Abstract: An external defibrillator includes a therapy delivery circuit, a sensor, and a processor. The therapy delivery circuit is configured to be electrically charged and to deliver electrical therapy to a patient. The sensor is configured to sense a physiological condition of the patient and generate data indicative of a probability that therapy will be delivered to the patient. The processor is configured to analyze data generated by the sensor to determine whether there is a threshold level of the probability that the therapy delivery will be delivered to the patient, if the probability is at least at the threshold level, charge the therapy delivery circuit, and determine whether therapy delivery is advisable based on the physiological condition of the patient after determining whether the probability is at least at the threshold level.

Abstract: A cardiac medical device and associated method control delivery of dual chamber burst pacing pulses in response to detecting tachycardia. A number of cardiac cycles occurring in a first cardiac chamber are identified subsequent to the dual chamber pacing pulses. The number of sensed intrinsic events occurring in a second cardiac chamber during the first chamber cardiac cycles is determined as a number of second chamber events. The tachycardia episode is classified in response to the number of second chamber events.

Abstract: This disclosure is directed to techniques for treating tachyarrhythmias, such as atrial or ventricular fibrillation, in which a number of electrodes are employed to deliver electrical stimulation to a patient's heart in a manner designed to terminate the tachyarrhythmia episode.

Abstract: An apparatus comprises a cardiac signal sensing circuit, a physiologic sensor circuit configured to provide a physiologic sensor signal representative of mechanical cardiac activity, a therapy circuit, and a control circuit. The control circuit includes a cardiac depolarization detection circuit, a tachyarrhythmia detection circuit, and a timer circuit. A time interval between a mechanical cardiac event and a detected fiducial electrical cardiac event is monitored. The control circuit is configured to correct the monitored time interval for variation with heart rate to form a corrected electromechanical time interval, initiate anti-tachyarrhythmia therapy when the corrected electromechanical time interval satisfies a specified time interval threshold value during a detected episode of tachyarrhythmia, and withhold anti-tachyarrhythmia therapy otherwise.

Abstract: A method for identifying oversensing in implantable medical devices (IMDs), such as implantable cardioverter defibrillators (ICDs), is described. A near-field electrogram signal and a far-field electrogram signal are obtained via a near-field electrode pair and a far-field electrode pair. The near-field electrogram signal is compared to the far-field electrogram signal and a determination of whether oversensing exists is made based on the comparison. In some instances, a scheduled therapy is withheld in response to determining that oversensing exists.

Abstract: Methods, systems and devices efficiently identify cardiac resynchronization therapy (CRT) pacing parameter set(s) that provide improved hemodynamic response relative to an initial CRT pacing parameter set, wherein each CRT pacing parameter set includes at least two CRT pacing parameters. User input(s) are accepted that specify a maximum amount of time and/or parameter sets that can be used to perform testing, and specify relative importance of parameters within the sets. Based on the accepted user input(s), there is a determination of how many different variations of each of the CRT pacing parameters can be tested, and based on this determination different CRT pacing parameter sets are selected and tested to obtain a hemodynamic response measure corresponding to each of the different sets tested. Additionally, one or more of the tested CRT pacing parameter sets, if any, that provide improved hemodynamic response relative to the initial CRT pacing parameter set is/are identified.

Abstract: Certain cardiac arrhythmias can be prevented by appropriate electrical stimulation of autonomic nerves innervating the heart. An implantable cardiac rhythm management device is configured to deliver such stimulation when an autonomic imbalance is predicted to be present via an endovascular electrode. Autonomic imbalance may be predicted to be present based upon circadian rhythms, detected heart rates, or detected heart rate variability.

Abstract: Various system embodiments comprise circuitry to determine when an arrhythmia has terminated, and a neural stimulator adapted to temporarily deliver neural stimulation therapy to assist with recovering from the arrhythmia in response to termination of the arrhythmia.

Abstract: Electrical crosstalk between two implantable medical devices or two different therapy modules of a common implantable medical device may be evaluated, and, in some examples, mitigated. In some examples, one of the implantable medical devices or therapy modules delivers electrical stimulation to a nonmyocardial tissue site or a nonvascular cardiac tissue site, and the other implantable medical device or therapy module delivers cardiac rhythm management therapy to a heart of the patient.

