1. A medical device for detecting the presence of a cardiac pulse, comprising: a piezoelectric sensor having a transducing element configured for placement on the surface of a patient's body, the transducing element being adapted to sense movement in the patient's body due to a cardiac pulse and produce piezoelectric signal data in response thereto; and processing circuitry configured to analyze the piezoelectric signal data for a feature indicative of the presence of a cardiac pulse and determine whether a cardiac pulse is present based on the feature.