Defibrillation:A medical procedure to restore normal heart rhythms by delivering an electric shock to the heart.

Defibrillator:Any medical device that has the ability to provide an electric shock to restore normal heart rhythms.

Dyspnea:Shortness of breath; occurs normally during intense physical exertion or at high altitude.

Dysrhythmia:An abnormal heart rhythm. Also known as arrhythmia.