Abstract: An implantable medical device, IMD, comprises atrial and ventricular sensing units for sensing atrial or ventricular electric events. The IMD also comprises atrial and ventricular pulse generators for generating atrial or ventricular pacing pulses. A controller controls the operation of the IMD (100) according to a first mode, in which the ventricular pulse generator is prevented from generating a back-up pulse if an evoked response detector fails to detect evoked response to a delivered ventricular pacing pulse, and a second mode, in which the ventricular pulse generator is controlled to generate a back-up pulse if no evoked response is detected following delivery of a ventricular stimulating pulse. The controller switches operation from the first mode to the second mode based on the evoked response detector failing to detect an evoked response to a delivered ventricular pacing pulse.

Abstract: An implantable medical device is provided for detecting transportless ventricular rhythm of a heart lacking atrial transport and comprises a housing, sensors configured to be located proximate to a heart, a sensing module to sense cardiac signals representative of a rhythm originating from the heart and a rhythm detection module. The rhythm detection module determines a change in AV association and identifies a potential ventricular complex with loss of atrial transport (VCLAT) based on the change in AV association.

Abstract: The technology disclosed herein relates to a method for lead analysis for an implanted medical device. A summary data record is retrieved associated with one or more episodes from an implanted medical device through a communication module. Episode selection criteria are applied to the summary data record by a processing module. One or more episode data records are retrieved from the implanted medical device for one or more episodes for which the episode selection criteria was satisfied. Noise detection criteria are applied to the episode data record.

Abstract: Tachyarrhythmia is treated by applying anti-tachycardia pacing through at least one multi-site electrode set located on, in or around the heart. The electrode set is arranged and located such that an electrical activation pattern having a wave-front between substantially flat and concave is generated through a reentrant circuit associated with the tachyarrhythmia. The electrode set may be one of a plurality of predefined, multi-site electrode sets located on, in or around the atria. Alternatively, the electrode set may be formed using at least two selectable electrodes located on, in or around the atria.

Abstract: Techniques for morphologic discrimination between beats of a tachyarrhythmia episode are described for selecting delivery of appropriate therapy. An exemplary method comprises nonordered binning of digitized amplitude values of signals associated with cardiac depolarizations. Monomorphic VT is discriminated from polymorphic VT without signal alignment. One exemplary method involves sensing electrical signals associated with depolarizations of a patient's heart during a tachyarrhythmia episode. The sensed electrical signals are converted to digital values and stored. The stored digital values are normalized and binned. At most, 5 pairs of beats or depolarizations are compared for morphologic similarity by determining the similarity between the binned values associated with each pair. The result of the comparison is used to select and deliver therapy to the patient.

Abstract: The disclosure describes techniques for delivering vagal stimulation to decrease the ventricular rate response during an atrial tachyarrhythmia, such as atrial fibrillation. Decreasing the ventricular rate response during an atrial tachyarrhythmia may facilitate increased ventricular pacing for cardiac resynchronization therapy (CRT), and may also reduce the likelihood of inappropriately detecting a ventricular tachyarrhythmia during the atrial tachyarrhythmia. Furthermore, the vagal stimulation may augment vagal tone, which may facilitate long term left ventricular reverse remodeling and decrease atrial and ventricular arrhythmic burden in heart failure patients. An example system that delivers CRT comprises a processor that detects an atrial tachyarrhythmia in one or more atria of the heart, and monitors at least one of a ventricular rate or degree of ventricular pacing subsequent to the detected atrial arrhythmia.

Abstract: Embodiments of the invention provide methods for the detection and treatment of atrial fibrillation (AF) and related conditions. One embodiment provides a method comprising measuring electrical activity of the heart using electrodes arranged on the heart surface to define an area for detecting aberrant electrical activity (AEA) and then using the measured electrical activity (MEA) to detect foci of AEA causing AF. A pacing signal may then be sent to the foci to prevent AF onset. Atrial wall motion characteristics (WMC) may be sensed using an accelerometer placed on the heart and used with MEA to detect AF. The WMC may be used to monitor effectiveness of the pacing signal in preventing AF and/or returning the heart to normal sinus rhythm (NSR). Also, upon AF detection, a cardioversion signal may be sent to the atria using the electrodes to depolorize an atrial area causing AF and return the heart to NSR.

Abstract: An implantable neurostimulator-implemented method for managing tachyarrhythmias through vagus nerve stimulation is provided. An implantable neurostimulator, including a pulse generator, is configured to deliver electrical therapeutic stimulation in a manner that results in creation and propagation (in both afferent and efferent directions) of action potentials within neuronal fibers of a patient's cervical vagus nerve. Operating modes of the pulse generator are stored. A maintenance dose of the electrical therapeutic stimulation is delivered to the vagus nerve via the pulse generator to restore cardiac autonomic balance through continuously-cycling, intermittent and periodic electrical pulses. A restorative dose of the electrical therapeutic stimulation is delivered to prevent initiation of or disrupt tachyarrhythmia through periodic electrical pulses delivered at higher intensity than the maintenance dose.

