There are 4 types of atrial septal defect (ASD): ostium secundum, ostium primum, sinus venosus, and unroofed coronary sinus. Secundum defects are the most common.
Most patients are asymptomatic. Untreated defects can produce right atrial enlargement, cardiac arrhythmias, and heart failure over time.
Secundum, primum, and coronary sinus defects with small shunts (ratio of pulmonary flow to systemic flow, Qp:Qs, <1.5) do not require treatment. Corrective closure is required if the shunt is larger (Qp:Qs ratio ≥1.5), there is right atrial enlargement, or the patient has a sinus venosus defect.
Corrective closure, if required, is usually performed at 2 to 4 years of age but can be performed at a younger age in symptomatic patients.
Percutaneous device closure is the preferred treatment for secundum defects, and surgical closure is reserved for larger secundum defects, technically challenging cases, and other defects.
If right-to-left shunting (Eisenmenger syndrome) occurs, the ASD is operable if the shunt is reversible with pulmonary vasodilators. If the shunt is irreversible, the treatment is largely supportive.
An atrial septal defect (ASD) is an opening in the atrial septum, excluding a patent foramen ovale.  There are 4 types of ASD: ostium secundum, ostium primum, sinus venosus, and unroofed coronary sinus.
Consultant in Paediatric and Adolescent Cardiology
Honorary Senior Lecturer
Paediatric and Adolescent Cardiology
Great Ormond Street Hospital and Institute of Child Health
SK declares that he has no competing interests.
Dr Sachin Khambadkone would like to gratefully acknowledge Dr Brandon Lane Phillips, Dr Frank Cetta, and Dr David J. Driscoll, previous contributors of this monograph. BLP, FC, and DJD declare that they have no competing interests.
Adult Congenital Heart Disease and Pulmonary Hypertension
Department of Cardiology
Children's Hospital Boston
Department of Medicine
Division of Cardiology
Brigham and Women's Hospital
AO declares that he has no competing interests.
Section of Transcatheter Treatment of Congenital Heart Disease in the Adult
Rovigo General Hospital
GR declares that he has no competing interests.
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