Understand Spontaneous Coronary Artery Dissection (SCAD)

The coronary arteries carry oxygen- and nutrient-rich blood to and around the heart. They are in essence fuel lines to the heart. When the flow of blood through a coronary artery is blocked, the heart is deprived of needed oxygen which will result in chest pain (angina).  If the blockage is severe enough, there can be damage and death to heart tissue which is called a heart attack or myocardial infarction. The majority of heart attacks come from plaque, which has either grown enough to block the artery or has cracked leading to a clot to form on the plaque. The clot then blocks the flow.  

SCAD is completely different. A spontaneous coronary dissection is a tear in the inner lining (called the tunica intima) of the artery.  The artery is composed of several layers, all of which surround where the blood flows which is called the lumen. A lumen is the inside space of a tubular structure, akin to where fuel flows for a fuel line in a car. When this tear occurs, blood flows between the inner and outer layers of the artery, causing further separation of the layers of the artery wall. In essence, the normal lumen of the artery becomes two lumens, one which feeds the downstream muscle (true lumen) and one which ends in a dead end (False lumen). The false lumen can compress the true lumen (where the blood is supposed to be flowing) restricting the amount of blood flowing through it, or even blocking it entirely, and causing a heart attack.