Thoracic Aortic Dissection

1. Clinical Overview

Summary

Thoracic Aortic Dissection is a life-threatening cardiovascular emergency caused by a tear in the aortic intima, allowing blood to enter the aortic media and create a false lumen that propagates along the vessel wall. This false lumen can extend proximally or distally, causing branch vessel occlusion (coronary, cerebral, spinal, visceral, or limb ischaemia), aortic rupture, pericardial tamponade, or acute aortic regurgitation. [1,2]

Incidence: 3-5 per 100,000 person-years, with male predominance (2-3:1). [3]

Classification: The Stanford Classification is most clinically relevant:

• Type A: Ascending aorta involved (regardless of entry site) → Surgical Emergency
• Type B: Descending aorta only (distal to left subclavian) → Medical management unless complicated [1,4]

Classic Presentation: Sudden-onset, severe, tearing/ripping chest pain radiating to the interscapular region. Pain is maximal at onset (not crescendo like ACS). Pulse deficit or blood pressure differential > 20mmHg between arms suggests branch vessel involvement. [5]

Diagnosis: CT Aortogram (gold standard - sensitivity 98-100%, specificity 95-98%). TOE is highly accurate (sensitivity 98%, specificity 95%) and can be performed at bedside in unstable patients. [6,7]

Management:

• Type A: Emergency surgical repair (ascending aorta replacement ± aortic root ± valve). Mortality without surgery is 1-2% per hour in first 48 hours. [8]
• Type B (uncomplicated): Aggressive blood pressure control (target SBP 100-120mmHg, HR less than 60bpm) with IV beta-blocker FIRST (labetalol/esmolol), then vasodilator if needed. [9]
• Type B (complicated): TEVAR (thoracic endovascular aortic repair) or open surgery for rupture, malperfusion, refractory pain/hypertension. [10]

Prognosis: Type A has 15-30% operative mortality but > 90% mortality if untreated in first week. Type B uncomplicated has ~10% in-hospital mortality with optimal medical therapy. [11,12]

Clinical Pearls

"Tearing Pain to the Back = Dissection Until Proven Otherwise": Classic description. Pain may migrate as dissection propagates distally or proximally. Absence of this pain does not exclude dissection (15-20% have atypical pain). [5]

Stanford Type A = Surgery, Type B = Medical: Type A (involving ascending aorta) is a surgical emergency regardless of symptoms. Type B (descending only) is managed medically unless complicated (rupture, malperfusion, uncontrolled pain/BP, rapid expansion). [1,4]

Pulse Deficit / BP Asymmetry: > 20mmHg difference between arms (15-30% of cases) or absent peripheral pulse indicates branch vessel involvement and higher mortality risk. Check all pulses (carotid, brachial, radial, femoral). [13]

Don't Give Thrombolysis!: Dissection can mimic MI if dissection occludes coronary ostia (usually RCA). Always exclude dissection before thrombolysing STEMI if pain is tearing, radiates to back, or pulse deficit present. [14]

Beta-Blocker Before Vasodilator: Never give vasodilators alone - reflex tachycardia increases aortic wall shear stress (dP/dt) and worsens dissection propagation. Beta-blockade reduces HR and contractility first. [9]

Widened Mediastinum has Low Sensitivity: Only 60-65% of dissections show widened mediastinum on CXR. Normal CXR does not exclude dissection if clinical suspicion high. [15]

---

2. Epidemiology

Incidence and Prevalence

• Incidence: 3-5 per 100,000 person-years in population-based studies. Likely underestimated due to pre-hospital deaths. [3]
• Acute Aortic Syndrome: Broader category (dissection, intramural haematoma, penetrating aortic ulcer) has incidence ~6 per 100,000 per year. [16]
• Peak Age: 60-70 years for Type B. Type A occurs earlier (mean 55-60 years), especially in connective tissue disorders. [17]
• Sex: Male predominance 2-3:1. [3]

Anatomical Distribution

From the International Registry of Acute Aortic Dissection (IRAD) data (> 6,000 patients): [18]

• Type A (Stanford): 60-65% of all dissections
• Type B (Stanford): 35-40% of all dissections
• DeBakey Type I (ascending + descending): 60%
• DeBakey Type II (ascending only): 10-15%
• DeBakey Type III (descending only): 25-30%

Risk Factors

Outcomes Data (IRAD Registry) [18]

• In-hospital mortality Type A: 22-28% with surgery, > 50% without surgery
• In-hospital mortality Type B: 10-12% uncomplicated medical, 30-35% complicated requiring intervention
• Predictors of mortality: Hypotension/shock, cardiac tamponade, renal failure, mesenteric ischaemia, age > 70

---

3. Pathophysiology

Microscopic Basis: Cystic Medial Necrosis

The underlying substrate for dissection is cystic medial degeneration (also called cystic medial necrosis): [25]

1. Smooth muscle cell apoptosis and loss of elastic fibres in tunica media
2. Accumulation of basophilic ground substance (proteoglycans) forming "cysts"
3. Fragmentation of elastic lamellae and collagen disorganization
4. Loss of vasa vasorum leading to medial ischaemia

Causes of Cystic Medial Necrosis:

• Genetic: Marfan (fibrillin-1 mutation), Ehlers-Danlos IV (COL3A1), Loeys-Dietz (TGFBR1/2)
• Acquired: Chronic hypertension, ageing, bicuspid aortic valve, inflammatory aortitis

Mechanism of Dissection

Stage 1: Intimal Tear

Most Common Sites (areas of maximum haemodynamic stress): [26]

• Ascending aorta (60%): 2-3cm above aortic valve, right lateral wall
• Aortic isthmus (35%): Just distal to left subclavian artery origin (ligamentum arteriosum tethering point)
• Descending thoracic aorta (5%): Variable location

Triggering Factors:

• Haemodynamic stress: dP/dt (rate of rise of ventricular pressure) is key. Acute hypertension, exercise, straining increase shear forces.
• Mechanical stress: Deceleration trauma creates shear at fixed points.

Stage 2: Blood Enters Media (False Lumen Creation)

• Blood dissects between inner 2/3 (intima + inner media) and outer 1/3 (outer media + adventitia) of aortic wall
• False lumen is typically larger than true lumen and has slower flow (higher thrombosis risk but also higher rupture risk)
• True lumen is usually compressed, smaller, and has faster flow

Stage 3: Propagation

Direction:

• Anterograde (distal): Most common. Extends down descending aorta, potentially to iliacs.
• Retrograde (proximal): Type A can extend back to aortic root/valve.

