In the first ECG shown, we see an irregular tachydysrhythmia.  He has had periodic episodes of rapid heart rate since the age of 19, but is in good health otherwise.  He is on Flecainide, 200 mg per day.   The rhythm might look like atrial fibrillation to many people, but there are signs of regular, fast flutter waves (arrows).  The irregularity is caused by variable conduction of the atrial flutter.  The QRS is slightly widened, possibly due to the Flecainide, a sodium-channel blocker which slows conduction.

The patient usually felt palpitations during these periods of rapid heart rate, but had no syncopal episodes, chest pain, or other concerning symptoms.

The next ECG shows more apparent flutter waves.  The ST elevation is due to artifact which can occur on manually-obtained ECGs due to the type of filtering.  It is not uncommon to see dramatic ST elevation on manually-obtained rhythm strips which disappears when a standard filtered 12-Lead is performed.   On other ECGs, the patient also had periods of NSR and frequent PACs. (ECGs not shown).

The third ECG was obtained after the patient underwent successful radiofrequency ablation for atrial fib / atrial flutter.  He is now off antiarrhythmics, and feeling well.

For instructors and students, this is a nice "before and after" series to illustrate successful ablation.