Heart Failure ✅ Flashcards
What is heart failure?
When the heart is unable to maintain adequate perfusion of the tissues for normal metabolism
What can the causes of heart failure be divided into?
- Volume overload
- Pressure overload
- Cardiac arrhythmias
- Ventricular dysfunction
- Other
What are the causes of volume overload leading to heart faiure?
- Left-to-right shunts
- Valvular regurgitation
- Complex regional cardiac lesions
- Arteriovenous malformations
Give 2 arteriovenous malformations that can lead to heart failure?
- Vein of Galen
- Haemangioma
What can cause pressure overload leading to heart failure?
- Left heart obstruction
- Acute hypertension
- Right heart obstruction
Give 3 causes of left heart obstruction leading to heart failure
- Aortic stenosis
- Coarctation of the aorta
- Hypoplastic left heart
Give 2 causes of acute hypertension that can lead to heart failure?
- Haemolytic uraemic syndrome
- Glomerulonephritis
Give a cause of right heart obstruction that can lead to heart failure
Pulmonary stenosis
What cardiac arrhythmias can lead to heart failure?
- Congenital complete heart block
- Supraventricular tachycardia
- Ventricular tachycardia
What causes of ventricular dysfunction can lead to heart failure?
- Myocarditis
- Cardiomyopathy
- Sepsis
- Anaemia
- Pericardial effusion/cardiac tamponade
- Ischaemia
What kinds of cardiomyopathy can lead to heart failure?
- Dilated
- Hypertrophic
- Restrictive
What can cause ventricular ischaemia leading to heart failure?
- Birth asphyxia
- Anomalous left coronary artery
What is the most likely underlying cause of heart failure dependent on?
The age of the child
What is the most likely underlying cause of heart failure in neonates and infants younger than 2 months?
Structural heart diesaes
What are the other causes of heart failure?
- Chronic hypertension
- Renal failure
- Metabolic disorders
- Endocrine disorders
- Anaemia
- Illicit or accidental drug ingestion
What happens to the heart muscle in chronic heart failure?
There is a decrease in contractility of the affected heart muscle
What effect does the decrease in contactility of the heart muscle in chronic heart failure have on the Starlin curve?
It shifts it to the right
What is the implication of the reduced contractility of the heart in chronic heart failure?
Increasing preload has a smaller effect on stroke volume than seen in a healthy heart, leading to a low cardiac output state
What does the low cardiac output state trigger in chronic heart failure?
Cardiac, autonomic, and hormonal compensatory changes
What do cardiac compensatory changes aim to do in the low cardiac output state of chronic heart failure?
Increase stroke volume
What do attempts to increase stroke volume through cardiac compensatory mechanisms in chronic heart failure lead to?
Increased wall tension
What effect does the increased wall tension due to cardiac compensatory mechanisms in chronic heart failure have?
Increases oxygen consumption of the myocardium
What structural changes can develop to compensate in chronic heart failure?
Cardiac hypertrophy or dilatation
Why might cardiac hypertrophy or dilatation develop in chronic heart failure?
To try and balance the increased presure and keep the wall stress unchanged
What might be required to treat cardiac dilation in chronic heart failure?
Diuretics
Why are diuretics used to treat dilation of the heart in chronic heart failure?
To reduce the preload
What autonomic compensatory changes might develop in early heart failure?
Increase in sympathetic stimulation
What triggers the increase in sympathetic stimulation in early heart failure?
Baroreceptors
How is increased sympathetic stimulation achieved in autonomic compensation for early heart failure?
Increased adrenal secretion of adrenaline and neural release of noradrenaline
What is the result of increased adrenaline and noradrenaline in early heart failure?
- Increases heart rate
- Increases cardiac contracility
- Increases blood pressure
How does adrenaline and noradrenaline increase the blood pressure in early heart failure?
By causing peripheral vasoconstriction
What negative effect can autonomic compensaotry changes in heart failure?
In the failing heart, the increase in afterload increases cardiac demands and will eventually further depress cardiac output
What effect does chronic adrenergic stimulation secondary to autonomic compensatory changes in chronic heart failure have?
- Hypermetabolism
- Arrhythmogenesis
- Direct myocardial toxicity
What effect does chronic adrenergic stimualtion have on the myocardium?
- Apoptosis
- Hypertrophy
- Focal myocardium
What does chronic exposure to high catecholeamine levels secondary to autonomic compensatory changes in chronic heart failure result in?
Decreased density of ß-adrenergic receptors on the myocardial surface
What does a decreased density of ß-adrenergic receptors on the myocardial cell surface result in?
Functional loss of the catecholamine-mediated inotropic response
What happens to the heart rate variability in chronic heart failure?
It is reduced
Why is the heart rate variability reduced in chronic heart failure?
Due to reduced sympathetic and vagal modulation at the sinus node
What is the clinical relevance of reduced heart rate variability in chronic heart failure?
It can be used as a prognostic marker
What hormones are involved in compensatory mechanisms in heart failure?
- Renin
- Angiotensin II
- Aldosterone
- ADH
- Endothelin
Why is renin released in heart failure?
Reduced blood flow to the kidneys results in a marked increase in renin production
What is the result of increased renin in heart failure?
It leads to stimulation of the renin-angiotensin-aldosterone system
What are the effects of angiotensin II?
- Acts as a potent vasoconstrictor
- Stimulates release of noradrenaline from sympathetic nerve terminals
- Inhibits vagal tone
- Promotes release of aldosterone
Where does angiotensin II act as a potent vasoconstrictor?
- Renal effect arterioles
- Systemic circulation
What is the action of aldosterone?
- Increases sodium and water reabsorption
- Increases excretion of potassium
Where does aldosterone act to increase the excretion of potassium?
In the renal tubules
What is the effect of aldosterone increasing sodium and water reabsorption?
- Increases blood volume and central venous pressure (preload)
- Increases peripheral oedema
What is the effect of volume expansion caused by aldosterone in chronic heart failure?
Leads to pressure overload resulting in the release of natriuretic peptides
What is the action of natriuretic peptides?
They antagonise the effect of angiotensin II on vascular tone and sodium reabsorption, causing vasodilation and natriuresis
Where does anti-diuretic hormone act?
On the renal collecting ducts
What is the action of ADH on the renal collecting ducts?
Increases water permeability and reduces urine formation
What is the result of the increased water permeability of the collecting ducts due to ADH action?
It increases total blood volume and so preload and afterload
What is endothelin secreted from?
Vascular endothelial cells
What is the function of endothelin?
It is a potent vasoconstrictor
Where does endothelin have pronounced vasoconstrictive effects?
On the renal vasculture
What does the vasoconstrive effect of endothelin on the renal vasculture promote?
The retention of sodium
What is the clinical relevance of plasma measurements of endothelin-1?
It is used as a prognostic indicator in heart failure
How effective are compensatory mechanisms in heart failure?
Only offer limited improvement
What is the limitation of compensatory mechanisms in chronic heart failure?
Increased cardiac filling initially increases cardiac output as per Starling’s law, but prolonged excessive filling results in progressive dilation of the heart, triggering hypertrophy and eventually failure
What is the result of increased renin in heart failur?
