http://www.nhlbi.nih.gov/health/dci/Diseases/hpl/hpl_what.html
National Heart, Lung, and Blood Institute, National Institutes of Health
This publication discusses palpitations (pal-pi-TA-shuns), which are feelings that your heart is skipping a beat, fluttering, or beating too hard or fast. You may have these feelings in your chest, throat, or neck. The page links to additional information about palpitations, including causes, who is at risk, signs and symptoms, diagnosis, treatments, and prevention.