Abstract: An implantable neurostimulator-implemented method for managing tachyarrhythmias upon a patient's awakening from sleep 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 comprising the cervical vagus nerve of a patient. Operating modes of the pulse generator are stored. An enhanced dose of the electrical therapeutic stimulation is parametrically defined and tuned to prevent initiation of or disrupt tachyarrhythmia upon the patient's awakening from a sleep state through at least one of continuously-cycling, intermittent and periodic ON-OFF cycles of electrical pulses. Other operating modes, including a maintenance dose and a restorative dose are defined.

Abstract: A cardiac rhythm management (CRM) device can extract ventilation information from thoracic impedance or other information, and adjust a delivery rate of the CRM therapy. A tidal volume of a patient is measured and used to adjust a ventilation rate response factor. The measured tidal volume can optionally be adjusted using a ventilation rate dependent adjustment factor. The ventilation rate response factor can also be adjusted using a maximum voluntary ventilation (MVV), an age predicted maximum heart rate, a resting heart rate, and a resting ventilation determined for the patient. In various examples, a global ventilation sensor rate response factor (for a population) can be programmed into the CRM device, and automatically tailored to be appropriate for a particular patient.

Abstract: An implantable cardiac device is configured and programmed to assess a patient's cardiopulmonary function by evaluating the patient's minute ventilation response. Such evaluation may be performed by computing a minute ventilation response slope, defined as the ratio of an incremental change in minute ventilation to an incremental change in measured activity level. The minute ventilation response slope may then be compared with a normal range to assess the patient's functional status.

Abstract: In general, the disclosure relates to the delivery of therapy according to a detected posture state of a patient. The disclosure contemplates a variety of techniques for managing therapy delivered to a patent. In one example, the disclosure relates to a technique including delivering therapy to a patient from a medical device, wherein the therapy is delivered to the patient according to a detected posture state of the patient; and automatically adjusting at least one aspect of the therapy delivered from a medical device based at least in part on one or more of time or patient posture state behavior, wherein automatically adjusting at least one aspect of therapy comprises suspending at least one aspect of the therapy or decreasing a posture state detection frequency.

Abstract: According to an embodiment of a method for using an implantable device to deliver a hypertension therapy to a patient, an activity level is sensed using the implantable medical device. The implantable device may be programmed with a mapping of the sensed activity level to intensity levels for the hypertension therapy. The method may determine a desired intensity for the hypertension therapy as a function of both a circadian rhythm template and the sensed activity level, and use the implantable device to deliver the hypertension therapy using the desired intensity.

Abstract: Pacing parameters may be adjusted to increase the cardiac output of a patient's heart while a patient is awake and/or active and the demand placed on the heart may be greatest, and to decrease or hemodynamic efficiency while a patient is at rest so that the heart itself has time to rest before the next period of higher demand for efficiency begins. This may aid in lessening the strain placed on the heart by making the heart work hard when needed such as when the patient is active, and by permitting the heart to “rest” when the patient is relatively inactive.

Abstract: The present invention is generally directed to methods, systems, and computer program products for coordinating musculoskeletal and cardiovascular hemodynamics. In some embodiments, a heart pacing signal causes heart contractions to occur with an essentially constant time relationship with respect to rhythmic musculoskeletal activity. In other embodiments, prompts (e.g., audio, graphical, etc.) are provided to a user to assist them in timing of their rhythmic musculoskeletal activity relative to timing of their cardiovascular cycle. In further embodiments, accurately indicating a heart condition during a cardiac stress test is increased.

Abstract: A method and device for delivering ventricular resynchronization pacing therapy in conjunction with electrical stimulation of nerves which alter the activity of the autonomic nervous system is disclosed. Such therapies may be delivered by an implantable device and are useful in preventing the deleterious ventricular remodeling which occurs as a result of a heart attack or heart failure. The device may perform an assessment of cardiac function in order to individually modulate the delivery of the two types of therapy.

Abstract: A medical device includes a sensor for sensing for an MRI gradient magnetic field and a microprocessor configured to operate in a signal processing mode in which electrical signals induced by the gradient magnetic field are not counted as cardiac events.

