| abstract |
A rate responsive cardiac pacemaker for implantation in a patient, comprising an activity sensor (3) means having a response characteristic limited to the frequency range below 4 Hz for detecting movement of the patient arising from physical exercise and generating an electrical signal representative thereof while discriminating against movement arising from random influences, means (9) for generating pulses at a controllably variable rate to stimulate the patient's heart at any of a plurality of selectable rates, and means (10a,10b) responsive to said signal for adjusting the rate of the pulse generating means relative to a base rate according to whether the patient is undergoing exercise or is at rest. |