[Role of transesophageal echography in the study of embolism of cardiac origin].

In the total population, cerebrovascular ischemic diseases account for 0.2-0.3% cases per year, and in the 20-40% of them it is possible to recognize a cardioembolic mechanism. The cardiological examination in patients with stroke is, therefore, aimed at detecting cardiac sources of emboli (left atrial, valvular, and ventricular thrombosis, atherosclerotic plaques of ascending aorta), and at identifying the cardiovascular disease directly or indirectly associated with ischemic stroke. Transesophageal echocardiography (TEE) is particularly suitable for this purpose, due to the proximity of the transducer to the posterior cardiac structures and to its better resolution. Many recent reports have demonstrated that TEE not only improves the recognition of known cardioembolic diseases (intracardiac thrombi, mitral stenosis, valvular prosthesis thrombosis, endocardial infectious diseases), but is also the most reliable non invasive technique suitable to detect atherosclerotic lesions of the ascending aorta. Furthermore, TEE allowed to recognize new anatomic and functional abnormalities, such as left atrial spontaneous echo contrast, atrial septal aneurysm, patent foramen ovale, frequently associated with stroke. Noteworthy, TEE is the only technique suitable for functional and anatomic evaluation of the left atrial appendage. The Authors studied by TEE the functional properties of left atrial appendage in patients with severe mitral stenosis with or without atrial fibrillation, as compared to patients with left atrial thrombosis. Results showed that fractional shortening of left appendage was greatly reduced, at the same extent in the 3 groups, demonstrating that abnormalities in left atrial appendage emptying could be a risk factor for atrial thrombosis. In order to compare TEE with the transthoracic 2D-echo for the detection of cardioembolic sources, the Authors studied 63 patients with ischemic stroke. TEE revealed a possible cardioembolic source in 70% of younger patients and in 50% of patients older than 45 years. These abnormalities were detected by TEE respectively in 10% and in 1.8% of cases. These data are in agreement with many other reports in literature, and suggest the usefulness of TEE in the evaluation of patients with ischemic stroke and no evidence of severe atherosclerotic cerebrovascular disease, in contrast to the poor role of TEE. Another important field is the prevention of stroke in patients at high risk of cardioembolic events. The role of TEE before and immediately after cardioversion in patients with atrial fibrillation has been recently studied by several papers. Cardioversion was proved at low risk of stroke when TEE did not show left atrial or left appendage thrombosis. Therefore, the transesophageal approach identifies patients needing prolonged anticoagulation (roughly 20%), avoiding an undue, potentially dangerous therapy.