ABSTRACT
Heart failure is caused by structural or functional cardiac dysfunction (von Klemperer and Bunce, 2007). It may be left-and/or right-sided – common causes are listed in Table 28.1.
Table 28.1 Common causes of heart failure
Left-sided Right-sided
Coronary artery disease Left ventricular failure Hypertension Tricuspid valve disease Cardiomyopathy Congenital defects
Left-sided failure is usually caused by coronary artery disease (Mehta and Cowie, 2006) and/or hypertension (Lakasing and Francis, 2006). Cardiovascular disease often affects both coronary and systemic arteries. While coronary heart disease affects heart structure, systemic vascular disease affects its function. Both contribute to the downward spiral of the syndrome. The World Health Organisation and International Society and Federation of Cardiology (McKenna, 1996) classify cardiomyopathies as
n dilated n hypertrophic n arrhythrombogenic right ventricular cardiomyopathy or dysplasia n restrictive;
the most common type being dilated. Cardiomyopathies are summarised in Table 28.2. The heart uses more energy than any other organ (Neubauer, 2007), extracting nearly all oxygen delivered by the coronary arteries. This leaves little reserve if demand increases. Sustained increased demand causes compensatory responses – tachycardia (Mehta and Cowie, 2006) and muscle enlargement. But both of these further increase oxygen and energy demand, so structural changes accelerate. Structural changes in the heart, together with vascular resistance to output, cause progressive problems with cardiac output, and so tissue perfusion. Left-sided heart failure causes pulmonary vascular congestion (von Klemperer and Bunce, 2007), causing
n breathlessness n limited exercise tolerance.
