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Aortic Dissection

RCEM Learning: Aortic Dissection 2014 ESC Guidelines on the diagnosis and treatment of aortic diseases: Document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult 2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

Background Information

Aortic dissection is a life-threatening condition:
  • Due to a tear in the aortic intima → blood to flow between layers of the vessel wall.
  • This creates a false lumen which can compromise blood flow and potentially rupture.

The 2 most common classification system for aortic dissection is Stanford and DeBakey. The Stanford classification is more important, as it is used to guide management and urgency.

The Stanford classification depends on whether the ascending aorta is involved or not:
  • Type A: any dissection that involves the ascending aorta (irrespective of the site of tear)
  • Type B: any dissection that does not involve the ascending aorta, including ones that involve the aortic arch

Some other sources also put emphasis on the site of the initial tear (proximal or distal to left subclavian artery).
Both the ESC and AHA guidelines focus on the involvement of the ascending aorta to guide classification and treatment urgency.

 

The DeBakey classification depends on the origin of the tear and the extent of the dissection:
  • Type I: tear originates in the ascending aorta + extends distally to involve the aortic arch +/- descending aorta
  • Type II: tear confined to the ascending aorta
  • Type III: tear originates in the descending thoracic aorta +/- extend distally
    • Type IIIa: tear confined to the descending thoracic aorta
    • Type IIIb: tear originates in the descending thoracic aorta + extend distally beyond the diaphragm

 

Patients typically present with a sudden onset of:
  • Severe tearing / ripping / sharp chest pain (most frequent symptom)
  • Back pain
Possible examination findings:
  • Pulse deficits
  • Features of aortic regurgitation
Other concurrent presentation / complications depending on the affected vessel:
  • Coronary artery → myocardial infarction
  • Carotid artery → stroke
  • Subclavian artery → acute upper limb ischaemia
  • Coeliac / mesenteric artery → bowel ischaemia
  • Renal artery → haematuria
  • Spinal artery → painless paraplegia
  • Iliac artery → acute lower limb ischaemia

Type A is more likely to present with anterior chest pain.
Type B is more likely to present with back or abdominal pain.
Note there is a significant overlap of presentation.

Guidelines

The following are based on ESC Guidelines.

  • D-dimer (can be elevated but not diagnostic alone)
  • ECG
  • Chest X-ray
    • Widen mediastinum (non-specific)
    • Pleural effusion (haemothorax)

  • Unstable patients → 1st line: TOE
    • If TOE provides a clear diagnosis, CT angiography may not be required immediately)
    • TOE has a role in excluding important complications like cardiac tamponade too in unstable patients
  • Stable patients → 1st line: CT angiography
Confirmatory test: CT angiography 

All patients: blood pressure control
Definitive management depends on the type of aortic dissection:
  • Type A: urgent open surgical repair
  • Type B:
    • Medical management is sufficient in most patients
    • Endovascular repair (TEVAR) may be required in complicated type B dissection or high-risk case

ESC guidelines recommend a systolic BP target of <120 mmHg:
  • Adequate pain management 
  • 1st line: IV beta blockers ( esmolol or labetalol)
    • Alternative to beta blockers: rate limiting CCBs 
  • 2nd line: vasodilators
    • Sodium nitroprusside
    • Calcium channel blockers
Vasodilators should only be added once the heart rate is well controlled with beta blocker to prevent reflex tachycardia

Labetalol is the historic agent of choice to control blood pressure in aortic dissection. However, it has a relatively long half-life of 3-5 hours.
RCEM states that esmolol is the treatment of choice due to its fast onset of action (<60 sec) and short half-life (9 min)
Both ESC and ACC/AHA guidelines do not explicitly state a preference between labetalol and esmolol. Both are considered effective 1st line treatment.
The choice between the two may depend on the clinical situation and depends on the patient’s specific needs.

References

Author: Laila Moharram
Editor:
Reviewer: