What is a vessel dissection?

Vessel Dissection: Definition, Types, and Management

A vessel dissection is a tear in the inner lining (intima) of an artery that allows blood to flow between the layers of the vessel wall, creating a false lumen separate from the true lumen, which can lead to vessel occlusion, aneurysmal dilation, rupture, or end-organ ischemia. 1

Pathophysiology

Vessel dissection occurs when blood enters the arterial wall through an intimal tear, creating:

• True lumen: The normal arterial channel
• False lumen: The new channel formed between the layers of the vessel wall
• Intimal flap: The layer separating the true and false lumens

The dissection can propagate:

• Antegrade: When the tear is proximal to the distal end of the dissection
• Retrograde: When the tear is located distal to the proximal end of the dissection 1

Types of Vessel Dissections

By Location:

1. Aortic Dissection

   • Type A (Stanford): Involves the ascending aorta
   • Type B (Stanford): Limited to the descending aorta
   • Type I (DeBakey): Involves ascending and descending aorta
   • Type II (DeBakey): Limited to ascending aorta
   • Type III (DeBakey): Limited to descending aorta 1

2. Carotid and Vertebral Artery Dissection

   • Common presentation includes head and neck pain with Horner's syndrome
   • May lead to TIA or stroke 2

3. Coronary Artery Dissection

   • Can mimic symptoms of acute myocardial infarction
   • More common in young females without traditional risk factors 3

By Pathological Classification:

1. Class 1: Classic dissection with true and false lumen
2. Class 2: Intramural hematoma
3. Class 3: Subtle dissection with bulging
4. Class 4: Plaque ulceration following rupture
5. Class 5: Iatrogenic or traumatic dissection 1

Clinical Presentation

Common symptoms include:

• Pain: Abrupt onset, maximal at onset (unlike myocardial infarction pain which increases gradually)
  • Retrosternal pain in proximal dissections
  • Interscapular/back pain in distal dissections 1
• Pulse deficits: Present in up to 50% of proximal aortic dissections
• Neurological deficits: Present in up to 40% of proximal aortic dissections
• Aortic regurgitation: Present in about half of patients with aortic dissection
• Syncope: May occur without typical pain history (20% of cases) 1

Mechanisms of Branch Vessel Compromise

Two main mechanisms can cause branch vessel compromise:

1. Static obstruction: The dissection intersects and narrows the vessel origin
2. Dynamic obstruction: The dissection flap compresses the true lumen or covers the branch vessel origin like a curtain 4

These mechanisms can lead to end-organ ischemia, including:

• Cerebral ischemia
• Limb ischemia
• Renal failure
• Mesenteric ischemia
• Spinal cord ischemia (paraplegia) 1

Diagnostic Imaging

Multiple imaging modalities can diagnose vessel dissection:

• Transthoracic and Transesophageal Echocardiography: First-line for aortic dissection (Class I recommendation) 1
• CT Angiography: Excellent for visualizing the full extent of dissection (Class I recommendation) 1
• MR Angiography: Useful for follow-up and in stable patients 1, 5
• Conventional Angiography: Helpful to define anatomy in visceral malperfusion and guide interventions (Class I recommendation) 1
• Intravascular Ultrasound: Highest accuracy among ultrasonic techniques, useful to guide percutaneous interventions (Class I recommendation) 1

Management

Treatment depends on the location and complications of the dissection:

Aortic Dissection:

• Type A: Typically requires emergency surgical repair
• Type B: Often managed medically unless complications develop 1

Medical Management:

• Focus on decreasing forces on the aortic wall by reducing blood pressure 1
• Beta-blockers are first-line therapy 1

Interventional/Surgical Management:

• Indications: Malperfusion syndrome, aneurysmal dilation, rupture, persistent pain
• Options:
  • Stent placement: For branch vessel obstruction (Class I recommendation)
  • Balloon fenestration: For dynamic obstruction of branch arteries
  • Surgical repair: For ascending aortic dissections 1

Complications and Prognosis

Without treatment, mortality rates are high:

• Type A: 1-2% mortality per hour in the first 48 hours
• Type B: Better prognosis with medical management alone

Long-term complications include:

• Aneurysmal dilation of the false lumen
• Rupture
• End-organ ischemia
• Recurrent dissection 1

Follow-up

Regular imaging surveillance is essential:

• CT or MRI at 1,3,6, and 12 months after diagnosis, then annually
• Monitor for false lumen expansion, new entry tears, and branch vessel involvement 1

Key Pitfalls to Avoid

1. Misdiagnosis: Vessel dissection can mimic other conditions like myocardial infarction or pulmonary embolism
2. Delayed treatment: Prompt diagnosis and management are crucial to prevent complications
3. Inappropriate thrombolytic therapy: Should be avoided in suspected dissection as it can worsen the condition
4. Inadequate blood pressure control: Essential to prevent propagation of the dissection
5. Overlooking branch vessel involvement: Can lead to end-organ ischemia if not addressed 1