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| Transesophageal Echocardiographic Examination |
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Transesophageal echocardiography is an important intraoperative monitor not only for diagnosis and or confirmation of atrial septal communications, but also for estimating pulmonary artery pressures, and quantifying the degree of shunting. Furthermore, functional consequences of the shunting can be evaluated by assessing degree of chamber enlargement . Following the procedure TEE has added utility in assessing adequacy of the surgical repair. |
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| 2-D Examination and Doppler |
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| A thorough 2-D examination can characterize the specific defect and associated anomalies. The entire interatrial septum should be carefully scanned from multiple imaging planes to characterize the location and size of the ASD. The various subtypes are classified according to the location of defect and the TEE examination should be specifically focused on the imaging planes in region of the specific defect. |
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| Ostium secundum defects involve an absence of tissue in region of the fossa ovalis. Figures 1a and 1b. The mid-esophageal bicaval, right ventricular inflow-outflow and 4-chamber views with particular focus on the region of the fossa ovalis will enable the echocardiographer to delineate the size of the defect and the direction of shunting. False positive results (detected as echocardiographic drop out in the area of the fossa ovalis) can be avoided with the use of color flow Doppler and a contrast study. Color flow Doppler will demonstrate flow across the region of the defect and a contrast injection may display contrast in the left atrium. |
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| Ostium Secundum Defect |
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| Ostium primum defects involve a lack of tissue in the lower portion of the interatrial septum to the level of the atrioventricular valves. Mid-esophageal 4-chamber view will typically delineate the defect in the lower portion of the septum. Figures 2a and 2b . Color flow Doppler will display shunt flow in the region of the defect. |
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| Ostium Primum Defect |
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| Agitated saline contrast injection or 'bubble study' is a technique used to detect intracardiac shunting through an ASD. Demonstration of contrast within the left atrium suggests right to left shunting and a negative contrast effect is suggestive left to right shunting. |
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