Aortic Intramural Haematoma

Haemorrhage within the aortic media without an intimal tear or flow in a false lumen. It makes up about 5 to 20% of acute aortic syndromes. Rupture of the vasa vasorum is the main mechanism, with an ulcer like projection into the haematoma in some cases.

• Type A involves the ascending aorta (about 30 to 40%) and type B the descending aorta alone (about 60 to 70%). Risk factors: hypertension (about 80%), age over 65, atherosclerosis, trauma, connective tissue disease and cocaine use.
• Natural history: about 30 to 40% progress to dissection or rupture within days to weeks, about 10% rupture, and about a third of type B cases regress completely. Type A carries high early mortality without surgery (up to about 30 to 40%) and about 10 to 20% with surgery. Type B has about 5 to 10% 30-day mortality with medical therapy.
• Features of poor outcome: ascending aorta involvement, maximal aortic diameter 50 mm or more (ascending) or 40 to 45 mm or more (descending), haematoma thickness greater than 11 mm in type A or greater than 10 to 13 mm in type B, ulcer like projection, pericardial or pleural effusion, recurrent pain, and refractory hypertension.

• Abrupt severe chest, back or abdominal pain, often tearing or ripping and migrating. Hypertension at presentation. Pulse deficit, aortic regurgitation and neurological signs are less frequent than in dissection. Syncope and shock suggest tamponade or rupture.
• Differential diagnosis: aortic dissection, penetrating aortic ulcer, acute coronary syndrome, pulmonary embolism, leaking aortic aneurysm, pericarditis, pancreatitis, and oesophageal rupture.
• Complications: progression to dissection, rupture (tamponade, haemothorax), aneurysm formation, aortic regurgitation, malperfusion of branch vessels, and stroke.

• Unenhanced CT first: a crescent or ring of high attenuation (60 to 70 Hounsfield units) in the wall of 5 mm or more, with inward displacement of intimal calcification. Then CT angiography: no intimal flap and no false lumen opacification, with a wall that does not enhance.
• Transoesophageal echocardiography shows a crescentic wall thickening; MRI shows the haematoma age and is useful for follow up.
• ECG and troponin (exclude coronary involvement), D-dimer (greater than 0.5 micrograms/mL supports an acute aortic syndrome), chest X-ray (mediastinal widening), full blood count, creatinine, lactate, blood group and crossmatch of 4 to 6 units.
• Echocardiography for pericardial effusion and aortic regurgitation.

• Admit to intensive care and manage urgently as an aortic emergency with heart rate and pressure control and early imaging.
• Analgesia and heart rate and pressure control:
  • Morphine 2 to 5 mg IV titrated to pain, or fentanyl 25 to 50 micrograms IV.
  • Target heart rate 60 beats/min and systolic pressure 100 to 120 mmHg within the first hour, with rate control first: esmolol 500 micrograms/kg IV over 1 minute then 50 to 300 micrograms/kg/min (increase by 50 micrograms/kg/min every 4 minutes), or labetalol 20 mg IV then 20 to 80 mg every 10 minutes (maximum 300 mg) or infusion 0.5 to 2 mg/min.
  • If more pressure lowering is needed after rate control: nicardipine 5 to 15 mg/h, glyceryl trinitrate 5 to 100 micrograms/min, or sodium nitroprusside 0.25 to 10 micrograms/kg/min. Never start a vasodilator before rate control.
  • If beta blockers are contraindicated (severe aortic regurgitation, asthma, heart block): diltiazem 0.25 mg/kg IV then 5 to 15 mg/h.
  • Avoid anticoagulants, antiplatelet drugs and thrombolytics.
• Type A:
  • Urgent surgery: replacement of the ascending aorta with or without hemiarch, using hypothermic circulatory arrest with cerebral perfusion; a composite root replacement (valved conduit with coronary reimplantation) if the root or aortic valve is involved. Operative mortality about 10 to 20%.
  • Selected low risk patients (haematoma thickness less than 11 mm, ascending diameter less than 50 mm, no pericardial effusion, no refractory pain) can be treated medically in expert centres with repeat imaging at 24 to 72 hours and at 7 days; evidence is limited.
• Type B:
  • Medical therapy with esmolol 500 micrograms/kg IV over 1 minute then 50 to 300 micrograms/kg/min, or labetalol 20 mg IV then 20 to 80 mg every 10 minutes (maximum 300 mg), targeting heart rate 60 beats/min and systolic pressure 100 to 120 mmHg, repeat CT at 24 to 48 hours, 7 days, then at 1, 3, 6 and 12 months, then yearly.
  • Intervene for complications: rupture, malperfusion, refractory pain or hypertension, rapid expansion, an enlarging ulcer like projection, or a diameter greater than 55 mm. Thoracic endovascular aortic repair with a stent graft covering the lesion is the preferred operation (technical success greater than 90%, 30-day mortality about 5 to 10%); open repair when anatomy is unsuitable. Spinal cord ischaemia occurs in about 3%, so use cerebrospinal fluid drainage in high risk cases.
• Long term therapy:
  • Bisoprolol 2.5 to 10 mg daily (heart rate 60 to 70 beats/min), ramipril 2.5 to 10 mg daily, amlodipine 5 to 10 mg daily; target blood pressure less than 120 to 130 mmHg systolic. Losartan 50 to 100 mg daily in Marfan syndrome.
  • Atorvastatin 40 to 80 mg daily for atherosclerosis; smoking cessation; avoid fluoroquinolones, stimulants (cocaine, amphetamines) and heavy isometric lifting.
• Special groups:
  • Pregnancy: rare and very high risk; use labetalol 100 to 400 mg twice daily and nifedipine retard; avoid ACE inhibitors, ARBs and atenolol; deliver by caesarean section when the fetus is viable and the aorta is unstable; surgery with bypass carries fetal loss of about 20 to 30%.
  • Connective tissue disease: earlier intervention (ascending aorta 45 to 50 mm), genetic assessment and relative screening.
  • Elderly: more atherosclerosis and higher surgical risk; favour endovascular repair for type B.
  • Cocaine users: use benzodiazepines (lorazepam 2 mg IV), vasodilators and labetalol with caution.
  • Renal impairment: limit contrast and adjust drugs.
• Red flags: recurrent pain, haemodynamic instability, new pericardial or pleural effusion, new neurological deficit, limb or visceral ischaemia, rising aortic diameter.
• Follow up: CT or MRI at 1, 3, 6 and 12 months, then yearly for life; blood pressure and heart rate at each visit; repeat imaging for any new symptoms.