Abstract: An arrhythmia control system and method having automatic determination of the tachycardia confirmation interval. The interval is dynamically set at the minimum of an absolute detection interval and a value calculated as a function of either average sinus interval or tachycardia cycle length or both. The continued presence or the reversion of a pathologic tachycardia can be reliably confirmed, particularly when the patient experiences an elevated heart rate due to, for example, exercise, prior to onset of the tachycardia.

Abstract: An apparatus and method for tachyarrhythmia reversion uses multiple sensitivities programmed for automatic operation. A first (medium) sensitivity is used normally for the detection of sinus rhythm and ventricular tachycardia. A second (higher) sensitivity is designed for differentiating ventricular fibrillation from asystole. A third (lower) sensitivity can also be programmed into the device to differentiate between R-waves and high amplitude current of injury T-waves which may occur post shock. Following the delivery of antitachycardia therapy in the form of either antitachycardia pacing therapy or cardioversion shock therapy, there is a pause, or post therapy pacing delay for a period of time prior to the commencement of bradycardia support pacing. The magnitude of the delay period is substantially greater than the normal bradycardia support pacing standby interval.

Abstract: Apparatus and method for treating tachyarrhythmias wherein the presence of a patient tachyarrhythmia is detected and a first antitachyarrhythmia therapy (antitachycardia pacing) is given at a first energy level. The haemodynamic condition of the patient is measured and a length of time to therapy switchover is continually derived during the application of the first antitachyarrhythmia therapy. The length of time to switchover is a function of the haemodynamic condition of the patient. When the time following detection of the patient tachyarrhythmia exceeds the length of time to switchover, a second antitachyarrhythmia therapy (a high energy shock) at a second energy level is provided. The average cardiac cycle length may be used as an indicator of the haemodynamic condition.