12. Heart Failure and Circulatory Oedema Flashcards
What is heart failure?
The heart can’t meet CO requirement due to either impairment of ventricular filling or ejection
Classify LV heart failure
Systolic/ reduced ejection fraction
Diastolic/ preserved ejection fraction
Give the formula for CO
HR x SV
Give the formula for SV
End diastolic volume - end systolic volume
Give the formula for ejection fraction
SV/ EDV
Give the pathophysiology of systolic heart failure
Heart has reduced contractibility: more blood is left in the heart after systole (increase ESV)
Low SV > Low CO > Low EF
Give the pathophysiology of diastolic heart failure
Wall is thicker, decreasing compliance and filling
Reduced filling > low EDV > low SV > low CO
How is the ejection fraction preserved in diastolic heart failure?
EF= SV/EDV and both are reduced
How does the heart compensate in compensated heart failure?
- Frank-Starling law
- Increase sympathetic activity
- RAAS
- ANP
What is Frank-Starling law?
More stretching of cardiac muscle (increased EDV) cause an increased strength of contraction
How does increasing sympathetic activity affect the heart?
Increases contractibility and causes vasoconstriction to increase venous return
What is ANP?
Atrial Natriuretic Peptide
Release in response to atrial dilatation, causes peripheral dilatation
Used as a biochemical marker for heart failure
What are the causes of left heart failure?
Ischaemic heart disease Hypertension Aortic and mitral valve disease Cardiomyopathy and myocarditis Arrhythmia
What is found at autopsy in mitral stenosis?
LA dilatation
What does acute left heart failure result in?
Pulmonary oedema and severe breathlessness
Cardiogenic shock causes renal and hepatic failure
Hypoxic cerebral damage
