An implantable cardiac stimulating device employs an automatic defibrillation
threshold tracking process that uses a measured pacing stimulation threshold to
estimate the patient's defibrillation threshold on a dynamic, ongoing basis, using
changes in the defibrillation threshold to re-calculate new defibrillation parameters
(e.g., energy settings) on a periodic basis as a patient's heart changes over time.
The defibrillation threshold estimation formula may involve a variety of variables,
such as, for example, the patient's age and/or gender, and may include a selected
safety margin. New defibrillation parameters are loaded into the appropriate locations
of the device's memory, replacing the prior parameters, and are thereafter available
for use by the device for defibrillation therapy. The defibrillation threshold
tracking technique may be used in an external device, such as a programmer or external
cardiac stimulation device.
