Chronic heart failure
The European Society of Cardiology defines heart failure as a clinical syndrome in which patients have the following features: symptoms typical of heart failure (breathlessness, fatigue, ankle swelling); signs typical of heart failure (tachycardia, tachypnoea, pulmonary crackles, pleural effusion, raised jugular venous pressure, peripheral oedema, hepatomegaly); and objective evidence of a structural or functional abnormality of the heart at rest (cardiomegaly, third heat sound, cardiac murmurs, abnormality on the echocardiogram, raised natriuretic peptide concentration). Heart failure results in activation of the sympathetic nervous system and the renin–aldosterone–angiotensin system, and release of a number of hormones such as natriuretic peptides, and cytokines, including tumour necrosis factor amongst others. While neurohormone activation is initially compensatory and helps in the short term to maintain circulatory needs, ultimately it has detrimental effects on the myocardium and compromises its function further. These mechanisms are therefore therapeutic targets to improve symptoms and lessen the risk of death.