It goes under the skin and is wired into the heart that has the ability to monitor your heart rhythms and then if, in fact, you develop an irregularrhythm then the ICD acts to correct it and to restore normal rhythm.
Aspirin can also be used as a long term treatment for those with a history of heart attack and stroke, or who have peripheral arterial disease, stable angina or atrial fibrillation - an irregular heart rhythm.