METHOD AND APPARATUS FOR RATE-RESPONSIVE CARDIAC PACING

摘要

In a pacemaker, a method and apparatus for providing rate in response to the patient's breathing rate or respiratory minute ventilation or contraction strength, optionally augmented by the patient's activity level. An implantable pulse generator (IPG) has one or more pacing leads (18) having a proximal end (40) coupled to the IPG and a distal end in contact with a patient's heart. A pressure wave transducer (32) mounted in the IPG in relation to the proximal end (40) of the pacing lead (18) senses pressure waves transmitted from the distal end of the pacing lead (18) to the proximal end (40) thereof. The pressure waves originate from disturbances imparted to the lead by heart contractions and breathing. A further isolated, reference sensor (34) is also incorporated into the IPG in a similar fashion. An activity signal processor is coupled to the pressure wave or reference sensor (32, 34) for providing a patient activity physiologic signal. A respiration signal processor and a contraction strength signal processor are coupled to said pressure wave and reference transducer providing physiologic respiration rate and/or respiratory minute ventilation signals. A contraction strength signal processor is coupled to said pressure wave and reference transducers (32, 34) for nulling out common mode noise and providing physiologic contraction strength signals. Pacing rate control circuitry is responsive to one or more of the physiologic signals for setting the pacing rate to meet the metabolic demand.