Adjustable atrial and ventricular temporary electrode for low-energy termination of tachyarrhythmias early after cardiac surgery.

Supraventricular and ventricular tachycardias are common and serious postoperative complications early after cardiac surgery. We introduce a completely removable temporary adjustable defibrillation electrode (TADE) for low energy cardioversion/defibrillation of postoperative atrial and ventricular tachyarrhythmias. The electrode consists of three loops of steel wires connected to one steel wire, which are movable within an isolation sheet for adjusting the active surface to the individual size of the heart chambers. Evaluation of the electrode was performed in 10 open-chest beagles with a mean weight of 25.5 kg. The electrodes were first positioned on the left and right atrium. Atrial fibrillation (AF) was induced via a bipolar temporary heart wire. Atrial defibrillation thresholds (DFTs) were measured according to a step-down shock protocol (5-0.4 J). Thereafter, the electrodes were adjusted and positioned on the right and left ventricle. Ventricular fibrillation (VF) was induced and DFTs were recorded the same way. Aortic flow and pressure and left ventricular pressure were continuously monitored throughout the experiment. For termination of AF, mean DFTs were 0.4 +/- 0 J (lowest possible shock level) with a mean shock impedance of 70 +/- 7.6 ohms. VF was terminated with a mean DFT of 3 +/- 1.1 J with a mean impedance 56.1 +/- 7.9 ohms. Complete transcutaneous removal of the electrodes was possible in all animals without any complications. In conclusion, successful low energy termination of AF and VF is possible with the tested temporary adjustable electrode. A clinical study is planned for further evaluation.