Patent application number | Description | Published |
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 |
20110208077 | SYSTEM AND METHOD FOR EXPLOITING ATRIAL EELCTROCARDIAC PARAMETERS IN ASSESSING LEFT ATRIAL PRESSURE USING AN IMPLANTABLE MEDICAL DEVICE - Techniques are provided for assessing left atrial pressure (LAP) based on atrial electrocardiac signal parameters, particularly intra-atrial conduction delay (IACD) and P-wave duration. In one example, a pacemaker or other implantable device senses an intracardiac electrogram (IEGM) or a subcutaneous electrocardiogram (ECG), from which IACD and P-wave duration are derived. The device tracks changes, if any, in the parameters. A significant increase in either IACD or P-wave duration is associated with an increase in LAP. In some examples, conversion factors are calibrated for use with a particular patient to relate IACD and/or P-wave duration values to LAP values to provide an estimate of actual LAP. The conversion factors are pre-calibrated using LAP measurements obtained using a wedge pressure sensor. In other examples, IACD and P-wave duration are instead used to confirm the detection of an elevation in LAP initially made using impedance signals. Other confirmation parameters are described as well. | 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 |
20120184859 | SYSTEMS AND METHODS FOR CORROBORATING IMPEDANCE-BASED LEFT ATRIAL PRESSURE (LAP) ESTIMATES FOR USE BY AN IMPLANTABLE MEDICAL DEVICE - Various techniques are provided for assessing the reliability of left atrial pressure (LAP) estimates made by an implantable medical device based on impedance values or related electrical values. In one example, various cardioelectric and cardiomechanical parameters are used to corroborate LAP estimation in circumstances where the LAP estimates deviate from an acceptable, satisfactory or otherwise healthy range. The cardioelectric parameters include, e.g.: ST elevation; heart rate (HR); heart rate variability (HRV); T-wave alternans (TWA); QRS waveform parameters; P-wave duration; evoked response (ER) parameters; and intrinsic PV/AV/VV conduction delays. The cardiomechanical parameters include, e.g.: heart rate turbulence (HRT); cardiogenic impedance signals; heart sounds; and non-LAP blood pressure measurements, such as aortic pressure measurements. The device compares the cardioelectric and cardiomechanical parameters against corresponding baseline values to determine whether variations in the parameters corroborate the LAP estimates. If not, the LAP estimates are selectively cancelled or suspended, or the overall procedure is re-calibrated. | 07-19-2012 |
20130184545 | SYSTEM AND METHOD FOR DETECTING PULMONARY CONGESTION BASED ON STROKE VOLUME USING AN IMPLANTABLE MEDICAL DEVICE - Techniques are provided for detecting pulmonary congestion based on an increase in right ventricular (RV) stroke volume over left ventricular (LV) stroke volume. In one example, the device generates an index based on accumulated differences between RV stroke volume and LV stroke volume while RV stroke volume exceeds LV stroke volume, such that the index is indicative of an ongoing imbalance between RV and LV stroke volume. The index is compared to a suitable threshold to detect a severe imbalance indicative of pulmonary edema. Additionally, techniques are described for estimating RV and LV stroke volumes based on pulmonary artery pressure, left atrial pressure, aortic pressure, LV strain or on various intracardiac or extracardiac impedance measurements. | 07-18-2013 |