Subcutaneous insertable cardiac monitor optimized for long-term electrocardiographic monitoring

A subcutaneous implantable recorder for long-term electrocardiographic (ECG) monitoring, comprising:

• a hermetically sealed implantable housing and comprised of a biocompatible material that is suitable for implantation within a living body of a patient;
• at least one pair of ECG sensing electrodes;
• a power source comprised within the implantable housing;
• and
• electronic circuitry provided within the housing, the electronic circuitry comprising:
• a low power microcontroller comprising firmware and operable to execute under modular micro program control as specified in firmware;
• an ECG front end circuit interfaced to the microcontroller and configured to capture the cardiac action potentials sensed by at least the pair of ECG sensing electrodes which are output as ECG signals, the ECG front end comprising:
• a signal lead operable to sense the cardiac action potentials through one of the ECG electrodes;
• a reference lead operable to sense the cardiac action potentials through another of the ECG electrodes;
• a termination resistor, a filter capacitor, and an operational amplifier through which a current of the sensed cardiac action potentials passes in a direct sequence prior to being output as the ECG signals;
• a memory electrically interfaced with the microcontroller and operable to store samples of the ECG signals;
• and
• one or more physiological sensors interfaced to the microcontroller, wherein the microcontroller is configured to store data received from the one or more physiological sensors in the memory.