AORTIC DISSECTION

✓ Medically ReviewedDISEASEID: MDBT0177🚨 TRIAGE: EMERGENCYICD-10: I71.0

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Definition

CLINICAL DEFINITION

Aortic dissection is a life-threatening cardiovascular emergency characterised by a tear in the tunica intima of the aortic wall, allowing blood to surge into the media and create a propagating false lumen. It is classified anatomically (e.g., Stanford Type A or B) based on the involvement of the ascending aorta, which dictates the urgency of surgical versus medical management.

IN PLAIN ENGLISH

Aortic dissection is a severe medical emergency where the inner layer of the aorta, the body's main artery, tears. Blood rushes through the tear and causes the inner and middle layers of the artery to separate, which can block blood flow to vital organs or cause the artery to rupture.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Aortic dissection is NOT a true aneurysm, which involves the abnormal dilation of all three intact layers of the arterial wall, although dissection can occur within a pre-existing aneurysm. It is also distinct from an intramural haematoma (which lacks an intimal tear) and a penetrating atherosclerotic ulcer.

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Word Breakdown

dis-

=apart, away

aort-

=aorta (from Greek 'aorte', from 'aeirein' meaning to raise or hang)

-ion

=condition or process

Literal Meaning: The condition of cutting apart or separating the layers of the aorta

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Abbreviations

AD=Aortic Dissection — standard abbreviation in clinical documentation.

TAAD=Type A Aortic Dissection — involves the ascending aorta.

TBAD=Type B Aortic Dissection — involves the descending aorta distal to the left subclavian artery.

TEE=Transoesophageal Echocardiography — key imaging modality for haemodynamically unstable patients.

CTA=Computed Tomography Angiography — gold standard imaging for haemodynamically stable patients.

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Synonyms & Variants

Dissecting Aneurysm of Aorta›Aortic Dissecting Aneurysm›

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Category-Specific Context

As a Disease, aortic dissection represents an acute structural failure of the aortic wall. It is classified primarily by the Stanford system into Type A (involving the ascending aorta, requiring emergency surgery) and Type B (involving only the descending aorta, typically managed medically unless complicated), which forms the basis for all triage and treatment algorithms.

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Clinical Context & Usage

CLINICAL SETTINGS

Emergency DepartmentCardiothoracic SurgeryIntensive Care UnitCardiology WardVascular Surgery

USAGE & DOCUMENTATION NOTES

In clinical documentation, 'acute aortic syndrome' is often used as an umbrella term encompassing classic aortic dissection, intramural haematoma, and penetrating atherosclerotic ulcer. Clinicians frequently document 'Stanford Type A' or 'Stanford Type B' to immediately convey surgical urgency. 'Tearing' or 'ripping' pain radiating to the back is the classic descriptor, though its absence does not rule out the diagnosis.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

The process begins with a tear in the tunica intima, often at sites of maximal haemodynamic stress such as the ascending aorta or the aortic isthmus. Blood enters the medial layer under systemic pressure, cleaving the laminar planes of the smooth muscle and elastic fibres to create a blood-filled false lumen. This propagation can extend antegrade or retrograde, potentially compromising branch vessels (e.g., coronary, carotid, mesenteric, or renal arteries) leading to malperfusion syndromes. The weakened outer wall (adventitia) may rupture into the pericardium, pleural space, or mediastinum.

PRIMARY CAUSES

Chronic Hypertension

Sustained high blood pressure causes medial hypertrophy and vasa vasorum narrowing, leading to ischaemic degeneration of the aortic media and predisposing to intimal tearing.

Connective Tissue Disorders (e.g., Marfan syndrome, Loeys-Dietz syndrome)

Genetic mutations in fibrillin-1 or TGF-beta receptors cause structural weakness of the extracellular matrix in the aortic media.

Bicuspid Aortic Valve (BAV)

Associated with intrinsic aortopathy and abnormal flow dynamics causing cystic medial necrosis, predominantly affecting the ascending aorta.

Pre-existing Aortic Aneurysm

Dilation of the aorta increases wall stress, accelerating medial degeneration and increasing the risk of intimal tear.

Aortitis (e.g., Takayasu arteritis, Giant Cell Arteritis)

Inflammatory infiltration of the aortic wall leads to structural weakening, necrosis, and subsequent dissection.

Trauma or Iatrogenic Injury

Deceleration injuries or endovascular procedures cause direct mechanical disruption of the intima.

