Aneurysm & Dissections

Aortic dissection- starts with a tear in the intima of the aortic lining. The tear allows a column of blood under pressure to enter the aortic wall, forming a haematoma which separates the intima from the adventitia and creates a false lumen. Signs and symptoms The typical patient is a man in his 60s with hypertension and sudden onset of chest pain. The majority of patients with aortic dissection, present with a sudden severe pain of the chest or back, classically described as 'ripping'. However, some may describe mild pain in the chest, back or groin, and it is easy to dismiss such cases as musculoskeletal. In aortic dissection, pain is abrupt in onset and maximal at the time of onset. In contrast, the pain associated with acute myocardial infarction starts slowly and gains in intensity with time. It is usually more oppressive and dull. The pain migrates as the dissection progresses. This is also very important. In proximal dissections, the pain is usually retrosternal, but with distal dissections the location is between the scapulae and in the back. Hypertension is typically associated with distal aortic dissection. Although tearing is the classical description, the pain is described as sharp more often than tearing, ripping, or stabbing. Angina due to involvement of the coronary arteries. Paraplegia due to involvement of the spinal arteries. Limb ischaemia due to distal aortic involvement. Neurological deficit due to carotid artery involvement. Pulse deficit may be present initially, may develop, or may occur transiently.  There is a difference in blood pressure in limbs on the right and left side of the body.

Mortality risks of aortic dissection: Aortic rupture has an 80% mortality. Up to 20% die before reaching hospital. The diagnosis is not made until postmortem in 15%. Without surgery (with involvement of the ascending aorta) 40% die within 24 hours and 80% die within two weeks. Although successful surgery increases the chances of survival to about 80%, operative mortality is in the region of 25%.

Complications: Hypotension (due to cardiac tamponade or MI) An aortic diastolic murmur occurs in 50% due to aortic regurgitation.  After a period of pain, cardiac failure may result from gross aortic regurgitation. Cardiac tamponade  (pericardial friction rub, jugular venous distension or a paradoxical pulse) Involvement of the coeliac artery can produce persistent abdominal pain, elevation of acute phase proteins, and increase of lactate dehydrogenase. Transient pulse differences suggest involvement of the brachiocephalic or subclavian arteries. Neurological symptoms may be found. A superior vena cava obstruction syndrome may be seen. When dissection involves the distal aorta, it often involves the renal arteries.

Definition: An arterial aneurysm is a localised abnormal dilatation of an artery due to a weakness in the arterial wall. The artery wall becomes weakened and balloons out. Common sites are: abdominal aorta, iliac artery, popliteal artery, femoral artery, cerebral vasculature (circle of Willis and middle cerebral artery) Relative incidence of abdominal aneurysms: 1.3-12.7% Symptoms: Ruptured AAA presents with a classical triad of pain in the flank or back, hypotension and a pulsatile abdominal mass; however, only about half have the full triad. The patient will complain of the pain and may feel cold, sweaty and faint on standing. The following symptoms are listed with approximate frequency of presentation: Abdominal pain (60%) Back pain (70%) Syncope (30%) Vomiting (20%) Examination A patient with a ruptured aneurysm at any level is likely to look pale and unwell and to be cold and sweaty. The pulse will be rapid, weak and thready. Hypotension is common. With a ruptured AAA there may well be a pulsatile mass in the vicinity of the bifurcation of the aorta. This is a few centimetres above the umbilicus and a little to the left. It may be tender and a bruit may be audible. Bleeding causes peritoneal irritation and it may appear as an acute abdomen. The following findings are listed with approximate frequency: Palpable mass (90%). Tenderness (80%). Systolic blood pressure (BP) below 80 mm Hg (40%). NB: presentation can be atypical, eg intestinal obstruction from haematoma or an apparent irreducible inguinal hernia. Rare presentations are: Severe haematemesis from an aorto-duodenal fistula. A fistula into the inferior vena cava, producing lower limb oedema and high-output cardiac failure. Differentials: The differential diagnosis for ruptured AAA involves other causes of abdominal pain, including acute abdomen.Screening:Screening by ultrasound is feasible to allow early diagnosis. The idea is to offer a single scan to men aged 65. If negative, this effectively rules out abdominal aortic aneurysm (AAA) for life. Benefits: reduction in mortality, because the vast majority of deaths from aortic aneurysms are due to rupture of an undiagnosed aneurysm, which might be prevented by elective treatment.

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Aneurysm