14. Aneurysms & Aortic Dissection Oedema & Shock Flashcards
Define the term aneurysm
Localised, permanent abnormal dilatation of blood vessel
Clinicopahtological characteristics of abdominal aortic aneurysm
Most common
Erosion and replacement of the media by an adjacent complicated atheroma
Thrombus formation may lead to emboli
Where would you find saccular aneurysms?
Brain
Where are leutic aneurysms found?
Ascending aorta or arch of aorta
What is a false aneurysm?
A blood filled space that forms round a blood vessel usually after injury/rupture.
What are the classical triad symptoms for abdominal aortic aneurysm?
Pain in the neck
Hypotension
Pulsatile abdominal mass
What happens in a dissecting aortic aneurysm?
Blood is forced through a tear in intima
Haemotoma in the media -propagated along blood vessel
Sharp tearing pain
What are the possible outcomes dissecting aortic aneurysm?
Blood ruptures through adventita- massive haemorrhage into the pericardium and other structures
Blood will re-enter the aortic lumen - Double barrelled aorta
Blood may extend down tributary arteries- compress lumen- results in end-organ infarction
Describe the parthenogenesis of AAA?
Degeneration of the media of the vessel
Cystic medial necrosis
Mucois degeneration, elastic fibre fragmentation
What are the risk factors assocaited with AAA?
Hypertension
Bicuspid aortic valve
marfan syndrome
What is marfan syndrome?
Point mutations in fibrillin gene prevent normal deposition of elastin in extracellular matirx
Characteristics of Berry Aneurysms?
occur in circle of willis
NOrmal muscular arterial wall replaced by fibrous tissue
Arise at points of branching
More common in young, hypertensive patients
What does the rupture of a berry aneurysm produce?
Saubarachnoid haemorrahage
What are the symptoms of Saubarachnoid haemorrahage?
Thunderclap headache Stiff neck Nausea and vomiting Loss of consciousness Stroke like symptoms
Characteristics of Charcot-bouchard aneurysms
Micro-aneurysms Occur in intercerebral capillaries Rupture leads to intracerebral haemorrhage Associated with both -hypertension -diabetic vascular disease
Define oedema?
Excess fluid in the intersitial tissues
Define effusion
A collection of fluid in a potential space
What are the 4 categories of pathogenesis of oedema?
- Inflammatory
- Venous
- Lymphatic
- Hypoalbuminaemic
Describe the inflammatory pathogenesis of oedema
Increased vascular permeability
Describe the venous pathogenesis of oedema
Increased intravenous pressure
Describe the lymphatic pathogenesis of oedema
Obstruction of lymphatic drainage
Describe the hypoalbuminaemic pathogenesis of oedema
Reduced plasma osmotic pressure
What us pitting oedema?
redistribution of the excess fluid when pressure is applied leaving pits
What is a pulmonary oedema?
Abnormal accumulation of fluid in the intra-alveolar spaces of the lungs
What are the causes of pulmonary oedema?
Left ventricular failure
Renal failure
Acute respiratory distress syndrome
Pulmonary inflammation or infection
What is a cerebral oedema?
Abnormal accumulation of fluid in brain parenchyma
One part of brain herniates from one anatomical part to another
Define shock
A pathological process that results in inadequate blood flow to sustain normal organ function
What are the causes of shock?
Cardiogenic shock- MI
Hypovolaemic shock-Haemorrhage
-Increased vascular permeability/dilatation
What are the phases of shock?
Compensatory phase
Progressive phase
Irreversible phase
Failure of multiple organs
What are compensatory mechanisms for shock?
Constriction of vessels in “non-vital” tissues to increase peripheral resistance
Increased heart rate
Dilation of cerebral vessels
What signs will the clinical examination show for shock?
Cold
Clammy
Has an increased in heart rate
What are the consequences of shock?
Renal failure
Acute respiratory distress syndrome
Cerebral infarction
Infarction
What is acute tubular necrosis?
Kidney injury characterised by acute tubular cell injury and dysfunction
Leading to possible renal failure
What are the features of acute respiratory distress syndrome?
A severe lung condition
Severe inflammation of alveolar walls
Accumulation of inflammatory cells and inflammatory proteinaceous material
Severely impaired oxygen transfusion
High mortality
Type II pneumocytes that line the alveoli die
