INTERNAL RIGHT ATRIAL CARDIOVERSION OF CHRONIC ATRIAL-FIBRILLATION - EFFECTS OF LOW-ENERGY BIPHASIC SHOCKS

Atrial fibrillation (AF) is associated with the loss of organized atri al contractions, a risk factor for thromboembolic events and hemodynam ic deterioration. Therefore, the restoration of sinus rhythm, when fea sible, is 1 of the major therapeutic options in patients with AF. For this purpose, antiarrhythmic drugs or external direct current (DC) sho cks are attempted. Transthoracic electrical cardioversion has been sho wn to be effective in <80% of cases,(1,2) leaving > 20% off patients i n AF. Internal cardioversion, which was introduced in the 1970s, has i nitially been disappointing.(3-5) However, in 1987, Levy et al(6) intr oduced intracavitary high-energy shocks (200 to 300 J) with a high suc cess rate, a result that was subsequently confirmed in patients who co uld not be converted by external DC shocks,(7) even when associated wi th pharmacologic methods.(8) Moreover, internal shocks were reported t o have some side effects due to the high-energy level delivered.(1,9) Efforts have recently been. made to lower this level. Different proced ures have been proposed. The procedure most frequently reported has be en the;right atrial-left atrial (via the coronary sinus or left pulmon ary artery) DC shock. The success rate remains high with an energy lev el of generally < 5 J.(10-13) The main limitation for this intracavita ry technique is the need for coronary sinus lead placement. This promp ted us to study the efficacy of internal cardioversion with a ''modera te'' energy level, but with a simpler procedure.