Implantable systems, and methods for use therewith, are provided for monitoring myocardial stability based on a signal that is indicative of functioning of a patient’s heart for a plurality of consecutive beats. The efficient analog to digital converter includes a coarse analog to digital converter coupled to an input analog signal. Since ordinary CCD camera is used, the cost of the imaging system has been sharply reduced for the equipment’s construct and maintenance compared with PETSPECT or \u03b3 camera. The optical combiner is in front of both the red and white LEDs, slightly above the white LEDs in vertical placement. The magnetic logic device can be used for an all-function-in-one magnetic chip.