Rate: Can extend 1-2cm per hour initially. Propagation creates spiral path around aorta.

Stage 4: Complications

Malperfusion Mechanisms: [27]

1. Static obstruction: Dissection flap extends into branch vessel ostium
2. Dynamic obstruction: True lumen compression by false lumen during systole reduces branch perfusion
3. Thromboembolism: Thrombus from false lumen embolizes to branch

Classification Systems

Stanford Classification (Most Clinically Useful) [1]

• Type A: Ascending aorta involved (any part proximal to innominate artery), regardless of entry tear location
• Type B: Descending aorta only (all disease distal to left subclavian artery origin)

Clinical Significance: Type A requires emergency surgery. Type B is managed medically unless complicated.

DeBakey Classification [4]

• Type I: Entry tear in ascending, propagates to descending (60%)
• Type II: Confined to ascending aorta only (10-15%)
• Type III: Entry tear in descending aorta (25-30%)
  • "IIIa: Descending thoracic only"
  • "IIIb: Extends below diaphragm"

Note: DeBakey I + II = Stanford A; DeBakey III = Stanford B

Penn Classification (Surgical Focus)

Based on presence/absence of malperfusion and circulatory collapse. Used for surgical planning.

---

4. Differential Diagnosis

Acute aortic dissection is the "great mimicker" and must be distinguished from other acute chest pain syndromes.

Clinical Decision Tools

ADD-RS Score (Aortic Dissection Detection Risk Score) [30]

Designed to identify patients at risk requiring imaging:

Score Interpretation:

• 0-1: Low risk (~7% have dissection). Consider D-dimer to rule out (if less than 500ng/mL + score 0-1, NPV 96%). [31]
• 2-3: High risk (~31-84% have dissection). Imaging mandatory.

Note: ADD-RS is sensitive but not specific. High clinical suspicion should always prompt imaging regardless of score.

---

5. Clinical Presentation

Symptoms

Painless Dissection (5-10%): Associated with neurological presentation (stroke, paraplegia), tamponade, or Marfan syndrome. Higher mortality due to delayed diagnosis. [33]

Signs

Atypical Presentations (15-20% of cases) [33]

1. Isolated neurological: Stroke/TIA without chest pain (5-8%)
2. Isolated syncope: Especially elderly, Marfan (2-3%)
3. Isolated abdominal pain: Mesenteric ischaemia, renal infarction (3-5%)
4. Congestive heart failure: Severe acute AR (Type A) presenting as pulmonary oedema (5-10%)
5. Sudden death: Tamponade, rupture, MI (2-5% present after collapse/cardiac arrest)

---

6. Investigations

Bedside Tests

Blood Tests

Novel Biomarkers (research/limited availability):

• Smooth muscle myosin heavy chain: Released from aortic medial smooth muscle. Sensitivity 90%, specificity 93%. Not widely available. [37]
• Calponin: Smooth muscle protein. Shows promise but not validated for clinical use.

Definitive Imaging

CT Aortogram Findings [6]

Definitive Signs:

1. Intimal flap: Linear filling defect separating true and false lumens (pathognomonic)
2. Double lumen: Two contrast-filled channels separated by flap

Supportive Signs: 3. Differential flow: False lumen usually has delayed/reduced contrast opacification (slower flow) 4. Cobweb sign: Residual strands of media in false lumen 5. Beak sign: Acute angle between dissection flap and aortic wall 6. Entry/re-entry tears: Breaks in intimal flap where blood flows between lumens

Complications Visualized:

• Pericardial effusion (haemopericardium if hyperdense)
• Pleural effusion (haemothorax - usually left-sided)
• Branch vessel involvement (narrowing/occlusion of coronary ostia, arch vessels, visceral arteries)
• Aortic regurgitation (indirect - dilated aortic root, retrograde flow)

True vs False Lumen Differentiation (important for surgical/endovascular planning):

---

7. Management

Immediate Resuscitation (ABCDE Approach)

Every suspected dissection is a medical emergency until proven otherwise.

Airway & Breathing

• High-flow oxygen (15L/min via non-rebreather) if hypoxic or in shock
• Protect airway if reduced GCS (risk of tamponade/stroke)
• Consider intubation if haemodynamic collapse, but avoid hypertensive response to laryngoscopy (pre-treat with beta-blocker, short-acting opioid)

Circulation

• Large-bore IV access x2 (14-16G)
• Cardiac monitoring (ECG, BP, SpO2)
• Arterial line for continuous BP monitoring (essential for titrating antihypertensives)
• Blood pressure measurement in BOTH arms (if > 20mmHg difference, use higher reading for monitoring to ensure adequate cerebral/coronary perfusion)
• Avoid excessive fluid resuscitation (increases BP and risk of propagation/rupture) unless severe hypotension

Analgesia

• IV Morphine 5-10mg (titrate to pain relief)
• Adequate pain control reduces sympathetic drive and BP
• Avoid NSAIDs (antiplatelet effect increases bleeding risk)

Blood Products

• Group & Save immediately
• Crossmatch 6-10 units for Type A (surgical requirement)
• Activate Major Haemorrhage Protocol if ruptured/hypotensive

---

Blood Pressure and Heart Rate Control (CRITICAL)

Goal: Reduce aortic wall stress by lowering dP/dt (rate of rise of left ventricular pressure).

Targets: [9]

• Systolic BP: 100-120 mmHg (or lowest tolerated without end-organ hypoperfusion)
• Heart Rate: less than 60 bpm
• Mean Arterial Pressure: 60-75 mmHg

Step 1: IV Beta-Blocker (FIRST-LINE)

Rationale: Reduces HR and myocardial contractility → reduces dP/dt → reduces shear stress on aortic wall. NEVER give vasodilators before beta-blockade (reflex tachycardia worsens shear stress).

Contraindications to Beta-Blockers:

• Severe bronchospasm (alternative: diltiazem/verapamil 5mg IV, then 5-15mg/h infusion)
• High-degree AV block (alternative: directly to vasodilator with caution)
• Decompensated heart failure (use with caution; may need inotropic support)

Step 2: Vasodilator (if BP still > 120mmHg after beta-blockade)

CRITICAL PRINCIPLE: Beta-blocker BEFORE vasodilator. If vasodilator given alone, reflex tachycardia increases dP/dt and worsens dissection.

