System and method for classifying tachycardia arrhythmias having 1:1 atrial-to-ventricular rhythms
First Claim
1. A system, comprising:
- at least one cardiac lead including at least three electrodes;
control circuitry coupled to the at least three electrodes, where the control circuitry receives a first cardiac signal which includes indications of ventricular depolarizations and a second cardiac signal which includes indications of atrial depolarizations, and where the control circuitry includes;
a ventricular depolarization detector circuit to detect the occurrence of ventricular depolarizations in the first cardiac signal;
an atrial depolarization detector circuit to detect the occurrence of atrial depolarizations in the second cardiac signal;
a cardiac data analyzing circuit coupled to the ventricular depolarization detector circuit and the atrial depolarization detector circuit, where the cardiac data analyzing circuit analyzes ventricular depolarizations for the occurrence of a tachycardia episode, and when the tachycardia episode occurs the cardiac data analyzing circuit analyzes the ventricular depolarizations and the atrial depolarizations to determine whether a one-to-one association of atrial depolarizations to ventricular depolarizations exists;
a cycle length interval circuit coupled to the cardiac data analyzing circuit, where the cycle length interval circuit calculates both first intervals between detected ventricular depolarizations and first predetermined cardiac events and calculates second intervals between detected atrial depolarizations and second predetermined cardiac events when the cardiac data analyzing circuit detects the tachycardia episode having the one-to-one association of atrial depolarizations to ventricular depolarizations; and
a microprocessor coupled to the cycle length interval circuit, where the microprocessor determines a first variability characteristic for a first predetermined series of the first intervals and a second variability characteristic for a second predetermined series of the second intervals and classifies the tachycardia episode as occurring in either an antegrade direction or a retrograde direction based on a comparison of the first variability characteristic and the second variability characteristic.
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Abstract
An implantable cardioverter/defibrillator includes a tachycardia detection system that detects one-to-one (1:1) tachycardia, which is a tachycardia with a one-to-one relationship between atrial and ventricular contractions. When the 1:1 tachycardia is detected, the system discriminates ventricular tachycardia (VT) from supraventricular tachycardia (SVT) based on analysis of a cardiac time interval. Examples of the cardiac time interval include an atrioventricular interval (AVI) and a ventriculoatrial interval (VAI). A template time interval is created during a known normal sinus rhythm. The system measures a tachycardia time interval after detecting the 1:1 tachycardia, and indicates a VT detection if the tachycardia time interval differs from the template time interval by at least a predetermined percentage of the template time interval.
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Citations
15 Claims
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1. A system, comprising:
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at least one cardiac lead including at least three electrodes; control circuitry coupled to the at least three electrodes, where the control circuitry receives a first cardiac signal which includes indications of ventricular depolarizations and a second cardiac signal which includes indications of atrial depolarizations, and where the control circuitry includes; a ventricular depolarization detector circuit to detect the occurrence of ventricular depolarizations in the first cardiac signal; an atrial depolarization detector circuit to detect the occurrence of atrial depolarizations in the second cardiac signal; a cardiac data analyzing circuit coupled to the ventricular depolarization detector circuit and the atrial depolarization detector circuit, where the cardiac data analyzing circuit analyzes ventricular depolarizations for the occurrence of a tachycardia episode, and when the tachycardia episode occurs the cardiac data analyzing circuit analyzes the ventricular depolarizations and the atrial depolarizations to determine whether a one-to-one association of atrial depolarizations to ventricular depolarizations exists; a cycle length interval circuit coupled to the cardiac data analyzing circuit, where the cycle length interval circuit calculates both first intervals between detected ventricular depolarizations and first predetermined cardiac events and calculates second intervals between detected atrial depolarizations and second predetermined cardiac events when the cardiac data analyzing circuit detects the tachycardia episode having the one-to-one association of atrial depolarizations to ventricular depolarizations; and a microprocessor coupled to the cycle length interval circuit, where the microprocessor determines a first variability characteristic for a first predetermined series of the first intervals and a second variability characteristic for a second predetermined series of the second intervals and classifies the tachycardia episode as occurring in either an antegrade direction or a retrograde direction based on a comparison of the first variability characteristic and the second variability characteristic. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method, comprising:
