Aortic dissection

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Key Recommendations

Suspect aortic dissection if the patient presents with chest, back, or abdominal pain that has an abrupt onset, is severe in intensity, or is described as sharp' or 'stabbing' and maximal at onset, particularly if they have any high-risk conditions such as:[2][15]

Marfan syndrome (or other connective tissue diseases)[18]
A family history of aortic disease
Known aortic valve disease or thoracic aortic aneurysm
Previous aortic manipulation (including cardiac surgery)[18]

Always take a comprehensive acute history;missing the diagnosis of aortic dissection may be catastrophic.[15] Although a typical patient with aortic dissection is a male in their 50s, always consider the diagnosis in younger patients even if they have no risk factors.

Always organise ECG, chest x-ray (if the patient’s clinical status allows), and blood tests (to detect complications of aortic dissection or other differentials) initially.[2][6][18] The European Society of Cardiology recommends transthoracic echocardiography (TTE) should also be used as an initial investigation.[2][30] However, TTE is not widely available in many emergency departments in the UK.[2][18] Further imaging for definitive diagnosis is also required urgently; computed tomography (CT) is used as first line (and as an alternative to TTE).[14] Trans-oesophageal echocardiography (TOE) and magnetic resonance imaging (MRI) are alternatives.[2][14][18]

Choice of imaging will depend on the patient’s haemodynamic status, the likelihood of aortic dissection, and local availability and expertise.[2]

Full recommendations

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History

Marfan syndrome (or other connective tissue diseases)[18]
A family history of aortic disease
Known aortic valve disease or thoracic aortic aneurysm
Previous aortic manipulation (including cardiac surgery)[18]

Other risk factors include:

Hypertension[18]
- This is the most important predisposing factor for aortic dissection; it has been reported in 77% of patients with aortic dissection and is often poorly controlled.[16]
Male sex[18]
Older age[18]
Recent history of heavy lifting[18]
Use of cocaine[18]

Always take a comprehensive acute history.

Practical tip

Missing the diagnosis of aortic dissection may be catastrophic. Although a typical patient with aortic dissection is a male patient in their 50s, always consider the diagnosis in younger patients even if they have no risk factors.

Chest pain is the most common symptom.[2][18]

Although the classic textbook description is of acute 'tearing' or 'ripping' pain, patients more commonly report the abrupt onset of severe 'sharp' or 'stabbing' pain, maximal at onset.[6]
The pain associated with aortic dissection may be located retrosternally, interscapularly, or in the lower back.
Anterior chest pain is typically associated with an ascending dissection; interscapular pain usually occurs with a descending dissection.
Pain may migrate through the thorax or abdomen, and the location of pain may change with time as the dissection extends.[18]

A minority of patients present with syncope, or without pain. It is important to recognise that no single symptom of aortic dissection is pathognomonic for the condition, as there is overlap with cardiac, pulmonary, abdominal, and musculoskeletal disorders.[15]

Symptoms of visceral or extremity ischaemia may also be present.

If the patient presents with an incidental finding of chronic dissection on imaging, ask about:[2]

History of a previous acute pain event. However, acute chest pain may also indicate rupture.
Symptoms related to an enlarging dissection (such as hoarseness or new onset of chest pain)

Physical examination

Assess the patient urgently for signs of shock, heart failure, and cardiac tamponade. See Shock, Acute heart failure, and Cardiac tamponade.

However, be aware that some patients with dissection may be haemodynamically stable.[6]

Check for evidence of a perfusion deficit, which includes:

A pulse deficit (reduction or absence of a pulse)[2]
- A pulse deficit is particularly common in a proximal dissection affecting the aortic arch.[15]
- The deficit may be unilateral or bilateral depending on the level of the intimal flap.
- A pulse deficit may also feature in more distal aortic dissections (e.g., of the descending aorta) but these are less common than in more proximal dissections.
- A pulse difference in the lower limbs may also be evident, and in some cases may lead to acute limb ischaemia.
Systolic blood pressure difference between the patient’s arms[2]
- Measure blood pressure in both arms. A difference in systolic blood pressure of greater than 20 mmHg between the two arms is a key sign of aortic dissection.[6]
A focal neurological deficit (in conjunction with pain), which includes:
- Paraesthesia
- Weakness
- Paraplegia

Auscultate the chest; a diastolic decrescendo murmur may be heard which indicates aortic insufficiency.

Other features of aortic dissection include:

Reduced conscious level
A left pleural effusion - see Pleural effusion.

