Thoracic Aortic Aneurysm:
The Walking Time Bomb

The human body is made up of many different systems that allow the body to function in a variety of ways. But in order to keep these systems working properly, the body needs nourishment and exercise. This should include a low-fat, low-cholesterol diet that will aid in the reduction of the plaque (fatty buildup) that narrows the arteries and aid in controlling high blood pressure and high cholesterol. Additionally, to lower many of the causes for maladies within the human body, salt intake need to be reduced and to stop smoking. Those who do not follow these precautions are susceptible to a condition called aortic aneurysm. It is a deadly condition that needs to be attended to as soon as possible.
A thoracic aneurysm is an abnormal ballooning or bulge in the wall of an artery caused by a weakening in the wall of a high pressure artery. The areas within the aorta that an aneurysm is known to occur is the aortic root, aortic arch and the ascending and descending aorta. An aneurysm can occur in anyone of these sections and can grow large enough to rupture which causes severe bleeding inside the chest cavity (Thoracic Aortic Aneurysm, 2012).
Anytime you have a blood vessel with a weakened area that begins to bulge, it has the possibility of rupturing. A majority of aneurysms occur in the aorta, the largest artery in the body which carries oxygen-rich blood away from the heart to all parts of the body. The aorta comes out from the left ventricle of the heart and travels through the chest (thoracic) down into the abdomen where it is termed abdominal aorta (Thoracic Aortic Aneurysm, 2012). The Thoracic Aortic Aneurysm (TAA) accounts for one in four aortic aneurysms. With the aneurysm being in the aorta there is a greater risk of death due to massive internal bleeding. “Sixty percent of thoracic aortic aneurysms involve the aortic root and/or ascending aorta, 40% involve the descending aorta, 10% involve the arch, and 10% involve the thoracoabdominal aorta” (Isselbacher, p. 816, 2005).
About 15,000 Americans die each year from ruptured thoracic aortic aneurysms, but if detected in time, they can usually be repaired with surgery. “Hundreds of thousands of unsuspecting people are walking around with what amounts to a time bomb in the aorta: a weakened portion, or aneurysm, that may rupture and kill them” (Brody, 1994).
To distinguish an aortic aneurysm they have been classified by their shape along with where they appear on the aorta. The aorta wall is made up of three layers: endothelium (inner cellular), media middle (muscular) and the adventitia (tough outer). A true aneurysm contains all three layers. When the inner layers are torn apart from traumatic injuries leaving only the outer layer, it is then classified as pseudoaneurysm. A severe fall or a motor vehicle accident is the major contributors to a thoracic aneurysm. The area that is most common is the proximal descending aorta due to the relatively mobile aortic arch. Sudden decelerations from the front or the side (car accident) along with falls from great heights can cause the aorta to be compressed between the sternum and the spine (Chest Trauma, 2004).
Fusiform aneurysms are classified as true aneurysms with the weakness along an extended section and involving the entire circumference which appears as a bulge. Saccular aneurysms are typically pseudoaneurysms that appear like a blister on the side of the aorta. They are caused by trauma or a penetrating aortic ulcer. The most common aneurysm is the degenerative aneurysm which is a result of the breakdown of the connective tissue and the muscular layer. Some causes for this type of aneurysm is cigarette smoking, high blood pressure or genetics. Dissecting aneurysms are when the aorta begins to tear within its wall causing all three layers to separate causing the wall to weaken and the aorta to grow larger. If the dissecting aneurysm is on the ascending side it is treated with emergency surgery whereas the descending aneurysms will be treated with medication. The dissecting aneurysm is not that common but is the most common of the acute aortic syndromes and if left untreated can be lethal (Aortic Aneurysms, 2012).