---

Definitive Management

Management is dictated by Stanford Classification:

              CONFIRMED AORTIC DISSECTION
              (CT Aortogram/TOE)
                        ↓
              STANFORD CLASSIFICATION?
         ┌──────────────┴──────────────┐
    TYPE A                          TYPE B
    (Ascending Aorta                (Descending Only)
     Involved)                           ↓
         ↓                     UNCOMPLICATED vs COMPLICATED?
   EMERGENCY SURGERY          ┌──────────────┴──────────────┐
         ↓                UNCOMPLICATED              COMPLICATED
   TRANSFER TO                    ↓                         ↓
   CARDIOTHORACIC             MEDICAL                   INTERVENTION
   CENTRE (if not             MANAGEMENT                    ↓
   already there)                 ↓                    TEVAR (preferred)
         ↓                   ICU/HDU                   or OPEN SURGERY
   SURGICAL OPTIONS:              ↓                         ↓
   - Ascending Aorta       Strict BP Control          POST-INTERVENTION
     Replacement           (SBP 100-120, HRless than 60)       ICU CARE
   - +/- Aortic Root       IV Beta-blocker +
     Replacement           Vasodilator
     (Bentall if AR)           ↓
   - +/- Aortic Valve      Serial Imaging
     Repair/Replace        (CT q6-12h if stable,
   - +/- Arch Repair       daily if unstable)
     (Hemiarch/Total)          ↓
   - +/- CABG              TRANSITION TO ORAL
     (if coronary          ANTIHYPERTENSIVES
      involvement)         (Beta-blocker +
         ↓                  ACE-I/ARB)
   POST-OP ICU CARE            ↓
         ↓                  DISCHARGE with
   LIFELONG                SURVEILLANCE PLAN
   SURVEILLANCE                ↓
                           LIFELONG
                           SURVEILLANCE

---

Type A Dissection: Surgical Emergency

Indication: ALL Type A dissections require emergency surgery unless:

• Moribund/unsurvivable injuries
• Patient declines surgery
• Extreme frailty/comorbidities precluding surgery

Mortality without surgery: 1-2% per hour in first 48 hours. 50% dead by 48h, 90% by 1 week. [8]

Operative mortality: 15-30% (varies by age, comorbidities, complications). [11,39]

Surgical Principles [39]

1. Median sternotomy
2. Cardiopulmonary bypass (CPB) with systemic cooling to 18-28°C (hypothermic circulatory arrest for arch work)
3. Resect intimal tear and diseased ascending aorta
4. Replace ascending aorta with Dacron graft (interposition graft)
5. Assess aortic root:
   • If root normal: supracoronary graft (replace ascending only)
   • If root dilated/AR: Bentall procedure (composite valve-graft, reimplant coronaries)
   • If valve salvageable: valve-sparing root replacement (David/Yacoub procedure)
6. Assess aortic arch:
   • If tear in arch or arch aneurysm: hemiarch (partial arch replacement) or total arch replacement
   • Reconstruct arch vessels (brachiocephalic, left carotid, left subclavian)
7. Assess coronaries: If dissection extends to ostia → CABG
8. Obliterate false lumen distally (glue layers together with BioGlue)

Complications:

• Bleeding (re-exploration in 10-20%)
• Stroke (5-10% - embolic or hypoperfusion during CPB)
• Renal failure (10-20%)
• Paraplegia (rare in Type A - less than 2%)
• Tamponade (5-10%)
• Multi-organ failure

---

Type B Dissection: Medical vs Intervention

Uncomplicated Type B: Medical Management [9]

Definition: No rupture, no malperfusion, controlled BP, controlled pain, stable.

Management:

1. ICU/HDU admission for continuous monitoring
2. Strict BP/HR control (as above: SBP 100-120, HR less than 60)
3. Serial imaging: CT aortogram at 24-48h, then Day 7, then discharge. Monitor for:
   • Expansion of false lumen (> 1cm increase concerning)
   • Periaortic haematoma (impending rupture)
   • Pleural effusion (haemothorax)
   • Development of complications
4. Transition to oral antihypertensives once stable:
   • Beta-blocker (bisoprolol, atenolol, metoprolol) - continue lifelong
   • ACE inhibitor/ARB (ramipril, losartan) - add if BP not controlled
   • Calcium channel blocker (amlodipine) - 3rd line
   • Target SBP less than 120mmHg long-term
5. Pain management: Avoid sympathetic surge
6. Early mobilization once pain/BP controlled (3-7 days)

Outcomes: 10-12% in-hospital mortality. 90% survive to discharge. [18]

Complicated Type B: Intervention [10,40]

Indications (any of the following):

1. Rupture: Haemothorax, periaortic/mediastinal haematoma
2. Malperfusion (static or dynamic):
   • Visceral: Mesenteric ischaemia (abdominal pain, lactate > 2)
   • Renal: AKI, severe hypertension (renin-mediated)
   • Limb: Ischaemic limb (5 Ps: pain, pallor, pulseless, paraesthesia, paralysis)
   • Spinal: Paraplegia/paraparesis
3. Refractory hypertension: Cannot achieve SBP less than 140mmHg despite maximal medical therapy
4. Refractory pain: Persistent severe pain despite adequate analgesia (suggests ongoing propagation)
5. Rapid expansion: Aortic diameter increase > 1cm in less than 1 year, or false lumen diameter > 22mm

TEVAR (Thoracic Endovascular Aortic Repair) - Preferred Approach: [10,40]

• Technique: Endovascular stent-graft deployed via femoral artery to cover proximal entry tear → redirects flow to true lumen → false lumen thrombosis
• Advantages: Less invasive than open surgery. Lower 30-day mortality (10% vs 30%). Faster recovery.
• Disadvantages: Requires suitable anatomy (landing zones proximal/distal to tear). Risk of stent migration, endoleak, retrograde Type A dissection (1-2%).
• Outcomes: 30-day mortality 10-15%. Spinal cord ischaemia 3-8% (cover extensive thoracic aorta → intercostal occlusion). [40]

Open Surgical Repair (if TEVAR not feasible):

• Left thoracotomy, Gott shunt or CPB
• Higher morbidity/mortality than TEVAR (30-day mortality 25-35%)
• Reserved for TEVAR failures or unsuitable anatomy

Malperfusion Management:

• Visceral/renal/limb malperfusion: Urgent TEVAR to decompress true lumen. If static obstruction, may need fenestration (surgical/endovascular creation of flap tear to equalize pressures) or branch vessel stenting. [27]
• Spinal cord ischaemia: Optimize spinal perfusion pressure (MAP > 80mmHg), CSF drainage (lumbar drain, target pressure less than 10mmHg). Often irreversible if complete paraplegia > 6h.

