This is called a transthoracic echocardiogram. A transesophageal echocardiogram is done by inserting a probe with a transducer down the esophagus. This provides a clearer image of the heart because ...

The red letters in gray shaded area indicate the probe sequences used in panel D. Gray shaded area indicates the upstream control element. Blue color indicates the core promoter region. D. EMSA assay.