M-mode and two-dimensional echocardiography--contributions and limitations in management of interatrial and interventricular septal defects and conotruncal anomalies.

The relative contributions of M-mode and two-dimensional echocardiography to the management of a congenital cardiac anomaly reflects their individual sensitivity to the physiologic and anatomic alterations of the lesions. The integration of these imaging techniques should not be based on their historical relationship. Two-dimensional imaging has, in most cardiac laboratories, become the cardiac ultrasound technique of choice for patients suspected of having defects in the atrial and ventricular septum or anomalies of the conotruncus. Two-dimensional examination of intra- and extracardiovascular anatomy displays defects in both the interatrial and interventricular septae and permits their segmental localization. Anomalies of great vessel relationships are detailed by two-dimensional presentation of the ventriculo-arterial attachments. M-mode echocardiography's strength remains its presentation of temporal/spatial data. Combined M-mode/two-dimensional imaging facilitates quantitation of chamber dimensions as well as vessel and semilunar root diameters.