Abstract: Systems and methods involve an intrathoracic cardiac stimulation device operable to provide autonomous cardiac sensing and energy delivery. The cardiac stimulation device includes a housing configured for intrathoracic placement relative to a patient's heart. A fixation arrangement of the housing is configured to affix the housing at an implant location within cardiac tissue or cardiac vasculature. An electrode arrangement supported by the housing is configured to sense cardiac activity and deliver stimulation energy to the cardiac tissue or cardiac vasculature. Energy delivery circuitry in the housing is coupled to the electrode arrangement. Detection circuitry is provided in the housing and coupled to the electrode arrangement. Communications circuitry may optionally be supported by the housing. A controller in the housing coordinates delivery of energy to the cardiac tissue or cardiac vasculature in accordance with an energy delivery protocol appropriate for the implant location.

Abstract: A new pacemaker apparatus for treating the physiological electric conduction of the heart that includes a conduction abnormality in a ventricle. The pacemaker includes a pulse generator and a pacing electrode located in the heart, the pulse generator providing pacing signals to the pacing electrode. The pacemaker further includes a signal generation circuit that generates electrical signals from heart-related feedback signals that indicate that the pacing electrode is delivering the pacing signals in a region at or near the His bundle of the heart. The combination of the pulse generator and the signal generation circuit indicates that the pacing electrode is delivering the pacing signals in the region, at or near the His bundle of the heart, to electrically bypass the conduction abnormality of the heart in the ventricle.

Abstract: Tools and methods are particularly suited for certain cardiac conditions involving use of a catheter for pacing of the right and left ventricles from a lead in the right ventricle, e.g., to facilitate mechanically and/or electrically synchronous contractions for resynchronization. Certain aspects involve pacing and/or mapping by generating pulses for delivery to a cardiac site useful for improving heart function as measured, e.g., by QRS width, fractionation, late LV activation timing, mechanical synchronicity of free wall and septal wall, effective throughput/pressure, or a combination thereof. In one embodiment, an implantable pulse generator includes circuitry for generating pacing profiles, with signals of opposite polarities, specifically selected for delivery on electrodes at a site near the septal wall of a right ventricle of the heart.

Abstract: Pacing post-conditioning (PPC) therapy is applied to a patient to minimize ischemic injury associated with MI and/or reperfusion injury associated with a post-MI revascularization procedure. In various embodiments, a PPC therapy is delivered by executing a pacing protocol with pacing parameters determined and dynamically adjusted based on patient-specific factors to ensure efficacy and safety of the patient.

Abstract: Cardiac pacemakers and methods of pacing a heart are disclosed.

Abstract: A method and medical device for delivering an atrial pacing pulse to an atrial chamber to generate an evoked atrial depolarization, delivering a stimulation pulse to an atrioventricular node during a stimulation window to increase a PR interval of the heart, the stimulation window having a start time corresponding to the delivered atrial pacing pulse so that the stimulation pulse is delivered during a refractory period corresponding to the evoked atrial depolarization, and delivering a ventricular pacing pulse to a first ventricular chamber during the increased PR interval to cause a contraction of the first ventricular chamber to occur prior to a contraction of a second ventricular chamber to increase dyssynchrony between the contraction of the first ventricular chamber and the contraction of the second ventricular chamber.

Abstract: An aspect of the present subject relates to an implantable medical system. An embodiment of the system includes a baroreflex stimulator, a myocardial infarction detector, and a controller. The baroreflex stimulator applies a baroreflex stimulation signal through an electrode. The myocardial infarction detector detects an event indicative of myocardial infarction, The controller is connected to the baroreflex stimulator and to the myocardial infarction detector, and is adapted to apply a baroreflex therapy in response to a detected event indicative of myocardial infarction. Other aspects are provided herein.

Abstract: Techniques may automatically disable an exposure mode that was enabled for operation in the presence of a disruptive energy field. For example, an implantable medical device (IMD) automatically disables the exposure operating mode when (i) the amount of time that has elapsed since enabling the IMD exceeds a threshold amount of time and (ii) a disruptive energy field is detected before the amount of time exceeds the threshold amount of time and the disruptive energy field is not currently detected. When either of these conditions is not met, the IMD continues to operate in accordance with the exposure operating mode.

