Diseases Of The Aorta III: Diagnosis, Prognosis And Management Of Aneurysms Of The Aorta
Destruction of the elastic fibres in the midia leads to stretching of the remaining fibrous tissue and dilatation involving all the layers of the aorta. The aneurysms may be fusiform or secular and may involve the thoracic or abdominal portions of the aorta.
75% of all aneurysms involve the abdominal aorta and the commonest site is below the renal arteries. The vast majority are caused by arteriosclerosis. In 60% of cases, there is associated hypertension. Next in frequency to be affected is the descending thoracic aorta. The causes include arteriosclerosis, traumatic false aneurysms, tertiary syphilis and mycotic aneurysms. “The most frequent cause of aneurysms of the ascending aorta is cystic medial necrosis secondary to Marfan’s syndrome. Other causes include Ehler’s Danlos syndrome, hypertension and aging. Syphilis used to be a frequent cause when this disease was more prevalent. Aneurysms of the aortic arch are the least frequent and they are caused by arteriosclerosis of tertiary syphilis.
These depend on the location of the aneurysm, their size and pressure effects. Many are asymptomatic, detected on routine physical examination and/or X-ray examination. Some may present as pulsating mass in front or behind the chest or in the abdomen. The pulsations of the aneurysm lead to painful erosion of adjacent bones such as the vertebrae or the sternum. Aneurysms of the ascending aorta and the arch give rise to pressure effects on neighbouring structures. Complications such as vocal cord paralysis, cough and dysphagia result from pressure on the left recurrent laryngeal nerve, trachea or esophagus respectively. Aneurysm of the arch of the aorta may give rise to “tracheal tug”. This physical sign is elicited by gently pulling up the larynx with the neck extended, when a tug is felt coinciding with the expansile pulsation of the aorta. Untreated, the aneurysms tend to expand and rupture. Thrombosis within the aneurysm leads to embolisation and occlusion of distal vessels.
Aortic Aneurysm In Chest X-ray
Diagramatic Representation Of Aortic Aneurysm
Diagnosis, Prognosis And Management
Thoracic aneurysms are diagnosed by X-ray and fluoroscopy. The expansile pulsation can be seen. The walls of the aneurysm show calcification in many cases of which can be diagnosed on plain X-ray of the abdomen. Ultrasonography helps to assess the size and shape of the aneurysm and to detect clots. It is most useful in assessing abdominal aneurysm. CT scanning can delineate the aneurysm clearly and detect those with risk of rupture. Aortography clearly visualizes the nature of the aneurysm and its contents.
The size of the lesion, presence of associated hypertension and ischemic heart disease and the presence of symptoms determine the prognosis. Abdominal aneurysms bigger than 6cm in diameter tend to rupture (50% in 10 years). Small aneurysms which are asymptomatic have a better prognosis.
Definitive treatment of the aneurysm is surgery which aims at resection and reconstruction with a woven Dacron graft. Surgery is indicated for symptomatic cases and those larger than 6cm. The surgical mortality is 8.5 to 9.5%. Medical management is to treat the underlying cause and associated conditions such as hypertension.
© 2014 Funom Theophilus Makama