Acute aortic syndrome
Flap, true and false lumen, and the complications that make type A a surgical emergency — plus the artefacts that fool you.
Numbers to remember
- TTE sensitivity for type A dissection is only ≈77–80%, and much lower for the arch and descending aorta — a negative TTE never excludes it [173]
- ADD-RS ≥1 had a sensitivity of about 96% in IRAD, but most patients with ADD-RS ≥1 do not have dissection [203]
- Intramural haematoma: crescentic wall thickening >5 mm without an intimal flap [9,173]
- Type A dissection with pericardial effusion: surgery, not pericardiocentesis [9,31]
Questions echo must answer
Acute aortic syndrome includes dissection, intramural haematoma and penetrating aortic ulcer [9,10,174]. CT angiography is the usual confirmatory test. Bedside TTE in the emergency room detects type A involvement and its complications quickly, and TOE in the operating room guides the repair [173,174].
- Is there an intimal flap in the ascending aorta?It must be seen in two views, move independently of the aortic wall, and separate two lumens with different colour flow [173].
- ComplicationsAortic regurgitation (mechanism), pericardial effusion or tamponade, regional wall-motion abnormality (coronary involvement, usually RCA), aortic rupture [9,173].
- ExtentArch and descending aorta from the suprasternal view; abdominal aorta subxiphoid [173].
- AlternativeACS, PE, pericarditis [195].
Acquisition protocol
- PLAX, high-left and right parasternalAortic root and ascending aorta at consistent levels; look for a mobile flap [9,18].
- PSAX-AVFlap in cross-section; AR mechanism (prolapse of the flap, cusp prolapse, annular dilatation).
- A5C / A3C colourAR severity.
- SuprasternalArch and proximal descending aorta; colour for true and false lumen [173].
- Subcostal / abdominalAbdominal aorta flap; pericardial effusion.
- PericardiumEffusion, echogenic haemopericardium, tamponade signs.
- LVRegional wall motion (RCA or left main compromise).
- M-modeUse it to distinguish a true flap from reverberation artefact [173].
- Ascending aorta flap (two views)
- Aortic dimensions
- AR mechanism and grade
- Pericardial effusion or tamponade
- Regional wall motion
- Arch and descending aorta
- Abdominal aorta
Diagnosis & severity
| Finding | Echo features |
|---|---|
| Classic dissection | Mobile intimal flap separating a true lumen (systolic expansion, forward systolic flow) from a false lumen (slow flow, spontaneous contrast or thrombus) [173] |
| Intramural haematoma | Crescentic or circular wall thickening >5 mm, no flap, displaced intimal calcium [9,173] |
| Penetrating aortic ulcer | Crater-like outpouching through calcified plaque, usually descending aorta (better seen on CT and TOE) [9] |
| Entry tear | Colour flow crossing the flap [173] |
ADD-RS risk score [203]
One point from each category: high-risk conditions (Marfan, family history, known aortic valve disease, recent aortic manipulation, known aneurysm); high-risk pain features (abrupt, severe, ripping or tearing); high-risk examination features (pulse deficit, systolic BP difference, focal neurological deficit plus pain, new AR murmur plus pain, hypotension or shock). A score of 0–3 guides the diagnostic pathway [174,203].
Thresholds that change management
- Flap in the ascending aorta → type A dissection. Immediate cardiothoracic surgery; CT angiography if it does not delay surgery [9,10,174].
- Suspected dissection with a negative TTE → CT angiography (or TOE if unstable) [173,174].
- Pericardial effusion in type A dissection → go to theatre. Controlled pericardial drainage only in extremis [9,31].
- Type B → blood pressure and heart-rate control; endovascular treatment for complications (malperfusion, rupture, expansion) [9,174].
- Coronary involvement (new wall-motion abnormality) must not lead to thrombolysis or anticoagulation without imaging the aorta [9,138].
Pitfalls & mimics
PitfallReverberation artefact in the ascending aorta mimics a flap. An artefact lies at twice the distance of a strong reflector (often the posterior aortic wall or right PA), moves in parallel with that reflector, has blurred borders, and colour flow passes straight through it [173].
- A normal root diameter does not exclude dissection, and a dilated root is not diagnostic.
- Left brachiocephalic vein and pericardial recesses mimic a false lumen in suprasternal views.
- TTE misses the distal ascending aorta and arch. Use CT or TOE.
- ACS mimicry: inferior ST elevation from RCA involvement. Look at the aorta and for AR before giving antithrombotics.