Acute aortic syndrome and dissection

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Acute aortic syndrome (AAS) comprises acute aortic dissection, intramural haematoma and penetrating atherosclerotic ulcer, with rupture as a shared catastrophic endpoint. Dissection creates an intimal entry and false lumen; intramural haematoma is blood within the media without an obvious communicating tear on initial imaging; penetrating ulcer traverses an atherosclerotic intima into the media. These entities can coexist or evolve, so a report should state location, entry, extent, branch involvement, rupture signs and organ consequences rather than stop at the umbrella term.

Stanford classification drives immediate routing. Type A is any dissection involving the ascending aorta, even when the tear is in the arch or descending segment. Type B has no ascending involvement and classically begins distal to the left subclavian artery. Acute type A mortality rises rapidly without operation and requires immediate cardiothoracic repair. Uncomplicated acute type B disease begins with intensive anti-impulse therapy and surveillance; complicated type B disease, especially rupture or malperfusion, is treated urgently, usually with thoracic endovascular aortic repair when anatomy permits.

Pain is often abrupt, maximal at onset and severe, but absence of a textbook tearing description does not exclude disease. Syncope, stroke, paraplegia, myocardial ischaemia, acute aortic regurgitation, heart failure, abdominal pain, oliguria or limb ischaemia may dominate. Dynamic malperfusion occurs when the mobile flap obstructs a branch origin according to pressure between true and false lumens; static malperfusion extends dissection into the branch or thromboses it. Both can produce organ injury and require anatomy-specific repair rather than blood-pressure treatment alone.

ECG-gated CTA from neck to pelvis is the acute diagnostic standard because it shows the whole aorta, entry tear, false-lumen patency, branch perfusion, haemorrhage and access anatomy. Focused TTE rapidly identifies tamponade, proximal dilatation, severe regurgitation or ventricular dysfunction but cannot exclude distal disease. TOE is particularly useful in unstable patients who cannot leave resuscitation or theatre. MRI is accurate but usually too slow and inaccessible for an unstable emergency. D-dimer below 500 ng/mL can contribute to a validated low-probability exclusion pathway, but must not delay imaging in high-probability disease.

Initial treatment reduces shear and impulse while definitive decisions happen. Give adequate analgesia, establish arterial-line and ECG monitoring, and lower heart rate with intravenous labetalol or esmolol before adding intravenous nicardipine or a nitrate if pressure remains high. ESC targets heart rate at or below 60 and systolic pressure below 120 mmHg. Those targets assume adequate perfusion: hypotension, tamponade, rupture, severe aortic regurgitation, cardiogenic shock, brain or spinal injury and mesenteric or limb malperfusion demand individualized support and urgent mechanical correction.

Follow-up depends on lesion and treatment. ESC recommends imaging medically treated type B AAS or intramural haematoma at 1, 3, 6 and 12 months after onset, then yearly if stable. After TEVAR for AAS, image at 1, 6 and 12 months, then yearly through year five if no abnormality; after open AAS surgery, use CCT and TTE within 6 months, CCT at 12 months and then yearly if stable. Abnormalities after TEVAR shorten CCT follow-up to every 3–6 months, and longer-term spacing is considered only after defined years without complications or residual patent false lumen.

Key points

Suspect acute aortic syndrome with abrupt severe chest, back or abdominal pain plus aortic disease, pulse deficit, new regurgitation, neurological deficit or shock.
Stanford type A involves the ascending aorta and needs immediate surgery; type B begins distal to the left subclavian artery without ascending involvement.
Complicated type B means rupture or impending rupture, malperfusion, persistent or recurrent pain, uncontrolled hypertension or disease progression and usually needs urgent intervention.
Obtain ECG-gated CT angiography from neck to pelvis as soon as possible; use transoesophageal echocardiography when CT is unavailable or instability precludes transfer.
Begin analgesia and anti-impulse therapy immediately when perfusion permits, targeting systolic pressure below 120 mmHg and heart rate at or below 60 beats per minute.
Give intravenous beta blockade before adding a vasodilator; if beta blockade is contraindicated, use intravenous non-dihydropyridine calcium-channel rate control.
Do not force standard pressure targets in shock, tamponade, severe regurgitation or cerebral, spinal or visceral malperfusion; preserve threatened-organ perfusion while definitive treatment is organized.
Type A malperfusion usually proceeds to immediate central repair; significant mesenteric malperfusion may require expert angiographic branch reperfusion before or directly after aortic surgery.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Hypertensive medial injury

Chronic pressure and medial degeneration predispose older adults to an intimal tear, especially in the descending thoracic aorta.