Abstract: An implantable neurostimulator-implemented method for enhancing post-exercise recovery through vagus nerve stimulation is provided. An implantable neurostimulator, including a pulse generator configured to deliver electrical therapeutic stimulation in a manner that results in creation and propagation (in both afferent and efferent directions) of action potentials within neuronal fibers including a patient's cervical vagus nerve. An operating mode is stored in the pulse generator. An enhanced dose of the electrical therapeutic stimulation is parametrically defined and tuned to prevent or disrupt tachyarrhythmia through continuously-cycling, intermittent and periodic electrical pulses. The patient's physiological state is monitored during physical exercise via at least one sensor included in the implantable neurostimulator, and upon sensing a condition indicative of cessation of the physical exercise, the enhanced dose is delivered for a period of time the enhanced dose to the vagus nerve.

Abstract: A cardiac rhythm management (CRM) system delivers anti-tachyarrhythmia therapies and uses patient-specific and/or tachyarrhythmia event-specific information to automatically set and adjust one or more arrhythmia detection durations. In one embodiment, the CRM system initializes and updates the one or more arrhythmia detection durations using patient-specific information such as medical history and recent medical trends. In another embodiment, the CRM dynamically adjusts the one or more arrhythmia detection durations using the patient's hemodynamic performance. One example of such an arrhythmia detection duration is a sustained rate duration (SRD) that starts when a tachyarrhythmia such as a supraventricular tachyarrhythmia is detected. An anti-tachyarrhythmia therapy is delivered only if the tachyarrhythmia sustains throughout the SRD.

Abstract: The disclosure herein relates generally to methods for treating heart conditions using vagal stimulation, and further to systems and devices for performing such treatment. Such methods may include monitoring physiological parameters of a patient, detecting cardiac conditions, and delivering vagal stimulation (e.g., electrical stimulation to the vagus nerve or neurons having parasympathetic function) to the patient to treat the detected cardiac conditions.

Abstract: Exemplary methods and apparatuses are disclosed that provide for determination of an atrio-ventricular delay on a beat-to-beat basis by determining a P-wave duration from electric signals corresponding to electric potentials in a heart, and determining the atrio-ventricular delay on a beat-to-beat basis such that the atrio-ventricular delay for an individual heart cycle depends on the P-wave duration of a same or an immediately preceding heart cycle.

Abstract: A cardiac medical device and associated method control delivery of dual chamber burst pacing pulses in response to detecting tachycardia. In one embodiment, a single chamber pacing pulse is delivered in response to detecting a tachycardia. Dual chamber pacing pulses are delivered subsequent to the single chamber pacing pulse. An intrinsic depolarization is sensed subsequent to delivering the dual chamber pacing pulses. The tachycardia episode is classified in response to the sensed intrinsic depolarization.

Abstract: The disclosure herein relates generally to methods for treating heart conditions using vagal stimulation, and further to systems and devices for performing such treatment. Such methods may include monitoring physiological parameters of a patient, detecting cardiac conditions, and delivering vagal stimulation (e.g., electrical stimulation to the vagus nerve or neurons having parasympathetic function) to the patient to treat the detected cardiac conditions.

Abstract: A medical device performs a method for computing an estimate of a physiological variable. The method includes sensing a physiological signal and measuring an event of the physiological signal. The device initializes a value of a long-term metric of the event measurement, wherein the long-term metric corresponds to a time interval correlated to a response time of the physiological variable to changes in the event. The estimate of the long-term metric is updated in a memory of the medical device using a previous long-term metric and a current measurement of the event. The device detects a need for computing the physiological variable and computes an estimate of the physiological variable using the updated long-term metric.

Abstract: A cardiac rhythm management (CRM) system includes an implantable medical device that delivers anti-tachyarrhythmia therapies including anti-tachyarrhythmia pacing (ATP) and a hemodynamic sensor that senses a hemodynamic signal. The implantable medical device includes a hemodynamic sensor-controlled closed-loop ATP system that uses the hemodynamic signal for ATP capture verification. When ATP pulses are delivered according to a selected ATP protocol to terminate a tachyarrhythmia episode, the implantable medical device performs the ATP capture verification by detecting an effective cardiac contraction from the hemodynamic signal. The ATP protocol is adjusted using an outcome of the ATP capture verification.

