Aortic disease Flashcards
What is aortic dissection?
Tear in the aortic intima allows blood to surge into the aortic wall, causing a split between the inner and outer tunica media and creating a false lumen.
What is the aetiology of aortic dissection? (x8)
- Hypertension
- Aortic atherosclerosis
- Connective tissue disorder
- Congenital cardiac abnormalities such as aortic coarctation (narrowing)
- Aortitis
- Iatrogenic e.g., during angiography or angioplasty
- Trauma
- Crack cocaine
What are the two classifications for aortic dissection?
Type A: ascending aorta tear (most common); Type B: descending aorta tear distal to left subclavian artery.
What is the pathophysiology of aortic dissection?
Predisposing factors leads to degenerative changes in the smooth muscle of the aortic media. These changes and high-pressure blood flow rips the tissue of the media apart along the laminated plane splitting the inner two-thirds and the outer one-third of the media apart. Dissection creates a false lumen which may occlude branches of the aorta.
What is the epidemiology of aortic dissection: Gender? Age? Where? Incidence?
Most common in males between 40 and 60. More common in the West. Worldwide incidence is 1 in 100 000.
What are the symptoms of aortic dissection? (x1 + x6)
- Sudden central ‘tearing’ pain which may radiate to the back (may mimic an MI)
- Aortic dissection can lead to occlusion of the aorta and its branches. Hence:
- Carotid obstruction: hemiparesis, dysphasia, blackout
- Coronary artery obstruction: angina/MI leading to chest pain
- Subclavian obstruction: ataxia, loss of consciousness
- Anterior spinal artery: paraplegia
- Coeliac obstruction: abdominal pain from ischaemic bowel
- Renal artery obstruction: anuria, renal failure
What are the signs of aortic dissection? (x4)
- Murmur on the back below left scapula, descending to abdomen
- BP: hypertension discrepancy between arms of at least 20mmHg, wide pulse pressure. Check BP for differential: If hypotensive, may signify cardiac tamponade (check pulsus paradoxus)
- Aortic insufficiency: collapsing pulse, early diastolic murmur over aortic area
- Palpable abdominal mass if dissection extends down
What are the investigations for aortic dissection? (x5 (x5))
- Bloods: D-dimer is positive and highly sensitive, FBC (in case of haemorrhage), U&E (check renal function for renal artery obstruction), LFTs (check liver function for coeliac artery obstruction), lactate (for malperfusion). Also type and cross blood for transfusion with rupture risk/surgery preparation.
- CXR: widened mediastinum
- ECG: often normal. Signs of left ventricular hypertrophy or inferior MI if dissection compromises the ostia of the right coronary artery (entrance point above aortic valve)
- CT thorax: visualise false lumen
- Echocardiography: transoesophageal is highly specific
What are the complications of aortic dissection?
Aortic rupture, cardiac tamponade, pulmonary oedema, MI, syncope, cerebrovascular, renal, mesenteric, or spinal ischaemia from occlusion (from expansion of false aneurysm).
What is abdominal aortic aneurysm?
Dilation of the aorta with a diameter at least 1.5 times the expected anteroposterior diameter of that segment, given the patient’s sex and body size (or at least 3cm).
What is the aetiology of an abdominal aortic aneurysm? (x8)
- SMOKING
- Alcohol
- Hypertension
- Genetic susceptibility
- Atherosclerosis
- Infection
- Trauma
- Arteritis
What long-term condition is protective against abdominal aortic aneurysm?
Diabetes
What is the pathophysiology of abdominal aortic aneurysm? (x3)
- Proteolytic degradation of aortic wall connective tissue: matrix metalloproteinases and other proteases from macrophages and aortic smooth muscle cells are secreted into the ECM.
- Inflammation and immune responses: infiltration by macrophages and lymphocytes.
- Elastin levels decrease progressively down the aorta. Diminished elastin is associated with aortic dilation which also predisposes to rupture.
What is the epidemiology of abdominal aortic aneurysm: Age? Gender?
50-79 years old. 4-6 times more common in men.
What are the signs and symptoms of abdominal aortic aneurysm?
Triad of palpable pulsatile abdominal mass, abdominal, back or groin pain, and hypotension.