Heritable aortopathy

Marfan, Loeys-Dietz, vascular Ehlers-Danlos and non-syndromic gene variants permit acute dissection at younger ages and smaller diameters.

Atherosclerotic ulcer disease

Penetrating ulcer arises through diseased intima, typically in older patients with extensive atherosclerosis and descending aortic involvement.

Iatrogenic or pregnancy stress

Aortic instrumentation, cardiac surgery and pregnancy-related haemodynamic stress can trigger wall injury in a susceptible aorta.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
False lumen propagation
Pressurized blood splits medial layers longitudinally, expanding a false lumen and threatening rupture, valve support and branch perfusion.
2
Dynamic branch obstruction
A mobile flap and false-lumen pressure intermittently collapse the true lumen across a branch origin, producing pressure-dependent malperfusion.
3
Static branch obstruction
Dissection extends into a branch with thrombosis or fixed narrowing, so central pressure control alone cannot reliably restore flow.
4
Proximal catastrophe
Ascending propagation can disrupt aortic valve commissures, occlude coronary ostia or rupture into the pericardium causing tamponade.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Abrupt maximal painRed flag

Severe chest, interscapular, abdominal or migrating pain reaches maximum intensity rapidly and may track with propagation.

Proximal complicationRed flag

New diastolic murmur, pulmonary oedema, myocardial ischaemia, pericardial effusion or tamponade suggests ascending involvement.

Malperfusion syndromeRed flag

Stroke, paraplegia, abdominal pain with lactate rise, oliguria, pulse loss or acute limb ischaemia signals branch compromise.

High-risk background

Known aneurysm, bicuspid valve, connective-tissue disorder, family dissection, recent aortic procedure or pregnancy raises pre-test probability.

Complicated type BRed flag

Persistent pain, uncontrolled hypertension, rupture signs, rapid expansion or organ ischaemia converts medical surveillance into an urgent intervention pathway.

Red flags requiring action

Hypotension in suspected dissection can mean rupture, tamponade, severe aortic regurgitation, myocardial ischaemia or organ malperfusion; do not reflexively give antihypertensives.
Any ascending aortic involvement is Stanford type A and requires immediate cardiothoracic surgical management, irrespective of where the entry tear lies.
Persistent pain, refractory hypertension, rapid expansion, rupture, shock or cerebral, coronary, mesenteric, renal, spinal or limb malperfusion makes type B dissection complicated.
A normal chest radiograph, non-specific ECG or low-risk isolated symptom does not exclude acute aortic syndrome when pre-test probability remains high.
Thrombolysis or routine anticoagulation for presumed myocardial infarction, stroke or pulmonary embolism can be catastrophic when dissection remains plausible.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
First-line: ECG-gated CT angiography from neck to pelvisFirst stepFirst line
Why
Confirm AAS and map entry, extent, branches, rupture and access.
Interpretation and limitations
State Stanford type, proximal and distal extent, true and false lumens, branch obstruction, pericardial or pleural blood and impending rupture features.
02
Focused transthoracic echocardiography
Why
Detect tamponade, regurgitation and proximal cardiovascular complications at bedside.
Interpretation and limitations
A positive proximal finding accelerates surgery, but a normal or limited TTE does not exclude dissection elsewhere in the aorta.
03
Transoesophageal echocardiography
Why
Image the thoracic aorta in unstable or perioperative patients.
Interpretation and limitations
Use when transfer to CT is unsafe or CT unavailable; TOE also assesses valve, root and dynamic flow but has blind segments and requires expertise.
04
ECG and serial cardiac biomarkers
Why
Identify coronary malperfusion and competing acute coronary syndrome.
Interpretation and limitations
Ischaemic changes do not exclude dissection; coronary involvement may be part of type A disease and changes operative planning.
05
Blood count chemistry coagulation lactate and cross-match
Why
Measure haemorrhage, organ malperfusion and readiness for major intervention.
Interpretation and limitations
Rising lactate, creatinine or transaminases supports organ injury but normal early results cannot safely exclude dynamic malperfusion.
06
ADD-RS with D-dimer in selected low-risk presentations
Why
Support a validated rule-out strategy when clinical probability is low.
Interpretation and limitations
D-dimer below 500 ng/mL lowers likelihood in the correct pathway; high probability or concerning features still require immediate imaging without assay delay.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Acute coronary syndrome

Myocardial infarction may coexist through coronary malperfusion; assess ECG and troponin while avoiding premature antithrombotic treatment if dissection is plausible.

