Abstract: A method for use in an implantable medical device comprises the steps of monitoring respiration with an amplifier having a gain, generating a moving apneic threshold based on recent respiration cycles, accumulating differences between amplitudes of respiration cycles and the moving apnea detection threshold and comparing the accumulated differences against an apnea detection threshold to detect the onset of an episode of apnea. The method further comprises measuring respiration levels upon detecting the onset of apnea, confirming the episode of apnea based upon the respiration levels measured upon detecting the onset of apnea; and adjusting one of the gain of the amplifier and the apnea detection threshold so that the time from the detection of onset of apnea to the time of confirmation of the episode of apnea is within a predetermined time range following the detection of the onset of apnea.

Abstract: A system and method for determining a patient's degree of cardiac vascular blockage or, equivalently, a patient's risk of cardiac ischemia, based on the time interval between the onset of exercise activity and the onset of an episode of cardiac ischemia. In one embodiment, an implantable cardiac device may obtain an EGM and possibly other measures of patient physiologic activity. These measures are used to determine when the patient has initiated exercise activity. Analysis of the EGM then detects an elevated or depressed ST segment, which typically indicates an episode of cardiac ischemia. The time interval between the onset of exercise and the onset of ischemia is a metric reflecting the patient's degree of vascular blockage or, equivalently, the patient's risk of ischemia. Other metrics may be derived, such as a substantially workload-level invariant measure determined as the product of the exercise workload level and the ischemia onset time interval.

Abstract: An exemplary method generates a map of a pacing parameter, a sensing parameter or one or more other parameters based in part on location information acquired using a localization system configured to locate electrodes in vivo (i.e., within a patient's body). Various examples map capture thresholds, qualification criteria for algorithms, undesirable conditions and sensing capabilities. Various other methods, devices, systems, etc., are also disclosed.

Abstract: An exemplary method generates a map of a pacing parameter, a sensing parameter or one or more other parameters based in part on location information acquired using a localization system configured to locate electrodes in vivo (i.e., within a patient's body). Various examples map capture thresholds, qualification criteria for algorithms, undesirable conditions and sensing capabilities. Various other methods, devices, systems, etc., are also disclosed.

Abstract: A system and method of sensing relatively low magnitude signals of interest in a sensing environment with at least intervals of relatively high magnitude noise of comparable or overlapping frequency spectra as the signals of interest. The systems and methods can be implemented in an efficient, low-power manner to facilitate long term monitoring of low magnitude physiologic signals, for example in an in vivo or implantable manner. An amplifier can be arranged with a threshold detector driving a normally closed switch such that the input to or output from the amplifier can be opened when the noise exceeds a threshold. A filter, such as a moving average filter, can be included to smooth the amplified output and compensate for the amplified signal lost when the threshold is exceeded. The systems and method facilitate implantable nerve sensing in high noise environments, such as from myopotentials.

Abstract: Techniques are provided for evaluating heart failure within a patient. In one example, the implantable device detects a decrease, if any, in selected morphological parameters derived from the intracardiac electrogram (IEGM) that are indicative of possible heart failure, such as paced depolarization integrals (PDI) or peak-to-peak amplitudes of QRS-complexes. The device also detects a decrease, if any, in transthoracic impedance, which is also indicative of possible heart failure. Acute heart failure is indicated if there is a decrease in the morphological IEGM parameters but no significant decrease in transthoracic impedance. Chronic heart failure is indicated if there is a decrease in transthoracic impedance but no significant decrease in the morphological IEGM parameters. If both transthoracic impedance and the morphological IEGM parameters are found to be decreasing significantly, the device issues a warning of severe heart failure.

Abstract: A patient's response to therapy such as CRT is assessed by cross correlation of a patient's evoked response and physical activity surrogates. Based on the cross correlation, a determination may be made as to whether or how much the therapy is helping the patient's physical activity. For example, the degree of cross correlation index between IEGM parameters and activity threshold parameters may be used to assess whether the patient's heart condition improves the patient's physical activity. The therapy may then be modified as necessary in the event the patient is not sufficiently responding to the therapy.

Abstract: Elasticity of a cardiovascular vessel of a patient is monitored to provide an indication of whether the patient's health is changing. In some aspects the elasticity of a cardiovascular vessel is determined irrespective of the current blood pressure level of the patient at the time the elasticity is determined. For example, vessel elasticity may be determined based on a defined set of data that maps vessel elasticity with reflectance times for different blood pressure levels. In some implementations, this set of data corresponds to a set of iso-pressure lines.

Abstract: An implantable cardiac stimulation device provides an intracardiac electrogram with reduced respiratory modulation effect. The device includes a sensing circuit that senses cardiac activity and provides an intracardiac electrogram signal extending over a plurality of cardiac cycles, a respiration monitor that monitors respiration associated with the sensed cardiac activity, and a cardiac cycle selector that selects a set of intracardiac electrogram cardiac cycles of the plurality of cardiac cycles in response to the monitored respiration. A processing circuit processes the selected set of intracardiac electrogram cardiac cycles to provide the intracardiac electrogram with reduced respiratory modulation effect.

Abstract: Embodiments include methods and devices for detecting ischemia in a patient and treating the ischemia with a pacing therapy that increases cardiac efficiency, output, or both, without substantially increasing myocardial oxygen consumption. Such therapy may also be used to mitigate the adverse effects of decreased blood flow to the ischemic tissue by increasing the blood flow an oxygenation thereto.

