An ECG signal is acquired in multiple channels, and sources of interference are filtered from the signals. A covariance matrix is then formed with the channels of data. The invention then employs matrix mathematics to discover a set of eigenvectors that organize the variability of data in a multi-dimensional space along new directions, orthogonal to each other and ranked in order of significance. For each eigenvector, a corresponding eigenvalue is calculated. In addition, coefficients are calculated which correspond to the portion of each eigenvector that is necessary to reconstruct each original vector. From the eigenvector solution of the covariance matrix, the angles between the eigenvectors and the original vectors are determined. The eigenvector coefficients and the angles between the eigenvectors and the original vectors are related by a cosine relationship. The angles calculated for each particular ECG test are compared to a reference set of angles to determine whether the electrodes are placed in the standard ECG electrode placement, an alternative electrode placement, or an incorrect electrode placement.
The two ECG channels are graphed as an X-Y pair where the X coordinate is the voltage in a first ECG channel and the Y coordinate is the voltage in a second ECG channel. Because neither of the coordinates is a measure of time, the system and method can collect ECG data over an extended period and collapse the data into a single display region.
Cardiac monitoring and/or stimulation methods and systems that provide one or more of monitoring, diagnosing, defibrillation, and pacing. Cardiac signal separation is employed to detect, monitor, track, and/or trend closed-loop cardiac resynchronization therapy using cardiac activation sequence information. Devices and methods involve sensing a plurality of composite cardiac signals using a plurality of electrodes, the electrodes configured for implantation in a patient. A source separation is performed using the sensed plurality of composite cardiac signals, producing one or more cardiac signal vectors associated with all or a portion of one or more cardiac activation sequences. A cardiac resynchronization therapy is adjusted using one or both of the one or more cardiac signal vectors and the signals associated with the one or more cardiac signal vectors. In further embodiments, the cardiac resynchronization therapy may be initiated, terminated, or one or more parameters of the resynchronization therapy may be altered.
Cardiac monitoring and/or stimulation methods and systems that provide one or more of monitoring, diagnosing, defibrillation, and pacing. Cardiac signal separation is employed for automatic capture verification using cardiac activation sequence information. Devices and methods sense composite cardiac signals using implantable electrodes. A source separation is performed using the composite signals. One or more signal vectors are produced that are associated with all or a portion of one or more cardiac activation sequences based on the source separation. A cardiac response to the pacing pulses is classified using characteristics associated with cardiac signal vectors and the signals associated with the vectors. Further embodiments may involve classifying the cardiac response as capture or non-capture, fusion or intrinsic cardiac activity. The characteristics may include an angle or an angle change of the cardiac signal vectors, such as a predetermined range of angles of the one or more cardiac signal vectors.
