A blog about what is new (and old) in the world of active implantable medical devices

Intermedics’ Circadia Central Venous Temperature-Sensing Pacemaker (ca. 1993)

Posted on by Posted in Bradycardia, Cardiac Pacing, History, Intermedics (1974-1999), Museum

Intermedics Circadia central-venous-temperature-sensing rate-responsive pacemaker

Back side of Intermedics Circadia pacemaker. Labeling shows special connector for temperature-sensing lead.

The Circadia pacemaker was one of the very few devices that had a lead-borne thermistor to measure cental venous temperature (CVT) as a sensor for rate-response.

A unique feature of this pacemaker was an iridium-oxide (IrOx)-coated button welded to the can.  It was believed that this button would improve unipolar IEGM sensing and reduce unipolar pacing thresholds (it didn’t).

Click here for more detail CVT-sensing rate-responsive pacemakers.

A very detailed engineering discussion on CVT-sensing pacemakers is available at Mayotte MJ. “Rate adaptation by temperature.” In: Webster JG, ed. Design of Cardiac Pacemakers. IEEE Press, Piscataway, NJ, 1995: 335–368.