Heart Failure Flashcards
Definition of heart failure
A clinical syndrome comprising of dyspnoea, fatigue or fluid retention due to cardiac dysfunction, either at rest or on exertion, with accompanying neurohormonal activation
A state in which the heart is unable to pump blood at a rate commensurate with the requirements of the tissues or can only do so from high pressures
What does HF stand for?
Heart failure
Types of HF
Heart failure due to LVSD due to IHD
Heart failure due to severe aortic stenosis
What does LVSD stand for?
Left ventricular systolic dysfunction
Examples of myocardial injury in the pathology of HF
Coronary artery disease HTN DM Cardiomyopathy Valvular disease
What does myocardial injury lead to?
Neurohormonal stimulation
Myocardial toxicity
What is involved in ventricular remodelling?
Fibrosis and scarring and myocytes healing
Pathology of systolic dysfunction
If failing or damaged heart - as circulatory volume increases, the heart dilates, the force of contraction weakens and CO drops further.
Decreased CO then activates RAAS further (which increases salt and water retention)
This is then viscous cycle of RAAS activation, circulatory volume increases and cardiac performance deteriorates further.
As heart starts to dilate, the cardiac myocytes undergo hypertrophy and then fibrosis and thus the heart is further weakened
When does HF usually occur?
Following sustained HTN (diastolic dysfunction/preserved ejection fraction HF)
Following myocardial damage i.e. an MI (i.e. systolic dysfunction)
What happens when CO falls?
Body registers this as loss in circulatory volume - vasoconstrictor system activation (sympathetic systems)
Salt and water retaining system (RAAS)
What does RAAS stand for?
Renin Angiotensin Aldosterone system
What does RAAS cause the release of?
Angiotensin II
Aldosterone
What does RAAS result in?
Salt and water retention
Vasoconstriction
Hypertrophy and fibrosis of cardiac myocytes
What does activation of the sympathetic system cause activation of?
Noradrenaline
Adrenaline
What does the release of noradrenaline and adrenaline result in?
Vasoconstriction
Stimulates renin release which feeds into RAAS system
Myocyte hypertrophy
What causes salt and water excretion and vasodilation?
Natriuretic peptide system ANP/BNP (weaker than RAAS)
What do ANP and BNP stand for?
Atrial natriuretic peptide
Brain natriuretic peptide
What do ANP and BNP do?
Potent vasodilators and natriuretic peptides
Does the body have a weak or strong system to excrete and retain salt and water?
Retain - very strong
Excrete - weak
Risk factors for HF
Age HTN (LVH) Chronic heart disease Obesity DM Hyperlipidaemia Coronary artery disease Valvular heart disease Alcoholism Infection (viral) Congenital heart defects Smoking High or low haematocrit level OSA
What does OSA stand for?
Obstructive sleep apnoea
What is the number 1 risk factor for heart failure?
HTN
If sufficiently severe, almost any structural cardiac abnormality will cause HF; e.g.
LVSD
Valvular heart disease
Pericardial constriction or effusion
LV diastolic dysfunction/HF with preserved systolic dysfunction/HF with normal ejection fraction
Cardiac arrythmias; tachy or brady
Myocardial ischaemia/infarction (usually with LVSD)
Restrictive cardiomyopathy e.g. amyloid
Right ventricular failure; primary or secondary to pulmonary HTN
Causes of LVSD
Ischaemic heart disease (usually MI)
Dilated cardiomyopathy (DCM)
Severe aortic valve disease or mitral regurg
Explain DCM further
An umbrella term - means LVSD not due to IHD or secondary to another lesion i.e. valves/VSD
Causes of DCM
Inherited
Toxins e.g. alcohol, catecholamines (pheochromocytoma or stress cardiomyopathy)
Viral; acute myocarditis or chronic DCM
HIV, Lyme’s disease, Chagas disease
Sarcoidosis, hemochromatosis, SLE, mitochondrial disease
Muscular dystrophies
Peri partum cardiomyopathy
HTN
Isolated non compaction
Tachycardia related cardiomyopathy
Right ventricular pacing induced cardiomyopathy
End stage hypertrophic cardiomyopathy
End stage arrhythmogenicity RV cardiomyopathy
How does HF affect neurohormonal factors?
RAAS - salt and water retention - adverse haemodynamics - LV hypertrophy / remodelling and fibrosis - hypokalaemia and hypomagnesia SNS - arrhythmogenic - adverse haemodynamics - increases renin etc
Overall effects of neurohormonal activation
Vasoconstriction
Endothelial dysfunction
Renal sodium retention
Mean age for HF
74 y/o
What is a potent predictor of death in HF?
Left ventricular systolic dysfunction
Presentation of HF
Breathlessness Fatigue Oedema Reduced exercise capacity Tachycardia Raised JVP Chest crepitations or effusions 3rd heart sound Displaced or abnormal apex beat
What classification is used for HF?
New York Association (NYHA) classification
What does NYHA look at in HF?
Exercise tolerance
Symptoms
NYHA class I
No limitation of exercise, no symptoms during usual activity
NYHA class II
Mild limitation of exercise, Comfortable with rest or symptoms with mild exertion
NYHA Class III
Moderate limitation, comfortable only at rest
NYHA Class IV
Severe limitation, any physical activity brings on discomfort and symptoms occur at rest
Investigations for LVSD
Antibodies / viral serology Ferritin FBC RFTs, TFTs Consider causes and exclude them ECG CXR ECHO Coronary angiography Cardiac MRI
What would a cardiac MRI show?
Infarction
Inflammation
Fibrosis
What is needed to diagnose HF?
Symptoms and signs of HF (rest or exercise)
AND
Objective evidence of cardiac dysfunction
AND
Response to therapy i.e. diuretics (in doubtful cases)