Abstract: An ECG analysis system is responsive to patient ECG data for performing an analysis of the ECG data to determine whether acute MI is present. The system first analyzes the ECG data by standard ECG analysis to determine whether acute MI is present. This analysis is followed in a first mode of operation by ACI-TIPI analysis to estimate the probability of acute MI from patient characteristics and the ECG data. In a second mode, when the standard ECG analysis is definitive as to the presence of acute MI the ACI-TIPI analysis is not run and the user is presented with only the results of the standard interpretation. If the standard ECG analysis is indeterminate as to the presence of acute MI, then the ACI-TIPI analysis is run and the results of the ACI-TIPI analysis are presented to the user.

Abstract: Cardioprotective pre-excitation pacing may be applied to stress or de-stress a particular myocardial region delivering of pacing pulses in a manner that causes a dyssynchronous contraction. Such dyssynchronous contractions are responsible for the desired cardioprotective effects of pre-excitation pacing but may also be hazardous. Described herein is a method and system that uses measures of a patient's heart rate or exertion level to control the duty cycles of intermittent pre-excitation pacing.

Abstract: An apparatus comprises a cardiac signal sensing circuit configured to sense an electrical cardiac signal from at least one of an atrium or ventricle of a heart of a subject, a therapy circuit configured to provide electrical pacing therapy and electrical neural stimulation therapy to the subject, and a control circuit. The control circuit is configured to initiate delivery of the electrical pacing therapy, initiate a blanking period in a time relationship to the delivery of electrical pacing therapy, and initiate delivery of the electrical neural stimulation therapy to the subject during the blanking period. At least one sense amplifier of the cardiac signal sensing circuit is disabled during the blanking period.

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 ventricularly paced beats and supraventricular beats. The processor collects separate reference data for each beat type indicative of the normal values of a cardiac feature associated with these beat types. The processor performs an ischemia test by separately comparing present values of the cardiac feature for each beat type with the reference values for the corresponding beat type.

Abstract: Improving cardiac response in terms of pressure, ejected volume, and filling and ejection times by cardiac reverse remodelling, including temporary, occasionally harmful stimulation sequences. An original pacing configuration (a) is switched to a modified pacing configuration (b) in a direction opposite to that of an optimization of the hemodynamic parameters, to cause an immediate change in the response to controlled stimulation of the myocardium. This response is assessed based on: the maximum value (P (b, a)) achieved by the peak-to-peak (PEA (i)) of the first peak of endocardial acceleration (PEA) after a pacing configuration change, the mean PEA value (A (b, a)) after stabilization, the PEA variability (V (b, a)) around this average value, and the duration (T (b, a)) of stabilization after the pacing configuration change.

Abstract: Methods, devices, kits and compositions to treat a myocardial infarction. In one embodiment, the method includes the prevention of remodeling of the infarct zone of the ventricle using a combination of therapies. The method may include the introduction of structurally reinforcing agents. In other embodiments, agents may be introduced into a ventricle to increase compliance of the ventricle. The prevention of remodeling may include the prevention of thinning of the ventricular infarct zone. Another embodiment includes the reversing or prevention of ventricular remodeling with electro-stimulatory therapy. The unloading of the stressed myocardium over time effects reversal of undesirable ventricular remodeling. These therapies may be combined with structurally reinforcing therapies. In other embodiments, the structurally reinforcing component may be accompanied by other therapeutic agents. These agents may include but are not limited to pro-fibroblastic and angiogenic agents.

Abstract: A cardiac pacing system comprising one or more leadless cardiac pacemakers configured for implantation in electrical contact with a cardiac chamber and configured to perform cardiac pacing functions in combination with a co-implanted implantable cardioverter-defibrillator (ICD). The leadless cardiac pacemaker comprises at least two leadless electrodes configured for delivering cardiac pacing pulses, sensing evoked and/or natural cardiac electrical signals, and bidirectionally communicating with the co-implanted ICD.

Abstract: In general, the disclosure describes techniques for detecting lead related conditions, such as lead fractures or other lead integrity issues. As described herein, delivering an electrical signal through selected electrodes may result in, reveal, or amplify noise if a lead related condition is present. A processor may detect electrical noise indicative of the lead related condition subsequent to the delivery of the electrical signal, and identify a lead related condition in response to detecting the noise.

Abstract: A leadless intra-cardiac medical device (LIMD) includes a housing configured to be implanted entirely within a single local chamber of the heart.

