Performance of temporary epicardial stainless steel wire electrodes used to treat atrial fibrillation: A study in patients following open heart surgery

AF is the most common arrhythmia following open heart surgery Transthoracic cardioversion is used when pharmacological treatment fails to restore SR, or is ineffective in controlling ventricular response rate. We report on th e performance of temporary atrial defibrillation wire electrodes implanted on the epicardium of patients undergoing open heart surgery. Epicardial sta inless steel wire electrodes for both pacing/sensing and atrial defibrillat ion were placed at the left and right atrium during open heart surgery in 1 00 consecutive patients (age 65 +/- 9 years; male/female 77/23). Electrophy siological studies performed postoperatively revealed a test shock (0.3 J) impedance of 96 +/- 12 Omega (monophasic) and 97 +/- 13 Omega (biphasic). A F was induced by burst stimulation in 84 patients. All patients were succes sfully converted to SR. The mean energy of successful shocks was as 3.1 +/- 1.9 J. Atrial pacing and sensing were accomplished in all patients. Pacing threshold was 1.9 +/- 1.7 V(0.5 ms) in the left atrium and 2.1 +/- 2 V in the right atrium. P wave sensing was 2.5 +/- 1.6 mV in the left atrium and 2.3 +/- 1.4 mV in the right atrium. No complications were observed with sho ck application, nor with lead extraction. Atrial defibrillation using tempo rary epicardial wire electrodes can be performed successfully and safely in patients following cardiac operations. The shock energy required to restor e SR is low. Electrical cardioversion in the absence of anesthesia should b e feasible.