Transoesophageal echocardiography (TOE) has opened a new sonographic window to the heart and the thoracic aorta. The technical development of this ultrasound based diagnostic tool, as well as its clinical application in a large variety of important cardiovascular diseases, has been cultivated scientifically mainly by European cardiologists within the last 15 years. Miniaturised electronic phased array transducer technology incorporated in a gastroscope-like instrument formed the basis for the breakthrough of TOE in clinical cardiology.1 The wide clinical application of TOE in the past has without doubt significantly improved our diagnostic possibilities and contributed much to a better understanding of the pathophysiology of many diseases such as aortic dissection or cardiogenic stroke. Both factors influenced significantly the therapeutic management and led to a better outcome of a variety of cardiovascular diseases.

This review will focus on the clinical application of TOE. There is general agreement that a TOE examination is indicated in all patients where conventional transthoracic echocardiography (TTE) fails to provide conclusive diagnostic information (for example, emphysema) or where TTE is impossible (during surgery). Beyond that TOE is generally performed when it is expected to add important information to the data first obtained by TTE, because of the higher image resolution or the potential to acquire images of cardiac or vascular structures that usually are not accessible by the transthoracic approach.