Abstract: Techniques are described for use with an implantable cardiac stimulation device for performing paired/coupled pacing either alone or in conjunction with dynamic overdrive/underdrive pacing. In one technique, dynamic overdrive/underdrive pacing is delivered to the ventricles using paired pulses during an episode of atrial fibrillation. The use of paired pulses during dynamic ventricular overdrive/underdrive pacing helps lower and stabilize the ventricular rate to thereby reduce the risk of a ventricular arrhythmia. In another technique, the inter-pulse interval between paired pulses is optimized to lengthen the resulting refractory period to improve hemodynamics. Preferably, the optimized inter-pulse interval is used when applying dynamic ventricular overdrive/underdrive pacing with paired pulses so that the benefits of both techniques are obtained. The optimization technique is also applicable to setting the coupling interval for use with coupled pacing.

Abstract: A method and device for delivering anti-tachycardia pacing (ATP) therapy that includes an electrode to sense cardiac signals and to deliver the therapy, sensing circuitry, electrically coupled to the electrode, to detect the tachycardia event in response to the sensed cardiac signals, and a processor to control delivery of the therapy.

Abstract: An implantable medical device (IMD) and methods of operating the same to treat a tachyarrhythmia are disclosed herein. In accordance with this method, an arrhythmia of the heart is classified based on one or more supraventricular tachycardia (SVT) rejection rules, which differentiate between a first group of heart rhythms that do not require treatment and a second group of heart rhythms that possibly require treatment. Diagnostic/therapeutic pacing can then be performed to further discriminate the second group of heart rhythms as being within a first sub-group of heart rhythms and a second sub-group of heart rhythms which are to be treated by applying a ventricular tachycardia (VT)/ventricular fibrillation (VF) therapy sequence. In another implementation, the order in which the IMD performs diagnostic/therapeutic pacing and analyzes passive detection and classification criteria can be reversed.

Abstract: For terminating a high frequency arrhythmic electric state of a biological tissue an electric signal representative of the present electric state of the biological tissue is obtained. From the electric signal a dominant frequency of the present electric state is determined, and from the dominant frequency it is determined whether the present electric state of the biological tissue is a high frequency arrhythmic electric state. Further, a dominance level indicative of how dominant the dominant frequency is in the high frequency arrhythmic electric state is determined from the electric signal. Depending on the at least one dominant frequency, at least one series of electric pulses at intervals is generated. The electric pulses are applied to the biological tissue starting at a point in time at which the dominance level exceeds a predefined threshold value for the biological tissue being in a determined high frequency arrhythmic electric state.

Abstract: Approaches for determining threshold values for one or more arrhythmia rate zones and/or the number of rate zones are described. A probability function for heart rate is determined using collected and measured heart rate values. One or more heart rate probability values are selected. Thresholds for arrhythmia rate zones are determined from the probability function based on the selected probability values. Determining the rate zone thresholds may involve determining a threshold for a lower rate limit and/or determining one or more tachyarrhythmia rate zone thresholds. The number of rate zones may also be determined based on the probability function.

Abstract: An implantable medical device (IMD) having a therapy circuit for delivering atrial pacing and a control circuit for detecting a return to sinus rhythm. The control circuit determines the duration of an atrial arrhythmia preceding the return to sinus rhythm, and controls the therapy circuit to deliver transient atrial pacing based on the atrial arrhythmia duration.

Abstract: An implantable medical device uses an implantable sensor for acquiring a physiological signal that is received by a digital signal processor. The digital signal processor is a multi-channel signal processor including a first signal processing channel having a first sensitivity for sensing the physiological signal and a second signal processing channel having a second sensitivity different than the first sensitivity for sensing the physiological signal.

Abstract: An exemplary method includes delivering a cardiac pacing therapy using an electrode configuration for left ventricular, single site pacing or left ventricular, multi-site pacing, measuring a series of interventricular conduction delays using the left ventricular pacing and right ventricular sensing (IVCD-LR), comparing the interventricular conduction delay values to a limit and, based on the comparison, deciding whether to change the electrode configuration for the left ventricular pacing. Other exemplary methods, devices, systems, etc., are also disclosed.

