Aorta dissection is a tear in the inner layer of a weakened area of your aorta. The main artery of the body, supplying oxygenated blood to the circulatory system is called aorta. An aortic dissection begins abruptly when a tear occurs in the inner layer of a weakened area of your aorta. Blood surges through the tear, causing the inner and middle layers to separate (dissect). As diverted blood flows between the tissue layers, the normal blood flow to parts of your body may be slowed or stopped, or the aorta may rupture completely. Aortic dissection is a life-threatening condition that can cause sudden death if it is not recognized and quickly treated. Treatment includes several types of surgeries and medication
Where is the aorta?
The aorta runs throughout your torso. It begins at the main pumping chamber of your heart (the left ventricle), extends up through the front middle of your chest, arches from front to back under the base of your neck, then travels downward along the front of your spine — through your chest (thoracic aorta) and abdomen (abdominal aorta) — before branching just below your navel to two other arteries called the right and left common iliac arteries. Your aorta is the main artery that delivers oxygen and nutrient-rich blood from your heart to the rest of your body. The wall of your aorta is made up of three tissue layers — an inner layer (intima), middle layer (media) and outer layer (adventitia).
Types of Aortic dissection
There are two main types of aortic dissection: Stanford Type A Aortic Dissection and Stanford Type B Aortic Dissection.
Stanford Type A Aortic Dissection: This type of dissection occurs in the first part of the aorta, closer to the heart, and can be immediately life-threatening. It usually requires emergency surgery to repair or replace the first segment of the aorta where the tear started (ascending aorta +/- the arch and/or aortic valve).
Stanford Type B Aortic Dissection: This type of tear begins farther down the aorta (descending aorta beyond the arch), and farther from the heart. Like the type A dissection, this usually extends from the descending aorta into the abdominal segment (abdominal aorta), but doesn’t involve the first part of the aorta in the front of the chest. Surgery may or may not be needed immediately, depending on exactly where the dissection is located and if it is or isn’t cutting off blood flow to your organs. These operations usually can be performed with a stent-graft device inserted into the aorta.
Another classification system (DeBakey Classification) defines dissection by three types. Type 1 originates in the ascending aorta and extends through the downstream aorta. Type 2 originates and is limited to the ascending aorta (both would be considered Stanford Type A). Type 3 originates in the descending aorta and extends downward (similar to Type B).
Signs and symptoms of aortic dissection
The most common characteristic signs and symptoms of aortic dissection is its abrupt start. It can happen at any time, while doing anything, or at rest or when you’re sleeping.
It includes sudden severe, sharp pain in your chest or upper back, also described as a tearing, stabbing or ripping feeling, Shortness of breath, fainting or dizziness, low blood pressure, rapid weak pulse, heavy sweating, confusion, loss of vision, stroke symptoms, including weakness or paralysis on one side of your body, trouble talking. About 40% of patients die immediately from complete rupture and bleeding out from the aorta. If you have any of the above symptoms of aortic dissection, seek emergency care.
What causes aortic dissection?
Aortic dissection happens because there is an underlying, slow breakdown of the cells that make up the walls of your aorta. The breakdown has likely been going on silently for many years before the weakened area of the aortic wall finally gives way, resulting in a tear, which leads to the aortic dissection.
Why does the aortic wall weaken in some people? It’s believed that most aortic dissections are caused by an underlying vulnerability that may be inherited. In others, the stress to the aortic wall from constant high blood pressure can weaken the aorta wall in susceptible people, resulting in a tear and dissection.
Aortic dissection in the ascending aorta (the section closest to the heart where the pressure is the highest) is nearly two times more common than those that occur in the descending aorta. Tears in the aorta typically occur in areas where the stress on the wall of the aorta is highest.
Factors increasing risk of developing aortic dissection
Factors that can increase your risk of developing aortic dissection includes:
· ongoing high blood pressure (hypertension). This is the most important risk factor. High blood pressure causes direct damage to the layers of aortic tissue, causing loss of elastic fibers, breakdown of the wall structure and increased wall stiffness.
· Atherosclerosis (or buildup of plaque in the arteries)/high cholesterol and smoking.
· Aortic aneurysm: This is an abnormal enlargement or bulge in the aortic wall.
· Aortic valve disease.
· Congenital (“born with”) heart conditions like a bicuspid aortic valve (has two leaflets instead of the normal three).
· Connective tissue disorders, such as Marfan syndrome and Ehlers –Danlos syndrome. These are genetically linked problems that can be passed down to family members.
· Other hereditary thoracic aortic conditions that primarily affect the aorta that are also genetically caused.
· Family history of aortic dissection.
· Vasculitis specifically aortitis. This inflammatory disease affects the body’s blood vessels.
· Traumatic injury to the chest (e.g., after a high-speed car crash or serious fall from a height of > 20 feet).
· Age between 50 and 65 years. The aortic wall loses its elasticity with age.
· Being pregnant and having high blood pressure during delivery, activities that extend periods of high blood pressure, such as cocaine or amphetamine use.
· Strenuous powerlifting may increase the speed of development of aneurysms or dissection in susceptible people.
Cold weather and aortic rupture or dissection
Several studies have reported a seasonal variation in the incidence of in aortic rupture or dissection, the incidence of aortic dissection and rapture were found to be higher in winter time than in summer, The underlying cause is unknown, but hypertension and tobacco smoking are predisposing factors to aortic aneurysm rupture.
Exposure to tobacco smoke is known to be greater indoors in cold weather and there is a winter peak of blood pressure in hypertensive patients. A relatively high positive correlation was found between the incidence of acute aortic dissection and the mean atmospheric pressure in some of the studies.
Winter is also characterized by pro-thrombotic state. Fibrinogen levels demonstrate wide seasonal variation, increasing up to 23% during the colder months. Moreover, activation of the sympathetic nervous system and secretion of catecholamine are increased in response to cold temperatures. This could result in an increase in blood pressure through increased heart rate and peripheral vascular resistance. This enhances the forces that act to produce wall deformation, and increase friction and shear stress on the internal surface. The consequent vascular damage may progress, culminating in arterial dissection and rupture of the aorta.
Can aortic dissection be prevented?
Many of the factors that increase the risk of developing aortic dissection can’t be changed, such as being born with certain heart conditions, connective tissue disorders, or genetic triggers associated with having a family history of aortic dissection. However, like many other medical diseases and conditions, you can decrease some of your risks by changing the risk factors that can be modified.
These risks include: lowering high blood pressure to the goal of 120/80 mm/Hg with medication, dietary changes and other measures recommended by your healthcare provider, quitting smoking/using tobacco products and maintaining a healthy weight, wearing your seat belt to prevent injury to your chest in case of an accident. Seeing your healthcare provider for regularly scheduled check-ups and any other times you experience a change in your health. It’s important for first-blood relatives of a person who had an aortic dissection to be screened for their risk of aortic disease. They can be closely followed and treated before an aortic event occurs.