Aortic Aneurysm


The aorta is the largest artery in the human body. It stretches from the aortic valve (from the heart) until the middle third of the abdomen, where it divides into the two common iliac arteries. It carries oxygenated blood necessary for the body’s metabolism.

The aorta is divided into two major segments: thoracic aorta and abdominal aorta. Thoracic aorta has three parts: the ascending aorta, the aortic arch and the descending thoracic aorta. The first segment of the ascending aorta is called the aortic root. From here, the coronary arteries emerge,  which  carry blood to the heart muscle. Abdominal aorta has two segments: suprarenal and infrarenal (segments above and below the arteries which carry blood to the kidneys).images

The dimensions of the aorta differ according to age, sex and body size. The ascending aorta and aortic arch measure about 3cm in diameter; the thoracic descending aorta measures between 2 to 2.3 cm and the abdominal aorta, about 1.7-1.9 cm in the infrarenal segment. Aging leads to a slight general expansion of the aorta (aortic ectasia). It is considered that the maximum diameter of the ascending aorta should not exceed 4 cm. The aortic wall has three layers: the inner layer or intimate;  the middle layer and the outer, called adventitia.

Aortic aneurysm (from Ancient Greek – Aneurysm = expansion) is a pathological dilatation of a segment of the aorta, with a tendency to expansion and rupture. It can affect all segments of the aorta. By consensus, it is considered aneurysm when the diameter of the dilated segment is 50% higher than normal for the area (3 cm for the abdominal aorta and 4.5 cm for the ascending aorta).

Aortic aneurysms are classified in different ways. Considering the form, they are fusiform (when the expansion is symmetrical and affects the entire circumference of the vessel) or sacciforme (when the expansion is asymmetrical and affects only part of the circumference of the aorta). Depending on the affected segment (location), they are called aneurysms of the ascending aorta, of the aortic arch, of the descending thoracic aorta and abdominal aorta aneurysms. If the aneurysm affected both the descending and the abdominal and thoracic aorta, it is called thoracicoabdominal. Aortic aneurysm may be true (when its wall is composed of all three layers) or false (when the aneurysm wall is composed only of external layers like the intramural hematoma = accumulation of blood between the aortic wall layers).

Risk Factors

-smoking: Aortic aneurysms occur more frequently in people who smoke or former smokers (especially aneurysms of the abdominal aorta).

-age: people over 65 were more frequently affected by aortic aneurysms (of the abdominal aorta).

-sex: they occur more frequently in men (about five times more).

atrial hypertension (high blood pressure in the vessels and aorta): untreated, it  leads to dilation of the aorta.

hypercholesterolemia (high level of fats in the blood) increases the risk of aortic aneurysms.

-family history: people who have or have had a family history of aortic aneurysm are at greater risk. This suggests a genetic predisposition. There are certain inherited diseases in which the aneurysm of the aorta occurs (usually the ascending aorta): Marfan syndrome, vascular Ehlers-Danlos syndrome, Loyes-Dietz syndrome.

Symptoms

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Patients with aortic aneurysm are asymptomatic for long periods of time, the disease is often discovered by chance, during investigations for other purposes.

Symptoms usually appear when the aneurysm is large and they are manifested by pain (caused by high blood pressure or compression of the aorta wall surrounding organs) or if complications arise: wall aneurysm thrombosis (blood clot formation inside or that blocks the origins of the vessels that irrigate various organs) or rupture of the wall, called aortic dissection (a serious threatening complication).

In case of aneurysms of the ascending aorta and the aortic annulus, fatigue and dyspnea on exertion are caused by aortic insufficiency.

Diagnosis

The diagnosis of aortic aneurysm is an imagistic one and involves visualization and measurement of the affected segment.

Investigations

– transthoracic cardiac ecography: ascending aorta and aortic arch aneurysms are well seen.

transesophageal cardiac ecography: visualizes the entire thoracic aorta.

– abdominal aortic ecography:  is useful for abdominal aortic aneurysms.

– aortography : is an invasive method that uses dye, radiates and is rarely used.

-radiography: is a painless method, irradiates and detects only the ascending aorta aneurysms.

– Computed Tomography(CT) is useful in measuring the expansion of the aneurysm and its diameter. It has the disadvantage that it radiates and uses dye.

– Nuclear magnetic imaging (MRI) is as useful as CT, is a non-invasive method that does not irradiate and does not require dye. Most centres prefer CT in measuring the extension and diameter of the aneurysm.

Treatment

-in the case of small aortic aneurysms, periodical tracking and correcting the risk factors (quitting smoking, drug therapy of hypertension, lowering the blood cholesterol and treatment of diabetes)

-Avoiding intense physical effort and trauma;

– the drug therapy is suitable for patients with small aneurysms, where there is not a high risk of complications, or for patients with low life expectancy (old age, terminal illness) and high surgical risk. It aims primarily correcting risk factors. It uses different drug classes: beta blockers (metoprolol, nebivolol, atenolol, carvedilol), angiotensin converting enzyme inhibitors (perindopril, enalapril, ramipril, zofenopril), angiotensin receptor blockers (valsartan, telmisartan, irbesartan, candesartan) calcium channel blockers (amlodipine, lecarnidipina) for hypertension; statins (simvastatin, atorvastatin, rosuvastatin) for dyslipidemia. In some studies it was found that treatment with beta blockers or angiotensin receptor blockers reduce the rate of expansion of the aneurysm;

-surgical treatment: it suits patients with great aneurysms, with a high risk for rupture (usually the dissection risk increases very much if the aneurysm is over six centimetres in diameter) or patients with small aneurysms but with complications (dissection, compression, pain). Surgical treatment may be endovascular or through classical approach.

-endovascular treatment: it is inserted into the aorta (through an artery), a device that excludes the aneurysm and after that the portion is linked. This kind of treatment is less invasive, it has lower peri and post-operative risks, hospitalization and recovery take less. It can be used, however, only in some aneurysms of the aorta according to their anatomy (usually for those of the descendant aorta).

Classic surgery (vascular) involves replacing a the portion with the aneurysm with a prosthesis. It has higher risks and recovery and hospitalisation take longer. It it the most commonly used method and it it chosen when the diameter of the aneurysms exceeds 5.5-6 centimetres, regardless of the affected segment ( for asymptomatic and uncomplicated aneurysms)

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Symptomatic or complicated aneurysms are operated regardless of their size. Aneurysms of the ascending aorta in genetic diseases (Marfan syndrome, bicuspid aortic) are operated if the aneurysm’s diameter exceeds 5 cm (there is a higher risk for complications from this type of aneurysm). Patients with aortic aneurysms under 5centimetres in diameter should be checked periodically with ultrasound (every six months) to determine the pace of expansion and the moment surgery is needed.

Complications

Evolution in time for aortic aneurysms is expanding with increased risk of rupture. There is no rule regarding the pace of expansion. Some aneurysms grow slowly and steadily over time, others have long periods of stagnation and then increase sharply. Patients with aortic aneurysm should be checked by a cardiologist and


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  1. March 13, 2015

    […] – Dissecting aneurysm of the aorta […]

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