Pulmonary vascular disease Flashcards
Which arteries supply the lung?
Pulmonary arteries and Bronchial arteries
What is the pressure like in the pulmonary circulation?
Low pressure = 1/5th pressure in systemic circulation
Do the pulmonary arteries have a low or high incidence of atheromas?
Low incidence
What is pulmonary oedema and what spirometry pattern does it cause?
Accumulation of fluid in the lungs
Restrictive
What are the causes of pulmonary oedema?
Haemodynamic (increase in hydrostatic pressure due to heart failure) Cell injury (More localised oedema due to damage to alveoloar lining cells/capillary endothilium)
If oedema due to cell injury is generalised what can this lead to?
Adult respiratory distress syndrome
What is ARDS also known as and why?
Shock lung because it is associated with circulatory shock
What are the causes of ARDS?
Sepsis, diffuse infection (virus/mycoplamsa), severe trauma, reactive oxygen species
What is the pathogenisis of ARDS?
Bacterial endotoxin causing systemic infection
Infiltration of inflammatory cells which produce oxygen free radicals.
Release of cytokines which drive the immune response
ROS damage the cell membranes
What are the pathological findings in ARDS?
Fibrinous exudate lining alveolar walls (hyaline membranes)
Cellular regeneration
Inflammation
What are the potential outcomes for ARDS?
Death
Resolution
Fibrosis
Patients are often ventilated as there is a high chance of mortality but also resolution
What is an embolus?
Detached intravascular mass carried in the blood to a site in the body distant from its point of origin
What are the types of emboli?
Thrombi, Fat, Air, foreign bodies, tumour, amniotic fluid
What are the risk factors for PE and DVT (virchow’s triad)?
1) Endothilial damage
2) Hypercoaguable blood
3) Abnormal/turbulent flow
How does a PE present and what is the presentation dependent on?
Sudden death, Severe chest pain, dyspnoea, haemoptysis, pulmonary infarction, pulmonary hypertension
Dependent on: size of embolus, cardiac and respiratory function
Small pulmonary emboli are common. What is the most common sign?
Pulmonary hypertension
What is a pulmonary infarct and is a PE sufficient to cause a pulmonary infarct?
Ischaemic necrosis
PE is necessary but not sufficient as there are bronchial arteries. However bronchial artery can be compromised (eg cardiac failure)
What is the difference between primary and secondary pulmonary hypertension?
Primary- no known cause and occurs in young women
Secondary- due to another cause, more common
How does pulmonary hypertension develop?
1) Hypoxia => pulmonary vasoconstriction
2) Increased flow through pulmonary circulation (congenital heart disease)
3) Blockage (PE) or loss (emphysema) of pulmonary vascular bed
4) Back pressure from left ventricular failure
What morphalogical changes are seen in pulmonary hypertension?
Medial hypertrophy of arteries
Intimal thickening (fibrosis) of arteries
Atheroma
Right ventricular hypertrophy- detected on CXR/ECG
Plexogenic change/necrosis (extreme cases (congenital or primary pulmonary hypertension
What is cor pulmonale?
Heart disease secondary to lung disease
Lung disease leading to pulmonary hypertension => right ventricular hypertrophy => Right ventricular dialitaion => right heart failure
What are the cardiac causes of pulmonary venous hypertension?
Left ventricular failure
Mitral regurgitation or mitral stenosis
Cardiomyopathy
What is the normal MAP in the pulmonary vasculature and what is defined as pulmonary hypertension?
Normal = 12-20mmHg
Pulmonary hypertension >25mmHg