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Drug-Induced Causes

💊 Fluoroquinolones (e.g., ciprofloxacin, levofloxacin) ↗

Mechanism: Upregulation of matrix metalloproteinases leading to collagen degradation and structural weakening of the aortic wall.

→ Avoid fluoroquinolones in patients with known aortic aneurysm or high-risk connective tissue disorders unless no alternative exists.

💊 Sympathomimetics (Cocaine, Amphetamines) ↗

Mechanism: Acute severe hypertensive crisis and increased shear stress on the aortic wall.

→ Immediate aggressive blood pressure control using intravenous beta-blockers followed by vasodilators; manage as a hypertensive emergency.

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Epidemiology

Prevalence:The incidence of acute aortic dissection is approximately 2 to 6 per 100,000 person-years globally. It accounts for a significant proportion of acute aortic syndromes, with a higher prevalence in males and older adults, though younger patients with connective tissue disorders are distinctly at risk.

Age Group:Bimodal distribution: predominantly older adults (60s-70s) with chronic hypertension and atherosclerosis, and younger adults (20s-40s) with underlying connective tissue disorders, bicuspid aortic valve, or during pregnancy.

Sex Predilection:Male

Geographic Distribution:Globally distributed, but incidence appears higher in regions with a high prevalence of uncontrolled hypertension and ageing populations. No specific endemic geographic concentration.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 EMERGENCY

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Sudden severe tearing chest or back pain with a pulse deficit or blood pressure differential between arms — raises high suspicion for aortic dissection with branch vessel compromise; requires immediate CTA or TEE and emergent surgical consultation.
Neurological deficits or acute limb ischaemia in the setting of chest or back pain — suggests dissection propagating into carotid, spinal, or iliac arteries; requires urgent vascular imaging before administering thrombolytics for presumed stroke.

URGENT EVALUATION TRIGGERS

Sudden onset of severe, 'tearing' or 'ripping' chest, back, or abdominal pain.
New aortic regurgitation murmur or signs of cardiac tamponade in a hypertensive patient.
Unexplained pulse deficit or >20 mmHg systolic blood pressure difference between arms.

Contraindications & Precautions

CONTRAINDICATIONS

Anticoagulation and Thrombolysis — absolutely contraindicated as they exacerbate bleeding into the false lumen and pericardium; frequently misdiagnosed as acute coronary syndrome
making careful differentiation critical.
Intra-Aortic Balloon Pump (IABP) — contraindicated due to the risk of expanding the dissection flap or causing aortic rupture.
Permissive Hypertension — contraindicated; blood pressure must be rapidly lowered to reduce aortic wall shear stress.

SPECIAL PRECAUTIONS

Avoid purely vasodilator therapy (e.g.
sodium nitroprusside) without prior beta-blockade
as reflex tachycardia increases aortic wall shear stress and propagates the dissection.
Transoesophageal Echocardiography (TEE) must be performed cautiously if severe cervical spine disease or oesophageal stricture is present.
Fluid resuscitation must be carefully balanced; excessive fluids can increase blood pressure and wall stress
while hypovolaemia from tamponade requires urgent surgical drainage.

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Aortic Rupture — catastrophic bleeding into the pericardium (tamponade)
pleural space
or mediastinum
leading to rapid exsanguination.
Acute Aortic Regurgitation — retrograde propagation into the aortic root disrupts the valve commissures
causing severe heart failure.
Cardiac Tamponade — rupture or transudation of blood into the pericardial sac
causing obstructive shock.
Malperfusion Syndromes — extension of the dissection flap into branch vessels causing myocardial infarction
stroke
acute limb ischaemia
mesenteric ischaemia
or acute kidney injury.

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Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Acute Coronary Syndrome (ACS)

Presents with similar severe chest pain; critical to distinguish because administering anticoagulants or thrombolytics for ACS in a patient with aortic dissection is fatal.

Intramural Haematoma (IMH)

Part of the acute aortic syndrome spectrum but lacks an intimal tear or false lumen on imaging; managed similarly but has distinct pathophysiological characteristics.

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Acute Myocardial Infarction

Key Distinguishing Feature: Pain is typically crushing rather than tearing, may radiate to the jaw or arm, and ECG shows ischaemic changes. However, dissection can cause secondary MI if it involves the coronary ostia.

