In atrial septal defect, when echocardiography is performed, there can be enlargement of the right atrium and right ventricle, widening of the right ventricular outflow tract, homogeneous motion of the septum and the posterior left ventricular wall, and localized loss of echo in the middle of the septum or interruption of septal continuity. When color Doppler is performed, the direction of blood flow can be clarified and the shunt bundle can be seen flowing from the left atrial defect site to the right atrium, and the shunt flow can be estimated by measuring the velocity of the blood flow. The diagnosis is usually made clear by echocardiography and color Doppler examination.