ABC of heart failure: Investigation
Clinical assessment is mandatory before detailed investigations are conducted in patients with suspected heart failure, although specific clinical features are often absent and the condition can be diagnosed accurately only in conjunction with more objective investigation, particularly echocardiography. Although open access echocardiography is now increasingly available, appropriate pre-referral investigations include chest radiography, 12 lead electrocardiography, and renal chemistry.
The chest x ray examination has an important role in the routine investigation of patients with suspected heart failure, and it may also be useful in monitoring the response to treatment. Cardiac enlargement (cardiothoracic ratio <50%) may be present, but there is a poor correlation between the cardiothoracic ratio and left ventricular function. The presence of cardiomegaly is dependent on both the severity of haemodynamic disturbance and its duration: cardiomegaly is frequently absent, for example, in acute left ventricular failure secondary to acute myocardial infarction, acute valvar regurgitation, or an acquired ventricular septal defect. An increased cardiothoracic ratio may be related to left or right ventricular dilatation, left ventricular hypertrophy, and occasionally a pericardial effusion, particularly if the cardiac silhouette has a globular appearance. Echocardiography is required to distinguish reliably between these different causes, although in decompensated heart failure other radiographic features may be present, such as pulmonary congestion or