The rhythm demonstrated in Figure 2 is AVNRT as evidenced by narrow QRS complexes, regular rhythm, and retrograde P waves (terminal positive deflection in V1 and negative deflection in aVF) within 60 ms of the QRS complex. A heart rate of 170 bpm is unusually fast for sinus tachycardia, especially in a resting individual. Furthermore, the P waves do not precede the QRS complexes to suggest a sinus rhythm. VT is characterized by wide QRS complexes and AV dissociation, which are not present in this patients ECG. Wolf-Parkinson-White syndrome classically demonstrates a short PR interval with a characteristic delta wave. There are no flutter waves to suggest atrial flutter.2
2. Blomström-Lundqvist C, Scheinman MM, Aliot EM, et al. ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmiasexecutive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Supraventricular Arrhythmias). J Am Coll Cardiol 2003;42:1493-531.
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