Cardiovascular System >
Aortic Dissection
“Tear in inner layer of aorta → leading to haematoma between intima and media layer of aorta”
Risk Factors
- Male between 40-80 years old – peak at 60-80 years
- Marfan syndrome
Aetiology
- Hypertension (increases risk of rupture)
- Trauma
- Deceleration injury- motorcycle accident
- Iatrogenic injury during valve replacement/ graft surgery
- Vasculitis w aortic involvement ( syphilis)
- Recreational drug-Amphetamines/cocaine
- Atherosclerosis
- 3rd-trimester pregnancy
- Congenital
- CT disease- Marfan, Ehlers- Danlos syndrome
- Bicuspid aortic valve
- Coarctation of aorta
Pathophysiology
- Transverse tear in intima → blood entering space in between intima and media forming a false lumen
- Causes the formation of haematoma, which can move and increase in size
- A rise in pressure can cause the aortic wall to rupture leading to occlusion of branching vessels → ischaemia in area
- Second intima tear can result in re-entry into the normal aortic lumen
Classifications of Aortic Dissection
- Stanford ( more common) → by aorta involvement e.g. ascending/ descending aorta
- Type A– Ascending Aorta ( proximal to brachiocephalic artery- extends proximally to aortic arch & distally to descending aorta)
- Type B – any dissection not involving ascending,
- Tx: medically * BB, vasodilators
- DeBakey → by origin and extent
- Type I: originates in ascending aorta to aortic arch & descending aorta
- Type II: dissection originated and restricted to ascending aorta
- Type III descending aorta, extends distally
- Type IIIa – descending thoracic aorta above level of the diaphragm
- Type IIIb extends below diaphragm
Clinical Presentation
- Sudden severe tearing/ ripping pain
- In anterior chest or back
- Interscapular or retrosternal pain
- Neck & jaw or abdomen (colicky pain )
- Migrated as dissected wall propagates caudally
- Further signs
- HTN/ Hypotension
- Asymmetrical BP and pulse readings bw limbs
- Syncope diaphoresis, confusion or agitation
- Heart murmur- aortic regurgitation in proximal dissection
Investigations
- Detect aortic dissection risk score (ADD- RS )
- ECG
- Lab studies: D- Dimer ( elevated), evaluate for signs of end-organ damage, troponin, BMP, lactate
- Pre-op labs- CBC, type & screen, BMP, coagulation panel
- Imaging:
- CXR, AP view
- CT angiography of chest, abdomen et pelvis
- MRA of chest, abdomen and pelvis
- Transoesophageal echocardiography
- Catheter angiography, ultrasound
Management
- Surgery – !only in pat w suspected of confirmed dissection!
- Open surgery w/ graft
- Endovascular treatment w aortic stent implantation ( type B dissection and if the operative risk to high)
- Stanford A – immediate surgery
- Stanford B – treat conservatively unless a complication
- (end-organ damage, Hypotension, persistent severe chest pain or HTN) propagation of dissection, expanding aneurysm/ haematoma)
- Blood Pressure Control:
- Hypotensive patients:
- !avoid inotropes- worsen aortic wall stress
- Haemodynamic support:
- Target MAP of 70 mmHg or euvolemia
- IV fluids,
- Vasopressor support if pat remain hypotensive
- Norepinephrine, phenylephrine,
- Identify & treat comorbidities
- Hypertensive patients:
- Control HTN- control & target 100-120 mmHG & HR ≤ 60bpm
- Start w IV blocker – to avoid reflex tachycardia
- Esmolol, labetalol
- Follow w vasodilator ( IV sodium nitroprusside)
- If BB contraindicated – calcium channel blocker ( verapamil, diltiazem)
- Hypotensive patients:
- Supportive Care:
- The patient may require sedation – analgesia ( Morphine)
- Identify & treat complications (AKI & mesenteric ischaemia)
- Avoid thrombolytic tx in patients w suspected aortic dissection
Complications
- Aortic rupture & acute blood loss – acute back and flank pain
- MI
- Aortic regurgitation
- Cardiac tamponade combined w cardiogenic shock
- Pericarditis
- Stroke
- Bleeding into thorax, mediastinum & abdomen
- Arterial occlusion & ischaemia depending on location
Prevention
- BP control
- Smoking cessation
- Screening
- Repair of rapidly expanding aneurysm