An automatic cardiac ventricular defibrillator.

摘要

An automatic cardiac ventricular defibrillator and a defibrillation of the cardiac ventricles of a heart wherein both the mechanical and electrical activities of the ventricles are sensed and used as operating controls. Electrical activity is detected and measured with a pair of electrodes (5, 6) and the waves of an electrocardiogram (ECG) are analyzed. When such electrical analysis indicates that ventricular fibrillation is present and persists, an electrical circuit (20) is actuated for detecting mechanical pumping activity of the heart. Mechanical pumping activity is measured by the change in impedance between the pair of electrodes (5, 6) in one of the ventricles (3). The change of ventricular impedance is caused by varying volume of blood contained within the ventricles (3) and depends upon whether the ventricles (3) are in a contracted or relaxed state. The defibrillator (40) is actuated only when both the mechanical and electrical activity of the ventricles indicate a need for defibrillation. Because some conditions may be encountered which closely resemble ventricular fibrillation, the defibrillator quantitatively preprogramms and weights the relative importance of the electrical and mechanical signs from the heart.