Interatrial communications (atrial septal defects)

Interatrial communications (shunts between the atrial chambers) are often referred to as atrial septal defects (ASDs), although only secundum and vestibular defects are true defects within the atrial septum.

Other atrial level shunts that result in similar physiological effects are sinus venosus defects, ostium primum defects, and unroofed coronary sinus defects.

Corrective closure is recommended if Qp:Qs (ratio of pulmonary blood flow to systemic blood flow) is ≥1.5.

Sinus venosus defect with partial anomalous pulmonary drainage and unroofed coronary sinus (especially if associated with a persistent left superior vena cava) should be corrected irrespective of shunt volume.

Correction is usually performed between ages 2 to 4 years, but can be done in younger patients if haemodynamically not well tolerated.

Percutaneous device closure is the preferred treatment for secundum defects.

Surgical closure is indicated for large defects, defects with missing rims that prevent secure placement of a catheter device, or if associated lesions need corrective surgery simultaneously.

Pulmonary hypertension can develop, leading to shunt reversal (Eisenmenger's syndrome). Patients need detailed pre-operative assessment to confirm that pulmonary vascular resistance is responsive to medical management. If pulmonary vascular resistance remains high, corrective closure may not be tolerated.

An interatrial communication is a congenital cardiac defect that occurs as the result of incomplete separation between the left and right atrium.

There are five types of interatrial communication: secundum, ostium primum, sinus venosus, coronary sinus, and vestibular.

Only secundum and vestibular defects are located in the true atrial septum and are, therefore, ASDs. Primum defects, sinus venosus defects, and coronary sinus defects have historically been classed as ASDs due to the left-to-right shunt they produce; however, they are more precisely described as interatrial communications as they are not located in the true septum.[1]Naqvi N, McCarthy KP, Ho SY. Anatomy of the atrial septum and interatrial communications. J Thorac Dis. 2018 Sep;10(suppl 24):S2837-47. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6174145 http://www.ncbi.nlm.nih.gov/pubmed/30305943?tool=bestpractice.com [2]Redington AN, Anderson RH, Spicer DE. Interatrial communications. In: Wernovsky G, Anderson RH, Kumar K, et al, eds. Anderson’s Pediatric Cardiology. 4th edition. Philadelphia, PA: Elsevier; 2019.​