Abstract: Methods and systems for identifying tachyarrhythmia episode types and delivering therapy to mitigate the identified tachyarrhythmia episode types are described. Electrogram signals of cardiac activity are sensed and stored by an implantable cardiac device. Tachyarrhythmia episodes are detected and tachyarrhythmia episode types are identified based on characteristics of the electrogram signals. In preparation for performing ablation, a tachyarrhythmia episode is induced. The features of the induced tachyarrhythmia episode are compared to characteristics of the identified episode types. A similarity between the induced tachyarrhythmia episode and at least one of the episode types identified from the stored electrogram signals is indicated to facilitate performing the ablation.

Abstract: An implantable medical device (IMD) identifies suspected non-lethal ventricular arrhythmia, and takes one or more actions in response to the identification to avoid or delay delivery of a defibrillation or cardioversion shock. The IMD employs number of intervals to detect (NID) thresholds for detection of ventricular arrhythmias. When a NID threshold is met, the IMD determines whether the ventricular rhythm is a suspected non-lethal rhythm despite satisfying a NID threshold. In some embodiments, the IMD increases the NID threshold, i.e., extends the time for detection, in response to identifying a rhythm as a suspected non-lethal rhythm, and monitors subsequent ventricular beats to determine if the increased NID threshold is met before detecting a ventricular arrhythmia and delivering therapy. The IMD can determine whether a rhythm is a suspected non-lethal arrhythmia by, for example, comparing the median ventricular cycle length (VCL) to the median atrial cycle length (ACL).

Abstract: A method for mapping abnormal electrical activity, including obtaining electrical signal data from respective locations in a heart of a living subject, and automatically analyzing the signal data to identify complex fractionated electrograms (CFEs) therein. The method further includes analyzing the CFEs so as to identify reentry locations comprised in the respective locations, and displaying information derived from the identification in relation to a map of the heart.

Abstract: A device for detecting cardiac ischemia is disclosed. The device includes a processor that is configured to distinguish between two different heart beats types such as left bundle branch block beats and normal sinus beats. The processor applies different ischemia tests to the two different beat types, and generates alert when it detects ischemia.

Abstract: The present invention, in illustrative embodiments, includes devices for analyzing cardiac signals in an implantable cardiac stimulus system. Within the analysis, a threshold may be defined related to a cardiac event rate. If the cardiac event rate does not exceed the threshold, filtering of captured cardiac signals occurs, including attenuating T-waves. If the cardiac event rate does exceed the threshold, circuitry for analog filtering or programming for digital filtering is bypassed to avoid attenuating low frequency components of the captured cardiac signals.

Abstract: Techniques for determining whether a lead related condition exists based on analysis of a cardiac electrical signal associated with a non-sustained tachyarrhythmia (NST) are described. In some examples, the techniques include determining the duration of intervals between consecutive cardiac events, e.g., R-R intervals, during an NST. The techniques may further include determining one or more metrics based on the durations of the intervals during the NST. Examples of metrics include an average, a minimum, a maximum, a range, a median, a mode, or a mean. A lead related condition is identified based on the values of the one or more metrics, e.g., by comparison to respective thresholds. In some examples, an alert is provided or a therapy modification is suggested if a lead related condition is identified.

Abstract: A neuromodulation system for treating acute heart failure syndromes includes a first catheter having a parasympathetic therapy element adapted for positioning within a first blood vessel such as a superior vena cava, and a second catheter sympathetic therapy element adapted for positioning with a second, different, blood vessel such as the pulmonary artery. The catheters comprise a system in which one of catheters is slidably disposed over the other of the catheters. The system may further be slidably disposed over a third elongate element such as a Swan-Ganz catheter positionable within a pulmonary artery, such that the Swan-Ganz may be used for monitoring parameters such as blood pressure and cardiac output during neuromodulation therapy.

Abstract: An implantable medical device includes a mechanical activity sensor configured to sense movements produced by contractions of a ventricular cavity and output a mechanical activity signal representative of the contractions. The implantable medical device also includes one or more circuits configured to detect a plurality of spontaneous ventricular depolarizations based on electrical potentials representative of the spontaneous ventricular depolarizations, calculate an escape interval, and provide an antibradycardia ventricular pacing therapy in an absence of a detected spontaneous ventricular event after the escape interval.

Abstract: To shorten the length of a lead, alleviate physical burden on a patient in installation of a device into a body, and miniaturize the device while allowing both treatment based on cardiac stimulation and nerve stimulation.

