Aortic dissection is a life-threatening condition where a tear in the intimal layer of the aorta allows blood to enter the medial layer, creating a false lumen that splits the aortic wall.
Epidemiology
- More common in men (M:F ratio ~2:1)
- Typically occurs between ages 40–70
- High mortality: 1–2% increase in mortality per hour after onset if untreated
- Most common predisposing factor: chronic hypertension
Etiology & Risk Factors
Major Causes
- Chronic Hypertension – most common
- Atherosclerosis
- Connective Tissue Disorders:
- Marfan syndrome
- Ehlers-Danlos syndrome (vascular type)
- Congenital Cardiac Anomalies:
- Bicuspid aortic valve
- Coarctation of the aorta
- Aortitis:
- Takayasu arteritis
- Giant cell arteritis
- Tertiary syphilis
- Trauma – especially deceleration injuries
- Iatrogenic – e.g., cardiac catheterization, surgery
- Substance Use:
- Cocaine
- Amphetamines
Classification (Stanford) – High-Yield
| Type | Description | Treatment Approach |
|---|---|---|
| A | Involves ascending aorta (± descending) | Surgical emergency |
| B | Involves only descending aorta | Medical ± surgical |
Clinical Features
History
- Sudden, severe chest pain:
- Often described as “tearing” or “ripping”
- Radiates to back, abdomen, or neck
- Often mimics acute myocardial infarction (AMI)
Associated Symptoms by Branch Obstruction:
| Artery Obstructed | Clinical Findings |
|---|---|
| Carotid | Stroke-like symptoms (hemiparesis) |
| Coronary (esp. RCA) | Chest pain, MI |
| Subclavian | Upper limb ischemia, hypotension |
| Renal | Acute kidney injury, anuria |
| Spinal artery | Paraplegia |
| Mesenteric (Celiac, SMA) | Severe abdominal pain (ischemia) |
Examination Findings
- Pulse/BP discrepancy (>20 mmHg between arms)
- Hypertension or hypotension (if tamponade or rupture)
- New murmur of aortic regurgitation (early diastolic)
- Collapsing/bounding pulse
- Unequal peripheral pulses
- Signs of shock or syncope
- Murmur: Left scapular or back region
- Widened pulse pressure
Investigations
Laboratory
- FBC, U&E, LFTs, Troponin (to rule out MI)
- Cross-match (urgent transfusion may be needed)
- Coagulation profile
Imaging
| Modality | Findings |
|---|---|
| Chest X-ray | Widened mediastinum, pleural effusion (late finding) |
| CT Angiography (CTA) | Gold standard – shows intimal flap & false lumen |
| Transesophageal Echo | Useful if unstable; bedside test |
| MRI Angiography | High sensitivity; for stable patients |
| ECG | Often normal, may show LVH or MI |
Management
Initial Emergency Care
- Oxygen, IV access, monitor vitals
- Pain control: IV opioids (e.g., morphine)
- Blood pressure control:
- First-line: IV beta-blocker (e.g., labetalol)
- Add nitroprusside if further BP reduction needed
- Goal: Lower SBP <120 mmHg and HR <60 bpm
Definitive Treatment
| Type | Management |
|---|---|
| Type A | Emergency surgery – replace affected aorta ± valve |
| Type B | Medical management first (BP control); surgery/stenting if complications |
Indications for Surgery in Type B:
- Persistent pain
- End-organ ischemia
- Dissection progression
- Aneurysm >5.5 cm or expanding
Complications – High-Yield
- Aortic rupture
- Cardiac tamponade
- Acute aortic regurgitation
- MI (coronary artery involvement)
- Stroke
- Renal failure
- Paraplegia
- Bowel ischemia
- Sudden death
High-Yield Pearls
Mnemonic – “DISSECT”:
- D – Difference in BP (arms)
- I – Intimal tear
- S – Sudden tearing pain
- S – Syncope or stroke signs
- E – ECG may mimic MI
- C – CT angiogram is diagnostic
- T – Type A = Thoracic surgical emergency
Vital to Differentiate from MI – misdiagnosis and giving thrombolytics can be fatal.
Always check bilateral pulses and BP in chest pain patients.