Abstract: An exemplary method includes acquiring cardiac electrical activity information; detecting an R wave; and based on the detecting, calling for delivery of energy to cells located in a structure outside of the myocardium only during a period time within the QRS complex corresponding to the detected R wave. The energy delivered may be electrical stimulation energy or mechanical energy.

Abstract: An exemplary method includes acquiring cardiac electrical activity information; detecting cardiac events within the information including T waves, QRS complexes and/or P waves; and calling for delivery of matter to the heart during a period of time based on the cardiac events. The delivery may occur between a detected T wave and its immediately subsequent QRS complex. The matter being delivered may include stem cells, progenitor cells, nutrients and/or drugs.

Abstract: An exemplary method includes acquiring cardiac electrical activity information, detecting a T wave and, based on the detecting, calling for delivery of matter to the heart where the matter may include one or more of stem cells, progenitor cells, nutrients and drugs. Another exemplary method includes calling for delivery of electrical energy to cells destined for implantation in the body or cells already implanted in the body. Such delivery may be timed according to cardiac electrical activity and/or delivered at an energy level below a capture threshold of neighboring tissue. Various other exemplary technologies are also disclosed.

Abstract: An exemplary method includes accessing cardiac information acquired via a catheter located at various positions in a venous network of a heart of a patient where the cardiac information comprises position information, electrical information and mechanical information; mapping local electrical activation times to anatomic positions to generate an electrical activation time map; mapping local mechanical activation times to anatomic positions to generate a mechanical activation time map; generating an electromechanical delay map by subtracting local electrical activation times from corresponding local mechanical activation times; and rendering at least the electromechanical delay map to a display. Various other methods, devices, systems, etc., are also disclosed.

Abstract: Techniques are provided for use by a pacemaker or other implantable medical device for detecting and tracking trends in cardiopulmonary fluid transfer rates—such as heart-to-lung fluid perfusion rates and lung-to-lymphatic system fluid excretion rates—and for detecting heart failure, dyspnea or other cardiopulmonary conditions. In one example, the device periodically measures transthoracic admittance values. A first exponential time-constant (k1) is determined using curve-fitting from admittance values obtained while the patient is in a sleep posture. Time-constant k1 is representative of the fluid perfusion rate. A second exponential time-constant (k2) is determined based on admittance values obtained while the patient is standing/walking/sitting. The second exponential time-constant (k2) is representative of the fluid excretion rate from the lungs.

Abstract: Techniques are provided for use in controlling rate-adaptive pacing within implantable medical devices such as pacemakers or implantable cardioverter-defibrillators (ICDs). In one example, a force-frequency relationship is determined for the heart of the patient, which is representative of the relationship between cardiac stimulation frequency and myocardial contractile force. To this end, various parameters are detected for use as surrogates for contractile force, including selected systolic pressure parameters and cardiogenic impedance parameters. Rate-adaptive pacing is then controlled based on the detected force-frequency relationship to, for example, deactivate rate-adaptive pacing if the slope and/or abscissa of the force-frequency relationship indicates significant contractility dysfunction within the patient. In other examples, rather than deactivating rate-adaptive pacing, control parameters are adjusted to render the rate-adaptive pacing less aggressive.

Abstract: An exemplary method includes acquiring cardiac electrical activity information, detecting a T wave and, based on the detecting, calling for delivery of matter to the heart where the matter may include one or more of stem cells, progenitor cells, nutrients and drugs. Another exemplary method includes calling for delivery of electrical energy to cells destined for implantation in the body or cells already implanted in the body. Such delivery may be timed according to cardiac electrical activity and/or delivered at an energy level below a capture threshold of neighboring tissue. Various other exemplary technologies are also disclosed.

Abstract: Methods and systems are presented for displaying patient activity data from implantable cardiac device (ICD). The method includes: sensing an activity level, storing the sensed activity level as a first coordinate of an activity data point, generating an average activity level from a predetermined number of sensed activity levels, storing the average activity level as a second coordinate of the activity data point, accumulating a number of times the activity data point having the first and second coordinates occurs, and storing the accumulated number of times. These steps are repeated for a predetermined period of time, and a plurality of activity data points each having an associated accumulated number of times is stored. The method further includes graphically displaying each of the plurality of activity data points with the associated accumulated number of times.

Abstract: Diagnosing a patient's cardiac health through histogram analysis of thoracic impedance is described. Data values indicative of thoracic impedance are measured from a patient over a sample period that includes multiple respiratory cycles. The values are distributed across multiple bins of a histogram. A diagnostic value for use in diagnosing a patient's cardiac health is derived from values in one or more of the bins. As one example, a diagnostic value representing minimum thoracic impedance during the sample period can be derived from values in the lowest-valued bins. Diagnostic values can be computed for multiple sample periods in the same fashion. A trend analysis is performed on the diagnostic values to determine whether the patient's cardiac condition is improving or worsening. The trend may be presented in a graphical form to provide a visual tool for assessing the patient's condition over time.

Abstract: A method of identifying a potential cause of pulmonary edema is provided. The method includes obtaining one or more impedance vectors between predetermined combinations of the electrodes positioned proximate the heart. At least one of the impedance vectors is representative of a thoracic fluid level. The method also includes applying a stimulation pulse to the heart and sensing cardiac signals of the heart that are representative of an electrophysiological response to the stimulation pulse. The method further includes monitoring the cardiac signals and at least one of the impedance vectors with respect to time to identify the potential cause of pulmonary edema.