Acute congestive heart failure: pathophysiological alterations

The goal of a healthy heart is to transfer blood coming to the ventricles from the low pressure venous system into the high pressure arterial system. In acute congestive heart failure (CHF), impaired cardiac function leads to failure to empty venous reservoirs and therefore to reduce delivery of blood into the arterial circulation (Michaelson 1983). Once heart failure occurs it has a high mortality rate. According to the Framingham Heart Study, 50% of patients with New York Heart Association class II or III heart failure died within 5 years. With class IV patients, 50% survived less than 1 year (Cupples 1987). The purpose of this article is first to define acute CHF. Secondly, the pathophysiological alterations that occur as a result of strained and misdirected compensatory mechanisms will be discussed to help critical care nurses to recognise why certain patients are at risk of developing acute CHF.