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Abdominal aortic aneurysm

Introduction

For introduction, etiology, and classification, see the corresponding pathology 2 topic.

Clinical features

Non-ruptured abdominal aortic aneurysm (AAA) is asymptomatic. They may be discovered incidentally, during screening, or on routine physical examination as a pulsatile abdominal mass or abdominal bruit.

Ruptured AAA is a different story. The mortality is 80%, and only 50% ever reach the hospital alive. Anterior ruptures into the abdominal cavity have the highest mortality and rarely reach the hospital alive. Posterior ruptures into the retroperitoneum limits bleeding somewhat, having a lower mortality.

Less than 1/3 of patients with rupture have a known history of AAA. The classical triad involves severe acute abdominal pain, a pulsatile abdominal mass, and haemodynamic instability. A symptomatic AAA is an indication of threatening rupture, including abdominal pain and tender AAA on palaption.

Cullen’s sign (periumbilical ecchymosis) and Grey-Turner sign (flank ecchymosis) are signs of ruptured AAA.

Diagnosis and evaluation

Palpation for a pulsatile abdominal mass is sensitive for normal-weighted people with larger aneurysms, but the larger the person’s abdominal circumference and the smaller the aneurysm, the lower the sensitivity.

Diagnosis is based on imaging which shows an aneurysmal dilation > 50% of the normal diameter, or > 3 cm. Imaging may be achieved with ultrasound or CT.

Treatment

Conservative treatment involves regular surveillance with ultrasound (1 – 3x a year), normalisation of blood pressure, smoking cessation, and removal of other risk factors. This is indicated for asymptomatic AAAs which are < 5,5 cm.

Elective surgery is indicated for aneurysms which are > 5,5 cm, or which expand > 1 cm per year. Emergency surgery is indicated for ruptured AAA. Symptomatic (threatening) AAA must also be treated immediately.

Surgery may be endovascular or open. Endovascular aneurysm repair (EVAR) is preferred. Entry to the aorta is achieved through the femoral or iliac arteries. An expandable stent graft is place inside the lumen of the AAA.

Thoracic aortic aneurysm

Introduction

For introduction, etiology, and classification, see the corresponding pathology 2 topic.

Clinical features

Thoracic aortic aneurysms (TAA) are often asymptomatic but may cause symptoms of compression of adjacent structures. Symptoms may include chest pain, back pain, hoarseness, coughing, and dysphagia.

Ruptured TAA causes severe pain and haemodynamic instability.

Diagnosis and evaluation

X-ray is not used in the evaluation of TAA, but several findings on chest x-ray may suggest TAA, most notably widened mediastinum and enlarged aortic knob.

CT/MR angiography is the gold standard for diagnosis of TAA, which shows an aneurysm > 50% of the normal diameter.

Treatment

The management of TAA is similar as for AAA. Surgery is indicated for symptomatic TAA of any size and asymptomatic TAA > 5,5 cm.

Conservative treatment involves regular surveillance with CT or MRI (1 – 3x a year), normalisation of blood pressure, smoking cessation, and removal of other risk factors. Surgery may be endovascular or open.

Aortic dissection

Introduction

For introduction, etiology, and classification, see the corresponding pathology 2 topic.

Clinical features

The typical symptom is a sudden, severe, ripping/tearing form of pain in the chest or back, between the shoulder blades. There may be additional symptoms due to ischaemia of major branches of the aorta or affection of other structures, including:

• Myocardial infarction – due to involvement of right coronary artery
• Heart failure, aortic regurgitation – due to involvement of the aortic valve
• Cardiac tamponade – due to involvement of pericardium
• Ischaemic stroke or syncope – due to involvement of carotid or brachiocephalic
• Paraplaegia – due to involvement of spinal/vertebral arteries
• Upper extremity pulselessness, hypotension – due to involvement of subclavian artery
• Mesenteric ischaemia – due to involvement of coeliac or mesenteric arteries
• Haemothorax

Patient may present with either hypertension or hypotension. Involvement of the subclavian artery may cause falsely low blood pressure when measured at the affected arm. A pulse deficit in one arm is suspicious for the diagnosis. A new diastolic murmur may be a sign of aortic regurgitation due to dissection of the aortic valve.

Diagnosis and evaluation

X-ray may be the initial evaluation and may show widened mediastinum and it may be normal.

The gold standard is CT angiography. Visualisation of two lumen or an intimal dissection flap gives the diagnosis. Echocardiography should always be performed to look for cardiac complications.

ECG should always be performed to look for inferior AMI.

Treatment

So-called anti-impulse therapy, involving medical treatment to decrease BP and HR (which reduces stress on the aortic wall), is always indicated. This involves beta blockers and vasodilators (nitroprusside/nicardipine).

Emergency surgery is indicated for Stanford type A dissections, and Stanford type B dissections with complications. Uncomplicated Stanford type B dissections has lower mortality when treated conservatively rather than with surgery.

Surgery involves the replacement of the affected part of the aorta with a prosthesis, or the insertion of a stent graft, or a combination of the two. An affected aortic valve must be replaced.

Possible procedures include Bentall procedure, Frozen elephant trunk, etc.