Unitary intravascular defibrillating catheter with bipolar sensing

Abstract

A unitary intravascular defibrillating catheter includes distal and proximal spring electrodes, displaced to such distance from one another that defibrillating shock is effected through a field including the interventricular septum and left ventricular free wall. In one embodiment of this catheter, the proximal electrode is placed in the region of the subclavian vein. Alternatively, it may be placed in the region of the third through seventh intercostal space. A unitary catheter is also described which includes an intermediate electrode, placed between distal and proximal electrodes. Selection of placement of electrodes either in the superior vena cava or in the region of the subclavian vein is medically indicated by physiological conditions of the individual patient. The cardioversion system further includes a unipolar or bipolar sensing circuit with at least one sensing electrode, and a cardioversion/defibrillation circuit with either two or three spaced apart spring electrodes. The sensing electrodes are spaced apart from one another, but they are kept sufficiently close to one another for isolated, localized R-wave sensing. The sensing electrodes further are positioned remotely of the cardioversion/defibrillation electrodes, to avoid post-shock abnormalities which otherwise would interfere with a timely R-wave sensing, and to substantially prevent the discharge of an unnecessary cardioversion pulse after return of the heart to normal cardiac rhythm.