摘要:
Systems and methods for improving hemodynamic data interpretation by accounting for the effects of patient posture is disclosed. In certain embodiments, a posture signal is acquired and used to categorize hemodynamic data according to posture to facilitate distinguishing posture-related changes in acquired hemodynamic data from those due to pathophysiologic changes. Posture information may be used to normalize data acquired in various postures to facilitate interpretation of such data. Baseline measurements of hemodynamic data acquired in various postures may also be used to subsequently detect changes in patient posture without the need for an implanted posture sensor.
摘要:
An implantable medical device system including a physiological sensor detects signal artifact in a signal waveform acquired by the sensor. Features of individual waveforms in the sensor signal are extracted. Sample waveforms are classified by expert observation into at least two classes including an artifact class. A distribution range for each of the extracted features from the sample waveforms is determined for each of the classes. Waveform classification criteria are established in response to the determined distribution ranges.
摘要:
The present invention provides an apparatus and method for monitoring muscle function based on an index derived from a pressure or force signal. The muscle function index is derived from an instantaneous muscle stiffness ratio computed as the ratio of the first time derivative of the pressure or force waveform to the corresponding instantaneous pressure or force. The instantaneous stiffness ratio, Ė/E(t), is in units of 1/sec and relates to the rate of strong bond formation and will be influenced by calcium handling properties of the muscle fibers and the intracellular calcium concentration. As such, an index derived from Ė/E(t) provides a measure of the inotropic status of the muscle.
摘要:
A method for estimating pulmonary artery diastolic pressure, for a single heart beat, includes establishing a time window for sampling and storing pressure data points from a right ventricular pressure transducer. The time window may be established according to predetermined parameters and/or according to one or more triggering events. An approximate time at which the pulmonary artery valve opens is determined, either via the sampled pressure data points, or via another form of more direct monitoring, during the time window, in order to estimate the pulmonary artery diastolic pressure. A plurality of sets of N pressure data points may be collected, from the sampled data, and, for each collected set, a weighted sum is calculated. Each weighted sum may be employed to evaluate a quality of the sampled data and/or to estimate the pulmonary artery diastolic pressure, if the more direct monitoring of the pulmonary artery valve is not employed.
摘要:
A system and method of determining hemodynamic parameters uses sensed ventricular blood pressure during a portion of ventricular pressure waveform following peak pressure. An estimated arterial diastolic pressure is based upon an amplitude of the sensed ventricular pressure corresponding to a time at which a first derivative of ventricular pressure as a function of time is at a minimum (dP/dtmin). Fill parameters such as isovolumetric relaxation constant, ventricular suction pressure, atrial kick pressure, and transvalve pressure gradient are derived from measured pressures representing minimum ventricular pressure, ventricular diastolic pressure, and diastasis pressure.
摘要:
A medical device system including a physiological sensor is configured to perform a method for detecting signal artifact in a signal waveform acquired by the sensor. A signal waveform is sensed in a patient using the physiological sensor and a fiducial point associated with the sensed waveform is identified. A point value is established using the fiducial point. Signal artifact is detected in response to the established point value and an established threshold, and at least a portion of the signal waveform is rejected in response to detecting signal artifact.
摘要:
An implantable medical device system including a physiological sensor detects signal artifact in a signal waveform acquired by the sensor. Features of individual waveforms in the sensor signal are extracted. Sample waveforms are classified by expert observation into at least two classes including an artifact class. A distribution range for each of the extracted features from the sample waveforms is determined for each of the classes. Waveform classification criteria are established in response to the determined distribution ranges.
摘要:
A medical device system including a physiological sensor is configured to perform a method for detecting signal artifact in a signal waveform acquired by the sensor. A signal waveform is sensed in a patient using the physiological sensor and a fiducial point associated with the sensed waveform is identified. A point value is established using the fiducial point. Signal artifact is detected in response to the established point value and an established threshold, and at least a portion of the signal waveform is rejected in response to detecting signal artifact.
摘要:
The present invention provides a system and method for estimating a blood flow waveform contour from a pressure signal. An arterial or ventricular pressure signal is acquired from a pressure sensor. Landmark points are identified on the pressure waveform that correspond to features of a flow waveform. In one embodiment, the landmark pressure waveform points correspond to the onset of flow, the peak flow, and the end of the systolic ejection phase. The landmark pressure waveform points define a contour that approximates the flow contour. Beat-by-beat flow contour estimation can be performed to allow computation of flow-related hemodynamic parameters such as stroke volume or cardiac output for use in patient monitoring and/or therapy management.
摘要:
A system and method for deliverying an ablation therapy that includes delivering the ablation therapy, delivering drive signals to establish a drive signal vector fields, determining impedance signals in response to the drive signals, determining a first impedance parameter in response to the first impedance signal and a second impedance parameter in response to the second impedance signal, determining whether there is a change in a hemodynamic status of the tissue subsequent to delivery of the ablation therapy in response to the first impedance parameter and the second impedance parameter, and adjusting delivery of the ablation therapy in response to determining whether there is a change in a hemodynamic status of the tissue.