If a patient presents with an incidental finding of chronic dissection, check for chronic malperfusion (abdominal pain, claudication).[2]

Investigations

Choice of investigations for diagnostic work-up of acute dissection is based on the patient’s haemodynamic status, likelihood of aortic dissection, and local availability and expertise.[2] Consider a formal assessment of the patient’s pre-test probability of aortic dissection - see Pre-test probability of aortic dissection below.[2]

Initially, all patients should have ECG (to rule out ST-elevation myocardial infarction), chest x-ray (if the patient’s clinical status allows), and blood tests (to detect complications of aortic dissection or other differentials).[2][6][18]
The European Society of Cardiology recommends that transthoracic echocardiography (TTE) should also be used as an initial investigation.[2][18] However, TTE is not widely available in emergency departments in the UK. In practice, computed tomography (CT) may be used initially if the patient is haemodynamically stable and TTE is unavailable or inconclusive.
- A protocol of non-enhanced CT, followed by contrast-enhanced CT angiography is recommended.[2][18]
- The accuracy of CT in the diagnosis of aortic dissection is high with sensitivity and specificity ranging around 98% to100%.[31]
If the patient is haemodynamically unstable, seek help from a senior colleague and organise urgent TTE.[2][32] Confirm the diagnosis using CT.[14] Trans-oesophageal echocardiography (TOE) is an alternative to CT.[2][14]
If the patient is haemodynamically stable and you have a high suspicion of dissection, organise urgent CT for definitive diagnosis.[14] TOE and MRI are alternatives.[2][14][18] Consider other investigations (such as D-dimer, high-sensitivity troponin) initially if you have a low clinical suspicion of aortic dissection.[2]

If the patient presents with an incidental finding of chronic dissection (such as mediastinal widening or prominent aortic knob on chest x-ray), diagnosis is confirmed by cross-sectional imaging such as contrast-enhanced CT, TOE, or MRI.[2]

More info: Pre-test probability of aortic dissection

The European Society of Cardiology recommends an assessment of the patient’s pre-test probability of having aortic dissection to determine choice of investigations for diagnostic work-up.[2] However, this approach has not been validated and is not always used in practice; check your local hospital protocols.[2]

The assessment of pre-test probability was proposed by the American College of Cardiology/American Heart Association (AHA) in a 2010 guideline on thoracic aortic disease (no longer available) and is based on the presence of any high-risk features of aortic dissection (see table below).[2] Classify the patient’s probability of aortic dissection as:[2]

Low if they have no high-risk features
Intermediate if they have any single high-risk feature
High if they have two or more high-risk features

[Figure caption and citation for the preceding image starts]: High-risk features of aortic dissectionCreated by the BMJ Knowledge Centre [Citation ends].

There are specific recommendations according to the patient’s pre-test probability. For example, if the patient’s pre-test probability is:[2]

High: refer the patient immediately to the surgical team and arrange expedited imaging with either trans-oesophageal echocardiography (TOE), CT, or MRI. TOE is preferred if the patient is haemodynamically unstable.
Intermediate: if you have ruled out alternative causes on ECG and chest x-ray (such as ST-elevation myocardial infarction), arrange expedited imaging with either TOE, CT, or MRI.
Low: investigate other possible causes first. If there is unexplained hypotension or a widened mediastinum on chest x-ray, consider TOE, CT, or MRI based on the individual clinical scenario, but particularly if the patient is older, has risk factors for aortic disease, or has syncope.

ECG

Always perform an ECG in any patient with acute chest pain to rule out ST-elevation myocardial infarction.[2][18] See ST-elevation myocardial infarction.

However, be aware that myocardial ischaemia or infarction may be present in 10% to 15% of patients with aortic dissection, which can mask the diagnosis of dissection.[2] This may be due to:

Aortic false lumen expansion causing compression or obliteration of the coronary ostia
Propagation of the dissection into the coronary arteries

Echocardiography

Organise TTE for all patients with suspected acute aortic dissection, depending on local availability and expertise.[2][18] If the patient is haemodynamically unstable, get help from a senior colleague and organise immediate TTE.[2][32]

Practical tip

In the UK, TTE is not available in many emergency departments and may give poor quality images.[18] In practice, organise CT if TTE is unavailable or inconclusive and the patient is haemodynamically stable.

