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.

A leadless pacing device may include a housing having a proximal end and a distal end, and one or more electrodes supported by the housing. The housing may include a body portion and a header. A distal extension may extend distally from the header of the housing, the distal extension including one or more electrodes. The header may include a guide wire port and a guide wire lumen may extend from the guide wire port through the header of the housing and through the distal extension. A fixation member may extend from the header of the housing. The header may be formed from an over mold process.

Semi-autonomous vehicle apparatus which is controlled by a plurality of control sources includes a vehicle which may function autonomously and apparatus for control of the vehicle by either an onboard driver or a driver not situated onboard. The vehicle may also be controlled by an off-vehicle computational device. Hierarchy setting apparatus determines which one or combination of the possible control entities take priority. Persons using the apparatus are identified by either a password or, preferably by providing identification based on a biologic feature. Management of impaired vehicle operators is provided for.

A ventricularly implantable medical device that includes a sensing module that is configured to detect an atrial fiducial and identify an atrial contraction based at least on part on the detected atrial fiducial. Control circuitry in the implantable medical device is configured to deliver a ventricular pacing therapy to a patient's heart based at least in part on the identified atrial contraction, and can automatically switch or revert the ventricular pacing therapies on the fly.

Devices and methods are described herein for treating cardiac conditions using electrical stimulation delivered to and sensing nerve activity from one or both of the AV node and nerve tissue innervating the AV node using one or more neural electrodes positioned in a location within the triangle of Koch of the right atrium.

A medical device is configured to determine time intervals between consecutive cardiac events sensed from a cardiac electrical signal, increase a value of a tachyarrhythmia interval count in response to each of the determine time intervals detected as a tachyarrhythmia interval. The device is further configured to detect normal sinus rhythm events and the decrease the value of the tachyarrhythmia interval count in response to a threshold number of detected normal sinus rhythm events.

An implantable medical device has a therapy module configured to generate a composite pacing pulse including a series of at least two individual pulses. The therapy module is configured to generate the composite pacing pulse by generating a first pulse of the at least two individual pulses by selectively coupling a first portion of a plurality of capacitors to an output signal line and generate a second pulse of the at least two individual pulses by selectively coupling a second portion of the plurality of capacitors to the output signal line.

An implantable medical device system capable of sensing cardiac electrical signals includes a sensing circuit, a therapy delivery circuit and a control circuit. The sensing circuit is configured to receive a cardiac electrical signal and sense a cardiac event in response to the signal crossing a cardiac event sensing threshold. The therapy delivery circuit is configured to deliver an electrical stimulation therapy to a patient's heart via the electrodes coupled to the implantable medical device. The control circuit is configured to control the sensing circuit to set a starting value of the cardiac event sensing threshold and hold the starting value constant for a sense delay interval. The control circuit is further configured to detect an arrhythmia based on cardiac events sensed by the sensing circuit and control the therapy delivery circuit to deliver the electrical stimulation therapy in response to detecting the arrhythmia.

A pacemaker has a housing and a therapy delivery circuit enclosed by the housing for generating pacing pulses for delivery to a patient's heart. An electrically insulative distal member is coupled directly to the housing and at least one non-tissue piercing cathode electrode is coupled directly to the insulative distal member. A tissue piercing electrode extends away from the housing.

An implantable device includes a memory and a processor coupled to the memory and configured to perform actions, including: receiving electrical signals from tissue of a patient; and in response to each of a plurality of triggers, storing a portion of the received electrical signals, occurring after the trigger and extending for a limited duration, in the memory on a first-in-first-out basis. Another an implantable device includes a memory; and a processor coupled to the memory and configured to perform actions, including: receiving electrical signals from tissue of a patient; and in response to each of a plurality of triggers, determining at least one feature of the received electrical signals; and storing the at least one feature in the memory on a first-in-first-out basis.