Abstract: A method for allowing cardiac signals to be sensed and pacing pulse vectors to be delivered between two or more electrodes. In one embodiment, cardiac signals are sensed and pacing pulse vectors are delivered between at least one of a first left ventricular electrode and a second left ventricular electrode. Alternatively, cardiac signals are sensed and pacing pulse vectors are delivered between different combinations of the first and second left ventricular electrodes and a first supraventricular electrode. In addition, cardiac signals are sensed and pacing pulse vectors are delivered between different combinations of the first and second left ventricular electrode, the first supraventricular electrode and a conductive housing. In an additional embodiment, a first right ventricular electrode is used to sense cardiac signals and provide pacing pulses with different combinations of the first and second left ventricular electrodes, the first supraventricular electrode and the housing.

Abstract: An implantable electroacupuncture device (IEAD) treats heart failure, coronary artery disease, myocardial ischemia or angina through application of stimulation pulses applied at acupoints GV20 and/or EXHN3. The IEAD comprises an implantable, coin-sized, self-contained, leadless electroacupuncture device having at least two electrodes attached to an outside surface of its housing. The device generates stimulation pulses in accordance with a specified stimulation regimen. Power management circuitry within the device allows a primary battery, having a high internal impedance, to be used to power the device. The stimulation regimen generates stimulation pulses during a stimulation session of duration T3 minutes applied every T4 minutes. The duty cycle, or ratio of T3/T4, is very low, no greater than 0.05. The low duty cycle and careful power management allow the IEAD to perform its intended function for several years.

Abstract: An RF protection circuit mitigates potentially adverse effects that may otherwise result from electromagnetic interference (e.g., due to MRI scanning of a patient having an implanted medical device). The RF protection circuit may comprise a voltage divider that is deployed across a pair of cardiac electrodes that are coupled to internal circuitry of the implantable medical device. Each leg of the voltage divider may be referenced to a ground of the internal circuit, whereby the different legs are deployed in parallel across different circuits of the internal circuitry. In this way, when an EMI-induced (e.g., MRI-induced) signal appears across the cardiac electrodes, the voltages appearing across these circuits and the currents flowing through these circuits may be reduced. The RF protection circuit may be used in an implantable medical device that employs a relatively low capacitance feedthrough to reduce EMI-induced (e.g., MRI-induced) current flow in a cardiac lead.

Abstract: Methods and devices are disclosed for employing mechanical measurements to synchronize contractions of ventricular wall locations. Accelerometers that may be placed within electrode leads are positioned at ventricular wall locations, such as the left ventricle free wall, right ventricle free wall, and the anterior wall/septum wall. The accelerometers produce signals in response to the motion of the ventricular wall locations. A processor may then compare the signals to determine a difference in the synchronization of the ventricular wall location contractions. The difference in synchronization can be determined in various ways such as computing a phase difference and/or amplitude difference between the accelerometer signals. One or more stimulation pulses may be provided per cardiac cycle to resynchronize the contractions as measured by the accelerometers to thereby constantly and automatically optimize the cardiac resynchronization therapy.

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: 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: An implantable cardiac stimulation device provides bichamber pacing. In accordance with a first embodiment, the device varies the interchamber pacing delay responsive to either sensed intrinsic activity or sensor measured activity of the patient. In another embodiment, the device times separate and independent AV intervals for providing pacing pulses to the right and left chambers.

Abstract: A leadless cardiac pacemaker configured for implantation in electrical contact with a left ventricular cardiac chamber and configured for leadless triggered left-ventricular pacing for cardiac resynchronization therapy (CRT) in response to conducted signals from a pulse generator.

Abstract: A method for monitoring a biological cardiac pacemaker is provided. The method may include stimulating a heart at a region selected for implantation of a biological pacemaker and sensing at least one electrical signal indicative of a cardiac depolarization originating in the region selected for implantation of the biological pacemaker. The method may further include sensing at least one subsequent electrical signal produced by the heart and determining if the subsequent electrical signal originated in the region selected for the biological pacemaker or another region of the heart. In an alternative embodiment, the method may include determining a template time difference between two points on cardiac complexes sensed in two or more different cardiac locations during normal sinus rhythm. The method may further include determining a time difference between two points on a subsequent cardiac complex sensed in two or more different cardiac locations.

