The daily educational pearl – aortic dissection

Aortic dissection

Risk factors:
– hypertension
– connective tissue disorders / vasculitis – Marfan’s, Ehlers-Danlos, giant cell arteritis
– congenital heart disease – bicuspid aortic valve

– cocaine / amphetamine use
– exertion
– trauma

– iatrogenic – intraaortic balloon pump insertion

Women with Marfan’s have increased risk of dissection during pregnancy.

Symptoms:

– pain

* present in 90% cases

* sharp, “tearing”, “ripping”

* anterior chest (ascending aorta) / neck + jaw (aortic arch) / interscapular area (descending aorta) / lumbar area or abdomen (descending aorta below diaphragm)

* migration of the pain occurs with propagation of the dissection

– neurological symptoms (focal weakness / altered mental state – involvement of carotid / vertebral or spinal arteries) – 17% of cases

– syncope

– signs of lower limb ischaemia (involvement of iliac arteries)

Physical exam:

– severe hypertension refractory to medical therapy if renal arteries are involved (renin release)

– signs of pericardial tamponade – hypotension / tachycardia / raised JVP / muffled heart sounds

– aortic regurgitation – 32% of patients

– pulse deficits / radio-radial or radio-femoral delay / discrepancies in BP between limbs – only 30% sensitivity

– signs of ischaemia – CVA (carotid / vertebral a.) / limb / peripheral neuropathy (spinal a.)

Investigations:

– ECG – 3% cases dissect into a coronary artery, most commonly RCA – inferior STEMI on ECG

– CXR – abnormal in 80% cases; possible findings (think about the anatomy of the aorta!)
1. mediastinal widening (>8 cm measured at the level on the aortic knuckle)
2. left pleural effusion
3. apical pleural cap
4. depression left main bronchus
5. trachea deviated to the right
6. ETT deviated to the right
7. NGT deviated to the right
8. obliteration of the aortopulmonary window
9. right paratracheal stripe > 3 mm
10. “calcium sign” (intimal calcification separated from the outermost part of the aorta by > 5 mm)

– CT thoracic aortogram is the diagnostic test of choice – if your DD is dissection and PE, do a CTPA as the radiologists can look at the aortic lumen on a CTPA but can’t diagnose a PE on a CTA

– echo – can show dissection of ascending aorta

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