Abstract: An implantable medical device includes a sensor configured to generate an endocardial acceleration (EA) signal representative of activity of a patient's heart. The device further includes one or more circuits configured to identify within the EA signal at least one EA signal component corresponding to at least one peak of endocardial acceleration, and extract from the at least one EA signal component at least two characteristic parameters. The one or more circuits are further configured to generate a composite index based on a combination of the at least two characteristic parameters, determine a plurality of values of the composite index for a plurality of pacing configurations, and select a current pacing configuration from among the plurality of pacing configurations based on the plurality of values of the composite index.

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: An active implantable medical device or pacing, resynchronization defibrillation and/or cardioversion, and/or a device for diagnosing patient conditions, having a predictive diagnosis of the patient's status. The device measures a physiologic parameter, notably the minute ventilation; measures a physical parameter, notably the acceleration; discriminates between phases of activity and rest of the patient; and includes a memory containing a plurality of fields selectively updated by statistical processing. These fields are comprising one first set containing data related to the patient's activity phases, and one second set containing data related to the patient's rest phases. The statistical processing is updating in a dissociated manner the first and second sets of fields, selectively as a function of the value taken by the status indicator, and the analysis evaluates at least one clinical status index based upon the data contained in the fields of both first and second sets.

Abstract: A portable medical device is provided with an internal accelerometer device. The medical device includes a circuit board, the accelerometer device, and a response module coupled to the accelerometer device. The accelerometer device is mechanically and electrically coupled to the circuit board, and it includes a plurality of mass-supporting arms for a plurality of electrically distinct sensor electrodes, piezoelectric material for the mass-supporting arm, and a proof mass supported by the mass-supporting arms. Each of the mass-supporting arms has one of the sensor electrodes located thereon. Acceleration of the proof mass causes deflection of the piezoelectric material, which generates respective sensor signals at one or more of the sensor electrodes. The response module is configured to initiate an acceleration-dependent operation of the portable medical device in response to generated sensor signals present at the sensor electrodes.

Abstract: A medical device delivers a therapy to a patient. Posture events are identified, e.g., a posture of the patient is periodically determined and/or posture transitions by the patient are identified, and each determined posture event is associated with a current therapy parameter set. A value of at least one posture metric is determined for each of a plurality of therapy parameter sets based on the posture events associated with that therapy parameter set. A list of the therapy parameter sets is presented to a user, such as a clinician, for evaluation of the relative efficacy of the therapy parameter sets. The list may be ordered according to the one or more posture metric values to aid in evaluation of the therapy parameter sets. Where values are determined for a plurality of posture metrics, the list may be ordered according to the one of the posture metrics selected by the user.

Abstract: One or more embodiments of the present disclosure relates to a method and/or system for classifying and/or treating heart rhythms. The present disclosure involves sensing electrical signals associated with depolarizations of a patient's heart. The sensed electrical signals are converted to digital values and storing the digital values. Normalizing solely a maximum and a minimum value of the stored digital values associated with a depolarization of the patient's heart without normalizing other stored digital values of the depolarization is another aspect of the present disclosure. The maximum and minimum values associated with the depolarization are compared to maximum and minimum values associated with a template derived from signals indicative of a heart depolarization of known type. A determination is made as to whether a match exists between the maximum and minimum values associated with the depolarization to the maximum and minimum values associated with a template.

Abstract: In an implantable medical device such as an implantable cardiac defibrillator, and a method for classifying arrhythmia events, IEGM signals are analyzed to detect an arrhythmia event and a respiratory pattern of the patient is sensed. At least one respiratory parameter reflecting characteristics of the respiratory pattern of the patient is determined based on the sensed respiratory pattern and a respiratory measure corresponding to a change of a rate of change of the at least one respiratory parameter is calculated. The detected arrhythmia event is classified based on the respiratory measure and the IEGM signals, wherein arrhythmia events that satisfy at least a first criterion is classified as an arrhythmia event requiring therapy.

Abstract: The disclosure is directed towards posture-responsive therapy. To avoid interruptions in effective therapy, an implantable medical device may include a posture state module that detects the posture state of the patient and automatically adjusts therapy parameter values according to the detected posture state. A system may include an external programmer comprising a user interface that receives user input defining therapy parameter values for delivery of therapy to a patient, and user input associating one or more of the therapy parameter values with a plurality of posture states based on user input, a processor that automatically defines therapy parameter values for delivery of therapy to a patient when the patient occupies the posture states based on the association, and an implantable medical device that delivers the therapy to the patient in response to detection of the posture states.

