| Patent application number | Description | Published |
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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 |
| 20110208083 | DEVICE AND METHOD FOR ADJUSTING IMPEDANCE BASED ON POSTURE OF A PATIENT - An implantable medical device includes electrodes that are configured to be positioned within at least one of a heart and a chest wall of a patient. The device also includes an impedance measurement module, a patient position sensor, and a correction module. The impedance measurement module measures an impedance vector between a predetermined combination of the electrodes. The patient position sensor determines at least one of a posture and an activity level of the patient. The correction module adjusts the impedance vector based on the at least one of the posture and the activity level of the patient. | 08-25-2011 |
| 20120035493 | NEAR FIELD-BASED SYSTEMS AND METHODS FOR ASSESSING IMPEDANCE AND ADMITTANCE FOR USE WITH AN IMPLANTABLE MEDICAL DEVICE - A new model is provided for understanding and exploiting impedance or admittance values measured by implantable medical devices, such as pacemakers or cardiac resynchronization devices (CRTs.) The device measures impedance along vectors extending through tissues of the patient between various pairs of electrodes. The device then converts the vector-based impedance measurements into near-field individual electrode-based impedance values. This is accomplished, in at least some examples, by converting the vector-based impedance measurements into a set of linear equations to be solved while ignoring far-field contributions to the impedance measurements. The device solves the linear equations to determine the near-field impedance values for the individual electrodes, which are representative of the impedance of tissues in the vicinity of the electrodes. The device then performs or controls various device functions based on the near-field values, such as analyzing selected near-field values to detect heart failure or pulmonary edema. | 02-09-2012 |
| 20120035495 | SYSTEMS AND METHODS FOR EXPLOITING NEAR-FIELD IMPEDANCE AND ADMITTANCE FOR USE WITH IMPLANTABLE MEDICAL DEVICES - Various techniques are provided for use with an implantable medical device for exploiting near-field impedance/admittance. Examples include techniques for assessing heart chamber disequilibrium, detecting chamber volumes and pressures, calibrating near-field-based left atrial pressure (LAP) estimation procedures and for assessing the recovery from injury at the electrode-tissue interface. In one particular example, the implantable device assesses the degree of concordance between the left ventricle (LV) and the right ventricle (RV) by quantifying a degree of scatter between LV and RV near-field admittance values. An increase in RV admittance is indicative of RV failure, an increase in LV admittance is indicative of LV failure, and an increase in both LV and RV admittance is indicative of biventricular failure. | 02-09-2012 |
| 20120035681 | SYSTEMS AND METHODS FOR ESTIMATING LEFT ATRIAL PRESSURE (LAP) IN PATIENTS WITH ACUTE MITRAL VALVE REGURGITATION FOR USE BY AN IMPLANTABLE MEDICAL DEVICE - Various techniques are provided for use with an implantable medical device for estimating cardiac pressure within a patient based on admittance (or related electrical values such as impedance or conductance) that takes into account the presence of acute MR within the patient. Briefly, the device detects an indication of acute MR, if occurring within the patient. The device also applies electrical fields to tissues of the patient and measures electrical parameters influenced by the electrical field, such as admittance, impedance or conductance. The device then estimates cardiac pressure within the patient based on the measured electrical parameter and the indication of acute MR. In one example, different linear correlation functions are used to convert admittance values to left atrial pressure (LAP) values depending upon the presence or absence of acute MR within the patient. | 02-09-2012 |
