Abstract: Video monitoring apparatus for use in an application in which changes in relative spatial relationship of features of a biological tissue are to be observed. A video camera electronically produces a first image of the tissue and also electronically produces a subsequent image of the tissue after a period of time. A video display unit displays a representation of an image of the tissue derived from the camera. Circuitry connected to the camera and to the display unit electronically stores a representation of the first image of the tissue, and transmits the representation of the first image of the tissue to the display unit with a representation of the subsequent image of the tissue so that the first and subsequent images of the tissue appear superimposed. In this way, any differences in the relative spatial relationship of features in the images of the tissue are readily observed. A surgical reapposition monitor and methods are also disclosed.

Abstract: A pulse peak detector for generating a DC signal proportional to the peak amplitude of applied short duration input pulses of a repetitive train, includes a signal input circuit to which the pulses are applied, a first storage capacitor, a differential comparator connected to the input circuit and to the pulse storage capacitor for producing a saturation output signal having a time duration equal to the time during which the input pulse exceeds the amplitude of the level stored on the capacitor. The output pulse thus generated is coupled to an error amplifier and a second storage capacitor at the output of that amplifier, the second capacitor being DC coupled to the first. The time constants of the capacitors and their associated resistive charging circuits are selected so that the coupling circuit and the second storage capacitor has a time constant which is long relative to the repetition rate of the applied signals.