Week 11 - Heart Failure

Question 1

What is heart failure?

Answer 1

A state in which the heart fails to maintain an adequate circulation for the needs of the body’s despite an adequate filling pressure

Question 2

What are some causes of systolic heart failure?

Answer 2

• Main cause = Ischaemic heart disease
• Hypertension
• Dilated cardiomyopathy (bugs, alcohol/drugs/poisoning, pregnancy, idiopathic)
• Valvular heart disease/congenital
• Restrictive cardiomyopathy
• Hypertrophic cardiomyopathy
• Pericardial disease
• High-output heart failure
• Arrhythmias

Question 3

What are the different classes of heart failure?

Answer 3

Class I:
- No symptomatic limitation of physical activity
Class II:
- Slight limitation of physical activity
- Ordinary physical activity results in symptoms
- No symptoms at rest
Class III:
- Marked limitation of physical activity
- Less than ordinary physical activity results in symptoms
- No symptoms at rest
Class IV:
- Inability to carry out any physical activity without symptoms
- May have symptoms at rest
- Discomfort increases with any degree of physical activity

Question 4

What is congestive heart failure?

Answer 4

When both ventricles are affected

Question 5

What are the different types of heart failure?

Answer 5

• Left-sided
• Right-sided
• Biventricular
• Systolic
• Diastolic

Question 6

What are some causes of right-sided heart failure?

Answer 6

• Secondary to left HF
• Pulmonary embolism/hypertension
• Pulmonary/tricuspid valvular disease
• Left –> right shunts
• Isolated right ventricular cardiomyopathy

Question 7

What are the signs of right-sided HF?

Answer 7

• 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
• Ascites
• Pleural effusion

Question 8

What are some signs of left sided heart failure?

Answer 8

• Fatigue, shortness of breath upon exertion or when lying flat, waking from sleep with shortness of breath
• Tachycardia
• Cardiomegaly
• 3rd or 4th heart sound
• Functional murmur of mitral regurgitation
• Basal pulmonary crackles
• Peripheral oedema

Question 9

What is the Renin-Angiotensin-Aldosterone system?

Answer 9

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

Question 10

What does the sympathetic nervous system do in heart failure?

Answer 10

• 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)

Question 11

How can oedema form in heart failure?

Answer 11

• 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

Question 12

Which drugs can be used to manipulate cardiac output?

Answer 12

• 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

Question 13

What are the principles of management of heart failure?

Answer 13

• Correct underlying cause
• Non-pharmacological measures
• Pharmacological therapy
• Treat complications/associated conditions/cardiovascular risk factors

Question 14

Which drugs can be used to treat heart failure?

Answer 14

• ACE-inhibitors
• β-blockers
• Ca2+ channel blockers
• Organic nitrates
• Cardiac glycosides (increase CO and heart contractility by inhibiting the Na/K pump. raising the intracellular Na inhibits NCX so intracellular Ca2+ increases, leading to an increase in contractility)