Flashcards in Week 11 - Heart Failure Deck (14):
What is heart failure?
A state in which the heart fails to maintain an adequate circulation for the needs of the body's despite an adequate filling pressure
What are some causes of systolic heart failure?
- Main cause = Ischaemic heart disease
- Dilated cardiomyopathy (bugs, alcohol/drugs/poisoning, pregnancy, idiopathic)
- Valvular heart disease/congenital
- Restrictive cardiomyopathy
- Hypertrophic cardiomyopathy
- Pericardial disease
- High-output heart failure
What are the different classes of heart failure?
- No symptomatic limitation of physical activity
- Slight limitation of physical activity
- Ordinary physical activity results in symptoms
- No symptoms at rest
- Marked limitation of physical activity
- Less than ordinary physical activity results in symptoms
- No symptoms at rest
- Inability to carry out any physical activity without symptoms
- May have symptoms at rest
- Discomfort increases with any degree of physical activity
What is congestive heart failure?
When both ventricles are affected
What are the different types of heart failure?
What are some causes of right-sided heart failure?
- Secondary to left HF
- Pulmonary embolism/hypertension
- Pulmonary/tricuspid valvular disease
- Left --> right shunts
- Isolated right ventricular cardiomyopathy
What are the signs of right-sided HF?
- Relate to distension and fluid accumulation in areas drained by the systemic veins
- Fatigue, dyspnoea, anorexia, nausea
- Raised JVP
- Tender, smooth hepatic enlargement
- Dependent putting oedema
- Pleural effusion
What are some signs of left sided heart failure?
- Fatigue, shortness of breath upon exertion or when lying flat, waking from sleep with shortness of breath
- 3rd or 4th heart sound
- Functional murmur of mitral regurgitation
- Basal pulmonary crackles
- Peripheral oedema
What is the Renin-Angiotensin-Aldosterone system?
A system that is activated in heart failure in an attempt to maintain cardiac output
- Makes an already struggling heart work harder
- A drop in blood pressure stimulates renin release from the kidneys
- Angiotensinogen is converted to angiotensin I by renin, which is then converted to angiotensin II by angiotensin converting enzyme
- Angiotensin II can act on ATiR to cause vasoconstriction
- Or it can act on ATiiR to cause aldosterone release, which causes salt and H2O retention which hence increases blood volume
- ATiiR stimulation can also release nitric oxide (as does bradykinin) which causes vasoconstriction
What does the sympathetic nervous system do in heart failure?
- Causes vasoconstriction of blood vessels via the α1-receptor
--- This increases blood pressure, which increases the workload of the heart
- Innervation of the heart's β1-receptor will cause an increase in both chronotropy and inotropy
- It can stimulate the renin-angiotensin system
- Can cause direct cardiotoxicity (myocyte damage)
How can oedema form in heart failure?
- In left HF: pulmonary oedema can form
- In right HF: HF causes distension and fluid accumulation in areas drained by the systemic veins, which leads to systemic oedema
--- Can cause hepatomegaly and ascites
Which drugs can be used to manipulate cardiac output?
- ACE inhibitors: prevent the conversion of angiotensin I to angiotensin II
--- These have an indirect vasodilatory and diuretic effect, so reduce the workload of the heart
- Diuretics: reduce blood volume and thus oedema
- β-blockers: prevent the sympathetic innervation of the myocardium, hence reducing the wokload
What are the principles of management of heart failure?
- Correct underlying cause
- Non-pharmacological measures
- Pharmacological therapy
- Treat complications/associated conditions/cardiovascular risk factors