Ventritex, Inc.

Anthony Nathan

Benjamin D Pless

Michael B Sweeney

Roger Winkle

A method is disclosed for combined cardiac pacing and defibrillating with an implanted pacer/defibrillator having sensing and pacing leads connected to the atrium and the ventricle. P-waves and R-waves are sensed, and a V-V timer and a V-A timer are reset if an R-wave is sensed. If an R-wave is sensed during the V-V timer interval, a pacing stimulus to the ventricle is inhibited. If a P-wave is sensed during the V-A timer interval, a pacing stimulus to the atrium is inhibited. If an R-wave is sensed during the V-V timer interval, arrhythmia therapy is provided if an arrhythmia is determined to be present. If the sensed ventricular rate is greater than a selected tachycardia rate but is less than a selected fibrillation rate, than a determination is made whether the sensed atrial rate is greater than a selected fibrillation rate, and if so, the V-V and V-A timers are reset, but if the sensed atrial rate is not greater than a selected fibrillation rate, then arrhythmia therapy is provided. If an arrhythmia is present, the charging of a capacitor commences but if the arrhythmia ceases, the charging discontinues. If the capacitor is charged and the arrhythmia is still present, then a shock is delivered to the heart during a time period that is outside the vulnerable zones of the atrium and the ventricle.

Method for combined cardiac pacing and defibrillation

A method is disclosed for combined cardiac pacing and defibrillating with an implanted pacer/defibrillator having sensing and pacing leads connected to the atrium and the ventricle. P-waves and R-waves are sensed, and V--V timer and a V--A timer are reset if an R-wave is sensed. If an R-wave is sensed during the V--V timer interval, a pacing stimulus to the ventricle is inhibited. If a P-wave is sensed during the V--A timer interval, a pacing stimulus to the atrium is inhibited. In an R-wave is sensed during the V--V timer interval, arrhythmia therapy is provided if an arrhythmia is determined to be present. If the sensed ventricular rate is greater than a selected tachycardia rate but is less than a selected fibrillation rate, then a determination is made whether the sensed atrial rate is greater than a selected fibrillation rate, and if so, the V--V and V--A timers are reset, but if the sensed atrial rate is not greater than a selected fibrillation rate, then arrhythmia therapy is provided. If an arrhythmia is present, the charging of a capacitor commences but if the arrhythmia ceases, the charging discontinues. If the capacitor is charged and the arrhythmia is still present, then a shock is delivered to the heart during a time period that is outside the vulnerable zones of the atrium and the ventricle.

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Bushey Heath, United Kingdom

Anthony Nathan