Plaque — made of fat, cholesterol, and calcium — gradually builds up in your arteries, narrowing their lumen, throughout your life.
This irreversible process, which slowly progresses virtually since the day you were born, is called atherosclerosis. This process can be accelerated by genetic factors, or by leading an unhealthy lifestyle. For instance, eating junk food, cigarette smoking, and an inactive lifestyle are risk factors not only for atherosclerosis, but for almost every other cardiovascular disease.
The deterioration of the largest artery in your body – the aorta, which carries blood from the heart to other parts of your body, can ultimately lead to serious complications, and even premature death.
Atherosclerosis, alongside infections, blunt traumas, and various connective tissue diseases can all lead to reduced flexibility of the aorta. Blood continues to flow through the, now less flexible, aorta, while weak spots form in its wall.
Further damage of these weak spots leads to permanent dilatation of that part of the aorta, which Is called an aortic aneurysm. An aortic aneurysm is a permanent local enlargement of the aorta, where the aortic diameter is 50 percent larger than usual. Every part of the aorta can be affected by these changes, and for that reason, we differentiate between thoracic and abdominal aortic aneurysms.
Although aortic aneurysms, along with these complications can be surgically treated, survival rate of patients with these conditions is still poor. Therefore, timely diagnosis and proper treatment of aortic disease are essential when talking about the life quality of these patients.
There are four main complications related to the aortic aneurysm.
1. Compression
Large aneurysms may compress any nearby structure, but most commonly the roots of spinal nerves, causing numbness, or even pain. For example, when talking about abdominal aortic aneurysms, the characteristic symptom is back pain spreading to the legs, called sciatica. Because of the pulsations that aorta normally makes, sometimes even the vertebral bodies can be damaged.
Depending on the location, other structures or organs may be affected:
- A thoracic aortic aneurysm can compress the heart, preventing its normal function, or even lungs and airways, causing shortness of breath or coughing. Compression on the esophagus may present issues when swallowing food, and compressed vocal cords manifest in hoarseness.
- Am abdominal aortic aneurysm may also compress the small or the large bowel, or any other abdominal organ, as well as the surrounding blood vessels, ultimately preventing normal blood flow, which potentially leads to organ failure.
2/3. Thrombosis and embolization
In every aneurysm, the blood flows in a turbulent fashion, meaning that it is no longer moving fast and straight forward like it used to, but swirls instead in a chaotic way. Since the aortic wall is already injured, during this process, platelets in the blood are activated, which stick to the wall of the inside of the aortic wall or any blood chamber, eventually forming a blood clot – thrombus.
However, an embolus may block any blood vessel in its way, restricting blood supply, and therefore a shortage of oxygen, required for the normal functioning of any body part, finally resulting in death of the tissue in question. This process is called ischemia. Depending on which artery the embolus clogged, different symptoms may ensue. For example, embolization of large arteries that supply the legs may lead to amputation, whereas embolization of brain arteries manifest in stroke.
Other than that, microorganisms, such as viruses and bacteria may inhabit the space between the thrombi and the arterial wall, primarily because of reduced blood flow. Unfortunately, due to this inflammation, a great number of aneurysms are susceptible to infection, which other than creating further complications, also present a problem regarding surgical therapy and its risks.
4. Rupture
The most fatal complication regarding aortic aneurysms is the aortic rupture. If the aneurysms happens to burst, a hemorrhagic shock occurs due to the massive bleeding. Unless immediately treated, the patient can die within several minutes, which is why roughly half of the patients, unfortunately, don’t even reach the hospital alive.
Statistically speaking, aortic rupture is a significant cause of death, taking the 15th place as the overall cause of death in the USA, or the 10th place, if regarding only men older than 50.
The probability of aortic rupture is related, but not exclusive, to several factors:
- The diameter of the aneurysm
- Contributing risk factors
- Other diseases related to the cardiorespiratory system, such as high arterial blood pressure and chronic obstructive lung disease.
The weakest part of the aortic wall, and therefore, the place aneurysm will most likely develop, can happen on any part of the aorta. When aortic rupture occurs, there are two main scenarios:
- If the anterior (front) wall of the aorta bursts, the patient can easily die, even if treated quickly, because of massive bleeding which leads to a hypovolemic shock.
- If the posterior (rear) wall of the aorta happens to burst, the spine and other firm nearby structures will act as a natural barrier, preventing blood spilling into the abdominal cavity, and redirecting it towards the loose connective tissue located nearby. Due to these “lucky” circumstances, the patient, although in a bad general condition, is able survive for a couple more days, elevating the chances of a successful surgical procedure. Urgent aortic repair surgeries are infamous for their higher complication rate, with more than 30 percent mortality, even in the greatest medical centers in the world.
The aortic lumen may also communicate with the bowels, so if it bursts, the blood will end up in the digestive tract. This rare complication is known as an aortoenteric fistula. Similarly, an aortocaval fistula is possible, where the aneurysm erodes into the inferior vena cava.