Pathophysiology of Heart Failure

Question 1

Define heart failure.

Answer 1

Syndrome that arises when the heart is unable to maintain an appropriate blood pressure without support. - P. Harris
Definition of heart failure in man - a clinical syndrome caused by an abnormality of he heart and recognised by a characteristic pattern of haemodynamic, renal, neural and hormonal responses.

Question 2

What other organ normally fails as a result of heart failure?

Answer 2

Kidneys - they receive around 35-40% of cardiac output

Question 3

State some causes of heart failure.

Answer 3

Arrhythmia
Valve disease
Pericardial disease 
Congenital heart disease 
Cardiomyopathy

Question 4

What happens to the structure of the heart following myocardial infarction?

Answer 4

Part of the heart muscle will be weaker due to the formation of fibrous tissue, which leads to infarct expansion. The heart muscle will remodel and dilate in an attempt to maintain normal pumping activity.

Question 5

What is cardiomyopathy? What are the main types?

Answer 5

Heart disease in the absence of a known cause. The muscle becomes enlarged, thickened and/or stiffened.
Dilated, Hypertrophic, Restrictive and Arrthymic Right Ventricular Cardiomyopathy

Question 6

State some causes of dilated cardiomyopathy.

Answer 6

Congenital causes 
Idiopathic
Infectious causes - HIV, rickettsia
Toxins/Poisons - ethanol and cocaine 
Chemotherapeutic agents, antiviral agents

Question 7

What is restrictive cardiomyopathy? State some causes.

Answer 7

The heart is unable to relax easily so the relaxation is very slow and there is diastolic dysfunction.
Causes: infiltrative disease e.g. sarcoidosis and amyloidosis
Storage disease - haemochromatosis and haemosiderosis

Question 8

What is the commonest cause of death in heart failure?

Answer 8

Opportunistic arrhythmia

Question 9

What is the hormonal response to heart failure?

Answer 9

Increased sympathetic firing - increase in noradrenaline and adrenaline (because your body thinks that it is bleeding to death)
RAS system is switched on - try to retain more sodium and water
Vasoconstrictors are produced by endothelial cells (e.g. endothelin-1)

Question 10

What drugs are given to counteract these effect?

Answer 10

ACE inhibitors - block the RAS system
Beta blockers - MOST EFFECTIVE - they block the sympathetic drive
Aldosterone receptor antagonists (aldosterone receptors are high in heart failure)

Question 11

Other than troponin I and T, what other hormone is elevated in heart failure?

Answer 11

Atrial Natriuretic Peptide

Question 12

State some common symptoms of heart failure.

Answer 12

Tiredness
Orthopnoea - they have to sleep propped up
Peripheral oedema 
Increased venous pressure 
Increased heart rate 
Weak pulses

Question 13

What is a clear sign of heart failure in a chest X-ray?

Answer 13

Massively increased cardio: thoracic ratio

The widest part of the heart should be no more than 50% the width of the thorax

Question 14

What is the system used to classify heart failure patients based on functional capacity?

Answer 14

New York Heart Association Classification (PPQ!)
1 = barely any symptoms
4 = can’t get out of chair or in bed

Question 15

What are the different syndromes of heart failure and what symptoms are they associated with?

Answer 15

Acute heart failure - PULMONARY OEDEMA
Circulatory shock - cardiogenic shock (poor peripheral perfusion, oligouria, hypotension)
Chronic heart failure

Question 16

What do you give immediately if someone has pulmonary oedema?

Answer 16

Diuretics - to get rid of the fluid (increase urinary output)

Question 17

State some common drugs used in heart failure.

Answer 17

ACE inhibitors 
Beta blockers
Aldosterone antagonist - spironolactone
Digoxin (for atrial fibrilation)
Devices (cardiac resynchronisation, implanted cardioverter defibrillator)