Heart failure can be defined as an abnormality of cardiac structure
or function leading to failure of the heart to deliver
oxygen at a rate commensurate with the requirements of the
metabolizing tissues, despite normal filling pressures (or only
at the expense of increased filling pressures).1 For the purposes
of these guidelines, HF is defined, clinically, as a syndrome
in which patients have typical symptoms (e.g.
breathlessness, ankle swelling, and fatigue) and signs (e.g. elevated
jugular venous pressure, pulmonary crackles, and displaced
apex beat) resulting from an abnormality of cardiac
structure or function. The diagnosis of HF can be difficult
(see Section 3.6). Many of the symptoms of HF are nondiscriminating
and, therefore, of limited diagnostic value.2 – 6
Many of the signs of HF result from sodium and water retention
and resolve quickly with diuretic therapy, i.e. may be
absent in patients receiving such treatment. Demonstration of
an underlying cardiac cause is therefore central to the diagnosis
of HF (see Section 3.6). This is usually myocardial disease
causing systolic ventricular dysfunction. However, abnormalities
of ventricular diastolic function or of the valves, pericardium,
endocardium, heart rhythm, and conduction can also cause
HF (and more than one abnormality can be present) (see
Section 3.5). Identification of the underlying cardiac problem
is also crucial for therapeutic reasons, as the precise pathology
determines the specific treatment used (e.g. valve surgery for
valvular disease, specific pharmacological therapy for LV systolic
dysfunction, etc.).