Resources Contact Us Home
Method and device for optimally altering stimulation energy to maintain capture of cardiac tissue

Image Number 11 for United States Patent #6456879.

An improved system and method for performing automatic capture/threshold detection in an implantable cardiac stimulation device or any device capable of stimulating some body organ or tissue. Prior art systems determine the cardiac tissue's stimulation threshold by detecting an evoked response to a fixed duration stimulation pulse and then increasing the stimulation pulse's amplitude by a predetermined safety margin value. Such systems are inherently based upon a belief that the chronaxie of a particular patient's strength-duration curve is essentially fixed and that the rheobase is variable. While this may be true at some times during the patient's life, e.g., during the acute phase after lead implantation absent drug effects, it is reported that drugs alone may alter the chronaxie and it is believed that other factors may also affect the chronaxie either alone or in combination with the rheobase. Accordingly, the present invention compares the present stimulation pulse to at least two pulse duration regions and, if a loss-of capture criteria is met, alters the amplitude aid/or the duration of the stimulation pulse accordingly in order to take into account a rheobase and/or chronaxie shift. The decision of whether to increase amplitude and/or duration is dependent on the current operating point. For example, in an embodiment having two pulse duration regions, the amplitude and duration of the stimulation pulse may be increased in the first duration region below the chronaxie while, in the second duration region above the chronaxie, only the amplitude may be increased.

  Recently Added Patents
Air-fuel ratio control apparatus for an internal combustion engine
Manufacturing process for cellular screening substratum, resultant substratum, and method and apparatus for screening
Computer system for routing package deliveries
Reverse mapping method and apparatus for form filling
Substituted di-arylhydantoin and di-arylthiohydantoin compounds and methods of use thereof
Wristband with detachable labels
  Randomly Featured Patents
Method for the destructive scrubbing of methyl chloride gas
Method and apparatus for modifying the exit orifice of a satiation pouch
Packaged potable liquid and packaging for potable liquid
Storing digital video signals
Typewriter having means for automatic indication of candidate correct word for misspelled word, and/or automatic correction of misspelled word
Information presentation apparatus and information presentation method
Circuit for programming antifuse bits
Acoustic inspection method
Open vessel sealing instrument with cutting mechanism and distal lockout
Quiet "fan"