Abstract: An embodiment of the invention provides an apparatus for the detection and treatment of atrial arrhythmia comprising an electrical lead having proximal and distal portions. The distal portion is positionable in an atrial chamber and the end of the proximal portion is configured to be coupled to a pacemaker. The lead comprises a plurality of conductive wires clad with an insulative coating and has sufficient flexibility to be positioned in the atria from a percutaneous introductory site. The conductive wires are coupled to a plurality of pairs of bipolar electrodes positioned on a membrane attachable to an endocardial wall. The electrode pairs are distributed in a pattern defining an area for detecting a location of a foci of aberrant electrical activity located within or adjacent the area and sending a pacing signal to that location to prevent or stop an occurrence of atrial fibrillation caused by that foci.

Abstract: A pacing device and method for operating same is disclosed in which the point of origin of an arrhythmia is estimated in order to more provide more effective treatment. The origin of an arrhythmia may be estimated by analyzing the timing of electrical events as detected at different electrode sites and/or using different sensing vectors. Anti-tachycardia pacing (ATP) may then be delivered to the most appropriate location.

Abstract: A system, method, or device classifies an arrhythmia according to the temporal order in which a depolarization wave associated with a particular heart contraction is received at a plurality of electrodes. One or more antiarrhythmia therapies is mapped to each arrhythmia classification. When a particularly classified arrhythmia is detected, the correspondingly mapped therapy list is selected and an appropriate antiarrhythmia therapy delivered. In one example, the particular therapy delivered in response to an arrhythmia depends at least in part on its historical success in treating arrhythmias of that classification.

Abstract: A method for extinguishing a cardiac arrhythmia utilizes destructive interference of the passing of the reentry wave tip of an anatomical reentry through a depolarized region created by a relatively low voltage electric field in such a way as to effectively unpin the anatomical reentry. Preferably, the relatively low voltage electric field is defined by at least one unpinning shock(s) that are lower than an expected lower limit of vulnerability as established, for example, by a defibrillation threshold test. By understanding the physics of the electric field distribution between cardiac cells, the method permits the delivery of an electric field sufficient to unpin the core of the anatomical reentry, whether the precise or estimated location of the reentry is known or unknown and without the risk of inducting ventricular fibrillation. A number of embodiments for performing the method are disclosed.

Abstract: An implantable medical device operates to promote intrinsic ventricular depolarization according to a pacing protocol. When a cardiac rate exceeds a predetermined threshold, the implantable medical device modifies the pacing protocol parameters to promote AV synchrony.

Abstract: A computer-implemented system and method for selecting therapy profiles of electrical stimulation of cervical vagus nerves for treatment of chronic cardiac dysfunction is provided. An external programmer includes a plurality of therapy profiles stored in memory. The therapy profiles include different sets of stimulation parameters that cooperatively define alternating cycles of stimuli application and stimuli inhibition for a neurostimulator that are tuned to both efferently activate the heart's intrinsic nervous system and afferently activate the patient's central reflexes. A programming wand is configured to provide the set of stimulation parameters chosen by the user to the neurostimulator through wireless telemetry. Finally, an implantable neurostimulator device includes a stimulation therapy lead terminated by helical electrodes and electrically coupled to the neurostimulator.

Abstract: Apparatus and methods are described including identifying a subject as suffering from a condition selected from the group consisting of congestive heart failure, diastolic heart failure, acute myocardial infarction, and hypertension. In response to the identifying, an electrode is placed on the subject's aorta at an aortic site that is between a bifurcation of the aorta with the subject's left subclavian artery and a bifurcation of the aorta with the subject's fifth intercostal artery. The subject is treated by electrically stimulating the aortic site by driving a current into the aortic site, via the electrode. Other applications are also described.

Abstract: An implantable medical device delivers anti-tachyarrhythmia therapies including anti-tachycardia pacing (ATP). If a detected tachyarrhythmia is classified as a type suitable for treatment using ATP, the implantable medical device selects one of an atrial ATP (A-ATP) mode, a ventricular ATP (V-ATP) mode, and a concurrent atrio-ventricular ATP (concurrent AV-ATP) mode according to the characteristics of the detected tachyarrhythmia. The concurrent ATP mode is an ATP mode during which the atrial pacing pulses and the ventricular pacing pulses are delivered concurrently. In one embodiment, the concurrent AV-ATP mode includes a synchronized atrio-ventricular ATP (synchronized AV-ATP) mode during which atrial and ventricular pacing pulses are delivered synchronously and an independent atrio-ventricular ATP (independent AV-ATP) mode during which atrial and ventricular pacing pulses are delivered concurrently but timed independently.