Transoesophageal Echocardiography is useful in -

Transoesophageal echocardiography (TOE) involves passing an endoscope-like ultrasound probe into the oesophagus and upper stomach under light sedation and positioning it behind the LA. It is paicularly useful for imaging structures such as the left atrial appendage, pulmonary veins, thoracic aoa and interatrial septum, which may be poorly visualised by transthoracic echocardiography, especially if the patient is overweight or has obstructive airway disease. The high-resolution images that can be obtained makes TOE paicularly valuable for investigating patients with prosthetic (especially mitral) valve dysfunction, congenital abnormalities such as atrial septal defects, aoic dissection, infective endocarditis (vegetations that are too small to be detected by transthoracic echocardiography) and systemic embolism (intracardiac thrombus or masses) A vascular ring is a congenital defect in which there is an abnormal formation of the aoa and/or its surrounding blood vessels. The trachea and esophagus are completely encircled and sometimes compressed by a "ring" formed by these vessels, which can lead to breathing and digestive difficulties Ref Harrison 20edition pg 1441