Abstract: An apparatus and a method for discriminating between tachycardias of physiological origin, and those of pathological origin having similar atrial and ventricular rates, are disclosed. The apparatus includes two sensing electrodes for registering the electrograms from the atrium and the ventricle of the heart. There is further included a signal processing element for determining the times of atrial and ventricular events, and an algorithm for classifying the heart rhythm. The algorithm includes a means for discriminating between different types of heart rhythms having overlapping ventricular rates and having similar atrial and ventricular rates. The method utilizes an analysis of the relationships between successive atrial and ventricular intervals (i.e., atrial-atrial (AA), ventricular-ventricular (VV) and atrial-ventricular (AV) intervals) in discriminating between such heart rhythms.

Abstract: An apparatus and a method for discriminating between tachycardias of physiological origin, and those of pathological origin having similar atrial and ventricular rates, are disclosed. The apparatus includes two sensing electrodes for registering the electrograms from the atrium and the ventricle of the heart. There is further included a signal processing element for determining the times of atrial and ventricular events, and an algorithm for classifying the heart rhythm. The algorithm includes a means for discriminating between different types of heart rhythms having overlapping ventricular rates and having similar atrial and ventricular rates. The method utilizes an analysis of the relationships between successive atrial and ventricular intervals (i.e., atrial-atrial (AA), ventricular-ventricular (VV) and atrial-ventricular (AV) intervals) in discriminating between such heart rhythms.

Abstract: An implantable cardioverting/defibrillating pacemaker and method for treating arrhythmias of a patient's heart are disclosed. Bradycardia support pacing is initially provided at a normal standby rate, in the absence of a tachycardia. Upon detection and confirmation of a tachycardia, antitachycardia therapy in the form of antitachycardia pacing pulse therapy and/or cardioversion or defibrillation therapy is delivered to the heart. Thereafter, upon reversion of the tachycardia, bradycardia support pacing is again delivered to the heart but at a greater rate than the earlier normal standby rate and only for a predetermined time period. At the end of such time period, the bradycardia support pacing rate is returned to the normal standby rate, either directly or in decremental steps.

Abstract: A method and apparatus for delivering electrical therapy to the heart are disclosed. The apparatus detects and confirms the arrhythmia. However, during confirmation, if the arrhythmia is present but not too severe, it is allowed to continue in the hope that it will spontaneously revert. The arrhythmia is reconfirmed later and, if it is still present, electrical therapy is delivered to the heart. Thus, for mild arrhythmias, electrical shock therapy is withheld for a specified time period in the hope that the arrhythmia will revert spontaneously. More severe arrhythmias which are not hemodynamically sustaining are immediately electrically shocked in an effort to revert the heart back to normal sinus rhythm.

Abstract: A multiprogrammable, telemetric, implantable defibrillator contains a high energy shock system to revert VT/VF's to normal sinus rhythm and a multi-programmable VVI bradycardia support system. When the apparatus is in an automatic shock sequence, there are two points of reconfirmation: at the programmed minimum time to shock and after the full charge has been reached, or at thirty seconds, whichever comes first. Reconfirmation involves testing the tachycardia detection output (TDO). If the TDO is high, reconfirmation occurs. If the TDO is low, reconfirmation will not occur and the device will subsequently dump the discharge. Two reconfirmations must occur before a shock is delivered to the patient. If the TDO is low at either reconfirmation, the charge will be dumped.