Patent ID: 7203535
Filing Date: 2007-04-10
Classification: A61N

Abstract:
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.