Method and apparatus for discriminating between tachyarrhythmias
First Claim
1. Within an implantable medical device, a method of confirming a ventricular tachycardia sense event declared when the apparent ventricular heart rate exceeds a tachycardia rate comprising:
- sensing the PQRST electrogram of the heart across an internal lead vector defined by a pair of vectorcardiogram sense electrodes implanted in the body and defining an internal lead vector in the body having a vector orientation in relation to reference sagittal, horizontal, and frontal planes of the body;
declaring a ventricular tachycardia sense event when a feature of the PQRST electrogram satisfies ventricular sense event detection criteria characteristic of an R-wave, and is therefore an apparent R-wave, and the interval between successive ventricular sense events satisfies tachycardia rate criteria;
deriving a QRS vectorcardiogram of the QRS segment of the sensed QRST electrogram quantifying the orientation and magnitude of the vector of the QRS wave;
deriving a T-wave vectorcardiogram of the T-wave of the sensed QRST electrogram quantifying the orientation and magnitude of the vector of the T-wave;
determining that the apparent R-wave is a true depolarization R-wave or a re-polarization T-wave satisfying the sense event detection criteria from characteristic features of one or both of the derived QRS vectorcardiogram and T-wave vectorcardiogram; and
confirming the declaration of the ventricular tachycardia sense event when the apparent R-wave is determine to be a true depolarization R-wave.
1 Assignment
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Accused Products
Abstract
Implantable medical devices (IMDs) are adapted for developing a vectorcardiograph (VCG) from signals across pairs of electrodes. Sense amplifiers of the IMD are calibrated to correlate the signals to reference sagittal, horizontal and frontal planes of the body. Polar coordinate data is plotted over the time of occurrence of the sensed PQRST electrogram as at least one of an x-axis vector projected into the reference sagittal plane as a sagittal VCG, a y-axis vector projected into the reference horizontal plane as a horizontal VCG, a z-axis vector projected into the reference frontal plane as a frontal VCG, and an xyz-vector in 3-D space. The VCG loops plotted by each of the vectors can also be derived. Thresholding and template matching techniques determine one or more of the maximum vector magnitude and orientation, average axis vector magnitude and orientation, the loop shape, and the loop area representing a particular heart rhythm.
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Citations
12 Claims
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1. Within an implantable medical device, a method of confirming a ventricular tachycardia sense event declared when the apparent ventricular heart rate exceeds a tachycardia rate comprising:
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sensing the PQRST electrogram of the heart across an internal lead vector defined by a pair of vectorcardiogram sense electrodes implanted in the body and defining an internal lead vector in the body having a vector orientation in relation to reference sagittal, horizontal, and frontal planes of the body;
declaring a ventricular tachycardia sense event when a feature of the PQRST electrogram satisfies ventricular sense event detection criteria characteristic of an R-wave, and is therefore an apparent R-wave, and the interval between successive ventricular sense events satisfies tachycardia rate criteria;
deriving a QRS vectorcardiogram of the QRS segment of the sensed QRST electrogram quantifying the orientation and magnitude of the vector of the QRS wave;
deriving a T-wave vectorcardiogram of the T-wave of the sensed QRST electrogram quantifying the orientation and magnitude of the vector of the T-wave;
determining that the apparent R-wave is a true depolarization R-wave or a re-polarization T-wave satisfying the sense event detection criteria from characteristic features of one or both of the derived QRS vectorcardiogram and T-wave vectorcardiogram; and
confirming the declaration of the ventricular tachycardia sense event when the apparent R-wave is determine to be a true depolarization R-wave. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Within an implantable medical device, apparatus for confirming a ventricular tachycardia sense event declared when the apparent ventricular heart rate exceeds a tachycardia rate comprising:
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a pair of vectorcardiogram sense electrodes implanted in the body and means for defining an internal lead vector in the body having a vector orientation in relation to reference sagittal, horizontal, and frontal planes of the body;
means for sensing the PQRST electrogram of the heart across an internal lead vector defined by means for declaring a ventricular tachycardia sense event when a feature of the PQRST electrogram satisfies ventricular sense event detection criteria characteristic of an R-wave, and is therefore an apparent R-wave, and the interval between successive ventricular sense events satisfies tachycardia rate criteria;
means for deriving a QRS vectorcardiogram of the QRS segment of the sensed QRST electrogram quantifying the orientation and magnitude of the vector of the QRS wave;
means for deriving a T-wave vectorcardiogram of the T-wave of the sensed QRST electrogram quantifying the orientation and magnitude of the vector of the T-wave;
means for determining that the apparent R-wave is a true depolarization R-wave or a re-polarization T-wave satisfying the sense event detection criteria from characteristic features of one or both of the derived QRS vectorcardiogram and T-wave vectorcardiogram; and
means for confirming the declaration of the ventricular tachycardia sense event when the apparent R-wave is determine to be a true depolarization R-wave. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification