How does aortic dissection occur?

• The initiating event is either a primary intimal tear with secondary dissection into the media or a medial hemorrhage that dissects into and disrupts the intima. • The pulsatile aortic flow then dissects along the elastic lamellar plates of the aorta and creates a false lumen. • The dissection usually propagates distally down the descending aorta and into its major branches, but it may propagate proximally. • Distal propagation may be limited by atherosclerotic plaque. In some cases, a secondary distal intimal disruption occurs, resulting in the reentry of blood from the false to the true lumen.