Abstract: An implantable medical device is connected to a multipolar LV lead and an implantable sensor. The sensor signal from the sensor is used to identify a time point of mitral valve closure for a cardiac cycle when a ventricular pulse generator generates pacing pulses that are applied to the electrodes of the multipolar LV lead according to a pacing sequence. A time interval processor determines the time interval from onset of LV activation to the time point of mitral valve closure. This procedure is repeated for multiple different pacing sequences of a sequence set. The pacing sequence that resulted in shortest time interval is then selected by a selector as the currently optimal pacing sequence for the patient.

Abstract: According to certain examples, an implanted medical device is used to determine a mass attribute of a patient. The patient's phrenic nerve is stimulated, and the diaphragmatic response is measured by an accelerometer. The measured response is analyzed in certain embodiments to determine a mass attribute. This information can help in the diagnosis of, and efficient response to, edema.

Abstract: An implantable medical device, IMD, (100) is connectable to at least one ventricular lead (210) having a ventricular basal electrode (214) and a ventricular apical electrode (212). The IMD (100) comprises a pulse generator (120) for generating pacing pulses applied to a heart (10) through the ventricular lead (210). The operation of this pulse generator (120) is controlled by a controller (130) that is configured to control the pulse generator to first deliver a pacing pulse to the ventricular basal electrode (214) to stimulate the basal portion of the ventricle (12, 14) before a pacing pulse is delivered to the apical portion of the ventricle (12, 14) by the ventricular apical electrode (212). This pulse sequence achieves a biologically more correct cardiac stimulation and a contraction pattern that reduces the risk for valvular regurgitation.

Abstract: A device is presented for evaluating whether an episode of sleep apnea is occurring in a patient suffering from chronic sleep apnea disorder, for delivery of appropriate therapy. The device includes circuitry adapted to respond to a cardiac signal generated by the heart. Switching circuitry diverts passage of the heart signal through both a high impedance path and a substantially lower impedance path, and a differential amplifier processes the resulting signal pairs to ascertain the difference in magnitude between the two signals of each pair. An analyzer thereof determines changes in the patient's ventilation, from which inordinately reduced patient ventilation is detected to assess possible occurrence of an episode of sleep apnea. If the analyzer denotes change of ventilation between otherwise regular respiratory cycles, an actual episode of sleep apnea is indicated.

Abstract: A remote external interface for an implantable cardiac function management device is configured to be communicatively coupled to the implantable cardiac function management device via a network to a local external interface and via telemetry between the local external interface and the implantable cardiac function management device. The remote external interface includes a communication circuit and a processor circuit. The communication circuit is configured to communicate with the implantable cardiac function management device. The processor circuit is configured to perform an analysis of physiologic data received from the implantable cardiac function management device in response to operation of the implantable cardiac function management device using a plurality of therapy control parameter sets. The processor circuit can be further configured to select a particular therapy control parameter set using the analysis.

Abstract: Generally, the disclosure is directed one or more methods or systems of cardiac pacing employing a right ventricular electrode and a plurality of left ventricular electrodes. Pacing using the right ventricular electrode and a first one of the left ventricular electrodes and measuring activation times at other ones of the left ventricular electrodes. Pacing using the right ventricular electrode and a second one of the ventricular electrodes and measuring activation times at other ones of the left ventricular electrodes. Employing sums of the measured activation times to select one of the left ventricular electrodes for delivery of subsequent pacing pulses.

Abstract: Techniques are provided for use with implantable medical devices equipped to deliver paired postextrasystolic potentiation (PESP) pacing within a patient having an intact ventricle and a weakened ventricle. A first interpulse interval is determined for use with paired PESP pacing of the intact ventricle sufficient to achieve only relatively minimal potentiation within the intact ventricle. A second interpulse interval is determined for use with paired PESP pacing of the weakened ventricle sufficient to achieve relatively more significant potentiation within the weakened ventricle. Then, paired PESP pacing is delivered to the intact ventricle using the first interpulse interval while paired PESP is also delivered to the weakened ventricle using the second interpulse interval to reduce contractility disequilibrium within the heart caused by the weakened ventricle to achieve a matching of natural contractilities. In this manner, dual ventricular, independently timed, continuous PESP is provided.

