Atrial Septal Defect, Ostium Secundum

Incidence in USA: 140,000 with ostium secundum ASD (70–80% of ASDs).

Accounts for 7% of all congenital cardiac defects but roughly one-third (30–40%) of congenital cardiac defects in pts older than 40 y.

Gender prevalence: Females >males, with a 2:1 ratio in isolated ASDs.

Familial incidence: Significant if associated with P-R prolongation or forearm and hand abnormalities (Holt–Oram syndrome).

Increased incidence in high altitude.

Periop mortality rate 1%

Later in course, associated with atrial dysrhythmias, pulm Htn, and right heart failure

Increased risk of atrial dysrhythmias, heart block (rare), and air embolus with surgical repair

Risk of infections endocarditis and paradoxical air embolization with IV access.

Failure of closure of midseptal fossa ovalis.

Usually asymptomatic early in life.

15% incidence of associated noncardiac anomalies.

Associated with mitral valve prolapse (10–20%).

L-to-R shunt increases pulm blood flow (shunt fraction proportional to ASD size).

Late in course: Pulm Htn, right heart failure with possible shunt reversal, supraventricular arrhythmias.

Uncorrected defect carries a mortality rate of 6% per y > age of 40.

Diagnose by echocardiography and Doppler color flow echocardiography.

>80% spontaneous closure in the first year of life for small defects.

Failure of septum secundum to fuse with septum primum secondary to defective formation or resorption of the septum primum, shortening of the septum secundum, or a combination of the three