Patent ID: 7974685

Claim:
A system comprising: an atrial contraction detector circuit, including an atrial rate detector circuit to detect an atrial rate between atrial contractions of a heart; a ventricular contraction detector circuit, including a ventricular rate detector circuit to detect a ventricular rate between ventricular contractions of the heart; a tachyarrhythmia classification circuit, configured to classify a tachyarrhythmia using a rhythm discrimination parameter having a value; and a processor, coupled to the atrial and ventricular contraction detector circuits and the tachyarrhythmia classification circuit, the processor configured to: determine a relationship between the atrial rate and the ventricular rate including comparing a difference between the atrial rate and the ventricular rate to a threshold value to determine whether the atrial rate is substantially equal to the ventricular rate; and when the difference between the atrial rate and the ventricular rate exceeds the threshold value thereby indicating that the atrial rate is not substantially equal to the ventricular rate, adjust the value of the rhythm discrimination parameter using the relationship between the atrial rate and the ventricular rate, including adjusting the value of the rhythm discrimination parameter using both of (1) information about whether the atrial rate exceeds the ventricular rate or vice-versa; and (2) a magnitude of the difference between the atrial rate and the ventricular rate.