Implantable device to diagnose and differentiate supraventricular and ventricular tachycardias; has unit to prevent therapy if heart rate is too fast during stimulation

摘要

The device has electrodes to stimulate atrioventricular or sino-atrial nodes and parasympathetic stimulation pulses. A unit determines the intervals between atrial or ventricular depolarisations. A unit programmes a frequency threshold, above which a ventricular rate is detected as a tachycardia. An inhibition unit prevents therapy if the heart rate during stimulation exceeds a calculated comparison value by more than a given amount. The device has electrodes to stimulate parasympathetic nerves in the atrioventricular or sino-atrial nodes, electrodes to stimulate the atria or ventricles or for defibrillation or cardioversion. A unit generates parasympathetic stimulation pulses for delivery by the electrodes. A unit determines the atrial or ventricular rate, to determine the intervals between atrial or ventricular depolarisations. A unit programmes a frequency threshold, above which a ventricular rate is detected as a tachycardia. A comparison unit compares the heart rate during stimulation with that before or without stimulation or with the frequency threshold and produces an output signal if the heart rate during stimulation exceeds the comparison value by more than a given amount. An inhibition unit inhibits ventricular, myocardial over-stimulation therapy or cardioversion or defibrillation therapy according to the output signal of the comparison unit.