THE SOCIETY OF THORACIC SURGEONS:
ALTHOUGH AORTIC DISSECTION IS RELATIVELY UNCOMMON, IT IS THE MOST FREQUENT EMERGENCY RELATED TO THE HUMAN AORTA. IT AFFECTS APPROXIMATELY THREE PEOPLE OUT OF EVERY 100,000 EACH YEAR, MOST OFTEN IN MEN WITH HIGH BLOOD PRESSURE IN THEIR 60S AND 70S.
What is Aortic Dissection?
Aortic dissection occurs when the innermost layer of the aorta (intima) tears and blood surges through the tear. Younger patients with inherited connective tissue disorders, such as Marfan Syndrome, and patients with bicuspid aortic valves (two leaflets on the valve instead of three) also are more likely to develop aortic dissection.
Consider the following analogy: the aorta is like an unopened roll of paper towels. The cardboard would be the intima, the innermost layer of the aorta through which blood flows. The layers of paper towels would be the muscle and connective tissue surrounding the intima (media layer). The plastic wrapper around the paper towels would be the added strength layer (adventitia layer).*
Using the paper towel analogy to describe aortic dissection, a tear would occur in the cardboard tube, causing the blood to plow through both the cardboard and paper towels, where it would create a false channel. The blood would either be contained by the plastic wrapper or the plastic wrapper would burst (i.e., the aorta ruptures).
* Credit for the “paper towel” analogy: Dr. Thomas E. MacGillivray, cardiac surgeon and Chief of Cardiac Surgery and Thoracic Transplant Surgery at Houston Methodist Hospital.
Why do people get aortic dissection?
Aortic dissection may occur for several reasons, including genetics, chronic high blood pressure, high cholesterol, smoking, trauma, and illegal drug use.
Some people are born with an alteration in specific genes that affect development of the aortic wall and predispose the aorta to enlargement and/or dissection. Syndromes that are associated with certain genetic defects include:
Familial Thoracic Aortic Aneurysm
A bicuspid aortic valve is a marker for a connective tissue syndrome and may be associated with valve problems, aortic root aneurysms, and ascending aortic aneurysms. These aneurysms have the potential to result in aortic dissection.
Chronically uncontrolled high blood pressure can put stress on the aortic wall over time and can lead to aneurysm and dissection. Patients with blood vessel disease related to years of high blood pressure, high cholesterol, and smoking can develop a calcification or ulcer of the aorta that may become the site where a dissection occurs.
The aorta also can dissect or rupture from trauma, such as during a high-speed motor vehicle accident or fall from a significant height. Additionally, cocaine and methamphetamine use can increase the likelihood of aortic dissection.
How do I know that I have an aortic dissection?
The most common symptom is severe pain, often described as a tearing or ripping feeling in the chest. The pain may radiate to the back or move down toward the abdomen. Because aortic dissection can affect the aortic valve or blood flow to any of the blood vessels that branch from it, you also can experience various other symptoms that would not necessarily lead you or your physician to suspect a problem with the aorta.
If the arteries that supply blood to the heart (coronary arteries) are affected, you would have chest pain that may seem like a heart attack. If the branches to the brain (carotid arteries) are affected, you would have symptoms of stroke, such as difficulty with speech, inability to move one side of your body, or loss of consciousness.
If the branches to the arms or legs (subclavian or iliofemoral arteries) are affected, you could develop numbness, tingling or pain in your arm(s) or leg(s), or inability to move your arm(s) or leg(s).
If the artery to your intestines (superior mesenteric artery) is affected, you may have nausea, abdominal pain, or bloody bowel movements.
If the arteries to your spinal cord (intercostal and lumbar arteries) are affected, you might not be able to move your legs. Blood flow to the liver and kidneys also can be affected; this would not necessarily cause symptoms but would show up in laboratory studies from a blood sample. Additionally, if the aortic valve becomes severely leaky because of the dissection, you might feel like you can’t breathe.