CVS 18 - Pathophysiology of heart failure Flashcards
Define heart failure.
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.
What other organ normally fails as a result of heart failure?
Kidneys - they receive around 35-40% of cardiac output
State some causes of heart failure
Arrhythmia Valve disease Pericardial disease Congenital heart disease Cardiomyopathy like CHD
What happens to the structure of the heart following myocardial infarction?
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.
What is cardiomyopathy? What are the main types?
Heart disease in the absence of a known cause. The muscle becomes enlarged, thickened and/or stiffened.
Dilated (DCM), Hypertrophic (HCM or HOCM or ASH), Restrictive and Arrhythmic Right Ventricular Cardiomyopathy (ARVC)
State some causes of dilated cardiomyopathy.
Congenital causes Idiopathic Infectious causes - HIV, rickettsia Toxins/Poisons - ethanol and cocaine Drugs - Chemotherapeutic agents, antiviral agents Metabolic disorders Collagen disorders etc
What is restrictive cardiomyopathy? State some causes.
The heart is unable to relax easily so the relaxation is very slow and there is diastolic dysfunction. Restricted so can’t dilate fully.
Causes: infiltrative disease e.g. sarcoidosis and amyloidosis
Storage disease - haemochromatosis and haemosiderosis
What is the commonest cause of death in heart failure? What are the other causes?
Opportunistic arrhythmia - sudden death
Other causes:
Progression of HF, cardiac event like MI
What is the hormonal response to heart failure?
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)
What drugs are given to counteract these effect?
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)
Other than troponin I and T, what other hormone is elevated in heart failure?
Atrial Natriuretic Peptide. If secreted means heart is impaired.
State some common symptoms/signs of heart failure.
Tiredness Breathlessness PND Orthopnoea - they have to sleep propped up Peripheral oedema Increased venous pressure Increased heart rate Weak pulses
What is a clear sign of heart failure in a chest X-ray?
Massively increased cardio: thoracic ratio
The widest part of the heart should be no more than 50% the width of the thorax
What is the system used to classify heart failure patients based on functional capacity?
New York Heart Association Classification (PPQ!)
1 = barely any symptoms
4 = can’t get out of chair or in bed
What are the different syndromes of heart failure and what symptoms are they associated with?
Acute heart failure - PULMONARY OEDEMA
Circulatory shock - cardiogenic shock (poor peripheral perfusion, oligouria, hypotension)
Chronic heart failure
