PassFinals
Cardiovascular

Aortic Dissection

A tear in the aortic intima drives blood into the media, splitting it into a true and a false lumen that can rupture or occlude branch arteries.

In a nutshell

Aortic dissection is blood tracking into the aortic wall through an intimal tear, creating a false lumen. Give analgesia and intravenous labetalol to a systolic of 100 to 120 mmHg and a heart rate of 60 to 75 beats per minute, then image with ECG-gated CT.

Classic presentation

A hypertensive 60-year-old with tearing chest pain radiating through to the back, worst at onset, a 30 mmHg difference between arm pressures and a new early diastolic murmur.

Key points

  • Modern Stanford anatomy defines type A by ascending involvement; the NHS England South pathway routes ascending and/or arch disease as type A. Follow the receiving service's classification.
  • Aortic Dissection Detection Risk Score (ADD-RS): one point each for a high-risk condition, high-risk pain and high-risk findings. 0 low, 1 intermediate, 2 to 3 high risk.
  • About 2,500 people a year have an acute dissection in England. Around 20% die before reaching any hospital and 50% before reaching a specialist centre.
  • Half of type A patients who do reach hospital die within 24 hours without surgery, so referral cannot wait for a second opinion or a repeat scan.
  • Diagnosis is delayed in 16% to 40% of cases; in one English region the mean time from arrival to CT was 8.4 hours.
  • Consider genetic testing in every patient under 60: heritable aortopathies such as Marfan and Loeys-Dietz syndrome present young.

First-line investigation

ECG-gated CT aortogram from the common carotid arteries to the common femoral arteries; bedside transthoracic echo first only if the patient is too unstable for CT.

Management

Resus, analgesia, anti-impulse

  • Resuscitation bay, senior emergency clinician, continuous blood pressure, heart rate and ECG monitoring, nil by mouth. The emergency department requests the CT and acts on the result.2,3
  • Morphine 2 to 5 mg IV every 5 to 30 minutes until pain is controlled. Pain relief is part of blood pressure control, not comfort.3,7
  • Labetalol 0.25 mg/kg IV over 2 minutes, then an infusion at 2 mg/minute for 10 minutes, increased to a maximum of 5 mg/minute.3,8
  • Targets: systolic 100 to 120 mmHg within 30 minutes of diagnosis, heart rate 60 to 75 beats per minute within 60 minutes. Use an arterial line.3
  • Asthma or COPD: esmolol IV 50 to 200 micrograms/kg/minute. If beta-blockade is contraindicated, use a non-dihydropyridine calcium channel blocker such as diltiazem.3,9,5
  • Only once the heart rate is at target, and on aortic-centre advice, add glyceryl trinitrate IV 10 to 200 micrograms/minute. Sodium nitroprusside is not licensed in the UK.3,10,11

Confirm the diagnosis

  • Score the ADD-RS. In a classical presentation go straight to CT and do not wait for a D-dimer.2,3
  • ADD-RS above 1, or 1 with a D-dimer above 500 nanograms/mL, means scan. At that cut-off D-dimer is 96.5% sensitive and 56.5% specific.2
  • ECG-gated CT aortogram, common carotid arteries to common femoral arteries, 2 mm slices, cannula in the right arm, non-contrast series first for intramural haematoma.2,3,5
  • Too unstable for CT: bedside transthoracic echo for effusion, tamponade, aortic regurgitation or a visible flap. It misses 30% of dissections.2,5

Type A goes to theatre

  • Stanford anatomy defines type A by ascending involvement and may call arch-only disease non-A-non-B. NHS England South instead routes ascending and/or arch disease as type A; refer immediately and follow the receiving service classification.1,3
  • The centre prepares theatre within 30 minutes and makes 4 units of group O blood available. Patients go straight to cardiac theatre where possible.3,5

Type B and transfer

  • Uncomplicated type B: medical management to the same targets under the aortic team. 15% to 20% need intervention, usually thoracic endovascular aortic repair (TEVAR).12,3
  • Complicated means rupture, malperfusion, rapid expansion, or refractory pain or hypertension. Refer urgently for TEVAR, revascularisation or laparotomy.3,5
  • Withhold antiplatelets, heparin and thrombolysis while dissection is possible, even with ST elevation: a dissected coronary ostium produces both pictures.4,3
  • Transfer by critical care transfer service or category 2 ambulance with a trained escort. Do not stop the anti-impulse infusion during transfer.3

After the acute phase

  • Switch to oral beta-blockade after 24 hours once targets are met and gut transit is preserved, up-titrating other antihypertensives as needed.5
  • Lifelong blood pressure control and interval CT or MRI of the residual aorta. Consider genetic testing in everyone under 60.3,5

Exam traps

  • A vasodilator given before beta-blockade causes reflex tachycardia and harder ventricular contraction, raising shear on the flap. Rate first, pressure second.
  • A normal D-dimer does not exclude dissection. At 500 nanograms/mL it is 96.5% sensitive and only 56.5% specific, and a classical history goes straight to CT.
  • 30% of patients have a normal ECG and 15% a normal chest X-ray. Neither result excludes the diagnosis.
  • ST elevation can be dissection occluding a coronary ostium. Withhold antiplatelets, heparin and thrombolysis until the aorta has been imaged.
  • Transthoracic echo misses 30% of dissections. It answers the tamponade question in shock; it cannot rule the diagnosis out.
  • Hypotension or shock scores on the ADD-RS and suggests rupture or tamponade. It is a reason to move faster, not to delay referral.

