by Y Tian

Created on: April 03, 2009   Last Updated: April 04, 2009

As early as the 4th century BC, humans have been fixated on the heart and what is represents. Although our knowledge of the heart and its functions has greatly advanced since then, whenever a patient is diagnosed with a heart condition, they immediately assume the worst. This is an understandable reaction as the heart is a central component of the body and essential for life to exist. However, unlike what people commonly think, heart failure (also known as cardiac failure) is not a pathological condition in which the heart "fails" as in stops working. So what exactly is heart failure?

According to Harrison's Principles of Internal Medicine, heart failure is defined as "a clinical syndrome in which an abnormality of cardiac structure or function is responsible for the inability of the heart to eject/fill with blood at a rate commensurate with the requirement of the metabolizing tissues." In simple words, it is a condition where the heart is unable to pump enough blood. Heart failure may occur as a consequence of most forms of heart disease but it is more frequently first seen when an acute disturbance places an additional load on an already excessively burdened heart. In developed nations, almost all heart failure is due to either ischemic heart disease, hypertension, valvular disease or congenital heart disease. However, childhood rheumatic fever causing heart failure secondary to mitral stenosis is still a major problem in poorer communities. The exact cause of the heart failure will naturally determine exactly what form of heart failure it is and subsequently, the signs and symptoms experienced by the patient.

While there are numerous ways of classifying heart failure including low-output vs. high-output, acute vs. chronic and backward vs. forward, the most common division is right-sided and left-sided heart failure, which refers to failure of the right and left ventricles respectively. After a ventricle is initially affected and fails to pump properly, there is a build-up of fluid in the veins upstream to it. Many of the clinical manifestations of heart failure are a result from this fluid accumulation and thus, indicate which side of the heart is affected.

In left-sided heart failure, fluid accumulates in the pulmonary veins in the lungs. This causes some of the excess fluid to leak into the lung alveoli (air sacs), causing difficulty in breathing. As a result, patients often experience shortness of breath during light exertion and in severe cases, even at

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