---

Special Scenarios

Pregnancy-Associated Dissection [23]

• 50% of dissections in women less than 40 occur during pregnancy (usually 3rd trimester/peripartum)
• Higher risk if Marfan, bicuspid AV, coarctation
• Management:
  • "Type A: Emergency surgery (maternal survival priority). Caesarean section if viable fetus (> 28 weeks), then immediate aortic repair."
  • "Type B: Medical management. Beta-blockers safe (labetalol preferred - also treats pre-eclampsia). Avoid ACE-I/ARB (teratogenic). Vaginal delivery with epidural (reduce BP surge). Caesarean if obstetric indications."

Cocaine/Amphetamine-Induced Dissection [22]

• Acute severe hypertension + tachycardia → dissection
• Often younger patients without traditional risk factors
• Management: Standard BP control. Benzodiazepines to reduce sympathetic drive. Avoid beta-blockers alone initially (unopposed alpha stimulation). Use labetalol (alpha+beta).

Iatrogenic Dissection

• Cardiac catheterization (0.02-0.06% risk), TAVI, intra-aortic balloon pump
• Often limited/localized dissection
• Management depends on extent (may be managed conservatively if limited)

---

8. Complications

Early Complications (In-Hospital)

Late Complications (Post-Discharge)

---

9. Prognosis and Outcomes

Acute Phase (In-Hospital)

Type A Dissection [11,18,39]

• Untreated mortality: 1-2% per hour for first 48h. 50% dead by 48h, 75% by 1 week, 90% by 1 month.
• Surgical mortality: 15-30% (varies by centre volume, patient age/comorbidities, complications)
  • "Best-case (uncomplicated, specialized centre): 10-15%"
  • "Worst-case (tamponade, shock, stroke, age > 75): 40-60%"
• Survival to discharge: 70-80% if surgery performed

Predictors of Operative Mortality (multivariate analysis): [45]

1. Pre-operative shock/hypotension (OR 3.5)
2. Cardiac tamponade (OR 2.8)
3. Age > 70 years (OR 1.8)
4. Renal failure/malperfusion (OR 2.2)
5. Stroke/coma (OR 3.0)
6. Coronary malperfusion/MI (OR 2.5)

Type B Dissection [18,46]

• Uncomplicated (medical): 10-12% in-hospital mortality
• Complicated (TEVAR): 10-20% 30-day mortality
• Complicated (open surgery): 25-35% 30-day mortality
• Survival to discharge: 85-90% uncomplicated, 70-80% complicated

Predictors of Mortality:

1. Rupture (OR 5.0)
2. Hypotension (OR 3.2)
3. Periaortic haematoma on CT (OR 4.5)
4. Mesenteric ischaemia (OR 6.0)
5. Renal failure (OR 2.5)

Long-Term Outcomes

Type A (Post-Surgical)

• 5-year survival: 60-75% [47]
• 10-year survival: 40-60%
• Cause of death: Cardiac (30%), rupture/re-dissection (15%), malignancy (10%), stroke (10%), other (35%)

Risk of Late Aortic Events (re-dissection, aneurysm, reoperation): [44,47]

• 5-year freedom from reoperation: 80-85%
• 10-year freedom from reoperation: 60-70%
• Higher risk if: Marfan syndrome, residual dissection in arch/descending aorta, persistent hypertension

Type B (Post-Medical/TEVAR)

• 5-year survival: 60-80% (uncomplicated medical ~80%, complicated ~60%) [46]
• 10-year survival: 50-70%
• Aortic-related events: 20-30% at 5 years (aneurysm formation requiring repair, re-dissection)

INSTEAD-XL Trial (TEVAR vs medical for uncomplicated Type B): [48]

• TEVAR had better aortic remodelling (false lumen thrombosis, true lumen expansion)
• TEVAR had lower aortic-related mortality at 5 years (11.1% vs 19.3%)
• Early mortality similar (1-2% both groups)
• Conclusion: TEVAR may be considered for uncomplicated Type B in suitable anatomy for long-term benefit, but medical management remains standard for acute phase

Quality of Life

• Physical function: 60-70% return to baseline activity by 6-12 months post-surgery
• Psychological impact: 30-40% have significant anxiety/depression (fear of recurrence, chronic pain)
• Return to work: 50-60% return to previous employment (lower if manual labour)

Surveillance

Lifelong imaging surveillance required for ALL dissection survivors: [49]

Intervention Thresholds:

• Ascending/arch/descending aneurysm: ≥5.5cm (or ≥5.0cm in Marfan, ≥6.0cm descending)
• Growth rate: > 0.5cm/year
• Symptoms: New chest/back pain (concern for impending rupture)

---

10. Evidence and Guidelines

Key Guidelines

Landmark Studies

Evidence Summary

Strong Evidence (Level A):

1. CT Aortogram is gold standard diagnostic (sensitivity 98-100%) [6]
2. Type A requires emergency surgery (mortality 1-2%/h untreated) [8]
3. Beta-blocker reduces aortic wall stress (should be first-line) [9]

Moderate Evidence (Level B):

1. TEVAR improves outcomes in complicated Type B vs medical alone [10,40]
2. BP target SBP less than 120mmHg reduces propagation/rupture risk [9]
3. Uncomplicated Type B medical management has 10-12% mortality [18]

Emerging Evidence:

1. TEVAR for uncomplicated Type B may improve long-term outcomes (INSTEAD-XL) [48] - awaiting further trials
2. Biomarkers (smooth muscle myosin) may aid rapid diagnosis [37] - not yet validated for clinical use
3. Genetic screening for familial aortopathy (ACTA2, MYH11 mutations) identifies at-risk relatives [54]

---

11. Patient and Layperson Explanation

What is an Aortic Dissection?

The aorta is the largest blood vessel in your body. It carries oxygen-rich blood from your heart to all your organs. The wall of the aorta has three layers (like a hosepipe).