Illustrations

Intimal tear creating a false lumenDiagram of an intimal tear allowing blood to split the aortic wall, forming a true and false lumen running alongside each other and potentially compromising branch vessels.PassFinals · original
Stanford classification of aortic dissectionDiagram contrasting type A ascending-aortic involvement with type B, which spares the ascending aorta; type A can extend distally and type B may still become complicated.AI-generated (OpenAI gpt-image-1) · AI-generated
CT angiogram showing type B dissectionAxial and coronal contrast CT images showing an intimal flap dividing the descending thoracic aorta into true and false lumens in a Stanford type B dissection.JasonRobertYoungMD, Wikimedia Commons · CC-BY-SA-4.0
Widened mediastinum on chest X-rayAnnotated frontal chest radiograph showing widened mediastinal and aortic contours as a possible clue to thoracic aortic disease, with a warning that a normal film does not exclude dissection.J. Heuser, Wikimedia Commons · CC-BY-SA-3.0

Key sources

  1. NICE HTG634: Aortic remodelling hybrid stent insertion during surgical repair of an acute type A aortic dissection (Section 2, recommendations 2.1 to 2.3. What a dissection is, the anatomy of type A and type B, and that acute type A dissection needs immediate surgery. Previously interventional procedures guidance IPG733; this is the chapter URL that renders.)
  2. Royal College of Emergency Medicine and Royal College of Radiologists, Diagnosis of Thoracic Aortic Dissection in the Emergency Department (Best Practice Guideline) (Introduction, Recommendations, and Appendix 1 (Aortic Dissection Detection Risk Score). Carries D-dimer sensitivity and specificity at 500 nanograms/mL. Also the ADD-RS scanning rule, the CT protocol, chest radiograph signs, and the proportions with a normal ECG, film or transthoracic echo.)Published 1 Mar 2025
  3. NHS England, South England Aortic Dissection Network: Supra-regional standard operating procedure on the acute management of aortic dissections, version 1.0 (Sections 'Principles of Anti-Impulse therapy', 'For the ED', and 'Anti-impulse protocol for ED & ACCTS Escorted Ambulance'. These carry the blood pressure and heart rate targets with their time limits, the labetalol regimen and the morphine titration. The same document gives the CT protocol, the ADD-RS risk bands and the referral and transfer pathway. Endorsed by the UK Aortic Society.)Published 1 Mar 2024
  4. RCEMLearning: Acute Aortic Dissection (Royal College of Emergency Medicine learning resource, not a guideline) (Blood pressure management section. States why a vasodilator used alone provokes a reflex increase in ventricular contractility and worsens the dissection, and why analgesia precedes antihypertensives. Also states that antiplatelets, heparin and thrombolysis are withheld when dissection is possible, even with an infarct pattern on the ECG.)
  5. 2024 ESC Guidelines for the management of peripheral arterial and aortic diseases, European Heart Journal 2024;45(36):3538-3700 (Recommendations for diagnostic work-up of acute aortic syndromes (Recommendation Table 44, listed at page 3622 in the contents). CT from neck to pelvis is first-line imaging, and transoesophageal echocardiography guides peri-operative management. Recommendations for medical treatment in acute aortic syndromes (Recommendation Table 45, page 3623). Switch to oral beta-blockers after 24 hours once intravenous anti-impulse targets are met. Use a non-dihydropyridine calcium channel blocker if beta-blockers are contraindicated. The article body needs a subscription; the contents render at this URL.)
  6. Healthcare Safety Investigation Branch (now Health Services Safety Investigations Body): Delayed recognition of acute aortic dissection (Summary of findings and sections 1.9, 4.1.2, 4.1.3, 4.1.5 and 4.2.3. Incidence of about 4.5 per 100,000 per year, roughly 2,500 cases a year in England. Death before reaching hospital or a specialist centre. Diagnostic delay in 16% to 40% of cases. Pain in up to 85%, and painless presentation in 6% to 17%.)Published 23 Jan 2020
  7. BNF: morphine (Adult acute pain dosing, including by slow intravenous injection, used here with the emergency-department titration in the South England standard operating procedure)
  8. BNF: labetalol hydrochloride (Hypertensive emergencies: by intravenous infusion, initially 2 mg/minute until a satisfactory response is achieved; also the contra-indications shared by systemic beta-blockers)
  9. BNF: esmolol hydrochloride (Adult intravenous infusion of 50 to 200 micrograms/kg/minute for tachycardia and hypertension)
  10. BNF: glyceryl trinitrate (Adult intravenous infusion of 10 to 200 micrograms/minute, maximum 400 micrograms/minute, and the requirement to monitor blood pressure and heart rate during infusion)
  11. BNF: sodium nitroprusside (Unlicensed use: not licensed for use in the UK)
  12. NHS England: Acute Aortic Dissection Pathway Toolkit, version 1.0 (Background and evidence sections. Death before hospital and within 24 hours without surgery in type A, and surgical mortality. Also the proportion of type B dissections needing intervention, and measured times from emergency department arrival to CT and from CT to surgery.)Published 15 Mar 2022

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.