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detecting atrial depolarizations and ventricular depolarizations; detecting a tachycardia episode from the ventricular depolarizations, where the tachycardia episode has a one-to-one association of atrial depolarizations to ventricular depolarizations; during the tachycardia episode that has the one-to-one association of atrial depolarizations to ventricular depolarizations, measuring first intervals between the ventricular depolarizations and first predetermined cardiac events and second intervals between the atrial depolarizations and second predetermined cardiac events; and classifying the tachycardia episode based on a comparison of variability characteristics of a series of the first intervals and a series of the second intervals; and where classifying the tachycardia episode includes calculating a first interval characteristic from the first intervals and a second interval characteristic from the second intervals; and where calculating the first interval characteristic includes calculating a first variance value from the first intervals, calculating the second interval characteristic includes calculating a second variance value from the second intervals, and classifying the tachycardia episode includes classifying the tachycardia episode based on the first variance value and the second variance value; and where the first predetermined cardiac events are subsequent ventricular depolarizations and the second predetermined cardiac events are subsequent atrial depolarizations, where measuring the first intervals includes calculating ventricular—
ventricular (VV)-intervals between the detected ventricular depolarizations and subsequently detected ventricular depolarizations, and measuring the second intervals includes calculating atrial—
atrial (AA)-intervals between the detected atrial depolarizations and subsequently detected atrial depolarizations; andwhere classifying the tachycardia episode includes classifying the tachycardia episode as an antegrade rhythm when the second variance is less than or equal to the first variance. - View Dependent Claims (12)
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13. A method, comprising:
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detecting atrial depolarizations and ventricular depolarizations; detecting a tachycardia episode from the ventricular depolarizations, where the tachycardia episode has a one-to-one association of atrial depolarizations to ventricular depolarizations; during the tachycardia episode that has the one-to-one association of atrial depolarizations to ventricular depolarizations, measuring first intervals between the ventricular depolarizations and first predetermined cardiac events and second intervals between the atrial depolarizations and second predetermined cardiac events; and classifying the tachycardia episode based on a comparison of variability characteristics of a series of the first intervals and a series of the second intervals; and where classifying the tachycardia episode includes calculating a first interval characteristic from the first intervals and a second interval characteristic from the second intervals; and where calculating the first interval characteristic includes calculating a first variance value from the first intervals calculating the second interval characteristic includes calculating a second variance value from the second intervals, and classifying the tachycardia episode includes classifying the tachycardia episode based on the first variance value and the second variance value; and where the first predetermined cardiac events are subsequent atrial depolarizations and the second predetermined cardiac events are subsequent ventricular depolarizations, where measuring the first intervals includes calculating ventricular-atrial (VA)-intervals between the detected ventricular depolarizations and subsequently detected atrial depolarizations, and measuring the second intervals includes calculating atrial-ventricular (AV)-intervals between the detected atrial depolarizations and subsequently detected ventricular depolarizations; and where classifying the tachycardia episode includes classifying the tachycardia episode as an antegrade rhythm when the second variance is less than or equal to the first variance. - View Dependent Claims (14)
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15. A method comprising:
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receiving a first cardiac signal; receiving a second cardiac signal; detecting a tachycardia episode based on the first cardiac signal and the second cardiac signal; selecting a first series of intervals based on predetermined features in the first cardiac signal and the second cardiac signal; selecting a second series of intervals based on predetermined features in the first cardiac signal and the second cardiac signal; determining a first characteristic based on variability of the first series; determining a second characteristic based on variability of the second series; comparing the first characteristic with the second characteristic; and classifying the tachycardia episode based on the comparison; and wherein classifying the tachycardia episode includes classifying the tachycardia episode as an antegrade direction tachycardia episode when the first characteristic has a value greater than the second characteristic.
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Specification