摘要:
Cardiac monitoring and/or stimulation methods and systems that provide one or more of monitoring, diagnosing, defibrillation, and pacing. Cardiac signal separation is employed to detect, monitor, track and/or trend ischemia using cardiac activation sequence information. Ischemia detection may involve sensing composite cardiac signals using implantable electrodes, and performing a signal separation that produces one or more cardiac activation signal vectors associated with one or more cardiac activation sequences. A change in the signal vector may be detected using subsequent separations. The change may be an elevation or depression of the ST segment of a cardiac cycle or other change indicative of myocardial ischemia, myocardial infarction, or other pathological change. The change may be used to predict, quantify, and/or qualify an event such as an arrhythmia, a myocardial infarction, or other pathologic change. Information associated with the vectors may be stored and used to track the vectors.
摘要:
A non-linear dynamic specified AV delay can be used, such as to help maintain cardiac resynchronization therapy, such as in patients with one or more symptoms of congestive heart failure.
摘要:
System and methods provide pacing therapy that modulates the atrioventricular (AV) delay to control ventricular interval variability. A base AV delay is determined as a function of heart rate. For each cardiac cycle, the base AV delay is modulated to reduce beat-to-beat variability of successive ventricular beats. The modulated AV delay compensates for variability of successive atrial beats. For example, modulation of the base AV delay may involve varying the AV delay inversely with a change in atrial interval.
摘要:
Methods and systems to modulate timing intervals for pacing therapy are described. For each cardiac cycle, one or both of an atrioventricular (A-V) timing interval and an atrial (A-A) timing interval are modulated to oppose beat-to-beat ventricular (V-V) timing variability. Pacing therapy is delivered using the modulated timing intervals.
摘要:
An implantable or ambulatory medical device can include a cardiac signal sensing circuit configured to provide a sensed cardiac depolarization signal of a heart of a subject, a respiration sensing circuit configured to provide a signal representative of respiration of the subject, and a control circuit communicatively coupled to the cardiac signal sensing circuit and the respiration circuit. The control circuit includes a tachyarrhythmia detection circuit configured to determine heart rate using the depolarization signal, determine a respiration parameter of the subject using the respiration signal, calculate a ratio using the determined heart rate and the determined respiration parameter, generate an indication of tachyarrhythmia when the calculated ratio satisfies a specified detection ratio threshold value, and provide the indication of tachyarrhythmia to a user or process.
摘要:
An implantable cardiac device is configured and programmed to assess a patient's cardiopulmonary function by evaluating the patient's minute ventilation response. Such evaluation may be performed by computing a minute ventilation response slope, defined as the ratio of an incremental change in minute ventilation to an incremental change in measured activity level. The minute ventilation response slope may then be compared with a normal range to assess the patient's functional status.
摘要:
An implantable pacing device for delivering ventricular pacing may be configured to intermittently and variably reduce the AV delay interval used in an atrial triggered pacing mode in a manner that simulates exercise. The device may be programmed to intermittently switch to and from a variably shortened AV delay mode according to defined entry and exit conditions.
摘要:
An indication of an actual or potential heart failure condition is computed. One example includes monitoring a first heart rate preceding a first onset of a first sinus tachyarrhythmia episode. Upon detecting the first sinus tachyarrhythmia episode, the indication is automatically provided using information about the first heart rate and how quickly the first onset occurs.