Implantable defibrillator electrode comparison using a boundary element model

The efficacy of six implantable defibrillator electrode configurations was compared using a boundary element model that incorporated a realistic thorax with detailed internal structure. Configurations 1-3 consisted of an (inferior) endocardial electrode positioned in the right ventricle (RV) together with a (superior) endocardial electrode positioned high or low in the superior vena cava (SVC) or in the pulmonary artery (PA). Configurations 4-6 were the same as 1-3 but with the addition of a subcutaneous (SQ) patch electrode on the left chest wall. The energy used to achieve minimum voltage gradients of 5 V/cm was much lower for configurations 4-6 with the SQ patch (2.9-3.8 J). Without the SQ patch, the PA electrode used less energy (10.3 J) than low (12.4) and high SVC (15.1). The subcutaneous patch results in substantial reductions in required voltage and energy for implantable defibrillators