the overall rate: <60 bpm → bradycardia, >100 bpm → tachycardia.
■ Determine the regularity: regular or irregular.
■ If irregular, is there any pattern?
■ Examine the P waves.
■ Is there a P wave before each QRS? Is there more than 1 P wave?
■ Are P waves absent?
■ What is the configuration of the P wave? Round? Saw toothed?
■ Do they look the same?
■ Do any occur earlier or later than expected?
■ Are any P waves located within the QRS or T wave?
■ Determine the PR interval.
■ Is it normal, prolonged, or shortened?
■ Can it be measured?
■ Is it the same for each beat? Any pattern?
■ Examine the QRS complex.
■ Is there a QRS after each P wave?
■ Do they look the same?
■ Do any occur earlier than expected?
■ Is there a pattern to QRS complexes occurring early?
CV