A young man with a narrow and a wide QRS tachycardia

Figure  1 shows electrocardiograms (ECGs) of a 22-year-old man with a history of palpitations. He was known at the emergency department because of a 2-year history of occasional episodes of a rapid heart rhythm. The ECGs recorded at those times, one shown in Figure 1B, always revealed a narrow QRS tachyc ardia with alternating R-R intervals of 280 and 320 ms. Each QRS complex is followed by a P wave. Those tachycardias were terminated by intravenous adenosine. The sinus rhythm ECG outside tachycardia is shown in Figure 1A.
Source: Heart Rhythm - Category: Cardiology Authors: Tags: Josephson and Wellens ECG Lessons: A Monthly Visit to the 12 Lead ECG Source Type: research