Your heart continuously pumps blood with an average rate of 70 beats per minute — sending two to three ounces of blood through your vessels with every single beat. Throughout your lifetime, over 40 million gallons (200 million liters) of blood will pass through your blood vessels. Because of all the pressure generated, that can be an awful lot of traffic for your arteries to handle. That’s where the aorta, the largest blood vessel in your organism, comes into play.
The aorta can be anatomically divided into five segments:
- The aortic bulb, which "launches" coronary branches that supply the whole heart muscle
- The ascending aorta
- The aortic arch, giving off branches for the head, neck, and arms
- The descending (thoracic) aorta that gives off branches for the ribs and some of the organs in the chest
- The abdominal aorta, beginning at the diaphragm, gives off branches to major organs
In the lower abdomen, the aorta finally splits into the left and right common iliac arteries, each then subsequently branching to the legs and other organs in the pelvis, supplying them with blood. The average diameter of the aorta is about one inch (or 2.5 cm).
Although the aorta is essentially an artery, its role subjects it far more pressure than any other artery in your body. This is why the aorta is both thicker and larger in diameter than other arteries. Besides that, its walls have to be very elastic and flexible to accept all the blood that exits the heart. Elastic fibers are especially thick in the ascending aorta, where the pressure is highest.
The walls of the aorta consist of three layers:
- The intima (inner layer), which is very smooth to allow uninterrupted blood flow
- The media (middle layer) consists mainly of elastic fibers and very little muscle (which makes it different from other arteries)
- The externa (outer layer), mostly made of collagen and elastic tissue
What is an aortic aneurysm?
The problems with aortic tissue occur when the cells found in the wall of the aorta begin to deteriorate. As a result, the aortic wall can’t expand and compress as it would normally and the aorta loses its flexibility. This weakness allows the aortic wall to expand, or bulge enormously.
Although the condition itself doesn’t always produce symptoms, untreated aneurysms can be life-threatening. As the bulge grows, complications start to appear. They include nerve compressions that can cause numbness or pain. Also, a blood clot forms that can later detach from the arterial wall and cause an embolus (leading to heart attacks, stroke, or distal artery clogs). But the most serious complication is the rupture of the aorta.
What are the types of aortic aneurysms?
When talking about types of aortic aneurysms, aneurysms of the aorta can be classified by type, shape, or location.
Seen from a clinical viewpoint, there are three main types of aortic aneurysms:
- True aneurysm, where the bulge is composed of all three layers of the blood vessel. They are usually located in the abdominal part of the aorta, just before it branches to the common iliac arteries.
- A false aneurysm, also called post traumatic aneurysm, or pseudoaneurysm, is typically formed between the middle and the outer layer of the arterial wall. The blood from the injured artery then passes through these layers, always maintaining communication between the vessel and the pseudoaneurysm.
- Dissecting aneurysm, where only the inner layer is injured, so that blood now flows between the layers, tearing and separating them on its way. As a result, blood now runs through both the regular lumen of the aorta and the newly formed “false” lumen. This ultimately means that organs receive less blood, which can lead to many further complications.
Aneurysms can also be classified by shape:
- Fusiform, more common in the aorta, which bulges out equally on all sides, evenly expanding the lumen of the aorta.
- Saccular, which bulge only on one side, creating a ball-shaped sack. Because it looks like a berry on a thin branch, this type of aneurysm is also called a “berry” aneurysm.
The third classification is according to the location of the aneurysm within the aorta, as different parts of the aorta suffer different pressures, and each have branches for specific body parts. They are classified as:
- Thoracic aorta aneurysm, which includes an ascending aorta aneurysm, aortic arch aneurysm, and descending aorta aneurysm.
- Abdominal aorta aneurysm (AAA), typically located below the arteries that supply the kidneys, although it can form above them.
- Large peripheral artery aneurysm.
Depending on the type and location of the aneurysm, you can expect different symptoms. However, keep in mind that aneurysms can expand to really impressive dimensions without showing any signs or symptoms, at least until they press against an organ or a nerve, or rupture. Based on the location of the rupture, the symptoms usually include sudden and strong pain in your chest, belly, or back. The pain is generally followed by a pulsating feeling in the affected area. Sometimes it can cause dizziness, render you unconscious, or even cause shock and death, because the organs don’t receive enough blood.
About half of the patients who have had an aneurysm rupture die, even if they reach the operating table. For this reason, it is essential to prevent and treat aneurysms before the overall state of the patient becomes critical.
If the aneurysm is small and doesn’t show any symptoms, you should have regular check-ups with your doctor. An ultrasound or CT scan once a year (or every six months in anything shows up suspicious) should be enough to keep your doctors informed about the state of your aorta. Meanwhile, always try to maintain a healthy lifestyle and ditch your bad habits.
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