Pulmonary embolism

Pleuritic pain, hypoxaemia and right-heart strain overlap, but whole-aorta CTA protocols may be adapted when both diagnoses remain credible.

Stroke without dissection

Focal neurology can dominate aortic dissection; pulse, pressure and chest findings should be checked before thrombolysis decisions.

Pericarditis or oesophageal disease

Positional pain, inflammation, rupture or perforation can mimic AAS, yet haemodynamic compromise still requires immediate cross-sectional or echocardiographic evaluation.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Worked caseRoute pain with neurological deficitFirst stepA patient develops abrupt chest pain, transient hemiparesis and unequal arm pressures.

1Recognize high pre-test probability from abrupt pain, neurological deficit and pressure asymmetry; call the cardiothoracic aortic service during ABCDE stabilization.
2Obtain bilateral observations where safe, arterial access, ECG, cross-match and focused echo, while arranging ECG-gated CTA from neck to pelvis without laboratory delay.
3If ascending involvement is present, classify Stanford type A and proceed to immediate central repair even if the neurological deficit has improved.
4Start analgesia and beta-blocker-led anti-impulse therapy only if pressure and perfusion tolerate it; avoid lowering pressure through cerebral or other threatened-organ perfusion.
5DefinitiveReview CTA for carotid, coronary, visceral, renal and limb branches, communicate malperfusion explicitly and verify definitive theatre or transfer activation.

02Definitive routingSeparate type A from type BDefinitiveCross-sectional imaging confirms an acute dissection and defines ascending involvement.

1Any ascending involvement is type A and requires immediate cardiothoracic surgery with anti-impulse stabilization performed concurrently.
2For type B, search actively for rupture, malperfusion, persistent pain, uncontrolled hypertension and progression before calling it uncomplicated.
3Treat complicated type B urgently, generally with TEVAR when anatomically suitable; manage uncomplicated type B with intensive medical therapy and close imaging.

03Malperfusion pathwayRestore organ flow without delayClinical organ dysfunction and imaging show branch compromise during acute dissection.

1Identify the threatened bed clinically and anatomically, distinguishing a radiological branch finding from malperfusion syndrome with organ dysfunction.
2In type A, proceed to immediate aortic surgery for cerebral, renal, limb or visceral malperfusion while coordinating adjunct branch intervention.
3For clinically significant mesenteric malperfusion, an expert aortic centre may perform invasive angiographic reperfusion before or directly after central repair.
4In complicated type B, use TEVAR to cover the entry and expand the true lumen, adding branch stenting, fenestration or bypass if perfusion remains inadequate.

04Medical stabilizationControl impulse while preserving perfusionAAS is suspected or confirmed and the patient is hypertensive without shock or critical malperfusion.

1Provide titrated opioid analgesia and intensive monitoring, including an arterial line, ECG, urine output and repeated neurological and limb examination.
2Titrate intravenous labetalol or esmolol to heart rate at or below 60 and systolic pressure below 120 mmHg when tolerated.
3Only after rate control, add a titratable intravenous vasodilator if pressure remains above target to avoid reflex tachycardia.
4If beta blockade is contraindicated, use intravenous non-dihydropyridine calcium-channel rate control and obtain critical-care pharmacy support.
5Raise the pressure target or support circulation when brain, spinal, visceral or limb perfusion is threatened, and correct the mechanical cause urgently.

Key medicines and prescribing safety2 treatments · regimens, roles and cautions

First-line anti-impulse rate control reduces heart rate, contractility and aortic wall shear before any vasodilator is added.

Intravenous labetalol

Give 50 mg intravenously over at least 1 minute with the patient supine; if necessary repeat 50 mg at 5-minute intervals until satisfactory response, to a maximum cumulative 200 mg. Continuously monitor pressure and pulse and stop escalation once the anti-impulse target or a safety limit is reached.