Aneurysms signs and symptoms depend upon the location, type and whether or not it interferes with other body structures. Aortic aneurysms are difficult to detect, due to the fact that they may be asymptomatic, although some can develop and become symptomatic. Aortic aneurysms may never rupture, but most will increase over time. It is not until an aneurysm grows large enough to restrict blood flow or rupture that it produces any symptoms (Aortic Aneurysm, 2012). Some aneurysms grow slowly, while others increase at faster rates thus increasing the risk of rupture.
As an aneurysm grows it produces a variety of symptoms including; back pain, tenderness in the abdomen and chest pain (Mayo Clinic staff, 2010). A thoracic aortic aneurysm many not have any symptoms until the aneurysm begins to leak or grow in size. The aortic arch or descending thoracic aneurysm may include symptoms such as: pain in the chest or back, dysphagia due to the pressure on the esophagus, hoarseness due from vocal cord pressure, and wheezing, coughing along with shortness of breath from of the pressure on the trachea (Thoracic Aortic Aneurysm, 2012). “An aortogram (a special set of x-ray images made when dye is injected into the aorta) can identify the aneurysm and any branches of the aorta that may be involved” (Brody, 2012). Severe pain associated with this type of aneurysm could signal a medical emergency, which can be life threatening (Mayo Clinic staff, 2010).
As stated earlier there are three places a thoracic aortic aneurysm can occur are the ascending, descending and aortic arch. The ascending thoracic aneurysm may include signs such as swelling of head and neck due to the pressure on the large blood vessels, and pain radiating from the chest and back into the neck and jaw. Heart failure can also occur when the ascending aneurysm affects the heart valve causing blood to flow back into the heart (Thoracic Aortic Aneurysm, 2012).
Thoracic aneurysms do not discriminate, but are more common in Caucasian individuals who are older than 60 years of age, with high blood pressure and cholesterol, and have participated in years of smoking or chewing tobacco products. Aortic aneurysms tend to be more prevalent in men than women, although with women the risk of rupture is much higher (Mayo Clinic staff, 2010). Atherosclerosis, the hardening of the arteries is the most common cause of a thoracic aortic aneurysm. Other risk factors for a thoracic aneurysm include: Marfan syndrome (a connective tissue disorders), Syphilis or trauma to the chest.
One of the most common ways to detect an aneurysm is during a routine x-ray or computed tomography (CT) scan performed for another reason. Although not all aneurysms are visible, the appearance of an aneurysm on an x-ray can be characterized by the widening of the mediastinal silhouette, tracheal deviation or an enlargement of the aortic knob. Follow up with a CT scan can determine if there is an aneurysm and will also show the exact location (Isselbacher, p. 818, 2005). If your physician suspects that you have an aneurysm additional tests such as magnetic resonance angiography (MRA), echocardiography (an ultrasound of the heart), or an angiography (an x-ray of the blood vessels) may be ordered.
The treatment of thoracic aortic aneurysms varies depending on the size of the aneurysm, the rate of growth, whether or not the aneurysm is leaking, dissected or ruptured and whether the patient is experiencing symptoms such as chest, back, jaw, or neck pain. Treatment can range from medications to surgery.
The progression of an aneurysm must be watched closely which is why once diagnosed, routine follow-up visits with a cardiologist are crucial. Small aneurysms rarely rupture and are usually treated with medications. A cardiologist may recommend Beta-blockers to control blood pressure and lower stress on the aortic wall in turn slowing the growth rate of an aneurysm. Medications such as statins may be prescribed for patients with high cholesterol. If the aneurysm is large or fast growing, surgery is needed to fix it (Mayo Clinic Staff, 2010).
Typically, on average an ascending aorta grows at a rate of .10 cm per year, while a descending aorta grows at a rate of .20 cm annually. Surgery should be performed if an aneurysm increases in size by .4 cm or more in one year. The decision to have surgery should take into account the risk of death, dissection or rupture of the aneurysm compared to the risk of surgery. The chart below shows yearly risk of complications based on aortic aneurysm size. It is recommended that asymptomatic ascending aortic aneurysms be resected at a size of 5.0-5.5 cm. If severe aortic insufficiency is present in the setting of a bicuspid valve, the ascending aorta should be resected when it is 4.5 cm in diameter. Descending thoracic and aortic arch aneurysms typically are resected when they exceed 6.0 cm in diameter (Thoracic Aortic Aneurysms, n.d.).
