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| 20080262361 | SYSTEM AND METHOD FOR CALIBRATING CARDIAC PRESSURE MEASUREMENTS DERIVED FROM SIGNALS DETECTED BY AN IMPLANTABLE MEDICAL DEVICE - Various techniques are provided for calibrating and estimating left atrial pressure (LAP) using an implantable medical device, based on impedance, admittance or conductance parameters measured within a patient. In one example, default conversion factors are exploited for converting the measured parameters to estimates of LAP. The default conversion factors are derived from populations of patients. In another example, a correlation between individual conversion factors is exploited to allow for more efficient calibration. In yet another example, differences in thoracic fluid states are exploited during calibration. In still yet another example, a multiple stage calibration procedure is described, wherein both invasive and noninvasive calibration techniques are exploited. In a still further example, a therapy control procedure is provided, which exploits day time and night time impedance/admittance measurements. | 10-23-2008 |
| 20090299672 | METHODS AND APPARATUS FOR NON-INVASIVE IMPLANTABLE PRESSURE SENSOR CALIBRATION - An economical, repeatable, and non-invasive method and apparatus for the calibration of implantable pressure sensors that can minimize patient discomfort and risk of infection. In one embodiment, a calibration system for calibrating a first pressure sensor coupled to a management device and implanted into a human patient is provided. The calibration system includes a mouthpiece, a pump, a second pressure sensor, and a computer. The pump provides a positive pressure into an airway of the human patient via the mouthpiece. The second pressure sensor measures the airway pressure of the human patient, and the computer is coupled to the pump and monitors pressures measured by the first and second pressure sensors. Here, the computer also calculates one or more calibration constants based on the pressures measured by the first and second pressure sensors and provides the calibration constants to the management device to calibrate the first pressure sensor. | 12-03-2009 |
| 20110125049 | Methods and Systems that Use Implanted Posture Sensor to Monitor Pulmonary Edema - In specific embodiments, a method to monitor pulmonary edema of a patient, comprises (a) detecting, using an implanted posture sensor, when a posture of the patient changes from a first predetermined posture to a second predetermined posture, (b) determining an amount of time it takes an impedance signal to achieve a steady state after the posture of the patient changes from the first predetermined posture to the second predetermined posture, where the impedance signal is obtained using implanted electrodes and is indicative of left atrial pressure and/or intra-thoracic fluid volume of the patient, and (c) monitoring the pulmonary edema of the patient based on the determined amount of time it takes the impedance signal to achieve the steady state after the posture of the patient changes from the first predetermined posture to the second pre-determined posture. | 05-26-2011 |
| 20110125207 | METHODS AND SYSTEMS THAT USE IMPLANTED POSTURE SENSOR TO MONITOR LEFT ATRIAL PRESSURE AND/OR INTER-THORACIC FLUID VOLUME - In specific embodiments, a method to monitor left atrial pressure and/or intra-thoracic fluid volume of a patient, comprises (a) monitoring posture of the patient using a posture sensor implanted within the patient, and (b) using portions of an impedance signal, obtained using implanted electrodes, to monitor the left atrial pressure and/or intra-thoracic fluid volume of the patient. Each portion of the impedance signal used to monitor the left atrial pressure and/or intra-thoracic fluid volume of the patient corresponds to a period after which the patient has maintained a predetermined posture for at least a predetermined period of time, and during which the patient has remained in the predetermined posture. | 05-26-2011 |
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| 20080287818 | PRESSURE MEASUREMENT-BASED ISCHEMIA DETECTION - In some aspects ischemia is indicated based on cardiac pressure measurements. For example, ischemia may be indicated based on an increase in an intraventricular electromechanical delay where mechanical contractions are detected by measuring pressure in a cardiac chamber. Ischemia detection also may involve obtaining timing information relating to a mechanical contraction of at least one ventricle to identify an intraventricular dyssynchrony. In this case, pressure measurements may be used to identify the timing of the mechanical contraction. Ischemia may be indicated based on a change in a time interval associated with a systolic interval of a ventricle. Ischemia also may be indicated based on an intracardiac electrogram-based indication of ischemia in conjunction with an increase in mean left atrial pressure and/or an increase in the size of a v-wave. | 11-20-2008 |
| 20090018597 | System and Method for Estimating Cardiac Pressure Based on Cardiac Electrical Conduction Delays Using an Implantable Medical Device - Techniques are provided for estimating left atrial pressure (LAP) or other cardiac performance parameters based on measured conduction delays. In particular, LAP is estimated based interventricular conduction delays. Predetermined conversion factors stored within the device are used to convert the various the conduction delays into LAP values or other appropriate cardiac performance parameters. The conversion factors may be, for example, slope and baseline values derived during an initial calibration procedure performed by an external system, such as an external programmer. In some examples, the slope and baseline values may be periodically re-calibrated by the implantable device itself. Techniques are also described for adaptively adjusting pacing parameters based on estimated LAP or other cardiac performance parameters. Still further, techniques are described for estimating conduction delays based on impedance or admittance values and for tracking heart failure therefrom. | 01-15-2009 |
| 20090287267 | System and Method for Estimating Cardiac Pressure Based on Cardiac Electrical Conduction Delays Using an Implantable Medical Device - Techniques are provided for estimating left atrial pressure (LAP) or other cardiac performance parameters based on measured conduction delays. In particular, LAP is estimated based interventricular conduction delays. Predetermined conversion factors stored within the device are used to convert the various the conduction delays into LAP values or other appropriate cardiac performance parameters. The conversion factors may be, for example, slope and baseline values derived during an initial calibration procedure performed by an external system, such as an external programmer. In some examples, the slope and baseline values may be periodically re-calibrated by the implantable device itself. Techniques are also described for adaptively adjusting pacing parameters based on estimated LAP or other cardiac performance parameters. Still further, techniques are described for estimating conduction delays based on impedance or admittance values and for tracking heart failure therefrom. | 11-19-2009 |