In an aortic dissection, the inner layer (the lining) tears. Blood then forces its way between the layers, creating a false channel inside the aortic wall. This is like water leaking between the layers of a hosepipe and causing a bulge.

Why is it dangerous?

The false channel can:

1. Block blood flow to vital organs (brain, kidneys, intestines, legs) → stroke, kidney failure, gangrene
2. Burst through the outer layer → massive internal bleeding → death within minutes
3. Leak into the sac around the heart (pericardium) → the heart cannot pump properly (cardiac tamponade)
4. Damage the heart valve → acute heart failure

Without treatment, 50% of people die within 2 days. It is one of the most dangerous heart emergencies.

What causes it?

High blood pressure is the most common cause (present in 70-90% of cases). Years of high pressure weaken the aortic wall.

Other causes:

• Genetic conditions that weaken connective tissue (Marfan syndrome, Ehlers-Danlos syndrome)
• Abnormal heart valve (bicuspid aortic valve)
• Injury (car crash with sudden deceleration)
• Pregnancy (especially in women with Marfan syndrome)
• Drugs (cocaine, amphetamines - cause sudden severe high blood pressure)

What are the symptoms?

Sudden, severe chest or back pain that feels like:

• "Tearing" or "ripping"
• "Worst pain of my life"
• Starts abruptly (like a light switch, not gradual)
• May move from chest to back as the tear extends

Other symptoms:

• Fainting
• Weakness in arms or legs
• Difficulty speaking (stroke)
• Severe shortness of breath

If you have these symptoms, call an ambulance immediately (999/911). Every minute counts.

How is it diagnosed?

CT scan (with dye injected into a vein) is the gold standard. It shows the tear and the false channel inside the aorta. The scan takes 5-10 minutes.

Sometimes an ultrasound of the heart through the gullet (TOE) is used if you are too unstable to move to the CT scanner.

How is it treated?

Treatment depends on where the tear is:

Type A (Tear in the upper part of the aorta, near the heart)

Emergency surgery is needed within hours.

• The surgeon opens your chest, stops your heart (you are on a heart-lung bypass machine), and replaces the damaged part of the aorta with an artificial tube (Dacron graft).
• Sometimes the heart valve also needs to be replaced.
• Surgery takes 4-8 hours.
• You will be in intensive care for several days.

Survival: 70-80% survive the surgery and go home. Without surgery, > 90% die within a week.

Type B (Tear in the lower part of the aorta, away from the heart)

Medication is usually sufficient if there are no complications.

• Drugs to lower blood pressure very strictly (target 100-120 mmHg) - this reduces stress on the aortic wall and stops the tear extending.
• You will be in intensive care/high dependency unit for several days with close monitoring.
• Scans are repeated to ensure the dissection is not getting worse.

If complications develop (bleeding, blood flow blocked to organs, uncontrolled pain), you may need a stent (a metal tube inserted through a small cut in the groin and guided into the aorta to cover the tear). This is called TEVAR (Thoracic EndoVascular Aortic Repair). It is less invasive than open surgery.

What happens after treatment?

Short-term (weeks-months)

• You will be on blood pressure medications for life (usually beta-blockers and ACE inhibitors). Keeping blood pressure low (less than 120/80 mmHg) is critical to prevent the dissection coming back.
• You will have CT scans every 6-12 months to monitor the aorta (look for enlargement or new tears).
• Recovery takes 3-6 months. Most people can return to light activities after 6-12 weeks.

Long-term (years)

• 20-40% develop an aneurysm (ballooning of the aorta) in the area of the dissection over 5-10 years. If it gets too large (> 5.5cm), you will need another operation (usually a stent).
• 5-10% have another dissection in a different part of the aorta.
• Lifelong imaging surveillance (CT or MRI scans every 6-12 months).
• Avoid activities that cause sudden spikes in blood pressure (heavy lifting, straining, intense exercise). Moderate exercise (walking, swimming) is encouraged.

What is the long-term outlook?

With modern treatment:

• Type A: 60-75% alive at 5 years, 40-60% at 10 years
• Type B: 60-80% alive at 5 years, 50-70% at 10 years

Key to survival: Taking blood pressure medications every day, attending all follow-up scans, and reporting any new chest/back pain immediately.

Can it be prevented?

If you have high blood pressure: Take your medications every day. Aim for blood pressure less than 120/80 mmHg.

If you have Marfan syndrome or a family history of aortic disease: Regular screening with echocardiograms/CT scans. Surgery to replace the aorta before it tears can be life-saving.

Lifestyle:

• Do not smoke
• Avoid cocaine and amphetamines
• Manage diabetes and cholesterol
• Regular gentle exercise (avoid heavy weightlifting, extreme straining)

---

12. Examination Focus

Common Exam Questions (Viva/OSCE/Written)

1. Classification

Q: What is the Stanford Classification of aortic dissection, and why is it clinically useful?

Model Answer: The Stanford Classification divides aortic dissection into:

• Type A: Ascending aorta involved (proximal to innominate artery), regardless of entry tear location
• Type B: Descending aorta only (distal to left subclavian artery)

It is clinically useful because it dictates management:

• Type A = Surgical emergency (mortality 1-2% per hour without surgery)
• Type B = Medical management unless complicated (then TEVAR/surgery)

The DeBakey classification (I/II/III) is anatomically detailed but less clinically actionable.

Mark Scheme: (1) Defines Type A and B correctly. (2) States Type A needs surgery. (3) States Type B is medical unless complicated. (4) Mentions DeBakey as alternative but less useful. (5) Bonus: mentions mortality rate Type A untreated.

---

2. Classic Presentation

Q: Describe the classic chest pain of aortic dissection. How does it differ from ACS?

Model Answer: Aortic Dissection Pain:

• Sudden onset ("like a light switch", maximal at onset)
• Severe (10/10, "worst pain of my life")
• Tearing/ripping/stabbing quality
• Radiation to back (interscapular for Type B, anterior for Type A)
• Migratory (pain moves as dissection propagates distally)

ACS Pain:

• Crescendo (gradual build-up over minutes)
• Pressure/crushing/squeezing quality
• Radiation to left arm, jaw, epigastrium
• Associated with dyspnoea, nausea

KEY DIFFERENTIATOR: Maximal at onset (dissection) vs crescendo (ACS). Tearing/back radiation strongly suggests dissection.

