P P Interval

Sinus Arrhythmia Overview Sinus rhythm with a beat-to-beat variation in the P-P interval (the time between successive P waves), producing an irregular ventricular rate. Characteristics Variation in the P-P interval of more than 120 ms (3 small boxes). The P-P interval gradually lengthens and shortens in a cyclical fashion, usually corresponding to the phases of the respiratory cycle. Normal sinus P waves with a constant morphology (i.e. no evidence of premature atrial contractions). Constant P-R interval (i.e. no evidence of Mobitz I AV block). Mechanism Sinus arrhythmia is a normal physiological phenomenon, most commnonly seen in young, healthy people. ...