ECG: Sinus arrhythmia and a junctional escape rhythm

Sinus arrhythmia and a junctional escape rhythm. Lead V1 and lead II rhythm strips show an irregular rhythm that initiates with sinus rhythm with sinus arrhythmia and a gradual slowing of heart rate. When the heart rate slows below a rate of approximately 35 bpm, a junctional escape beat appears followed by an atrial premature complex (note the different P wave morphology in lead V1 compared with initial sinus beats). The variation in rate and the presence of some QRS complexes not preceded by a P wave contribute to this rhythm being incorrectly labeled as atrial fibrillation by a preliminary ECG machine interpretation.