What is the diagnosis and management of aortic dissection?

Diagnosis and Management of Aortic Dissection

Computed tomography angiography (CTA) is the recommended first-line imaging modality for diagnosing aortic dissection due to its high sensitivity and specificity (>95%), with management determined by Stanford classification: immediate surgical intervention for Type A dissections and initial medical management with beta-blockers and blood pressure control for uncomplicated Type B dissections. 1

Clinical Presentation and Risk Factors

• Typical symptoms:

  • Severe chest pain (often described as tearing or ripping)
  • Hypotension or syncope
  • May mimic acute myocardial infarction or pulmonary embolism 2

• Major risk factors:

  • Advanced age
  • Male gender
  • Long-term history of arterial hypertension
  • Presence of aortic aneurysm
  • Genetic connective tissue disorders (Marfan, Loeys-Dietz, Ehlers-Danlos syndrome)
  • Bicuspid aortic valves 2

Diagnostic Imaging

Recommended Imaging Algorithm:

1. For stable patients:

   • Proceed directly to CTA chest with IV contrast
   • Consider adding abdomen/pelvis imaging for complete evaluation
   • If CTA is negative but clinical suspicion remains high, consider TEE or MRI as second-line tests 1

2. For unstable patients:

   • Bedside TTE to assess for obvious dissection, pericardial effusion, or aortic regurgitation
   • If available quickly, proceed to TEE for definitive diagnosis
   • CTA if patient can be stabilized for transport 1

3. For patients with contrast contraindication:

   • MRI is preferred if patient is stable
   • Non-contrast CT combined with TEE if MRI unavailable 1

Imaging Modalities Comparison:

Imaging Modality	Sensitivity	Specificity	Key Advantages	Limitations
CTA	>95%	>95%	Rapid, widely available, evaluates entire aorta	Requires contrast, radiation exposure
TEE	99%	89%	Bedside availability, good for unstable patients	"Blind spot" in distal ascending aorta, operator-dependent
MRI	~100%	~100%	Highest accuracy, no radiation	Limited availability in emergencies, longer acquisition time
TTE	59-80%	-	Bedside screening tool	Limited sensitivity [1]

Critical Diagnostic Goals:

• Confirm diagnosis
• Classify dissection type (Stanford A or B)
• Differentiate true and false lumen
• Localize intimal tears
• Assess side branch involvement
• Detect aortic regurgitation
• Identify extravasation or effusions 3

Management

Stanford Type A (Involving Ascending Aorta):

• Immediate surgical intervention is required 1
• For hemodynamically unstable patients:
  • Intubation and ventilation
  • TEE as the sole diagnostic procedure before calling surgeon
  • Surgery based on findings of cardiac tamponade by TTE
  • Avoid pericardiocentesis as it may cause recurrent bleeding 3

Stanford Type B (Limited to Descending Aorta):

• Initial medical management for uncomplicated cases
• Endovascular intervention (TEVAR) for complicated cases 1

Medical Management:

• Blood pressure and heart rate control:

  • Target systolic BP: 100-120 mmHg
  • Target heart rate: ≤60 beats/min 1

• Beta-blockers are mandatory first-line treatment:

  • Options include propranolol, esmolol, metoprolol, atenolol, and labetalol
  • Initial dose titrated to achieve target heart rate and blood pressure 3, 1

• Vasodilators (e.g., sodium nitroprusside):

  • Only after adequate beta-blockade
  • Initial dose 0.25 μg/kg/min, titrated to maintain systolic BP between 100-120 mmHg 3, 1

• Volume management if hypotensive:

  • Rule out blood sequestration in false lumen, pleural or pericardial space 3

Long-term Management and Follow-up

• Imaging follow-up:

  • 1,3,6, and 12 months, then yearly if stable 1

• Blood pressure control:

  • Maintain below 135/80 mmHg long-term
  • Continue beta-blockers as preferred agents 1

• Risk reduction strategies:

  • Statin therapy
  • Genetic counseling and family screening (three generations) if hereditary disorder is suspected 1

Common Pitfalls and Caveats

• Using multiple imaging techniques unnecessarily can lead to dangerous time delays; one definitive test is usually sufficient 3
• False-positive TEE findings are more common in the ascending aorta segment (specificity 78.8% vs. MRI 100%) 4
• Pericardiocentesis in cardiac tamponade may cause recurrent bleeding and should be avoided before surgery 3
• Laboratory testing plays a minor role in diagnosis but can help exclude other conditions 3
• Differentiating between true and false lumen is crucial for management decisions; the true lumen is typically smaller with systolic expansion, while the false lumen is often larger and may contain thrombus 1