CRITICAL PEARL: Dissection can cause MI (if extends to coronary ostia) → can have STEMI on ECG. Always exclude dissection before thrombolysis if atypical features (tearing pain, pulse deficit, back pain).

Mark Scheme: (1) Describes dissection pain features. (2) Describes ACS pain features. (3) Contrasts onset (abrupt vs crescendo). (4) Mentions quality (tearing vs crushing). (5) Bonus: highlights risk of MI in dissection and thrombolysis contraindication.

---

3. Blood Pressure Management

Q: Why must you give a beta-blocker BEFORE a vasodilator in acute aortic dissection?

Model Answer: Goal: Reduce aortic wall shear stress by lowering dP/dt (rate of rise of left ventricular pressure).

Beta-blocker FIRST (labetalol, esmolol):

• Reduces heart rate → longer diastolic filling time → lower peak systolic pressure
• Reduces myocardial contractility → reduces force of ventricular ejection → lowers dP/dt

If vasodilator given FIRST (GTN, nitroprusside):

• Lowers blood pressure → reflex tachycardia (baroreceptor response)
• Increased heart rate → increased dP/dt → worsens dissection propagation

Correct Sequence: Beta-blocker first → achieve HR less than 60 bpm → THEN add vasodilator if SBP still > 120 mmHg.

Target: SBP 100-120 mmHg, HR less than 60 bpm.

Mark Scheme: (1) States goal is to reduce dP/dt. (2) Explains beta-blocker reduces HR and contractility. (3) Explains vasodilator alone causes reflex tachycardia. (4) States correct sequence. (5) Bonus: mentions target BP/HR values.

---

4. Investigations

Q: What is the gold standard investigation for suspected aortic dissection? What findings confirm the diagnosis?

Model Answer: Gold Standard: CT Aortogram (CT angiography with IV contrast)

• Sensitivity: 98-100%
• Specificity: 95-98%

Diagnostic CT Findings:

1. Intimal flap (linear filling defect separating true and false lumens) - pathognomonic
2. Double lumen (two contrast-filled channels)

Supportive Findings:

• Differential contrast opacification (false lumen slower/reduced flow)
• Cobweb sign (residual medial strands in false lumen)
• Periaortic haematoma (impending rupture)
• Pericardial/pleural effusion (rupture)

Alternative if unstable: TOE (transoesophageal echocardiography) - can be done at bedside/in theatre. Sensitivity 95-98%, but blind spot at distal ascending aorta/proximal arch.

Mark Scheme: (1) States CT aortogram is gold standard. (2) Describes intimal flap and double lumen. (3) Mentions sensitivity/specificity. (4) Mentions TOE as alternative for unstable patients. (5) Bonus: describes supportive CT findings.

---

5. Type A Management

Q: A 60-year-old presents with sudden tearing chest pain. CT shows Stanford Type A dissection. What is your immediate management?

Model Answer:

ABCDE Resuscitation:

• High-flow oxygen if hypoxic
• Large-bore IV access x2
• Cardiac monitoring
• Arterial line for continuous BP monitoring

Blood Pressure Control:

• Target: SBP 100-120 mmHg, HR less than 60 bpm
• IV Labetalol 10-20mg bolus, then 1-2mg/min infusion (alpha+beta blockade)
• Add GTN infusion 0.5-10mg/h if SBP still > 120 mmHg

Analgesia: IV morphine 5-10mg (adequate analgesia reduces sympathetic drive)

Bloods:

• FBC, U&E, coagulation, Group & Save
• Crossmatch 6-10 units (for surgery)

Imaging: CT aortogram already done → confirms Type A

Definitive Management:

• EMERGENCY CARDIOTHORACIC SURGERY
• Transfer to specialist centre if not already there
• Surgery involves: ascending aorta replacement +/- aortic root (Bentall if AR) +/- aortic valve +/- arch repair +/- CABG (if coronary involvement)

Prognosis: 15-30% operative mortality. > 90% mortality if no surgery (1-2% per hour for first 48h).

Mark Scheme: (1) Resuscitation (airway, access, monitoring). (2) BP control with beta-blocker first. (3) Analgesia. (4) Crossmatch blood. (5) States emergency surgery and surgical options. (6) Bonus: mentions mortality with/without surgery.

---

6. Complications

Q: What are the major complications of aortic dissection? How do they present?

Model Answer:

Mark Scheme: (1) Lists 5+ major complications. (2) Describes mechanism for 3+. (3) Describes presentation for 3+. (4) States management principles. (5) Bonus: mentions poor prognosis for mesenteric ischaemia/paraplegia.

---

High-Yield Clinical Pearls for Exams

1. "Tearing pain to the back = dissection until proven otherwise" - Classic viva answer
2. Stanford Type A = Surgery, Type B = Medical - Memorize this mantra
3. Pulse deficit > 20mmHg between arms - High-yield clinical sign (15-30% of cases)
4. Don't thrombolyse if atypical MI - Dissection can cause RCA occlusion → inferior STEMI
5. Beta-blocker BEFORE vasodilator - Prevents reflex tachycardia worsening shear stress
6. Widened mediastinum low sensitivity - 60-65% only; normal CXR doesn't exclude
7. Type A mortality 1-2% per hour - Justify emergency surgery urgency
8. TEVAR for complicated Type B - Rupture, malperfusion, refractory pain/HTN
9. Lifelong BP control less than 120/80 mmHg - Critical for preventing recurrence
10. Marfan 1-2% annual dissection risk - Justify prophylactic aortic root replacement if > 5cm

---

13. References

Primary Sources

1. Erbel R, et al. 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. Eur Heart J. 2014;35(41):2873-926. PMID: 25173340. DOI: 10.1093/eurheartj/ehu281.

2. Nienaber CA, Clough RE. Management of acute aortic dissection. Lancet. 2015;385(9970):800-11. PMID: 25662791. DOI: 10.1016/S0140-6736(14)61005-9.

3. Olsson C, et al. Thoracic aortic aneurysm and dissection: increasing prevalence and improved outcomes reported in a nationwide population-based study of more than 14,000 cases from 1987 to 2002. Circulation. 2006;114(24):2611-8. PMID: 17145990. DOI: 10.1161/CIRCULATIONAHA.106.630400.

4. Daily PO, et al. Management of acute aortic dissections. Ann Thorac Surg. 1970;10(3):237-47. PMID: 5458238. (DeBakey classification original paper)

5. Hagan PG, et al. The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease. JAMA. 2000;283(7):897-903. PMID: 10685714. DOI: 10.1001/jama.283.7.897.

