Aortic dissection - vascular Flashcards
What is an aortic dissection?
Tear in intima
–> blood to surge into aortic wall
–> split between inner & outer tunica media
–> creating a false lumen
What are the classifications of an aortic dissection?
- Type A involving the ascending (±descending) aorta;
- type B involving only the descending aorta
De Bakey classification
- Type I: proximal tear, with dissection involving the ascending and descending aorta
- Type II: ascending aorta only
- Type III: descending aorta only
What is the process of aortic dissection?
What are the causes of aortic dissection?
conditions that –> degeneration of SM of aortic media
cystic medial degeneration
- elastin, collagen, smooth muscle breakdown in lamina media.
ruptured vasa vasorum
- see image
Marfan’s syndrome & Ehler Danlos syndrome (connective tissue disease)
- –> weakening of media –> predisposed to dilation + dissection
Hypertension
Aortic Atherosclerosis
Congenital cardiac abnormalities
- coarctation
Aortitis
- Takayasu’s aortitis, tertiary syphilis
Iatrogenic
- during angioplasty, angiography
Trauma
Cocaine
What are the risk factors for aortic dissection?
- hypertension
- Marfan syndrome, Ehlers-Danlos syndrome
- bicuspid aortic valve
- annulo-aortic ectasia
- dilation of proximal ascending aorta + aortic annulus (=fibrous ring marking separtation of the aorta from right ventricle)
- coarctation
- smoking
- family history of aortic aneurysm / dissection
Summarise the epidemiology of aortic dissection
- males > females
- 50+ yrs
What are the presenting symptoms of aortic dissection?
-
Sudden, central tearing chest pain
- ± radiation to back
- ~ –> occlusion of aorta + its branches:
- see image
What are the signs of aortic dissection on physical examination?
-
Murmur on back
- below L scapula, descending to abdomen
-
HTN
- BP discrepancy between arms of >20mmHg
-
Aortic insufficiency
- collapsing pulse, early diastolic murmur over aortic area, unequal
- arm pulses
- ± palpable abdominal mass
What are the primary investigations for a suspected aortic dissection?
- ECG
-
Chest x ray
- excludes pulmonary causes of chest pain
-
CT angiography
- diagnostic
bloods:
- FBC
-
cardiac enzymes
- excludes MI
-
serum creatinine
- high = renal function impaired
-
serum urea
- high = renal function impaired
-
aspartate transaminase
- high = liver functional impaired
- alanine transaminase
- high = liver functional impaired
- Serum lactate
- type & cross
What are the secondary investigations to consider for a suspected aortic dissection?
-
D-dimer i.e. fibrin degradation product (FDP)
- if +tive, little clinical meaning ; if -tive definitely not an aortic dissection
-
trans-oesophagael ECG > trans-thoracic (sens + spec)
- intimal flap seen
-
MR angiography
- rarely used in acute setting - hard to obtain
- Intravascular US
-
Smooth muscle myosin heavy chain protein
- released from damaged medial aortic SM
