This 73-year-old man is postoperative day 3 from an uncomplicated coronary artery bypass surgery:

• AV dissociation (sinus rhythm with accelerated idioventricular rhythm), followed by sinus rhythm with normal AV conduction
• Non-specific ST-T abnormality

In the first half of the tracing, there is AV dissociation with underlying sinus rhythm and accelerated idioventricular rhythm. The rate of the accelerated idioventricular rhythm is 80/min. Notice the sinus P waves preceding the last two QRS complexes of the arrythmia. As the sinus rate increases (>80/min), sinus rhythm replaces the idioventricular rhythm. Accelerated idioventricular rhythm is not an infrequent finding in the CCU and post cardiac surgery, and is usually well tolerated.