Do not give in cardiogenic shock, hypotension, uncontrolled or incipient heart failure, sick-sinus syndrome, second- or third-degree heart block, bradycardia below 45–50 beats per minute, or a history of wheeze or asthma. Stop further dosing for hypotension, important bradycardia, block, bronchospasm or worsening low-output or organ perfusion; tamponade, rupture, severe regurgitation and malperfusion require definitive correction rather than forced targets.

Lowers residual severe hypertension after heart-rate control while definitive aortic management proceeds.

Intravenous nicardipine infusion

Only after beta blockade or alternative rate control, start continuous intravenous nicardipine at 3–5 mg/hour for 15 minutes; increase by 0.5–1 mg/hour every 15 minutes to response, maximum 15 mg/hour, then reduce progressively to 2–4 mg/hour maintenance while the target remains necessary.

Never give as an unopposed bolus or first anti-impulse drug because reflex tachycardia can increase shear. Use a controlled pump with continuous pressure monitoring; halve the dose or stop for systemic hypotension or reflex tachycardia, and stop or retarget if neurological, spinal, renal, mesenteric or limb perfusion worsens. It is contraindicated in severe aortic stenosis, unstable angina, compensatory hypertension and within 8 days of myocardial infarction; use lower, cautious titration in older adults and hepatic or renal impairment.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Rupture and tamponade

Free rupture causes haemothorax or exsanguination, while proximal contained rupture into pericardium produces obstructive shock and arrest.

Aortic regurgitation

Root and commissural disruption causes an acute volume load, pulmonary oedema and cardiogenic shock requiring operative correction.

Coronary and cerebral malperfusion

Branch obstruction can cause myocardial infarction, stroke or coma and substantially increases operative risk without removing the need for expert repair.

Visceral renal or limb ischaemia

Mesenteric necrosis, acute kidney injury, paraplegia and limb loss can follow inadequate true-lumen or branch-vessel perfusion.

Late aneurysmal degeneration

Residual patent false lumen can enlarge after the acute event, requiring lifelong blood-pressure and cross-sectional imaging surveillance.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Use an arterial line for beat-to-beat pressure and continuous ECG while intravenous anti-impulse agents are titrated.
Repeat neurological, abdominal, renal and limb-perfusion assessment because dynamic malperfusion can appear or worsen after presentation.
Track urine output, lactate, creatinine, haemoglobin and acid-base status as adjuncts to clinical organ assessment.
For medically treated type B AAS or intramural haematoma, perform cross-sectional imaging at 1, 3, 6 and 12 months after onset, then yearly if stable.
After TEVAR for AAS image at 1, 6 and 12 months, then yearly through year five if normal; after open AAS surgery use CCT and TTE within 6 months, CCT at 12 months, then yearly if stable.
Image sooner for recurrent pain, uncontrolled hypertension, new deficit or enlarging residual aorta.
Screen for heritable aortic disease and arrange family assessment when age, phenotype or history indicates it.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Type follows involvement

A tear in the descending aorta that propagates retrogradely into the ascending segment is still Stanford type A.

Malperfusion is clinical

Branch narrowing on CT becomes malperfusion syndrome when it produces organ ischaemia or dysfunction and changes urgency.

Pressure targets have boundaries

Below 120 mmHg is an anti-impulse target for adequately perfused patients, not a mandate during shock or threatened-organ flow.

Rate control comes first

A vasodilator without prior beta blockade or alternative rate control can provoke tachycardia and increase wall stress.

Negative tests need context

Neither a normal chest radiograph nor an isolated low D-dimer safely overrules a high-risk clinical presentation.

11Common pitfallsFrequent interpretation and management errors.

01
Do not label a dissection type from the tear site alone; inspect whether the ascending aorta is involved.
02
Do not delay high-probability CTA while waiting for D-dimer, troponin or a chest radiograph.
03
Do not give an unopposed vasodilator before establishing rate control.
04
Do not push anti-impulse targets through hypotension, tamponade, rupture or critical organ malperfusion.
05
Do not call type B uncomplicated until rupture, pain, refractory pressure, progression and every major malperfusion territory are assessed.
06
Do not give thrombolysis or anticoagulation reflexively for stroke or myocardial ischaemia before considering dissection.

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