Description: a bluish discoloration in the skin, usually in the fingers, toes, lips, or ears, caused by an insufficient oxygen supply in the bloodstream.  Because generally a severe cardiac or lung problem exists if cyanosis is present, generally cyanosis only occurs in the presence of other symptoms.

Some causes related to cardiovascular disease: Cyanosis can be caused by any cardiac disease that produces a profound decrease in the cardiac output, most commonly cardiomyopathy.

Some causes related to other disorders: Severe lung disease, such as emphysema, severe asthma, or pulmonary embolus (blood clot in the lungs) can produce cyanosis.  

Significance: Because cyanosis almost always indicates significant heart or lung problems, it always needs to be evaluated immediately.

Links to heart failure