Inventors:
Edward Paul Romani - Holland PA
Assignee:
Hoffmann-La Roche Inc. - Nutley NJ
International Classification:
A61B 502
Abstract:
Ultrasonic apparatus for monitoring heartbeat activity from electrical Doppler signals derived from heartbeat motion comprising means for selective passing of the electrical Doppler signals at one of two operable bandpass ranges to a retunable resonant circuit which de-emphasizes non-resonant frequency content, means for detecting a phase shift between the input signals to and output signals from the resonant circuit to retune it at a preselected rate, and means for inhibiting the phase detector operation with one of two operable refractory periods to prevent artifact from showing as a phase shift, whereby the operable bandpass ranges and refractory period are in response to separate preselected recorded heart rate values.