ASD Sinus Venosus

Sinus Venosus Atrial Septal Defect

Ganesh Athappan MD Ashley Davidof f MD

Definition

Sinus Venosus ASD is an anomaly of fetal development characterized by a defect in the upper atrial septum close to the SVC .

It is almost always associated with anomalous pulmonary venous drainage of the right upper pulmonary vein into the SVC.

Physiologically there is a shunting of blood from the left atrium to the right atrium

Clinically they are usually asymptomatic . A systolic ejection murmur with a fixed splitting of the second heart sound is heard over the second left intercostal space. EKG shows an abnormal p wav axis due to the proximity of the defect to the SVC and S-A node. Echocardiography confirms the diagnosis of a primum ASD. The direction of atrial level shunting can be detected by color Doppler.

Treatment is by surgical correction.

Types of ASD’s

The drawing shows the interatrial septum and the defects associated with each of the components. Image a shows a single defect in the septum primum and this is called an ASD secundum, or a secundum ASD. This is the most common ASD. The second image (b) shows an A-V canal defect in green and it is in the lower portion of the septum and is commonly associated with a cleft mitral valve. The third and least common defect is the sinus venosus defect. (purple)