Abstract: Various aspects of the present subject matter provide a filter module. In various embodiments, the filter module comprises an input, an output, a signal path from the input to the output, a filter and a switch. The filter has a transfer response to attenuate a frequency of a neural stimulation signal. The switch is adapted to place the filter in the signal path when the neural stimulation signal is applied and to remove the filter from the signal path when the neural stimulation signal is not applied. Other aspects are provided herein.

Abstract: Methods, apparatus, and systems are provided to stimulate multiple sites in a heart. A controller senses electrical activity associated with sinus rhythm of the heart. A signal generator is configured to generate an electrical signal for stimulating the heart. Based on the electrical signal, a distributor circuit then distributes the stimulating signals, such as pacing pulses, to a heart. The distributor circuit may vary the delay time between stimulating signals, inhibit a stimulating signal, trigger application of a stimulating signal, or vary the characteristics, such as the pulse width and amplitude, of a stimulating signal.

Abstract: An implantable cardiac monitor upgradeable to an implantable pacemaker or an implantable cardiac resynchronization device allows the use of a single implantable medical device for monitoring cardiac conditions and later, if needed, for cardiac pacing. The implantable medical device includes a circuit that can be configured, by programming through an external programmer, to either the implantable cardiac monitor or the implantable pacemaker. The implantable medical device is first configured to and used as the implantable cardiac monitor for acquisition of physiological data indicative of a need for a pacing therapy if the pacing therapy is to follow, the implantable medical device is reconfigured from the implantable cardiac monitor to the implantable pacemaker, thus eliminating the need of using two implantable medical devices.

Abstract: In an implantable heart stimulating device and a method of the operation thereof, device has a control circuit that detects an evoked responses to delivered pacing pulses and to carry out an automatic capture routine. The control circuit is arranged to automatically temporarily disable the automatic capture routine on the basis of at least one of the following criteria: a1) if more than a predetermined number of threshold searches have been performed during a certain time, and b1) if a variable time delay with which the device operates is changed such that a pacing pulse may be delivered by the device during the evoked response time window.

Abstract: Embodiments of the invention are related to biosorbable batteries, amongst other things. In an embodiment, the invention includes a biosorbable battery assembly including an anode, a cathode, and a biosorbable separation element. The anode can include an anode material, wherein electrochemical oxidation of the anode material results in the formation of reaction products that are substantially non-toxic. The cathode can include a cathode material, wherein electrochemical reduction of the cathode material results in the formation of reaction products that are substantially non-toxic, the cathode material having a larger standard reduction potential than the material of the anode. The biosorbable separation element can be disposed between the anode and the cathode and can be configured to provide electrical insulation between the anode and the cathode.

Abstract: A medical device having an impedance measurement circuit connected to at least two intracorporeal measurement electrodes arranged to measure the impedance of tissue inside the body of a patient. The impedance measurement circuit is adapted to apply a measurement current/voltage signal to the electrodes to measure and calculate the impedance of the measurement tissue, and to apply the calculated impedance value to a storage unit. The stored impedance values are used, by an analysis unit, to measure the amount of visceral fat of the tissue object inside the body of the patient.

Abstract: Methods and systems to modulate timing intervals for pacing therapy are described. For each cardiac cycle, one or both of an atrioventricular (A-V) timing interval and an atrial (A-A) timing interval are modulated to oppose beat-to-beat ventricular (V-V) timing variability. Pacing therapy is delivered using the modulated timing intervals.

Abstract: Stimulation energy can be provided to a His-bundle to activate natural cardiac contraction mechanisms. Interval information can be used to describe a cardiac response to His-bundle stimulation, and the interval information can provide cardiac stimulation diagnostic information. For example, interval information can be used to discriminate between intrinsic conduction cardiac contractions and contractions responsive to His-bundle pacing.

Abstract: An assembly is provided for introducing a device within a heart of a patient. The assembly is comprised of a sheath having at least one internal passage. An intra-cardiac implantable medical device (IIMD) is retained within the at least one internal passage, wherein the IIMD is configured to be discharged from a distal end of the sheath. The IIMD has a housing with a first active fixation member configured to anchor the IIMD at a first implant location within a local chamber of the heart.

