It is known that the second injection is approximately 80-fold more reactogenic with fever, pain, myalgia, etc.  As part of that response, there can be a major surge in blood pressure due to release of catecholamines or stress hormones.[iii]  This increase in the change in pressure over the change in time for each heartbeat is the driving force to initiate the tear in the aorta. Once this happens, there is no turning back, the rip goes down the major blood tube and threatens the blood supply to the spinal cord, vital organs, and legs.

Each patient is different, with some having external rupture resulting in death.  Others require emergency surgery or endovascular stenting to restore blood flow to vital organs.  In the case of the optometrist, he was managed conservatively with medications to control blood pressure. Data from the International Registry of Acute Aortic Dissection (IRAD) indicates he faces a 22% 3-year mortality rate and this is increased by his history of prior aortic aneurysm (HR, 2.17; 95% CI, 1.03 to 4.59; P=0.04).[iv]