Contemporary Management of Atrial Flutter
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A 60-year-old dentist presents to the emergency room with palpitations for 3 hours. The ECG shows atrial flutter (AFl) with atrioventricular (AV) conduction varying from 2:1 to 4:1. He has known hypertension for which he takes 10 mg of enalapril daily. In the last 2 years he was seen twice because of AFl and on both occasions 1 mg of ibutilide IV resulted in the return of sinus rhythm with 1:1 AV conduction. Catheter ablation of the arrhythmia is discussed with the patient, to which he agrees and curative AFl ablation is scheduled in 4 weeks.
In 1906, Einthoven made an electrocardiographic recording of AFl.1 In 1913, Lewis called attention to the typical saw tooth pattern and the negative deflections of the atrial waves in leads II and III.2
During the next 50 years, there was much discussion about whether AFl was caused by a rapidly firing atrial focus or is the result of a large circus movement involving the atria. After mapping atrial activation with endocardial and esophageal recordings, Puech et al3 concluded that the flutter cycle in the human heart involved activation of the whole right atrium. Stimulation studies by Waldo et al4 revealed that in postoperative AFl the arrhythmia was based on a reentry mechanism involving a large atrial area. They demonstrated the presence of an excitable gap that allowed the speeding up of the flutter rate during atrial pacing and termination of the arrhythmia by pacing.
Mechanism and Types of Macroreentrant Tachycardias
With the use of endocardial activation mapping and stimulation studies, several investigators have shown that different types of macroreentrant atrial tachycardias are possible. As indicated in Figure 1, the circuit is usually located in the right atrium. In the circuit, a critical component of slow conduction is frequently present, often located in the isthmus of …