Disclosed are several embodiments of an electrode system for ventricular defibrillation, and the methods of using and implanting the electrode system. In one embodiment, the electrodes are in a generally base-apex configuration having a split conformal base electrode residing above the base of the ventricles (a transecting plane separating the atria from the ventricles) in the region of the atria and a conformal apex electrode in the form of a rotated conic section residing at the apex of the heart. In another embodiment, defibrillation is accomplished by the apex electrode acting against a catheter electrode situated high in the heart or in the superior vena cava.
The electrodes themselves are in the form of planar metallic mesh elements adapted to lie in contact with body tissue on an active surface, insulated on the opposite surface. In another embodiment, the conductive portions of the respective electrodes are developed from metallic plates, exposed on one surface and insulated on the other. The electrodes may be split, or may entirely surround the base and apex of the heart.
The disclosed electrode system is well adapted for easy implantation during an open heart surgery, or in a separate operation which can be performed in the mediastinal space without intrusion of the pleural space. The electrode system may be implanted for immediate stand-by defibrillation, or may be implanted during open heart surgery, used for post-operative monitoring, pacing and defibrillation, should the need arise, and then subcutaneously implanted for future association with an automatic defibrillating pulse generator. When employed after open heart surgery, the electrode system is preferably equipped with independent atrial and ventricular pacer electrodes.
Also disclosed are techniques for fixing the electrode system to the surrounding body tissue, and electrode leads which may be removed after the implanted electrodes have served their desired function, without disturbing the electrodes themselves.