ECG Diagnosis: Atrial tachycardia
Circulation ECG Challenge Response! Regarding the 25 year old woman with palpitations:
Diagnosis: Atrial tachycardia
The rhythm is regular, except for one long RR interval. The initial rate is 140 bpm and is followed by several complexes at a rate of 100 bpm. The QRS complex has a normal duration (0.08 sec) and morphology. The axis is normal between 0° and +90° (positive QRS complex in lead I and aVF). The QT/QTc intervals are normal (320/430 msec). There are no P waves before the first 10 QRS complexes and last 6 QRS complexes; there however P waves (+) noted after each of these QRS complexes with a long RP interval (└┘) and short PR interval (┌┐). The P waves are negative in leads II and aVF. This is a long RP tachycardia, There is a P wave before each of the next 4 QRS complexes (i.e. complexes 11-14) (*) with a stable PR interval (0.16 sec). This is a normal sinus rhythm. The etiologies for a long RP tachycardia include a sinus tachycardia (no the cause as the P waves are negative in leads II and aVF), an ectopic junctional tachycardia, atrial tachycardia, atrial flutter with 2:1 AV block or conduction, atypical atrioventricular nodal reentrant tachycardia (i.e. fast-slow), or an atrioventricular reentrant tachycardia. The arrhythmia terminates abruptly without a P wave (↑). This is the way atrial arrhythmias terminate. Therefore this is most likely atrial tachycardia. As there is only one P wave seen this is not atrial flutter. The P wave is different from the sinus P wave and is negative in leads II and aVF) and this is not sinus tachycardia. Arrhythmias generated within or require the AV node terminate with a non conducted P wave.
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