Atrial defibrillator and method for setting energy threshold values

An implantable atrial defibrillator adapted to be implanted beneath the skin of a patient for applying cardioverting electrical energy to the atria of a patient's heart when the atria are in fibrillation and in need of cardioversion, said atrial defibrillator being selectively operable in a test mode for setting the quantity of the cardioverting electrical energy to a threshold quantity and comprising:

• first sensing means for sensing atrial activity of the heart;
• atrial fibrillation detecting means responsive to said first sensing means for determining when the atria of the heart are in fibrillation and in need of cardioversion and when the atria of the heart are not in fibrillation;
• second sensing means for sensing electrical activations of the heart;
• enable means for selectively rendering said atrial defibrillator in said test mode;
• applying means responsive to said enable means, to said second sensing means, and to said atrial fibrillation detecting means determining that the atria are not in fibrillation for applying first electrical energy to the atria in timed relation to a sensed electrical activation of the heart to induce fibrillation of the atria and responsive to said atrial fibrillation detecting means determining that the atria are in fibrillation for repeatedly applying second electrical energy to the atria until said atrial fibrillation detecting means determines that the atria are not in fibrillation, said applying means increasing the quantity of said second electrical energy with each said repeated application;
• and
• means for storing a value, indicative of the quantity of said second electrical energy last applied to the atria, as said threshold quantity.

An implantable atrial defibrillator adapted to be implanted beneath the skin of a patient for applying cardioverting electrical energy to the atria of a patient's heart when the atria are in fibrillation and in need of cardioversion, a method for setting the quantity of the cardioverting electrical energy to a threshold quantity and comprising the steps of:

• sensing atrial activity of the heart;
• determining responsive to the sensed atrial activity when the atria of the heart are not in fibrillation;
• applying, responsive to determining that the atria are not in fibrillation, first electrical energy to the atria during a predetermined portion of a cardiac cycle of the heart to induce fibrillation of the atria;
• determining that the atria are in fibrillation;
• repeatedly applying second electrical energy to the atria until the atria are not in fibrillation, said last recited applying step including increasing the quantity of said second electrical energy with each said repeated application;
• and
• storing a value, indicative of the quantity of said second electrical energy last applied to the atria, as said threshold quantity.