Abstract: An implantable medical device is connectable to or comprises an activity sensor and determines a current activity level of a subject based on a sensor signal from the activity sensor. A time period during which the current activity level of the subject has exceeded a threshold level is also determined. A pulse generator controller controls a pulse generator to generate pacing pulses to be applied to the subject's heart at a pacing rate that is determined based on the current activity level and the length of the time period of activity at a level exceeding the threshold level.

Abstract: A method for operating an implantable medical device to obtain substantially synchronized closure of the mitral and tricuspid valves based on sensed heart sounds includes sensing an acoustic energy; producing signals indicative of heart sounds of the heart of the patient over predetermined periods of a cardiac cycle during successive cardiac cycles; calculating a pulse width of such a signal; and iteratively controlling a delivery of the ventricular pacing pulses based on calculated pulse widths of successive heart sound signals to identify an RV interval or VV interval that causes a substantially synchronized closure of the mitral and tricuspid valve. A medical device for optimizing an RV interval or VV interval based on sensed heart sounds implements such a method and a computer readable medium encoded with instructions causes a computer to perform such a method.

Abstract: Systems and methods for estimating caloric expenditure. The systems can include a physiological sensor to measure a patient's physical activity, and a posture sensor to measure the patient's posture. An estimated caloric expenditure can be calculated based on data from the physiological sensor and the posture sensor. For example, the estimated caloric expenditure can be calculated at least in part based on the posture data. For example, the estimated caloric expenditure can be validated based on the posture data.

Abstract: An implantable cardiac device includes a sensor for sensing patient activity and detecting phrenic nerve activation. A first filter channel attenuates first frequencies of the sensor signal to produce a first filtered output. A second filter channel attenuates second frequencies of the accelerometer signal to produce a second filtered output. Patient activity is evaluated using the first filtered output and phrenic nerve activation caused by cardiac pacing is detected using the second filtered output.

Abstract: An implantable cardiac device includes a sensor for sensing patient respiration and detecting phrenic nerve activation. A first filter channel attenuates first frequencies of the sensor signal to produce a first filtered output. A second filter channel attenuates second frequencies of the respiration signal to produce a second filtered output. Patient activity is evaluated using the first filtered output and phrenic nerve activation caused by cardiac pacing is detected using the second filtered output.

Abstract: A method and apparatus for treatment of hypertension and heart failure by increasing secretion of endogenous atrial hormones by pacing of the heart atria. Atrial pacing is done during the ventricular refractory period resulting in premature atrial contraction that does not result in ventricular contraction. Pacing results in the atrial wall stress, peripheral vasodilation, ANP secretion. Concomitant reduction of the heart rate is monitored and controlled as needed with backup pacing.

Abstract: A rate smoothing function used in implantable pulse generators uses detected triggering events, which cause the rate smoothing function to be activated or deactivated, and detected parameter adjusting events, which cause parameter(s) of the rate smoothing function to be changed. In one example, the activation/deactivation and/or change to the parameters of the rate smoothing function are temporary, and the pre-event state of the rate smoothing function is set to a post-adjusting state, such as after a first time interval. Rate smoothing may be selected, activated or deactivated, or adjusted based on a cardiac signal state, or based on an activity or other physiological sensor signal. The adjusted rate smoothing parameters may include an up-smoothing percentage to limit a speed of pacing rate increase and a down-smoothing percentage to limit a speed of pacing rate drop.

Abstract: Described are methods and devices for improving diastolic function with electrostimulation in heart failure patients who exhibit relatively normal systolic function. Such patients are characterized by impaired myocardial relaxation during diastole that prevents adequate filling of the ventricles during diastole to thereby reduce cardiac output. An implantable device is described for effecting strategic and periodic stimulation of the sympathetic nervous system to elicit myocardial adrenergic activation for improved myocardial relaxation.

