Techniques for using multiple physiological parameters to provide an early warning for worsening heart failure are described. A medical device monitors a primary diagnostic parameter that is indicative of worsening heart failure, such as intrathoracic impedance or pressure, and one or more secondary diagnostic parameters. The medical device detects worsening heart failure in the patient based on the primary diagnostic parameter when an index that is changed over time based on the primary diagnostic parameter value is outside a range of values, termed the threshold zone. When the index is within the threshold zone, the medical device detects worsening heart failure in the patient based on the one or more secondary diagnostic parameters. Upon detecting worsening heart failure, the medical device may, for example, provide an alert that enables the patient to seek medical attention before experiencing a heart failure event.

A cardiac pacing system having a pulse generator for generating therapeutic electric pulses, a lead electrically coupled with the pulse generator having an electrode, a first sensor configured to monitor a physiological characteristic of a patient, a second sensor configured to monitor a second physiological characteristic of a patient and a controller. The controller can determine a pacing vector based on variables including a signal received from the second sensor, and cause the pulse generator to deliver the therapeutic electrical pulses according to the determined pacing vector. The controller can also modify pacing characteristics based on variables including a signal received from the second sensor.

Techniques for switching an implantable medical device (IMD) from a first mode to a second mode in relation to signals obtained from internal sensors are described. The internal sensors may include a temperature sensor and a biosensor. In some examples, processing circuitry of the IMD may make a first preliminary determination that the IMD is implanted based on a first signal from the temperature sensor. In response to the first preliminary determination being that the IMD is implanted, the processing circuitry may make a second preliminary determination that the IMD is implanted based on a second signal from the biosensor. The processing circuitry may switch the IMD from a first mode to a second mode based on both the first preliminary determination and the second preliminary determination being that the IMD is implanted.

According to some aspects, a cardiac pacemaker for implantation within a subject is provided, the pacemaker including a housing, at least one sensor configured to detect an activity level of the subject, and at least one processor coupled to the sensor configured to detect inactivity of the subject based on output from the at least one sensor, produce a first signal configured to increase the heart rate of the subject to a first heart rate during a first time period, wherein the first heart rate is above a resting heart rate and below 100 beats per minute, and in response to determining that the first time period has elapsed, producing a second signal configured to increase the heart rate of the subject to a second heart rate during a second time period, wherein the second heart rate is between 100 and 140 beats per minute.

An implantable medical device system includes an extracardiac sensing device and an intracardiac pacemaker. The sensing device senses a P-wave attendant to an atrial depolarization of the heart via housing-based electrodes carried by the sensing device when the sensing device is implanted outside the cardiovascular system and sends a trigger signal to the intracardiac pacemaker in response to sensing the P-wave. The intracardiac pacemaker detects the trigger signal and schedules a ventricular pacing pulse in response to the detected trigger signal.

Techniques for using multiple physiological parameters to provide an early warning for worsening heart failure are described. A system is provided that monitors a multiple diagnostic parameters indicative of worsening heart failure. The parameters preferably include are least one parameter acquired from an implanted device, such as intrathoracic impedance. The system device derives an index of the likelihood of worsening heart failure based upon the parameters using a Bayesian approach and displays the resultant index for review by a physician.

Systems and methods are described for subject rehospitalization management. In an example, multiple physiologic signals can be obtained from a subject using multiple sensors. In response to a hospitalization event, pre-hospitalization characteristics of the multiple physiologic signals can be identified. Post-hospitalization characteristics of the multiple physiologic signals can be identified, including characteristics that differ from their corresponding pre-hospitalization characteristics. Later subsequent physiologic signals can be further monitored after the hospitalization event, such as using the same multiple sensors, and subsequent physiologic signal characteristics can be identified. In an example, a heart failure diagnostic indication can be determined using information about the pre-hospitalization characteristics, the post-hospitalization characteristics, and the subsequent characteristics. Information about relative changes in signal characteristics from multiple sensors can be used to identify particular subject physiologic signals to monitor during subsequent periods.

A system for monitoring blood pressure includes an implantable medical device (IMD) and an external device (ED). The IMD senses an electrogram (EGM) signal, identifies a feature thereof indicative of a ventricular depolarization, and transmits a conductive communication signal through patient tissue indicating when the ventricular depolarization occurred. The ED is worn against skin and configured to receive the conductive communication signal. The ED is also configured to sense a plethysmography (PG) signal and identify a feature thereof indicative of when a pulse wave responsive to the ventricular depolarization reaches a region of the patient adjacent the ED, and determine a delay time (TD) indicative of how long it takes the pulse wave to travel from the patient's heart to the region of the patient adjacent to the ED. The TD is a surrogate of the patient's blood pressure and useful for monitoring the patient's blood pressure and/or changes therein.

Methods and implantable medical devices (IMDs) are provided for monitoring a cardiac function of a heart. A heart sound sensor is configured to sense heart sound signals of the subject. The IMD includes a memory to store program instructions. The IMD includes a processor that, when executing the program instructions, is configured to identify S2 signal segment from the heart sound signals, analyze the S2 signal segment to identify a pulmonary valve signal (P2 signal) and an aortic valve signal (A2 signal) within an S2 signal segment of the heart sound signals. The processor is configured to determine a time interval between the A2 and P2 signals, characterize the S2 signal segment to exhibit a first type of S2 split based on the time interval, and identify a cardiac condition based on a comparison of the first type of S2 split and a cardiac condition matrix.

Disclosed are methods and systems for treating epilepsy by stimulating a main trunk of a vagus nerve, or a left vagus nerve, when the patient has had no seizure or a seizure that is not characterized by cardiac changes such as an increase in heart rate, and stimulating a cardiac branch of a vagus nerve, or a right vagus nerve, when the patient has had a seizure characterized by cardiac changes such as a heart rate increase.