Abdominal aortic aneurysm أم دم الأبهر البطني
INSTRUCTION Examine this patient's abdomen. This patient presented with low back pain; examine the abdomen. SALIENT FEATURES History · Remember, three quarters of the patients are asymptomatic. · Vague abdominal pain. · History of embolization. · Family history of rupture of abdominal aneurysm. · History of smoking. Examination · Large expansile pulsation along the course of the abdominal aorta. · Auscultate for bruit over the aneurysm and over the femoral pulses. · 'Trash' foot - digital infarcts in patient with easily palpable pulses (suggests either a popliteal or abdominal aneurysmal source of emboli) (BMJ 2000; 320:1193-6). · Examine all peripheral pulses. Proceed as follows: · Tell the examiner that you would like to check the following: - Urine for sugar. - Blood pressure. - Serum cholesterol. · Remember that: -Popliteal artery aneurysms often coexist and, in fact, their presence should prompt the physician to look for an abdominal aortic aneurysm. -Ninety per cent of atherosclerotic abdominal aortic aneurysms are present below the origin of the renal arteries and can involve the aortic bifurcation. -The infrarenal aorta is normally 2 cm in diameter; when it exceeds 4 cm an aneurysm is said to exist. -True arterial aneurysms are defined as a 50% increase in the normal diameter of the vessel. The aneurysmal process may affect any medium or large sized artery. -The vessels most commonly affected are the aorta and iliac arteries, followed by popliteal, femoral and carotid arteries. DIAGNOSIS This patient has a large pulsatile mass in the epigastrium (lesion) due to an aneurysm of the abdominal aorta (aetiology). Read classic reviews on this subject: N Engl J Med 1993; 328:1167; BMJ 2000; 320:1193-6. QUESTIONS Which investigations would you perform to confirm your diagnosis? · B mode ultrasonography of the abdomen - a simple, cheap and accurate screening test. · Large aneurysms require angiography. · Magnetic resonance imaging is useful, particularly as it does not require admin-istration of contrast. · Remember that plain abdominal radiography shows a calcified aneurysmal aortic wall in only half the cases. ADVANCED-LEVEL QUESTIONS How would you manage an abdominal aneurysm? · Pooled data suggest that aortic aneurysms of more than 55 mm carry a high risk of rupture and hence should be referred to the vascular surgeon for surgery if there are no confounding factors that increase the risk of surgery. · The UK small aneurysm trial studied 1090 patients with an aortic diameter of 40-50 mm and found a 30-day mortality of 5.8%, mean annual risk of rupture for small aneurysms of 1%, and no difference in survival between the treatment groups at two, four or six years (Lancet 1998; 352: 1649-55). Smaller aneurysms must be followed up; they enlarge at a rate of about 0.5 cma year. In selected cases an endovascular prosthesis is preferred. What factors predispose to rupture of the abdominal aneurysm? · Diameter of the aneurysm. · History of smoking. · Diastolic blood pressure. · COAD. · Family history of ruptured aneurysm. · Rate of expansion. · Inflammatory aneurysms. What is the prognosis of aneurysms greater than 55 mm? The mortality rate for a patient undergoing elective surgery is less than 5%, whereas that for a ruptured aneurysm is nearly 90%. In 1951, C. Dubost from Paris performed the first successful aortic resection for aneurysm.