Abstract: The disclosure provides a system that displays an indicator of patient posture state that changes according to posture state data. The posture state data may be transmitted from a medical device, for example, in or near real-time. In some examples, the disclosure relates to a method comprising receiving posture state data for a patient from a medical device; and presenting an indicator indicative of two or more of posture states based on the received posture state data, wherein each posture state of the two or more posture states is determined based on different detection criteria.

Abstract: Methods and/or devices for modifying the sampling rate for measuring a patient's intrinsic AV conduction time during cardiac therapy. For example, the sampling rate for measuring a patient's intrinsic AV conduction time may be modified (e.g., decrease or increased) based on one or more monitored physiological parameters, such as activity level and/or heart rate.

Abstract: The present invention relates generally to methods and systems for optimizing stimulation of a heart of a patient. Hemodynamical index signals reflecting a mechanical functioning of a heart of a patient are recorded at different hemodynamical states. Corresponding hemodynamical reference signals at corresponding hemodynamical states are recorded. At least one hemodynamical index parameter is extracted from the recorded hemodynamical index signals. The at least one hemodynamical index parameter is a measure of the mechanical functioning of the heart and a hemodynamical index model is created, wherein the hemodynamical index model is based on the at least one hemodynamical index parameter and a comparison between output results from the hemodynamical index model and corresponding hemodynamical reference signals. From this hemodynamical index model, a hemodynamical index can be derived, which then can be used in determining patient customized cardiac pacing settings of the cardiac stimulator.

Abstract: Intermittent delivery of ventricular pacing pulses synchronized to occur during an atrial diastole time period can be used to provide atrial stretch therapy and augment the production and release of atrial natriuretic hormone.

Abstract: A rate-adaptive pacemaker and a method for its operation in which the response factor for a minute ventilation sensor or other type of exertion level sensor is automatically set during a parameter adjustment mode that utilizes an activity level measurement to determine when the patient is at a target activity level with which is associated an appropriate target pacing rate. In a preferred embodiment, the target activity level corresponds to casual walking (e.g., 2 mph at a 4% grade) with a target pacing rate selected as appropriate for that level of activity in the individual patient.

Abstract: An implantable cardiac device is configured and programmed to assess a patient's cardiopulmonary function by evaluating the patient's minute ventilation response. Such evaluation may be performed by computing a minute ventilation response slope, defined as the ratio of an incremental change in minute ventilation to an incremental change in measured activity level. The minute ventilation response slope may then be compared with a normal range to assess the patient's functional status.

Abstract: Devices and methods for sleep detection involve the use of an adjustable threshold for detecting sleep onset and termination. A method for detecting sleep includes adjusting a sleep threshold associated with a first sleep-related signal using a second sleep-related signal. The first sleep-related signal is compared to the adjusted threshold and sleep is detected based on the comparison. The sleep-related signals may be derived from implantable or external sensors. Additional sleep-related signals may be used to confirm the sleep condition. A sleep detector device implementing a sleep detection method may be a component of an implantable pulse generator such as a pacemaker or defibrillator.

Abstract: A maximum pacing rate limiter for use in adaptive rate pacing in conjunction with a cardiac rhythm management system for a heart. The maximum pacing rate limiter may function to measure an interval, termed the ERT interval, between a paced ventricular evoked response and a T-wave. The maximum pacing rate limiter may further function to maintain the ERT interval at less than a certain percentage of the total cardiac cycle. In one disclosed embodiment, a maximum pacing rate limiter calculates an ERT rate based on the detected paced ventricular evoked response and the T-wave, and the pacing rate limiter module further communicates the minimum of the ERT rate and an adaptive-rate sensor indicated rate to a pacemaker.

Abstract: The disclosure described techniques for associating therapy adjustments with intended patient posture states. The techniques may include receiving a patient therapy adjustment to a parameter of a therapy program that defines electrical stimulation therapy delivered to the patient, identifying a posture state of the patient, and associating the patient therapy adjustment with the posture state when the patient therapy adjustment is within a range determined based on stored adjustment information for the identified posture state.

Abstract: Cardiac monitoring and/or stimulation methods and systems employing dyspnea measurement. An implantable cardiac device may sense transthoracic impedance and determine a patient activity level. An index indicative of pulmonary function is implantably computed to detect an episode of dyspnea based on a change, trend, and/or value exceeding a threshold at a determined patient activity level. Trending one or more pulmonary function index values may be done to determine a patient's pulmonary function index profile, which may be used to adapt a cardiac therapy. A physician may be automatically alerted in response to a pulmonary function index value and/or a trend of the patient's pulmonary index being beyond a threshold. Computed pulmonary function index values and their associated patient's activity levels may be stored periodically in a memory and/or transmitted to a patient-external device.

