To understand both of these conditions -
aortic aneurysm and
aortic dissections, we need to understand a little about what the aorta is.
Figure 1: The aorta with its different main branches
aorta is the largest blood vessel in the human body and serves as the main artery directing oxygenated blood from the heart to the rest of the body. The aorta arises from the left side of the heart (the left ventricle), arches and moves down through the length of the body till the lower part of the abdomen, where it then divides into two major branches that run down each lower limb.
The aorta and all its branches are called arteries. Arteries have elastic walls that allow them to respond to the pressure caused by the blood ejecting from the left side of the heart. The elastic wall itself has three layers.
aneurysm happens when a section of an artery experiences weakness in its arterial walls. This causes that part of the artery to swell out like a balloon.
An aneurysm can occur congenitally (when someone is born with an aneurysm) or as a result of a disease or an injury to the artery.
aortic aneurysm is when a part of the aorta's wall is weak, causing it to stretch and balloon out. Though an aortic aneurysm may occasionally cause some discomfort, the main concern is that as the wall stretches more, it becomes thinner and poses a risk of rupture. A ruptured aneurysm can be life threatening as it can cause massive internal bleeding.
aortic dissection refers to a tear in the elastic wall of the aorta.
The exact cause of an aortic dissection is not known but some of its risk factors are:
The tear when it occurs is often due to the damage of the inner lining of the aorta and is more common along the part of the aorta that travels in the chest area. When the tear happens in the aortic wall, the layers within the wall are forced apart by the blood entering into these tears. If the tears completely dissect (cut through) the aorta, massive and rapid blood loss occurs. Therefore, an aortic dissection is considered a medical emergency.
The diagnosis of an aortic aneurysm or aortic dissection is similar. There are different methods available to not only diagnose these conditions but to also help doctors to determine the best treatment options and follow-up plans.
CXRs may help to diagnose thoracic aneurysm or dissection.
Although they are not the best available method to diagnose these conditions, it is easily available and can help suggest and alert doctors of an abnormality of the aorta and prompt further tests.
Abdominal X-ray can sometimes diagnose aortic aneurysm but it is not very accurate.
Computed Tomography scans (CT scans), also known as "CAT Scan", is the preferred method of diagnosing an aortic abnormality through imaging.
However, to ensure a better image, a contrast medium (dye) is given intravenously before the image is taken. Therefore, this method may not be used in some patients, such as, those with known allergies or kidney problems, for example.
This is now the standard for preparing and planning patients for surgery (both endovascular and open).
An echocardiogram also known simply as an "ECHO", is basically an ultrasound for your heart that is able to take images of the heart as it pumps.
An echo helps to give a clearer picture of what is happening to the heart and the aorta and is useful especially when evaluating certain parts of the heart and the aorta.
It is also part of the work up to check the heart function before a surgery.
Magnetic resonance imaging (MRI) is similar to a CT scan. However, one of its benefits is that it does not use radiation to capture images. Instead it uses a powerful magnetic field to do so. Another benefit is that the contrast medium (dye) used in an MRI seems to be better tolerated in patients.
Aortic angiography is a procedure, which uses a contrast medium (dye) that is injected into the aorta and x-rays that are taken to determine how blood is flowing inside it.
If aneurysm develops slowly over many years, they are often asymptomatic (no symptoms).
However, if the aneurysm occurs in an artery that is near the surface of your skin, you will notice a growing bulge or mass that seems to throb. These can be painful.
When an aneurysm grows quickly or if it ruptures, the symptoms can occur suddenly. There will be pain and symptoms of shock due to blood loss such as:
Most of the time, the symptoms of an aortic dissection happen suddenly. These include:
Aortic aneurysm treatment depends on the size, location and the patient's state of health.
For example, if your aneurysm is small and there are no symptoms, your doctor will probably recommend a "watch and wait" approach. Here, regular scheduled appointments are made where any changes in the aneurysm is monitored by the various imaging methods such as CT scan or MRI.
However, if the aortic aneurysm is large or grows more than 1 cm per year, then surgery may be recommended for you.
There are various types of aortic surgery that are available to treat aortic aneurysm.
This is the standard surgery when the aortic aneurysm reaches the need for surgery. The procedure involves the replacement of the portion of the aorta that is swollen, with an artificial graft. The graft is made from a material that does not wear out and is sewn in place with a permanent suture material.
Compared to open surgery explained above, endovascular surgery allows for the repair of an aortic aneurysm with less trauma to the aorta, less blood loss and fewer days in intensive care during recovery.
Although it usually benefits those who are at high risk of complications during surgery, it may not be suitable for every person. Your doctor will be able to decide if this form of surgery is the better option for you.
During the procedure, a thin tube (or catheter) is inserted into the blood vessel via an artery in the leg. Attached to the catheter is a graft that is placed where the aneurysm is located using x-ray guidance. Once in place, the graft is expanded. The metal frame of the graft expands like a spring which serves to hold up the walls of the aorta. This graft reinforces the area of the weakened artery wall and prevents the risk of subsequent rupture of the aneurysm. The blood flow is directed away from the aneurysm and flows through the graft instead.
This procedure is done in patients with large aortic aneurysms located in various sections of the aorta. It is a more complex procedure that involves two stages.
Though no surgery or procedure is risk free, aortic surgeries have been performed for many years with good results and limited complications. Your doctor, prior to you giving consent for the surgery, will explain these and other risks in detail.