Thoracic Aortic Dissection

• Type A thoracic dissection involves the ascending aorta and is managed by cardiothoracic surgery.
• Uncomplicated Type B dissection does not involve the ascending aorta and is managed conservatively by cardiology.
• Abdominal aortic dissection is managed by vascular surgeons

Symptoms and clinical signs

• Chest or back pain radiating retrosternally or to neck, arms, interscapular area or abdomen
• Loss of consciousness and collapse
• Dyspnoea
• Initial BP may be elevated, normal or low
• BP discrepancy between limbs may be present
• Pulse deficit, which may be variable affecting any arm or leg combination
• Perfusion deficits can lead to any of the following:
• abdominal pain, bloody diarrhoea, absent bowel sounds
• renal failure
• paraplegia
• limb ischaemia
• Cardiac tamponade or evidence of myocardial infarction (MI) if dissection affects aortic root
• CVA symptoms

Aid to diagnosis of acute aortic dissection (AD)

• Presentation of acute aortic syndromes can be very variable and a high index of suspicion is required
• If typical chest pain, organise urgent CT scan and discuss with cardiology and cardiothoracic surgical team
• The following guidance can help improve diagnostic accuracy and guide investigation

Action

• If patient is haemodynamically unstable with likely aortic dissection – discuss urgently with cardiothoracic surgeon and cardiologist. Meanwhile arrange CT with appropriate monitoring

• Chest X-ray: PA film may show mediastinal widening but is not always present – absence does not exclude the diagnosis
• ECG: may be normal or can show myocardial ischaemia
• U&E, glucose
• FBC, clotting
• Group and save
• D-Dimer
• Arrange contrast CT scan of chest without delay regardless of renal function. CT imaging should extend from the jaw to knee (to assess dissection extent, organ malperfusions, and sites for safe cannulation)

The role of D-Dimer

• If D-dimer is elevated, the suspicion of aortic dissection is increased
• Typically, the level of D-dimer is immediately very high, compared with other disorders in which the D-dimer level increases gradually
• D-dimer yield the highest diagnostic value during the first hour
• If the D-dimer is negative, aortic intra-mural haematoma or penetrating aortic ulcer may still be present

• Nil-by-mouth.
• Do not give antiplatelet or anticoagulation medications
• Refer urgently to cardiothoracic surgeons

Pain and BP

• Control pain initially with intravenous opiates
• Maintain systolic BP between 100–120 mmHg. Give labetalol by IV bolus injection over at least 1 min – see Labetalol and repeat if necessary until systolic BP <120 mmHg
• Once systolic BP 100–120 mmHg, maintain with IV infusion of labetalol – see Labetalol
• If labetalol infusion fails to control BP, ADD IV infusion of glyceryl trinitrate (GTN) [50 mg in 50 mL sodium chloride 0.9% at 0.6 mL/hr (10 microgram/min), increasing to a maximum of 12 mL/hr (200 microgram/min)] – see Glyceryl trinitrate

Surgery

• Surgery is the treatment of choice for acute type A aortic dissection which has a mortality of 50% within the first 48 hr if not operated on
• Despite improvements in surgical and anaesthetic techniques perioperative mortality (25%) and neurological complications (18%) remain high. However, surgery reduces 1-month mortality from 90% to 30%

Type B aortic dissection

• Can be managed medically unless complicated
• Cardiothoracic surgeons consider surgical correction if:
• increasing aortic size (propagation) or increasing haematoma size
• compromise of major branches of the aorta
• impending rupture
• persistent pain despite adequate pain management
• bleeding into the pleural cavity
• development of saccular aneurysm

• Intramural haematomas (IMH) and penetrating atherosclerotic ulcers (PAU) can also present acutely with similar pain to dissection and should be managed in the same way as AD

• Early involvement of ITU/CCU with transfer to the appropriate level 2/3 facility
• Temperature, pulse, BP every 30 min, until clinically stable
• Urine output hourly, until clinically stable

• Rehabilitation from neurological or vascular complications may be necessary before discharge
• Discharge when BP controlled and clinically stable
• Initial follow up in cardiac surgical clinic
• Consider referral to specialised aorta clinic – particularly if any of the following features are present:
• family history of aortic disease or sudden death
• aged ≤55 yr
• bicuspid aortic valve or Marfan's syndrome
• Patients with severe/difficult-to-control hypertension should be referred to a hypertension clinic