CardioNerds (Dan Ambinder), episode lead Dr. Sarah Fahnhorst (ACHD Cardiologist at Spectrum Health in Grand Rapids, Michigan), and series co-chair Dr. Agnes Koczo (fellow at UPMC) learn about ASD from Dr. Richard Krasuski (ACHD Cardiologist and Director of ACHD at Duke University). Audio editing by CardioNerds Academy Intern, student doctor Adriana Mares An atrial septal defect (ASD) is a common congenital heart disease most often diagnosed in childhood, but initial presentation can be in adulthood. ASDs are abnormal communications between the left and the right atrium.  There are four types of ASDs with different embryologic origins. If the defects are large, they will require percutaneous or surgical closure. Unrepaired defects can lead to symptoms of shortness of breath, exercise intolerance, recurrent chest infections, or pulmonary hypertension. This episode of CardioNerds will review the natural history, embryologic origin, diagnostic modalities/findings, indication for closure and long term complications of repaired and unrepaired atrial septal defects.  The CardioNerds Adult Congenital Heart Disease (ACHD) series provides a comprehensive curriculum to dive deep into the labyrinthine world of congenital heart disease with the aim of empowering every CardioNerd to help improve the lives of people living with congenital heart disease. This series is multi-institutional collaborative project made possible by contributions of stellar fellow leads and expert faculty from several programs, led by series co-chairs, Dr. Josh Saef, Dr. Agnes Koczo, and Dr. Dan Clark. The CardioNerds Adult Congenital Heart Disease Series is developed in collaboration with the Adult Congenital Heart Association, The CHiP Network, and Heart University. See more Disclosures: None Pearls • Notes • References • Guest Profiles • Production Team CardioNerds Adult Congenital Heart Disease PageCardioNerds Episode PageCardioNerds AcademyCardionerds Healy Honor Roll CardioNerds Journal ClubSubscribe to The Heartbeat Newsletter!Check out CardioNerds SWAG!Become a CardioNerds Patron! Pearls - Atrial Septal Defects It’s a CLASSIC! – On physical exam a wide fixed split S2 along with a systolic ejection murmur due to increased blood flow across the pulmonary valve and potentially a diastolic rumble across the tricuspid valve are CLASSIC findings with atrial septal defects. Atrial septal defects are not all the same. There are four types of atrial septal defects: secundum ASD, primum ASD, sinus venosus and coronary sinus defects (NOTE – the latter are atrial level defects which actually do not involve the interatrial septum). The different types warrant a different approach to closure. Use your tools and if your suspicion is high for an atrial septal defect, keep looking. Sinus venosus defects can easily be missed since the superior vena cava is difficult to image in adults. Diagnostic tools include: history and physical exam (USE the stethoscope), ECG, echocardiogram, cardiac MRI, cardiac CT, and cardiac catheterization.Not all defects NEED to be closed immediately. Moderate-large defects with a shunt greater than 1.5:1 should be closed due to increased risk of pulmonary hypertension and arrhythmias, barring contraindications. Surgery was previously the gold standard for closure of ASDs, but many defects especially secundum atrial septal defects are closed in the cath lab.    Show notes - Atrial Septal Defects Notes (developed by Dr. Sarah Fahnhorst What are the four different types of atrial level defects?Secundum atrial septal defectMost common type of atrial septal defect (75%)Located in the center of the atrial septum (fossa ovalis)Hole in the primum septum due to deficiency of the septum secundumPrimum atrial septal defectAccounts for 15-20% of ASDLocated at the inferior portion of the atrial septumIn the spectrum of atrioventricular septal defects/endocardial cushion defectsDefect in the developme...