Consider TOE for definitive diagnosis of acute aortic dissection in addition to TTE, depending on local expertise and availability.[2]

For type A dissections (ascending), TOE may be performed in the ICU or operating theatre to confirm the diagnosis and better evaluate the aortic valve.
Sensitivity and specificity for TOE are higher than for TTE.
CT and MRI are alternatives, depending on local availability and the patient’s haemodynamic status.[2]

TOE can also be used to confirm the diagnosis of chronic dissection.[2][Figure caption and citation for the preceding image starts]: Trans-oesophageal echocardiography (transverse aortic section) showing a circumferential dissection of the ascending aorta in a 30-year-old patient with features of Marfan's syndromeBouzas-Mosquera A, Solla-Buceta M, Fojón-Polanco S. Circumferential aortic dissection. BMJ Case Reports 2009; doi:10.1136/bcr.2007.049908 [Citation ends]. Trans-oesophageal echocardiography (transverse aortic section) showing a circumferential dissection of the ascending aorta in a 30-year-old patient with features of Marfan's syndrome

Chest x-ray

Order a chest x-ray for all patients, if the clinical situation allows.[6]

If chest x-ray shows widening of the mediastinum or pleural effusion, this can indicate aortic dissection.[14] Organise further definitive imaging with CT. [14] TOE and MRI are alternatives.[2][33] However, if you have a high suspicion of aortic dissection, do not delay definitive imaging for aortic dissection, even if the chest x-ray is normal.[6]

Chest x-ray is of limited value for diagnosis of aortic dissection, particularly if the dissection is confined to the ascending aorta; it is normal in up to 40% of patients with aortic dissection.[2][18][34]
Chest x-ray may also show other causes of acute chest pain.[2]

Computed tomography (CT)

Use urgent CT as first-line imaging for definitive diagnosis of aortic dissection.[14] TOE and MRI are alternatives, depending on local expertise and availability and the patient’s haemodynamic status.[2][18]

In practice, CT may also be used as initial imaging for suspected aortic dissection instead of TTE if this is unavailable or inconclusive, and the patient is haemodynamically stable.

A protocol of non-enhanced CT, followed by contrast-enhanced CT angiography is recommended.[2] This should include CT of the chest, abdomen, and pelvis to visualise the extent of the dissection.

[Figure caption and citation for the preceding image starts]: CT scan showing dissecting aneurysm in a 45-year-old patient with Marfan syndrome experiencing chest pain [Citation ends].[Figure caption and citation for the preceding image starts]: CT of a 71-year-old man showing type II dissecting aneurysm of the ascending aorta. Haematoma around the proximal segment of the ascending aorta (panels A-D) compressed the right pulmonary artery, almost occluding its patency and limiting the perfusion of the reciprocal lung [Citation ends].

Blood tests

Order a D-dimer (preferably point-of-care) if you have a low clinical suspicion of aortic dissection.[2]

Despite a high sensitivity, D-dimer is not recommended as the sole screening tool for acute aortic dissection; while negative D-dimer may be helpful to rule out aortic dissection in a patient with a low clinical suspicion of dissection, a positive D-dimer lacks specificity when used in isolation.[35][36]
However, D-dimer is useful when considering the differential diagnosis (e.g., pulmonary embolism).[18][37]

Request a group and save +/- crossmatch if surgical intervention/transfusion is necessary.

Order the following blood tests in all patients to detect complications of aortic dissection (such as ischaemia) or other differentials:[2]

Full blood count
C-reactive protein
High sensitivity troponin
Creatinine
Liver function tests
Lactate
Blood gas
Creatine kinase
Procalcitonin

More info: Biomarkers

Several biomarkers show potential to assist in the diagnosis of aortic dissection, including smooth muscle myosin, calponin, matrix metalloproteinase 8, and soluble elastin fragments. These relate to injury of:

The vascular endothelial or smooth muscle cells (smooth muscle myosin)
The vascular interstitium (calponin, matrix metalloproteinase 8)
The elastic laminae (soluble elastin fragments).

However, none of these have currently been validated and they are not in use in clinical practice.[38]

Further investigations

Magnetic resonance angiogram

Magnetic resonance angiogram is the most accurate, sensitive, and specific test for aortic dissection, but is rarely used in the acute setting because it is more difficult to obtain than CT.[2][14][18] It should only be used if the patient is haemodynamically stable; CT and TOE are alternatives depending on local expertise and availability.[2][14][18]

Intravascular ultrasound

If the patient has a type B dissection (descending) and surgery is required, intra-operative intravascular ultrasound helps define the morphology of the dissection and assists in the treatment plan, particularly during endovascular treatment.[2][14][18]

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