Abstract: Described are methods and devices for improving diastolic function with electrostimulation in heart failure patients who exhibit relatively normal systolic function. Such patients are characterized by impaired myocardial relaxation during diastole that prevents adequate filling of the ventricles during diastole to thereby reduce cardiac output. An implantable device is described for effecting strategic and periodic stimulation of the sympathetic nervous system to elicit myocardial adrenergic activation for improved myocardial relaxation.

Abstract: A system and method for automatically adjusting the operating parameters of a rate-adaptive cardiac pacemaker. In accordance with the method, maximum exertion levels attained by the patient are measured at periodic intervals and stored. The stored maximum exertion levels may then be used to update a long-term maximal exertion level, and the slope of the rate-response curve is adjusted to map the updated long-term maximal exertion level to a maximum allowable pacing rate. The stored maximum exertion levels may also be used to update a sensor target rate which is used to adjust the slope of the rate response curve.

Abstract: A method and device for delivering ventricular resynchronization pacing therapy in conjunction with electrical stimulation of nerves which alter the activity of the autonomic nervous system is disclosed. Such therapies may be delivered by an implantable device and are useful in preventing the deleterious ventricular remodeling which occurs as a result of a heart attack or heart failure. The device may perform an assessment of cardiac function in order to individually modulate the delivery of the two types of therapy.

Abstract: An implantable medical device is connectable to or comprises an activity sensor and determines a current activity level of a subject based on a sensor signal from the activity sensor. A time period during which the current activity level of the subject has exceeded a threshold level is also determined. A pulse generator controller controls a pulse generator to generate pacing pulses to be applied to the subject's heart at a pacing rate that is determined based on the current activity level and the length of the time period of activity at a level exceeding the threshold level.

Abstract: A medical device delivers a therapy to a patient. Posture events are identified, e.g., a posture of the patient is periodically determined and/or posture transitions by the patient are identified, and each determined posture event is associated with a current therapy parameter set. A value of at least one posture metric is determined for each of a plurality of therapy parameter sets based on the posture events associated with that therapy parameter set. A list of the therapy parameter sets is presented to a user, such as a clinician, for evaluation of the relative efficacy of the therapy parameter sets. The list may be ordered according to the one or more posture metric values to aid in evaluation of the therapy parameter sets. Where values are determined for a plurality of posture metrics, the list may be ordered according to the one of the posture metrics selected by the user.

Abstract: Various system embodiments comprise a stimulator adapted to deliver a stimulation signal for a heart failure therapy, a number of sensors adapted to provide at least a first measurement of a heart failure status and a second measurement of the heart failure status, and a controller. The controller is connected to the stimulator and to the number of sensors. The controller is adapted to use the first and second measurements to create a heart failure status index, and control the stimulator to modulate the signal using the index. Other aspects and embodiments are provided herein.

Abstract: A method of synchronizing a heart rate with an activity rate of a patient includes determining the activity rate of the patient. The method also includes synchronizing a pacing pulse with a phase of the activity rate to improve a cardiac stroke volume of the patient. The synchronizing includes lowering the heart rate during down motion associated with the activity rate and increasing the heart rate during an up motion associated with the activity rate when a stride rate is slower than a target heart rate.

Abstract: Methods and devices for analyzing posture-induced changes to physiological parameters of a patient (e.g., ejection time, heart rate, etc.) to provide an assessment of one or more conditions of the patient.

Abstract: In general, the disclosure describes techniques for modifying therapy provided to a patient by a medical device. The techniques may be applicable to electrical stimulation therapy or other therapies. Modification of therapy may include adjustment of one or more therapy parameter values that define one or more characteristics of stimulation therapy delivered to a patient. The therapy modification may be based on activity of a patient that is detected by an IMD, such as a change in a detected posture state occupied by the patient. Different therapy modifications may be applied for different changes in detected posture state. An IMD may modify therapy based on a transition from one posture state to another posture state, and apply different modifications for different transitions. In some aspects, the modification may include a profile, such as a ramp up or ramp down in a parameter value over a period of time. The profile may be different for different posture transitions.

