[Nonthoracotomy internal defibrillation in dogs using a body surface electrode with a transvenous catheter electrode]

The efficacy of truncated exponential waveform shocks using a cardioverter-defibrillator catheter (Medtronic 6880) and body surface electrodes was examined in comparison with using a RV epicardial patch electrode and a LV epicardial patch electrode in fifteen pentobarbital-anesthetized dogs. The defibrillation thresholds (DFT) for 5 lead configurations were measured by the total energy, peak voltage and peak current: A) a body surface electrode (positioned at the right lateral chest wall) as the anode and a body surface electrode (positioned at the left lateral chest wall) as the cathode; B) a superior vena cava catheter electrode as the anode and a RV apex catheter electrode as the cathode; C1) a body surface electrode (positioned at left anterior chest wall) as the anode and a RV apex catheter electrode as the cathode; C2) a body surface electrode (positioned at the left lateral chest wall) as the anode and a RV apex catheter electrode as the cathode; and D) a RV epicardial patch electrode as the anode and a LV epicardial patch electrode as the cathode. The total energy at DFT for configurations C2 and D was lower than for configurations A, B, and C1, respectively (7.2 +/- 3.1 and 4.7 +/- 2.0 less than 18.9 +/- 3.8, 12.0 +/- 3.8 and 11.2 +/- 2.2 joules; p less than 0.05). The peak voltage at DFT for configurations C2 and D was lower than for configurations A, B, and C1, respectively (463 +/- 70 and 377 +/- 73 less than 767 +/- 85, 585 +/- 117 and 600 +/- 62 volts; P less than 0.05).