An aortic dissection is rare, but life threatening and may need surgery. If surgery is not the choice of treatment, the cardiologist will most likely prescribe a beta-blocker, which will decrease the blood pressure of the patient and reduce the likelihood of increasing dissection. A vasodilator may also use to reduce the systolic blood pressure, which decreases the aortic wall stress and the possibility of rupture. “Approximately 2,000 cases of aortic dissection occur yearly in the United States” (Aortic Dissection, 2008).
In cases where an aneurysm ruptures, immediate surgery is necessary. The rupture of an aneurysm causes severe internal bleeding and can be fatal. There are three main surgical options for a thoracic aortic aneurysm and are usually performed under general anesthesia. The repair involves aortic replacement using a stent graft most often made of Dacron material. Dacron is a trademark used for a strong synthetic polyester fabric which can be knitted or woven, woven grafts being more impervious and therefore more common. Collagen is added to the grafts to improve the healing process (Tseng, 2011).
The first of the procedures which is less invasive is known as an endovascular stent graft replacement or EVAR. This relatively new procedure involves feeding a stent through the femoral artery in the groin and through the aorta to the area of the aneurysm. X-ray images guide the surgeon in placing the stent. The graft allows the blood to flow through the stent instead of through the aneurysm. Stents may not be the answer for all patients and depend on various factors, including the location of the aneurysm everybody (Bupa's Health Information Team, 2010).
Open surgery, the most traditional method of treating aneurysms, is major surgery. It involves opening the chest to gain access to the aorta. A surgeon then inserts a graft, which can be a piece of a blood vessel taken from another place in the patient’s body or may be made of a synthetic elastic material similar to a normal aorta. The blood then flows through the graft inside the aorta instead of through the aneurysm. This prevents the aneurysm from growing larger and weakening everybody (Bupa's Health Information Team, 2010).
A third option is keyhole surgery, which involves making two or three small incisions in the chest. A tube-shaped telescopic camera that allows the surgeon to see the aneurysm on a monitor is then inserted through one of the incisions. A graft is passed through one of the other cuts and put into place with specially-designed surgical instruments. Keyhole surgery is less invasive than open surgery but isn't suitable for everybody (Bupa's Health Information Team, 2010).
The recovery period from surgery after a thoracic aortic aneurysm will depend on the condition of the patient. However, the typical time spent in recovery is four to six weeks, including five to eight days in the hospital. If a patient has additional medical conditions that need to be addressed, such as heart, kidney or lung disease, the recovery time may take as long as three months and in some cases longer. It is recommended that after undergoing surgery to repair an aneurysm, one must maintain the same heart-healthy lifestyle led by other heart surgery patients.
There are complications a patient may suffer after thoracic aneurysm surgery. Among them are heart attacks, irregular heartbeats, bleeding, strokes, and paralysis due to injury of the spinal cord, graft infection, and kidney damage. The danger involved will depend on the magnitude of the repair required, the length of the surgery, and the overall general health of the patient (Mayo Clinic Staff, 2010).
The aortic aneurysm has been called the walking time bomb. This is because most people do not even know that they have it until they are checked out for some other reason because most times there are no symptoms. An aortic aneurysm can appear anywhere along the thoracic aorta within any of the layers. A person’s lifestyles, diet, lack of exercise, along with trauma to the chest are all factors that could result in an aneurysm. There are a couple of procedures to repair an aneurysm, either by open chest surgery or endovascular surgery. All in all the best way to prevent an aneurysm is to maintain proper diet and exercise along with stopping the use of tobacco products.

References

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