A majority of cases of atrial fibrillation originate within the pulmonary veins. In atrial fibrillation, the atrial rate is between 400 and 600 beats per minute. Not all of these are conducted to the ventricles due to block in the AV node, but frequently the ventricular rate is 150 beats per minute in the absence of AV blocking medications (beta-blockers or non-dihydropyridine calcium channel blockers).

Ablation of atrial fibrillation, also known as “pulmonary vein isolation” or PVI, electrically disconnects the erratic electrical activity in the pulmonary veins (which are creating action potentials at a rate of 400-600 beats per minute) from the rest of the heart thus effectively eliminating the atrial fibrillation. Ablation for atrial fibrillation is complex, requires multiple catheters and is performed via venous access then puncturing the interatrial septum to obtain entry to the left atrium where the pulmonary veins empty.

Atrial flutter most commonly occurs in a reentrant circuit around the tricuspid valve. Ablation for this rhythm is easy since it requires only venous access to get the the right heart. Success rate is high and complication risk is low.