Patent ID: 7346388

Claim:
An implantable cardioverter/defibrillator (ICD), comprising: a sensing circuit to sense an atrial electrogram and a ventricular electrogram; an interval measurement circuit, coupled to the sensing circuit, to measure atrial intervals from the atrial electrogram and ventricular intervals from the ventricular electrogram; a tachycardia detection circuit, coupled to the interval measurement circuit, to detect a tachycardia based on at least one of the measured atrial intervals and the measured ventricular intervals; and a detection enhancement circuit including: a rate accuracy enhancement module coupled to the interval measurement circuit, the rate accuracy enhancement module including: a first selection module to select a set of atrial intervals from the measured atrial intervals and a set of ventricular intervals from the measured ventricular intervals, the first selection module including a set size module to determine a size of the set of atrial intervals and a size of the set of ventricular intervals based on at least one of one or more measured atrial intervals and one or more measured ventricular intervals; and a second selection module to select a subset of atrial intervals from the selected set of atrial intervals and a subset of ventricular intervals from the selected set of ventricular intervals, the second selection module including an interval exclusion module adapted to exclude one or more atrial intervals from the set of atrial intervals and one or more ventricular intervals from the set of ventricular intervals according to predetermined exclusion criteria; a rate calculator, coupled to the rate accuracy enhancement module, to calculate at least one average atrial rate based on the subset of atrial intervals and at least one average ventricular rate based on the subset of ventricular intervals; and a tachycardia classification module, coupled to the rate calculator, to classify the detected tachycardia as ventricular tachycardia (VT) when the at least one average ventricular rate is substantially higher than the at least one average atrial rate.