6. Shiga T, et al. Diagnostic accuracy of transesophageal echocardiography, helical computed tomography, and magnetic resonance imaging for suspected thoracic aortic dissection: systematic review and meta-analysis. Arch Intern Med. 2006;166(13):1350-6. PMID: 16831999. DOI: 10.1001/archinte.166.13.1350.

7. Evangelista A, et al. Echocardiography in aortic diseases: EAE recommendations for clinical practice. Eur J Echocardiogr. 2010;11(8):645-58. PMID: 20823280. DOI: 10.1093/ejechocard/jeq056.

8. Mehta RH, et al. Predicting death in patients with acute type a aortic dissection. Circulation. 2002;105(2):200-6. PMID: 11790702. DOI: 10.1161/hc0202.102246.

9. Suzuki T, et al. Clinical profiles and outcomes of acute type B aortic dissection in the current era: lessons from the International Registry of Aortic Dissection (IRAD). Circulation. 2003;108 Suppl 1:II312-7. PMID: 12970252. DOI: 10.1161/01.cir.0000087386.07204.09.

10. Nienaber CA, et al. Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial. Circ Cardiovasc Interv. 2013;6(4):407-16. PMID: 23922146. DOI: 10.1161/CIRCINTERVENTIONS.113.000463. (INSTEAD-XL)

11. Trimarchi S, et al. Contemporary results of surgery in acute type A aortic dissection: The International Registry of Acute Aortic Dissection experience. J Thorac Cardiovasc Surg. 2005;129(1):112-22. PMID: 15632832. DOI: 10.1016/j.jtcvs.2004.09.005.

12. Tsai TT, et al. Long-term survival in patients presenting with type B acute aortic dissection: insights from the International Registry of Acute Aortic Dissection. Circulation. 2006;114(21):2226-31. PMID: 17101856. DOI: 10.1161/CIRCULATIONAHA.106.622340.

13. von Kodolitsch Y, et al. Intramural hemorrhage of the thoracic aorta: diagnostic and therapeutic implications. Circulation. 1995;92(6):1465-72. PMID: 7664428. DOI: 10.1161/01.cir.92.6.1465.

14. Nienaber CA, et al. Aortic dissection: new frontiers in diagnosis and management: Part I: from etiology to diagnostic strategies. Circulation. 2003;108(5):628-35. PMID: 12900496. DOI: 10.1161/01.CIR.0000087009.16755.E4.

15. Earnest F 4th, et al. Complications of aortic dissection: a pictorial review. Radiographics. 2002;22 Spec No:S223-38. PMID: 12376613. DOI: 10.1148/radiographics.22.suppl_1.g02oc24s223.

16. Vilacosta I, San Román JA. Acute aortic syndrome. Heart. 2001;85(4):365-8. PMID: 11250953. DOI: 10.1136/heart.85.4.365.

17. Januzzi JL, et al. Characterizing the young patient with aortic dissection: results from the International Registry of Aortic Dissection (IRAD). J Am Coll Cardiol. 2004;43(4):665-9. PMID: 14975480. DOI: 10.1016/j.jacc.2003.08.054.

18. Pape LA, et al. Presentation, Diagnosis, and Outcomes of Acute Aortic Dissection: 17-Year Trends From the International Registry of Acute Aortic Dissection. J Am Coll Cardiol. 2015;66(4):350-8. PMID: 26205591. DOI: 10.1016/j.jacc.2015.05.029.

19. Golledge J, Eagle KA. Acute aortic dissection. Lancet. 2008;372(9632):55-66. PMID: 18603160. DOI: 10.1016/S0140-6736(08)60841-3.

20. Loeys BL, et al. The revised Ghent nosology for the Marfan syndrome. J Med Genet. 2010;47(7):476-85. PMID: 20591885. DOI: 10.1136/jmg.2009.072785.

21. Fedak PW, et al. Clinical and pathophysiological implications of a bicuspid aortic valve. Circulation. 2002;106(8):900-4. PMID: 12186790. DOI: 10.1161/01.cir.0000027905.26586.e8.

22. Hsue PY, et al. Acute aortic dissection related to crack cocaine. Circulation. 2002;105(13):1592-5. PMID: 11927528. DOI: 10.1161/01.cir.0000012524.44897.3a.

23. Regitz-Zagrosek V, et al. 2018 ESC Guidelines for the management of cardiovascular diseases during pregnancy. Eur Heart J. 2018;39(34):3165-241. PMID: 30165544. DOI: 10.1093/eurheartj/ehy340.

24. Daneman N, et al. Fluoroquinolones and collagen associated severe adverse events: a longitudinal cohort study. BMJ Open. 2015;5(11):e010077. PMID: 26597864. DOI: 10.1136/bmjopen-2015-010077.

25. Schlatmann TJ, Becker AE. Histologic changes in the normal aging aorta: implications for dissecting aortic aneurysm. Am J Cardiol. 1977;39(1):13-20. PMID: 831420. DOI: 10.1016/s0002-9149(77)80004-0.

26. Svensson LG, et al. Intimal tear without hematoma: an important variant of aortic dissection that can elude current imaging techniques. Circulation. 1999;99(10):1331-6. PMID: 10077516. DOI: 10.1161/01.cir.99.10.1331.

27. Williams DM, et al. The dissected aorta: percutaneous treatment of ischemic complications--principles and results. J Vasc Interv Radiol. 1997;8(4):605-25. PMID: 9228855. DOI: 10.1016/s1051-0443(97)70619-5.

28. Maraj R, et al. Meta-analysis of 143 reported cases of aortic intramural hematoma. Am J Cardiol. 2000;86(6):664-8. PMID: 10980221. DOI: 10.1016/s0002-9149(00)01062-2.

29. Ganaha F, et al. Prognosis of aortic intramural hematoma with and without penetrating atherosclerotic ulcer: a clinical and radiological analysis. Circulation. 2002;106(3):342-8. PMID: 12119251. DOI: 10.1161/01.cir.0000022164.26075.5a.

30. Rogers AM, et al. Sensitivity of the aortic dissection detection risk score, a novel guideline-based tool for identification of acute aortic dissection at initial presentation: results from the international registry of acute aortic dissection. Circulation. 2011;123(20):2213-8. PMID: 21555704. DOI: 10.1161/CIRCULATIONAHA.110.988568.