Abstract: A medical device detects a previously defined event, and controls delivery of therapy to a patient according to therapy information associated with the previously defined event. In exemplary embodiments, the medical device enters a learning mode in response to a command received from a user, e.g., the patient or a clinician. In such embodiments, the medical device defines the event, collects the therapy information, and associates the therapy information with the defined event while operating in the learning mode. In some embodiments, the medical device defines the event based on the output of a sensor that indicates a physiological parameter of the patient during the learning mode. The sensor may be an accelerometer, which generates an output that reflects motion and/or posture of the patient. The medical device may collect therapy information by recording therapy changes made by the user during the learning mode.

Abstract: A medical device delivers a therapy to a patient. Posture events are identified, e.g., a posture of the patient is periodically determined and/or posture transitions by the patient are identified, and each determined posture event is associated with a current therapy parameter set. A value of at least one posture metric is determined for each of a plurality of therapy parameter sets based on the posture events associated with that therapy parameter set. A list of the therapy parameter sets is presented to a user, such as a clinician, for evaluation of the relative efficacy of the therapy parameter sets. The list may be ordered according to the one or more posture metric values to aid in evaluation of the therapy parameter sets. Where values are determined for a plurality of posture metrics, the list may be ordered according to the one of the posture metrics selected by the user.

Abstract: An active implantable medical device for cardiac resynchronization therapy with effort based rate-responsive pacing is described. The device calculates a rate-responsive stimulation frequency based on output signal of an effort sensor between a base frequency (fbase) and a maximum frequency (fmax). The device determines a target stimulation frequency based on the difference between a first frequency and the maximum frequency (fmax). The first frequency is the higher frequency of the base frequency (fbase) and the spontaneous frequency of the patient. The device calculates a stimulation frequency that has an immediate increase in the pacing rate from the higher of the initial value of the current stimulation frequency, or the spontaneous frequency to the target stimulation frequency, within a predetermined time, or a predetermined number of cardiac cycles. A plurality of consecutive effort zones (Z1-Z4) is defined over the extent of the dynamic range of the output signal of the effort sensor.

Abstract: An implantable medical device includes a multi-axial acceleration sensor and an evaluation unit connected thereto. The evaluation unit is configured to (1) split the accelerometer output signal into at least two signal components, one of which is associated with a right-ventricular contraction and another of which is associated with a left-ventricular contraction; (2) detect events in the signal components, and/or determine signal features therein; and (3) determine at least one characteristic value K by evaluating the signal components, and/or the events and/or signal features therein.

Abstract: A portable medical device is provided with an internal accelerometer device. The medical device includes a circuit board, the accelerometer device, and a response module coupled to the accelerometer device. The accelerometer device is mechanically and electrically coupled to the circuit board, and it includes a plurality of mass-supporting arms for a plurality of electrically distinct sensor electrodes, piezoelectric material for the mass-supporting arm, and a proof mass supported by the mass-supporting arms. Each of the mass-supporting arms has one of the sensor electrodes located thereon. Acceleration of the proof mass causes deflection of the piezoelectric material, which generates respective sensor signals at one or more of the sensor electrodes. The response module is configured to initiate an acceleration-dependent operation of the portable medical device in response to generated sensor signals present at the sensor electrodes.

Abstract: Techniques are provided for use with implantable medical devices equipped to deliver paired postextrasystolic potentiation (PESP) pacing to control the paired pacing rate based on changes in patient activity. In one example, the current activity level of the patient is detected during paired pacing using an accelerometer. The cardiac output level needed to maintain the current activity level of the patient is determined with reference to pre-stored lookup tables relating activity levels with corresponding minimum necessary cardiac output levels for the particular patient. The minimum paired pacing rate sufficient to achieve the cardiac output level is then determined based, e.g., on stroke volume derived from cardiogenic impedance signals. Paired pacing is then delivered at the minimum paired pacing rate sufficient to achieve the needed cardiac output, thereby assuring that the paired pacing rate is sufficient to meet the current physiological demands of the patient without consuming too much oxygen.