Resources Contact Us Home
Dual chamber pacemaker system and method with improved switching between synchronous and asyncrhonous behavior

Image Number 6 for United States Patent #5531771.

A dual chamber pacemaker system having a dynamic tracking limit, as well as a dynamic pacing limit (flywheel rate), the two dynamic limits being normally coupled to a measure of the sensed atrial rate as long as such rate is physiological. When the atrial signal is lost, i.e., cannot be tracked, the pacemaker responds with asynchronous pacing and normally decrements both dynamic limits, taking the flywheel rate down toward a lower pacing limit. The pacemaker of this invention provides a freeze function whereby the dynamic pacing limit and dynamic tracking limit are maintained constant for a plurality of cycles following asynchronous operation, to improve the possibility of regaining tracking if an underlying physiological atrial signal reappears at about the rate prior to being lost. The freeze function may be timed out for a predetermined number of cycles, e.g., eight, or may have a reduced duration if a series of consecutive synchronous cycles is detected. In a second embodiment, the dynamic tracking limit is decreased without any freeze when the pacer goes into asynchronous operation, but the dynamic tracking limit which existed just before the switch to asynchronous operation is remembered; if the atrial rate reappears below this remembered dynamic tracking limit, the dynamic tracking limit is ramped upward to achieve quick tracking of the reappeared sinus rate. A further embodiment may incorporate the features of the first two embodiments, i.e., a short freeze followed by a period of remembering the value of DTL when async mode was initiated.

  Recently Added Patents
Oil extractor and the preparation method thereof
Carbonate and carbamate modified forms of glucocorticoids in combination with .beta..sub.2 adrenergic agonists
Editing device and editing method
Fuel cell system, and electric vehicle equipped with the fuel cell system
Method for manufacturing light emitting diodes
Digital media content distribution
Method for testing multi-chip stacked packages
  Randomly Featured Patents
Position detector with magnetic scale and magnetic sensor that has magnetic reluctance elements in non-overlapping relationship
Window component extrusion
Pet food composition containing semi-refined gelling agent
Method for molding plastic material into disk shaped sabstrate for an optical information record carrier
Papermaker's forming fabric with engineered drainage channels
Concrete screed with vertically adjustable gate
Support member and system for affixation to bed rails or bed frame
Multichannel porous ceramic fiber
Injecting air into the flow path of a turbomachine compressor
Image capture device having a scanning mode switching capability