Anatomy
Deficiency of septum primum, the thin flap valve of the foramen ovale. Septum primum grows down from the posterior-superior wall of the common atrium of the primitive heart tube and breaks down at its origin prior to closure of ostium primum to form the foramen ovale. ASD2 appears to be due to excessive or ectopic removal of septum primum so that it does not overlap with septum secundum, an infolding of the roof of the common atrium.
Pathophysiology
Majority are unrestrictive, such that the degree of shunting is determined by the relative compliance of each ventricle in diastole. Typically, a left to right shunt develops resulting in RV volume overload and pulmonary overcirculation. Typical presentation is school-age child with murmur or exercise intolerance. Qp/Qs is typically 2.5-3. Rarely, infants develop congestive heart failure, usually in the setting of prematurity or small left heart structures, including coarctation.
- Catheter-based ASD closure
- ASD2 may be closed by transcatheter device (shown here is Amplatzer ASD occluder) as an outpatient procedure.
- Not all ASD2 are amenable to transcatheter closure, most commonly due to a deficient posterior rim of the atrial septum on which the device must seat.
- Rarely, a device becomes acutely displaced (causing RVOTO) or erodes (causing pericardial effusion).
- Late risks include residual defect, erosion into the posterior atrial wall (which may cause a pericardial effusion), or LA thrombus.
- Secundum ASD repair
- Surgical ASD2 repair typically includes brief CPB, (often) a mini-sternotomy, and patch closure of a large, isolated atrial defect. Preoperative morbidity is rare; patients are frequently school-age, healthy and active, but tire with activity.
- Postoperative management includes monitoring for bleeding and (rarely) arrhythmias, pain control, ERAS early extubation and early mobilization.
- Closure of the pericardium in this operation may cause more prominent chest discomfort and diffuse (non-specific) ST changes due to pericardial inflammation.
- Post-pericardiotomy syndrome may occur within 1-2 weeks of surgery. Patients present with fever, chest pain, pericardial effusion (sometimes large). Treatment with NSAIDS or colchicine.
References
Brown, JACC, 2018 – Review of device-closure [PDF]
1952, NEJM – Atrial well – Boston