Implantable cardiac devices and methods for delivering low energy, pain-free defibrillation signals for ventricular arrhythmias

An implantable cardioverter-defibrillator comprising:

• a power source;
• a controller, powered by the power source, including an electronic processor, a memory, and a pulse generator;
• a His-bundle lead coupled to the controller and an electrode that is configured to make in electrical contact with the His-bundle of a patient's heart;
• a capacitor circuit including a capacitor configured to deliver a defibrillation shock to the His-bundle;
• and
• a sensing lead coupled to the controller and configured to make in electrical communication with the patient's heart, the sensing lead configured to detect electrical signals generated by the patient's heart, and
• wherein the controller is configured to
• receive the electrical signals provided by the sensing lead,
• process the electrical signals to determine if ventricular fibrillation is present,
• if ventricular fibrillation is detected on the electrical signals,
• determine a cycle length of the ventricular fibrillation and a set of pacing pulse characteristics for the ventricular fibrillation, wherein the set of pacing pulse characteristics includes at least a number of pulses, pulse duration, pulse cycle length, current, and voltage based on an average of the cycle length of the ventricular fibrillation, while transmitting a signal to the capacitor circuit to charge the capacitor,
• transmit instructions to the pulse generator to deliver a pulsed defibrillation signal in accordance with the set of pacing pulse characteristics to the electrode to terminate the ventricular fibrillation,
• decrease speed of delivery of the pulsed defibrillation signal to a normal sinus rate,
• process the electrical signals to determine if ventricular fibrillation is present after transmission of the pulsed defibrillation signal to the electrode,
• if ventricular fibrillation remains present in the electrical signals,
• transmit a signal to the capacitor circuit to deliver a defibrillation shock to the electrode,
• if ventricular fibrillation is no longer present in the electrical signals,
• transmit a signal to the capacitor circuit to discharge the capacitor.