A pacer for cardiac pacing and condition monitoring in which the electrical characteristics of the pacer are altered upon a temporary or permanent change in monitored conditions, such as the failures defined as a "loss of capture" or a "failure to sense", in which the timed relationship between the pacer signal generator and the cardiac signal is monitored to indicate detection of failure condition. The monitor acts to provide both increased stimulus to recover capture and to provide warning pulses indicating loss of capture or failure to sense, which are sufficiently discernible upon an electrocardiogram to enable later diagnosis, even after self-correction. After diagnosis, the monitor can be reset to its original condition by means of an external control, such as a magnet. The unit may be surgically implanted or employed externally. Remote or patient operated local failure detectors can be employed with the pacer to automatically detect, indicate, and provide an alarm if any prior intermittent sensing or capture failure occurred.