It is the clinical name for a blueish coloration of the skin that results from a reduction in arterial blood flow in the area. In a heart attack, patients usually have something called peripheral cyanosis, which is a blueish color in their extremities, especially around the hands and feet. They often feel cold, and their pulse may be reduced.
Peripheral cyanosis is the result of vasoconstriction in these arteries. The natural response of the organism in the event of myocardial infarction is to reduce blood circulation to the extremities trying to increase blood circulation in susceptible organs such as the heart, brain, and kidneys. Thus, looking at your hands and feet might be an important part of the physical exam performed by your doctor.