Abstract: Electronic circuit arrangements for generating at least two different constant currents at a load resistor, including a bridge circuit (especially an H bridge=H bridge circuit) having at least (in the case of an H bridge, precisely) four legs, and switching elements and a bridge branch between the legs, in which the load resistor is inserted, and at least two current sources which are connected to the legs of the bridge circuit in such a manner that it provides for current via one of the legs through the bridge branch and through a leg, connected to the other end of the bridge branch, with a corresponding switch position, the at least two current sources being adjustable if desired. The use of the circuit arrangement for generating such stimulation currents and corresponding procedures currents and methods.

Abstract: The invention relates to medical devices such as pacemakers, pulse generators, cardioverter-defibrillators and the like and more particularly relates to modular and reconfigurable medical system platforms and methods of designing, testing, controlling and implementing diverse therapies, diagnostics, physiologic sensors and related instrumentation using said medical system platforms. Methods, systems and devices provide a new design platform for implantable and external medical devices such as pacemakers, defibrillators, neurostimulators, heart monitors, etc. A real-time, highly flexible system of software and hardware modules enables both prototypes and products to respond to patient and customer needs with greater design and manufacturing efficiency. Certain embodiments integrate a general-purpose processor with interface circuitry to provide a standard platform for implementing new and conventional therapies with software models rather than custom circuitry.

Abstract: Techniques for adjusting pacing therapy based on ventriculo-atrial delay are described herein. These techniques may be used to control ventricular filling times during the delivery of pacing therapy. In some examples, a device or system delivers pre-excitation fusion pacing therapy to a ventricular chamber, determines a ventriculo-atrial delay interval for the ventricular chamber for at least one cardiac cycle, and adjusts the pacing therapy delivered by the implantable medical device to compensate for decreased ventricular filling time when the ventriculo-atrial delay interval is less than a threshold. In some examples, the device or system may adjust the pacing therapy by decreasing a pacing rate of the implantable medical device, increasing a pre-excitation interval for pacing of the ventricular chamber, and/or switching from a fusion pacing mode to a biventricular pacing mode.

Abstract: Embodiments of close loop optimization of atrio-ventricular (A-V) delay interval and/or inter-ventricular (V-V) timing are disclosed. An implantable medical device includes a housing that supports a processing means adapted for implantation in a patient. There can be two or more electrodes electrically coupled to the processing means where the two or more electrodes can be used for sensing a patient's cardiac signals, which include a far-field EGM. The processing means can determine a width of a P-wave from the sensed far-field EGM. Also included can be a means for delivering an adapted cardiac pacing therapy based upon the width of the P-wave, including revised A-V delay and/or V-V temporal intervals.

Abstract: A method and apparatus for treatment of heart failure by increasing secretion of endogenous naturetic hormones ANP and BNP such as by stimulation of the heart atria. Heart pacing is done at an atrial contraction rate that is increased and can be higher than the ventricular contraction rate. Pacing may include mechanical distension of the right atrial appendage. An implantable device is used to periodically cyclically stretch the walls of the appendage with an implanted balloon.

Abstract: A method and apparatus for treatment of hypertension and heart failure by increasing vagal tone and secretion of endogenous atrial hormones by excitory pacing of the heart atria. Atrial pacing is done during the ventricular refractory period resulting in atrial contraction against closed AV valves, and atrial contraction rate that is higher than the ventricular contraction rate. Pacing results in the increased atrial wall stress. An implantable device is used to monitor ECG and pace the atria in a nonphysiologic manner.

Abstract: An implantable heart stimulating device for indicating congestive heart failure (CHF) has a processor and a sensor combination that senses at least two heart events during one heart cycle at different locations of the heart. The processor is supplied with signals from the sensor combination relating to the sensed events, and determines therefrom at least one heart time interval between the sensed events in the same heart cycle. The processor determines a CHF indicator value representing a degree of CHF based on a variability measure calculated from at least two heart time intervals from at least two different heart cycles. The processor determines the CHF indicator value in relation to previous CHF indicator values.

Abstract: Electrodes and circuitry for monitoring and stimulating the exterior of the human body, comprising delivering stimulation pulses to stimulation electrodes applied to the exterior of the body, detecting an electrical potential at monitoring electrodes applied to the exterior of the body, positioning at least a first and second monitoring electrode at locations at which an electrical artifact caused by the electrical stimulation pulses is substantially cancelled in a signal formed from the electrical potentials detected at the first and second monitoring electrodes.