CVS S11 - Heart Failure

Question 0

Give some common causes of heart failure

Answer 0

Ischaemic heart disease
Arrhythmia
Hypertension
Dilated cardiomyopathy (due to pregnancy, alcohol, drugs, poisoning)
Valvular/congenital heart disease
Pericardial disease
Hypertrophic cardiomyopathy
Restrictive cardiomyopathy (eg amyloidosis)
High output heart failure

Question 1

Define heart failure

Answer 1

A state in which the heart fails to maintain adequate circulation for the demand of the body, despite adequate filling pressure

Question 2

Describe and explain the relationship between end diastolic pressure and cardiac output with increasing severity of heart failure

Answer 2

Starlings law states that CO increases with EDP up to a plateau where the ventricles cannot hold any more blood.
In heart failure, the heart cannot produce the same amount of force for a given level of force, so CO can actually decrease with increasing EDP

Question 3

Describe class I heart failure

Answer 3

No symptomatic limitation of physical ability

Question 4

Describe class II of heart failure

Answer 4

Slight limitation of physical ability
Ordinary physical activity results in symptoms
No symptoms at rest

Question 5

Describe class III of heart failure

Answer 5

Marked limitation of physical activity
Less than ordinary physical activity results in symptoms
No symptoms at rest

Question 6

Describe class IV of heart failure

Answer 6

Inability to carry out any physical ability without symptoms
May have symptoms at rest
Discomfort increases with any degree of physical activity

Question 7

Describe congestive heart failure

Answer 7

When both sides (left and right) of the heart are in heart failure

Question 8

How can lung disease cause right heart failure?

Answer 8

Chronic pulmonary disease can increase the resistance in the lung, meaning the right heart has to pump harder

Question 9

How does congestive heart failure usually occur?

Answer 9

The left heart fails, then blood backs up in the pulmonary vein and lungs, increasing the pressure and so the force of contraction required by the right ventricle, so right heart failure occurs secondary to left.

Question 10

What groups can heart failure be divided into?

Answer 10

Systolic heart failure
Diastolic heart failure
Left sided heart failure
Right sided heart failure
Congestive or biventricular heart failure

Question 11

What are the signs and symptoms of left sided heart failure

Answer 11

Fatigue
Shortness of breath upon exertion or lying flat (may wake from sleep)
Tachycardia
Cardiomegaly (and so displaced apex beat)
3rd and sometimes 4th heart sounds (gallop rhythm)
Functional murmur of mitral valve regurgitation
Basal pulmonary crackles
Peripheral oedema

Question 12

What are the common signs and symptoms of right sided heart failure?

Answer 12

Fatigue
Dyspnoea
Anorexia
Nausea
Raised JVP
Tender, smooth, hepatic enlargement
Pitting oedema
Ascites
Pleural effusion

Question 13

What are the common causes of right sided heart failure?

Answer 13

Most often secondary to left sided heart failure
Chronic lung disease
Pulmonary hypertension or embolism
Pulmonary/tricuspid valve disease
Left to right shunts (ASD/VSD)
Isolated right ventricular myopathy

Question 14

Broadly, how is the renin-angiotensin-aldosterone system (RAAS) involved in heart failure

Answer 14

The RAAS system is activated in cardiac failure in an attempt to maintain cardiac output BUT it has the effect of making an already struggling heart work harder

Question 15

Describe in detail the activation of the RAAS

Answer 15

Decreased BP stimulates a release of renin from the kidneys
Renin catalyses the conversion of angiotensin to angiotensin I
Angiotensin I is converted to angiotensin II by ACE
Angiotensin II is a powerful vasoconstrictor and promotes the release of aldosterone from the kidneys
Aldosterone causes water and salt retention, causing increased blood volume

Question 16

Describe the involvement of the sympathetic nervous system in heart failure

Answer 16

The sympathetic NS causes vasoconstriction by the stimulation of the α1 receptor.
This increases blood pressure which increases the workload of the heart by increasing preload and after load
Sympathetic stimulation of the hearts β1 receptors will cause an increase in both chronotropy and inotropy

Question 17

What drugs are useful in the treatment of heart failure?

Answer 17

ACE-inhibitors
Diuretics
β-blockers
Ca channel blockers
Organic nitrates
Cardiac glycosides

Question 18

How do ACE-inhibitors work?

Answer 18

They prevent the conversion of angiotensin I to angiotensin II
They therefore have a vasodilatory and diuretic effect, which is useful for reducing the workload of the heart
Control cardiac output

Question 19

How are diuretics useful in the treatment of heart failure?

Answer 19

They reduce blood volume and thus reduce oedema

Control cardiac output

Question 20

How are β-blockers useful in the treatment of heart failure?

Answer 20

They prevent sympathetic stimulation of β receptors of the heart so reduce inotropy and chronotropy
Control cardiac output

Question 21

How are Ca channel blockers useful in the treatment of heart failure?

Answer 21

Reduce contractility of the myocardium

Question 22

How are organic nitrates useful in the treatment of cardiac failure?

Answer 22

They act as veno/vasodilators so reduce BP

This reduces preload and after load so reduces the workload of the heart

Question 23

How are cardiac glycosides useful for the treatment of heart failure?

Answer 23

Inhibits the Na/K pump
Raised intracellular Na inhibits NXC
Therefore intracellular Ca is increased
So contractility is increased

Question 24

What are the main principles of management for heart failure?

Answer 24

Correct underlying cause
Non-pharmacological measures (diet, lifestyle, smoking cessation)
Pharmacological therapy (symptomatic improvement, delay progression, reduce mortality)
Treat complications/risk factors/associated conditions eg arrhythmias