Heart Failure Definition
Heart failure is not a single diagnosis, but rather a syndrome of multiple causes. Like fever or jaundice, heart failure mandates an investigation into specific causes to allow for effective therapies. Unlike these other illnesses, heart failure may evolve subtly and without initial detection. Comorbidities commonly complicate assessment. Heart failure threatens life through pump dysfunction and sudden death. In contrast to a heart attack where clogged arteries is an accepted mechanism, the pathophysiology of the heart failure syndrome is more diverse in initiation and progression. The 2013 ACCF/AHA Heart Failure Guidelines defined heart failure as “a complex clinical syndrome that results from any structural or functional impairment of ventricular filling or ejection of blood.”
Heart pump impairment resulting in symptoms. With a little imagination and thinking, this six word phrase provides a concise foundation for the entire problem of heart failure:
- Heart: It is necessary that any occurrence of clinical heart failure must include a primary or secondary involvement of the heart. If this is not evident, we either have not looked hard enough or it is not heart failure.
- Pump: A complete description of the heart includes multiple functions including electrical, hormonal, and structural components. For heart failure to be present, however, there must be a manifest effect on the ability of the heart to move blood in the circulation.
- Impairment: “Failure” may be too strong a word for the condition of the heart in most patients recognized as having “heart failure” or “congestive heart failure”. Failure implies a cessation of adequate function. For example, patients with “renal failure” are either on or in imminent need for dialysis to completely take over the function of the failing organ. Impairment implies a degree of insufficiency that, in general, does not require complete replacement therapy. It may only be unmasked by activity or stress. If given a letter grade, many patients’ heart function would rate a C+ rather than an F. Nevertheless, some degree of decreased function must be present for an individual to have heart failure.
- Resulting in: An initial insult to the heart may result in an immediate profound or a subtle progression to heart pump impairment only over time. Neurohormonal mechanisms may be activated and contribute to this syndrome. This may include adverse structural and biochemical remodeling. Any process affecting the heart must be causally related to an individual’s status to result in heart failure.
- Symptoms: The ACC/AHA classification of heart failure defines 4 stages of heart failure beginning with risk factors for heart failure, to asymptomatic heart impairment, to symptomatic heart failure, to advanced heart failure. Traditionally, clinical heart failure has been confined to the last 2 stages characterized by the occurrence of symptoms. Especially given the profound connotation of the term “heart failure” to caregivers and patients, I agree with this as a component of its definition. Although preceding conditions are important, patients with heart failure must currently have or previously have had symptoms associated with heart impairment–shortness of breath associated with lung congestion is common.