Pulmonary Embolism

Key Distinguishing Feature: Presents with pleuritic chest pain, dyspnoea, and hypoxia; CT pulmonary angiography shows filling defects in pulmonary arteries rather than an aortic intimal flap.

Oesophageal Rupture (Boerhaave Syndrome)

Key Distinguishing Feature: History of severe vomiting followed by chest pain; imaging shows pneumomediastinum and pleural effusion, not an aortic flap.

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Clinical Pearls

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The classic 'tearing' pain radiating to the back is highly specific but only present in a subset of patients; up to 10% of patients present with painless dissection or atypical symptoms, particularly the elderly or those with diabetes.

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A normal chest X-ray or non-specific ECG does not rule out aortic dissection. A widened mediastinum is classic but absent in up to 20-30% of cases. Always proceed to definitive cross-sectional imaging if clinical suspicion remains.

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Medical management requires 'anti-impulse' therapy: heart rate must be controlled first (target <60 bpm) with intravenous beta-blockers before adding vasodilators to lower systolic blood pressure (target 100-120 mmHg). Giving vasodilators first causes reflex tachycardia, increasing shear stress and propagating the tear.

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Stanford Type A involves the ascending aorta and is a surgical emergency due to the risk of coronary involvement, aortic rupture, and tamponade. Stanford Type B involves only the descending aorta and is typically managed medically unless complicated by malperfusion, rapid expansion, or rupture.

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Example Usage & SOAP

CLINICAL SENTENCE

"The patient presented to the Emergency Department with sudden-onset, severe tearing interscapular pain and a 30 mmHg systolic blood pressure differential between the right and left arms, prompting an urgent CTA which confirmed an acute Stanford Type B aortic dissection."

IN A SOAP NOTE

S: 62-year-old male with a history of poorly controlled hypertension presents with sudden, severe 'ripping' chest pain radiating to his mid-back that started 45 minutes ago. O: BP 195/110 mmHg (right arm), 160/90 mmHg (left arm). HR 112 bpm. Diaphoretic and in severe distress. Pulses 2+ in right upper extremity, 1+ in left upper extremity. Early diastolic murmur heard at the right sternal border. ECG shows LVH without acute ST-T wave changes. A: Acute aortic syndrome, highly suspicious for Stanford Type A aortic dissection given the ascending aorta involvement signs (diastolic murmur of AR, pulse/BP differential). P: 1. Immediate IV esmolol infusion to target HR < 60 bpm. 2. Add IV nicardipine to target SBP 100-120 mmHg. 3. IV morphine for pain control. 4. Emergent bedside TEE and immediate cardiothoracic surgery consultation. 5. Type and crossmatch 6 units PRBCs.

DIFFERENTIAL DIAGNOSIS CONTEXT

Differential for acute tearing chest pain: (1) Aortic Dissection — look for BP differentials, pulse deficits, new AR murmur, widened mediastinum on CXR; confirm with CTA. (2) Acute Coronary Syndrome — pain is usually crushing, ECG shows ST changes, elevated troponin; beware that dissection can cause secondary MI. (3) Pulmonary Embolism — pleuritic pain, dyspnoea, hypoxia, right heart strain on ECG; confirm with CTPA. (4) Oesophageal Rupture — history of severe retching, Mackler's triad (vomiting, chest pain, subcutaneous emphysema).

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Prognosis

SHORT-TERM OUTCOME

Extremely high mortality if untreated; Stanford Type A has a mortality rate of 1-2% per hour initially without surgical intervention. With prompt surgical repair, in-hospital mortality for Type A is approximately 15-25%. Uncomplicated Type B managed medically has an in-hospital mortality of around 10%.

LONG-TERM PROGNOSIS

Long-term survival depends on strict blood pressure control and surveillance for aneurysmal degeneration of the false lumen. 5-year survival for repaired Type A is roughly 60-80%. Complicated Type B requiring endovascular or open surgery carries higher long-term morbidity.

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References & Coding

ICD-10 DIAGNOSTIC CODE

I71.0

LITERATURE CITATIONS & GUIDELINES

[1]Erbel R, Aboyans V, Boileau C, et al. 2014 ESC Guidelines on the diagnosis and treatment of aortic diseases. Eur Heart J. 2014;35(41):2873-2926.

[2]Hiratzka LF, Bakris GL, Beckman JA, 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-e369.

[3]Isselbacher EM, Bonaca MP, Braverman AC, et al. 2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease. J Am Coll Cardiol. 2022;80(24):e223-e393.

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.