Heart Failure

Question 1

What is the definition of heart failure?

Answer 1

When the heart fails to pump blood (cardiac output) at a rate equal to the requirements of the metabolising tissues, or heart can only do so with an elevated filling pressure.

Question 2

What is the equation for cardiac output?

Answer 2

Heart rate x stroke volume = CO

Question 3

What are some neurohumoral controls of heart rate?

Answer 3

Sympathetic nervous system
Catecholamines
Renin-angiotensin

Question 4

What are some factors controlling stroke volume?

Answer 4

Ventricular dilatation (Frank Starling Law)
Venous return (Circulating blood volume)

Question 5

What are the three main categories of causes of heart failure?

Answer 5

Myocardial dysfunction
Volume/pressure overload
Overwork

Question 6

What is the most common cause of left sided heart failure?

Answer 6

Right sided heart failure

Question 7

What are some examples of myocardial dysfunction?

Answer 7

Impaired blood supply e.g. infarction, ischaemia
Muscule disease e.g. inflammation, amyloidosis

Question 8

What are some examples of volume/pressure overload?

Answer 8

Hypertension
Valve/Congenital disease
Endocardial/pericardial disease
Volume overload

Question 9

What are some examples of overwork?

Answer 9

Non-cardiogenic shock e.g. septic shock/haemorrhage
Excess stimulation e.g. hyperthyroidism

Question 10

Amongst all the causes of heart failure, which are the most common?

Answer 10

Ischaemic heart disease
High blood pressure
Valve disease - mitral and aortic
Shock

Question 11

What are the pathological changes of heart failure?

Answer 11

There are no specific features of a failing heart.
However, you may be able to see specific features of the cause e.g. inflammation, amyloidosis

Question 12

What are the abnormal responses in the heart to stress?

Answer 12

Abnormal molecular changes - induction of fetal genes, e.g. switch from alpha myosin to beta myosin.

Abnormal protein synethesis e.g. contractile proteins.

Production of cytokines, growth factors and neurohormonnes e.g. noradrenaline and angiotensin by myocytes resulting in paracrine/autocrine loops resulting in local myocyte damage. This is self perpetuating.

Myocardial remodelling e.g. cell hypertrophy, changes in the extracellular matrix (fibrosis) and myocyte death.

Question 13

What are the main macroscopic changes to the heart?

Answer 13

Dilated ventricles

Hypertrophy (increased weight and thickness)

Question 14

Which drug should you use for left sided heart failure?

Answer 14

Left sided heart failure causes peripheral oedema, so use spironolactone.

Question 15

What drug should you use for right sided heart failure?

Answer 15

Furosemide

Question 16

What are the three main types of cardiomyopathy?

Answer 16

Dilated pattern (flabby heart) e.g. inflammation, post infarction - this is most common

Hypertrophic pattern (gym bunny heart) e.g. HOCM

Restrictive pattern (straight jacket heart) e.g. amyloidosis

Question 17

What are some causes of dilated cardiomyopathy?

Answer 17

Idiopathic
Genetic e.g. muscular dystrophies
Toxic
Metabolic - iron overload
Pregnancy

Question 18

What are some causes of inflammatory cardiomyopathy?

Answer 18

Infection - VIRUS (coxsackie B), bacterial, protozoal (trypanosome, most common in South America)
Drug
Systemic disease e.g. SLE
Idiopathic e.g. Giant cell myocarditis

Question 19

What is the inheritance pattern of HOCM?

Answer 19

Autosomal dominant

Question 20

What is the clinical presentation of HOCM?

Answer 20

Young people suddenly develop syncome and SOB and sudden death due to arrythmia.

Question 21

What is restrictive cardiomyopathy?

Answer 21

Failure of the left ventricle to relax, hence failure to fill properly in diastole.

Question 22

What are some causes of restrictive cardiomyopathy?

Answer 22

Myocardial e.g. amyloid
Endocardial and pericardial disease e.g. endocardial fibrosis and pericardial fibrosis

Question 23

What is constrictive pericarditis?

Answer 23

Heart encased in dense fibrous tissue, sometimes calcified.

Question 24

Which valvular diseases can cause heart failure?

Answer 24

Mitral regurgitation

Aortic stenosis

Aortic regurgitation

Question 25

What is an example of congenital heart disease? What is the mechanism?

Answer 25

Ventriculoseptal defect

Right ventricular hypertrophy
High pressure on left ventricle forces blood through the defect and raises pressure in the thin walled right ventricle, eventually resulting in right heart failure.

Question 26

Why can lung disease cause pulmonary hypertension?

Answer 26

Any obstruction/destruction of pulmonary vessels will result in right ventricular failure e.g. pulmonary fibrosis

As will chronic hypoxia which results in vasocontriction e.g. COPD, lung fibrosis, cystic fibrosis

Question 27

What are some local complications of heart failure?

Answer 27

Arrythmias - can cause sudden cardiac death
Ischaemic damage

Question 28

What are some systemic complications of left sided heart failure?

Answer 28

Hypoperfusion of kidneys, GIT and brain

Pulmonary congestion and oedema

Question 29

What are some systemic complications of right sided heart failure?

Answer 29

Organ congestion and systemic oedema

Question 30

What is the result of hypoperfusion of the kidneys?

Answer 30

The kidneys retain salt and water due to the reduced GFR and therefore plasma volume increases, resulting in oedema