Systems and methods for pacing cardiac conductive tissue are described. A medical system includes an electrostimulation circuit to generate His-bundle pacing (HBP) pulses for delivery at or near a His bundle of the heart. A control circuit may time the delivery of the HBP pulses within a tissue refractory period subsequent to an intrinsic His-bundle activation of a first His-bundle portion. Based on an evoked His-bundle activation of a second His-bundle portion, the system may determine whether correction of intra-Hisian block has occurred. The system additionally includes a threshold test circuit to determine an individualized pacing threshold representing minimal energy to excite the His bundle and to correct the cardiac conduction abnormality.

Embodiments described herein generally relate to methods and systems for monitoring and responding to changes in a patient's physiologic status. A method includes sensing pulmonary arterial pressure (PAP) and thoracic impedance of a patient at rest. The method also includes detecting, based on the sensed PAP, whenever the patient's PAP at rest is outside an acceptable range of PAP measures for the patient at rest, and detecting, based on the sensed thoracic impedance, whenever the patient's respiration at rest is outside an acceptable range of respiration measures for the patient at rest. Various different actions are triggered depending upon whether the patient's PAP at rest is outside the acceptable range of PAP measures for the patient at rest, and whether the patient's respiration at rest is within the acceptable range of respiration measures for the patient at rest. Other embodiments relate to similar methods performed at other levels of exertion.

An implantable medical device for stimulating a heart, comprising a control unit, a memory unit, a stimulation unit for stimulating a cardiac region of a heart, and a detection unit for detecting an electrical signal of the heart. The memory unit comprises a computer-readable program that causes the control unit to perform the following steps: a) detecting capture thresholds during an observation period, each capture threshold detected in response to a sequence of pacing pulses delivered by the stimulation unit; b) storing the detected capture thresholds in the memory unit; c) determining threshold-to-threshold differences between two consecutive capture thresholds; and d) if a maximum determined threshold-to-threshold difference within the observation period is equal to or greater than a predetermined limit, adjusting a pacing output of the stimulation unit based on the maximum capture threshold determined within a first time period which is equal to or shorter than the observation period.

A method of pacing a His bundle of a patient heart using a stimulation system including a memory, a pulse generator, a stimulating electrode and at least one sensing electrode includes applying a plurality of impulses through the stimulating electrode to induce a plurality of responses from the patient heart. Each impulse of the plurality of impulses is delivered at a different impulse energy corresponding to a respective output setting of the stimulation system. The response characteristics for each of the plurality of responses are measured and each impulse is assigned a classification based on whether the respective response characteristics indicate capture of one or both of the His bundle and a ventricle of the patient heart. The output setting and classification for each impulse is then stored in the memory.

In some examples, a medical device system includes an electrode. The medical device system may include impedance measurement circuitry coupled to the electrode, the impedance measurement circuitry may be configured to generate an impedance signal indicating impedance proximate to the electrode. The medical device system may include processing circuitry that may be configured to identify a first component of the impedance signal. The first component of the impedance signal may be correlated to a cardiac event. The processing circuitry may be configured to determine that the cardiac event occurred based on the identification of the first component of the impedance signal.

Methods and systems for dynamically modifying pacing timing and backup pacing delivery in cardiac stimulation devices include applying pacing impulses, measuring corresponding responses, and, based on such responses, automatically modifying timing or operational settings of the stimulation device to improve pacing functionality. Among other things, the approaches described herein reduce unnecessary backup pacing impulses in HIS bundle pacing applications, facilitate fusion in bundle branch block applications, and automatically enable or disable backup pacing in response to achieving QRS complex correction.

Regulating cardiac activity may include pacing the patient's heart at a starting pacing rate and instigating an intrinsic heart beat search algorithm that includes pacing at a reduced rate for a period of time and capturing electrical signals representative of cardiac electrical activity while pacing at the reduced rate in order to determine a presence or absence of intrinsic heart beats. If intrinsic heart beats are not detected, the heart may be paced at a further reduced rate for a period of time. If intrinsic beats are detected, the heart may be paced again at the starting pacing rate. This may continue until intrinsic heart beats are detected or until a lower search rate limit is reached. Diagnostic data may be collected at each stage and transmitted to a display device for analysis by a physician or the like.

A computer implemented method and system for monitoring types of capture within a distributed implantable system having a leadless implantable medical device (LIMD) to be implanted entirely within a local chamber of the heart and having a subcutaneous implantable medical device (SIMD) to be located proximate the heart are provided. The method is under control of one or more processors of the SIMD configured with program instructions. The method collects far field (FF) evoked cardiac signals following the pacing pulses delivered by the LIMD for an event and analyzes the FF evoked cardiac signals to identify a type of HIS capture as loss of capture (LOC), selective capture, myocardial tissue-only (MT-only) capture, or a non-selective (NS) capture and records a label for the event based on the type of HIS capture identified.

According to various method embodiments, a person is indicated for a therapy to treat a cardiovascular disease, and the therapy is delivered to the person to treat the cardiovascular disease. Delivering the therapy includes delivering a vagal stimulation therapy (VST) to a vagus nerve of the person at a therapeutically-effective intensity for the cardiovascular disease that is below an upper boundary at which upper boundary the VST would lower an intrinsic heart rate during the VST.

In a medical device system, a computer apparatus is configured to receive body surface electrical signals from an electrode apparatus including multiple external electrodes. The computing apparatus generates electrical dyssynchrony data from the body surface electrical signals during delivery of His bundle pacing pulses and identifies effective His bundle capture based on the electrical dyssynchrony data. The computing apparatus generates an indication of His bundle capture in response to identifying the effective His bundle capture.