Atrial septal defects (ASDs) are one of the most common types of acyanotic congenital heart diseases, comprising 6-10% all congenital heart defects. They represent the most common congenital heart disease diagnosed during adulthood. Secundum ASD is a defect in the fossa ovalis (septum primum), or the superior limb of the septum secundum and is the most common type of ASD (80% of all ASDs).
ASD closure for secundum ASD is recommended regardless of symptoms in patients with evidence of right ventricular (RV) volume overload and no pulmonary arterial hypertension (PAH) or left ventricular (LV) disease. Percutaneous device closure has become the first choice for secundum defect closure in presence of a feasible morphology with a reported low risk of serious complications (≤1% of patients).
Subclinical electrocardiography (ECG) abnormalities, sinoatrial node (SAN) and atrioventricular node (AVN) conduction abnormalities have been reported in patients with ASDs. . The reported incidence of AVN block following ASD device closure varies widely from none up to 6.1%. High-grade AVN block after device closure typically occurs in the first 24-hour post-procedure and may mandates device removal for resolution of heart block.
The mechanism of AVN block after ASD device occlusion could be due to mechanical pressure on the AV node or edema related to trauma. Young age and large defect/device size may be a risk factor for AVN block. Deficient rims of the ASD may also have an impact on development of AVN block.
Whether or not there is a direct impact of ASD device closure on the functional properties of AVN and SAN is not well elucidated. Testing the electrocardiographic and electrophysiologic (EP) parameters of AVN and SAN before and after the procedure could obviously help understanding the real risk
