Congenital Heart Defects (acyanotic)

Atrial Septal Defect (ASD)


  • Associated with fetal etOH syndrome

  • Ostium primum defect (ASD 1): Associated with Down syndrome & other defects

  • Ostium secundum defect (ASD 2): MC and usually an isolated defect

  • If septum doesn't close all the way ➔ minor L ➔ R shunting

    • ↑ right sided volume leads to pulmonary HTN, RVH, RAE ➔ atrial arrhythmia

    • ↑ risk of paradoxical embolization (thrombi crosses defect and goes into circulation)

      • Can land in brain cryptogenic stroke, GI ➔ mesenteric ischemia, heart, or extremities

  • Atrial septum

    • One side of the septum - septum primum has a hole (ositum secundum)

      • Septum primum grows down. If it doesn't make it all the way down ➔ ASD 1

        • Defect at lower part of septum ➔ mitral valve problems

    • Other side of the septum - septum secundum covers ositum secundum and has a hole (foramen ovale)

      • Together they form a pseudo-valve allowing for blood to flow R ➔ L (only)

    • Septum primum and secundum fuse after birth and close off foramen ovale

  • Patent Foramen Ovale: means the ASD has some kind of tissue (flap) over hole


  • As an adult (by 40yo) undx pts will have sx from pulmonary congestion/HTN

    • Dyspnea, frequent respiratory infxns

  • Systolic ejection murmur at pulmonic valve

  • Wide & fixed split S2

    • Fixed = doesn't change with respiration

    • Mid-diastolic rumble from ↑ flow through tricuspid valve (Relative stenosis)

  • RAE ➔ arrhythmia, RV heave (left sternal border/subxiphoid)

  • Platypnea-orthodeoxia (rare): dyspnea and arterial desaturation in upright position that improves when supine

  • ↑ RA volume ➔ ↑ RV volume ➔

    • ↑ flow across pulmonic valve ➔ systolic ejection murmur

    • Prolonged RV emptying ➔ delayed pulmonic valve closure ➔ split S2

  • EKG may show Crochetage pattern: notched R-wave peak in inferior leads

    • ↓ sensitivity but ↑ specificity for ASD

  • ASD rarely ➔ Eisenmenger syndrome


  • ECHO

  • TTE good enough for DX but TEE better for sizing and position of defect

  • MRI if inconclusive echo

  • Cardiac cath is gold standard for measuring pulmonary to systemic flow ratio (Qp/Qs)


  • In children: Small 3-6mm ASD without clinically significant right side overload get monitored

    • Symptomatic or significant shunt ratio ➔ patch repair after age 2 (in hopes of spontaneous closure)

  • In adults: Generally want to close in adults with impairment or asx with RA/RV enlargement as long as no pulmonary HTN

    • Generally avoid closing when pulmonary HTN is present