Introduction to Chronic Heart Failure
Heart failure (HF) is a chronic, progressive pathophysiologic condition in which the heart cannot generate an adequate cardiac output, leading to insufficient perfusion of tissues or elevated diastolic pressure of the ventricles, which in turn increase pulmonary blood vessel pressure (McCance and Huether, 2010). In other words, according to the American Heart Association (AHA), the heart is unable to keep up with its workload. It is estimated that almost 10% of the US population older than age 65 exhibits symptomatic heart failure, and about 20% of all individuals older than age 40 have some form of myocardial dysfunction. Guidelines published by the European Society of Cardiology (ESC) have provided definitions and explanations of the adjectives and terms associated with the disorder. Physicians may use words with slightly different meanings. The word “acute” in the context of acute HF has caused some confusion because some clinicians use it to indicate severity (the medical emergency of life-threatening pulmonary edema), while others use it to indicate decompensated, recent-onset, or even new-onset HF. The overall consensus is that “acute HF” is an indicator of time rather than severity. Overall, physicians agree on three types of HF, namely new-onset HF, transient HF, and chronic HF (Table 1-1; Dickstein et al., 2008). New-onset HF refers to the first clinical presentation of HF. Transient HF refers to symptomatic HF over a limited time period, such as in the case of patients with mild myocarditis or those with myocardial infarction (MI). Progressive deterioration of HF over time leading to prolonged hospitalization is defined as chronic heart failure (CHF) and is the most frequently encountered type, accounting for 80% of all HF cases (Dickstein et al., 2008). Chronic heart failure is often also interchangeably used with “congestive heart failure” (Heart Foundation of Australia) and will be the focus of the present discussion.