An example system includes memory configured to store a plurality of lead impedances (LeadZs) and processing circuitry communicatively coupled to the memory. The processing circuitry is configured to determine a first sensed LeadZ, and determine a second sensed LeadZ. The processing circuitry is configured to determine a first difference between the first sensed LeadZ and the second sensed LeadZ, and determine a parameter based at least in part on the first difference. The first sensed LeadZ and the second sensed LeadZ are sensed during a same first cardiac cycle or adjacent cardiac cycles of a heart that is receiving pacing.

A medical device system determines first values associated with a first plurality of patient parameters associated with arrhythmic substrate and/or physiological triggers for acute cardiac events based on a first one or more of the physiological signals generated during the period and determines, based on the first values associated with the first plurality of patient parameters, whether to assess alterations in cardiac cellular electrophysiology and/or mechanical alterations of the patient. The system may, in response to determining to assess the alterations in cardiac cellular electrophysiology, determine second values associated with a second plurality of patient parameters relating to cardiac electrophysiology based on a second one or more of the physiological signals generated during the period and determine whether to generate an alert indicating that an acute cardiac event of the patient is predicted based at least in part on the second values associated with the second plurality of patient parameters.

The present invention provides monitoring of brain blood circulation in a patient with cardiac pacemaker for the prevention of symptoms associated with pacemaker syndrome and stroke. The monitoring of brain blood flow velocity is performed using a transcranial Doppler ultrasound device synchronized with an implanted cardiac pacemaker, to select the pacing mode that enhances cerebral perfusion in the patient. The system further detects microembolic signals in the cerebral circulation and triggers sonothrombolysis as well as release of thromolytic and neuroprotective agents for clot dissolution.

This document discusses, among other things, systems and methods to generate a first pacing waveform during a first pacing period and a second pacing waveform during a second pacing period, to alternate first and second pacing periods to provide pacing-based hypertension therapy to a heart of a patient to reduce patient blood pressure, to receive information indicative of patient metabolic demand, and to determine an adjusted pacing-based hypertension therapy parameter using the received information indicative of patient metabolic demand, wherein the first pacing waveform has a first atrioventricular (AV) delay and the second pacing waveform has a second AV delay longer than the first AV delay.

A medical device is configured to deliver anti-tachycardia pacing (ATP) in the presence of T-wave alternans. The device is configured to detect a ventricular tachyarrhythmia from a cardiac electrical signal received by the medical device. In response to the detected ventricular tachyarrhythmia, the device delivers a plurality of ATP pulses at alternating time intervals. The alternating time intervals comprise at least a first ATP time interval separating a first pair of the ATP pulses and a second ATP time interval different than the first ATP time interval. The second ATP time interval consecutively follows the first ATP time interval and separates a second pair of the ATP pulses.

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.

Systems and methods for monitoring physiologic response to Valsalva maneuver (VM) are disclosed. An exemplary patient monitor may detect a natural incidence of a VM session occurred in an ambulatory setting using a heart sound (HS) signal sensed from the patient. The patient monitor may include a physiologic response analyzer to sense patient physiologic response during the detected VM session, and generate a cardiovascular or autonomic function indicator based on the sensed physiologic response to the VM. Using the physiologic response to the VM, the system may detect a target physiologic event using the sensed physiologic response to the VM.

An intracardiac ventricular pacemaker includes a pulse generator for delivering ventricular pacing pulses, an impedance sensing circuit, and a control circuit in communication with the pulse generator and the impedance sensing circuit. The pacemaker is configured to produce an intraventricular impedance signal, detect an atrial systolic event using the intraventricular impedance signal, set an atrioventricular pacing interval in response to detecting the atrial systolic event, and deliver a ventricular pacing pulse in response to the atrioventricular pacing interval expiring.

Methods and devices herein are provided for managing atrial (A) pacing in connection with premature atrial contracts (PAC). The methods and devices obtain an atrial pace-on-PAC (APAC) interval and cardiac activity (CA) signals. The methods and devices are configured to: i) during a first cardiac beat; following a ventricular paced (VP) or ventricular sensed (VS) event, activate a timer for a post ventricular-atrial refractory period (PVARP) interval; and determine whether a first atrial refractory (AR) event occurs during the PVARP interval; ii) during a second cardiac beat; in response to the detecting that the first AR event occurred, initiate an APAC interval; during the APAC interval for the second cardiac beat, determine whether a second AR event occurs; and update a count of APAC events when the second AR event occurs; and iii) repeat i) and ii) for multiple cardiac beats, to track the count of APAC events.

A ventricular pacemaker is configured to determine a ventricular rate interval by determining at least one ventricular event interval between two consecutive ventricular events and determine a rate smoothing ventricular pacing interval based on the ventricular rate interval. The pacemaker is further configured to detect an atrial event from a sensor signal and deliver a ventricular pacing pulse in response to detecting the atrial event from the sensor signal. The pacemaker may start the rate smoothing ventricular pacing interval to schedule a next pacing pulse to be delivered upon expiration of the rate smoothing ventricular pacing interval.