31. Suzuki T, et al. Diagnosis of acute aortic dissection by D-dimer: the International Registry of Acute Aortic Dissection Substudy on Biomarkers (IRAD-Bio) experience. Circulation. 2009;119(20):2702-7. PMID: 19433768. DOI: 10.1161/CIRCULATIONAHA.108.833004.

32. Bossone E, et al. Presenting systolic blood pressure and outcomes in patients with acute aortic dissection. J Am Coll Cardiol. 2018;71(13):1432-40. PMID: 29598869. DOI: 10.1016/j.jacc.2018.01.064.

33. Imamura H, et al. Painless acute aortic dissection - diagnostic, prognostic and clinical implications. Circ J. 2011;75(1):59-66. PMID: 21041969. DOI: 10.1253/circj.cj-10-0183.

34. Harris KM, et al. Correlates of delayed recognition and treatment of acute type A aortic dissection: the International Registry of Acute Aortic Dissection (IRAD). Circulation. 2011;124(18):1911-8. PMID: 21969019. DOI: 10.1161/CIRCULATIONAHA.110.006320.

35. Berretta P, et al. Acute kidney injury in acute type A aortic dissection: correlation with mortality and long-term outcome. Eur J Cardiothorac Surg. 2015;48(3):e93-100. PMID: 26254453. DOI: 10.1093/ejcts/ezv289.

36. Nazerian P, et al. Diagnostic Accuracy of the Aortic Dissection Detection Risk Score Plus D-Dimer for Acute Aortic Syndromes: The ADvISED Prospective Multicenter Study. Circulation. 2018;137(3):250-8. PMID: 29030346. DOI: 10.1161/CIRCULATIONAHA.117.029457.

37. Suzuki T, et al. Biochemical diagnosis of aortic dissection: plasma level of smooth muscle myosin heavy chain. Circulation. 2006;114(Suppl):I364. (Abstract)

38. Evangelista A, et al. Insights from the international registry of acute aortic dissection: a 20-year experience of collaborative clinical research. Circulation. 2018;137(17):1846-60. PMID: 29685932. DOI: 10.1161/CIRCULATIONAHA.117.031264.

39. Trimarchi S, et al. Role of age in acute type A aortic dissection outcome: report from the International Registry of Acute Aortic Dissection (IRAD). J Thorac Cardiovasc Surg. 2010;140(4):784-9. PMID: 20875635. DOI: 10.1016/j.jtcvs.2009.11.014.

40. Fattori R, et al. Interdisciplinary expert consensus document on management of type B aortic dissection. J Am Coll Cardiol. 2013;61(16):1661-78. PMID: 23500232. DOI: 10.1016/j.jacc.2012.11.072.

41. Gaul C, et al. Neurological symptoms in type A aortic dissections. Stroke. 2007;38(2):292-7. PMID: 17194876. DOI: 10.1161/01.STR.0000254594.33408.b1.

42. Cambria RP, et al. Mesenteric ischemia complicating aortic dissection. J Vasc Surg. 1989;9(2):328-35. PMID: 2918628. DOI: 10.1016/0741-5214(89)90053-7.

43. Coselli JS, et al. Outcomes of 3309 thoracoabdominal aortic aneurysm repairs. J Thorac Cardiovasc Surg. 2016;151(5):1323-37. PMID: 26898972. DOI: 10.1016/j.jtcvs.2015.12.050.

44. Tsai TT, et al. Partial thrombosis of the false lumen in patients with acute type B aortic dissection. N Engl J Med. 2007;357(4):349-59. PMID: 17652650. DOI: 10.1056/NEJMoa063232.

45. Rampoldi V, et al. Simple risk models to predict surgical mortality in acute type A aortic dissection: the International Registry of Acute Aortic Dissection score. Ann Thorac Surg. 2007;83(1):55-61. PMID: 17184630. DOI: 10.1016/j.athoracsur.2006.08.007.

46. Erbel R, et al. Diagnosis and management of aortic dissection. Eur Heart J. 2001;22(18):1642-81. PMID: 11511117. DOI: 10.1053/euhj.2001.2782.

47. Halstead JC, et al. The fate of the distal aorta after repair of acute type A aortic dissection. J Thorac Cardiovasc Surg. 2007;133(1):127-35. PMID: 17198798. DOI: 10.1016/j.jtcvs.2006.07.043.

48. Brandt M, et al. Endovascular repair of acute type B aortic dissection: mid-term results. J Thorac Cardiovasc Surg. 2008;136(4):833-41. PMID: 18954620. DOI: 10.1016/j.jtcvs.2008.02.077.

49. Hiratzka LF, et al. 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with thoracic aortic disease. Circulation. 2010;121(13):e266-369. PMID: 20233780. DOI: 10.1161/CIR.0b013e3181d4739e.

50. Isselbacher EM, et al. 2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease. J Am Coll Cardiol. 2022;80(24):e223-e393. PMID: 36334567. DOI: 10.1016/j.jacc.2022.08.004.

51. Nienaber CA, et al. Randomized comparison of strategies for type B aortic dissection: the INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial. Circulation. 2009;120(25):2519-28. PMID: 19996018. DOI: 10.1161/CIRCULATIONAHA.109.886408.

52. Afifi RO, et al. Outcomes of patients with acute type B (DeBakey III) aortic dissection: a 13-year, single-center experience. Circulation. 2015;132(8):748-54. PMID: 26304668. DOI: 10.1161/CIRCULATIONAHA.115.015302.

53. Augoustides JG, et al. Observational study of mortality risk stratification by ischemic presentation in patients with acute type B aortic dissection: the Penn classification. Nat Clin Pract Cardiovasc Med. 2009;6(2):140-6. PMID: 19065136. DOI: 10.1038/ncpcardio1417.

54. Milewicz DM, et al. Genetic variants in ACTA2 and MYOCD and familial thoracic aortic aneurysms and dissections. Circ Cardiovasc Genet. 2010;3(6):526-35. PMID: 21062668. DOI: 10.1161/CIRCGENETICS.110.958066.

---

Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances and be made in consultation with appropriate specialists. Always follow local protocols and guidelines. In acute aortic dissection, immediate senior/specialist input (cardiothoracic surgery, vascular surgery, interventional radiology) is mandatory.