Abstract: A system and method are provided for determining an index of autonomic nervous system (ANS) or sympathetic nervous system (SNS) activity for use in patient monitoring or therapy delivery control. An ANS or SNS index is calculated as a function of multiple monitored physiological variables that strongly correlate to changes in autonomic or sympathetic tone. These ANS-influenced variables are derived from selected hemodynamic and/or electrical signals and may include variables relating to any of: the maximum rate of pressure rise (dP/dtmax), the maximum rate of pressure decline (dP/dtmin), pulse pressure (PP), pre-ejection time interval (PEI) and/or systolic time interval (STI), heart rate (HR), heart rate variability (HRV), and baro-reflex gain. Changes in the ANS or SNS index may be used to automatically adjust a device delivered therapy.

Abstract: Apparatus using one or more modes of statistical analysis with one or more monitored parameters of a patient's heart to identify and/or assess arrhythmias. Through use of the one or more modes of statistical analysis, a medical professional can be aided during evaluation of patient data for diagnosis of the patient. At least one of the monitored parameters may include one or more values used representatively for storage intervals of a selected length. As such, for each storage interval, a value may be determined for the one monitored parameter occurring at an upper percentile and a lower percentile. In addition, a median value may be determined for the one monitored parameter for each storage interval. Over a plurality of the storage intervals, these determined values can be used in one or more modes of statistical analysis to better identify and assess the arrhythmias.

Abstract: A method and apparatus concerning the retrieval and storage of status information obtained from patients having implantable medical devices (IMDs). When patients are having episodes during which symptoms are experienced relating to their medical condition, the collection of the patient's status information can be helpful to the patient's physician for diagnostic purposes. Telemetered signals recorded by the IMD can be transmitted from the IMD to a programmer. Such programmer is portable and sized so as to be carried by the patient. As such, mechanisms added to such programmers for use in retrieving and storing patient status information can provide more convenience for patients.

Abstract: A method of identifying sleep disordered breathing (SDB) in a patient includes monitoring a hemodynamic pressure, deriving high, middle, and low values representative of the distribution of the hemodynamic pressure over a storage interval, measuring a ratio of a lower range to a full range of the hemodynamic pressure based on the derived high, middle, and low values, and using the ratio to determine whether the patient has experienced an SDB episode. Certain embodiments of the invention compare the ratio to a threshold value to identify the occurrence of an SDB episode, while other embodiments of the invention identify the occurrence of an SDB episode by monitoring for a simultaneous increase in both the ratio and the full range of the hemodynamic pressure. In certain other embodiments of the invention, activity level and/or duration criteria may be employed to confirm the occurrence of an SDB episode detected using the ratio.

Abstract: A medical device chronically monitors cardiac function in a patient. An input circuit of the medical device receives a pressure signal representative of a pressure sensed within a ventricle of the patient's heart as a function of time. A processor derives from the pressure signal a myocardial performance index based upon pressures in the ventricle. The processor then provides an output based upon the myocardial performance index.

Abstract: A system and method are provided for sensing cardiac electrogram (EGM) signals and ventricular pressure signals and for using the sensed EGM and sensed pressure signals for estimating stroke volume (SV). A measure of cardiac output can be computed from the estimated SV and a heart rate determined from the EGM signals. The sensed ventricular pressure signal and the sensed EGM signal are used to derive landmark points such as an estimated pulmonary diastolic pressure, a mean pulmonary artery pressure, a peak right ventricular pressure (RVP), and various time intervals used in computing an area or a pulse contour integral. The pulse contour integral is used to estimate SV. The estimated pulmonary diastolic pressure, mean pulmonary artery pressure and CO computed from the estimated SV can be used to compute a pulmonary vascular resistance.

Abstract: A medical device monitors a patient to predict worsening heart failure. An input circuit of the medical device receives a pressure signal representative of a pressure sensed within a ventricle of the patient's heart as a function of time. A processor derives from the pressure signal a ventricular pressure index for a ventricular contraction based upon pressures in the ventricle. The processor then provides an output based upon the ventricular pressure index.

Abstract: A system and method are provided for determining an index of autonomic nervous system (ANS) or sympathetic nervous system (SNS) activity for use in patient monitoring or therapy delivery control. An ANS or SNS index is calculated as a function of multiple monitored physiological variables that strongly correlate to changes in autonomic or sympathetic tone. These ANS-influenced variables are derived from selected hemodynamic and/or electrical signals and may include variables relating to any of: the maximum rate of pressure rise (dP/dtmax), the maximum rate of pressure decline (dP/dtmin), pulse pressure (PP), pre-ejection time interval (PEI) and/or systolic time interval (STI), heart rate (HR), heart rate variability (HRV), and baro-reflex gain. Changes in the ANS or SNS index may be used to automatically adjust a device delivered therapy.

Abstract: The present invention demonstrates that continuous hemodynamic monitoring can be used to identify the optimal AV-delay in a pacemaker-treated patient with end stage heart failure. The AV-delay determines the timing of late diastolic filling in relation to the onset of ventricular contraction and the duration of diastolic filling. An optimal tuning of the AV-delay improves left ventricular filling pressures in patients with a DDD-programmed pacemaker and is particularly important in the presence of a compromised left ventricular function. It has been discovered that using the lowest ePAD pressure, an indirect parameter of the left ventricular end-diastolic pressure, as an indicator for the optimal AV interval. Importantly, measurements of the ePAD revealed the same optimal AV-delay as echocardiographic assessment of left ventricular diastolic filling by standard echocardiographic methods.