Definition:Â congenital defect of the atrial septum which is either isolated or associated with other cardiac abnormalities.Primum (15% isolated, 30% total), secundum (50-70%), sinus venosis (10%) and patent foramen ovale (ostium secundum which is <3 mm)
Physiology:
Usually shunts left to right through the defect. However this depends on the size of the defect and the compliance of the ventricles.
Certain situations can reverse the shunt to right to left: PA, PHT, pulmonary vascular obstructive syndrome, tricuspid atresia and severe Ebstein’s anomaly.
Clinical findings:
Isolated ASDs are usually asymptomatic in childhood. Most likely clinical findings are failure to thrive with a 2-3/6 ESM heard loudest upper LSE +/- a widely split S2.
CXR usually non specific, may show cardiomegaly.
ECG may show right axis deviation with signs of RVH. May also show RBBB with RsR in V1.
Diagnosis:
Echo
Preoperative management:
Usually asymptomatic so no preoperative management required.
May need additional nutritional support if FTT.
Preoperative preparation:
ECG, CXR, CUS, FBE, clotting, UECs, PRBC (4), FFP (2), platelets (2), cryoprecipitate (2).
Methylprednisolone in neonates.
Surgery:
Defect closed using a patch of pericardium or Dacron.
Direct closure (suturing) can be performed if the defect is small.
Due to being intracardiac – cardiopulmonary bypass is required.
Percutaneous repair:
Several devices used, does not require CPB and rarely needs PICU admission post operatively.
Timing:
PFO and small ASDs only require observation.
The majority of small (<6mm) isolated ASDs spontaneously close by 2 yrs of age.
Usually ASDs are closed if the Qp:Qs ratio is greater than 2:1 (large left to right shunt) or if there is moderately RVH.
Reversible PHT is another consideration.
Qp:Qs ratio is generally obtained via cardiac catheter.
Postoperative management:
- Usually able to be extubated 4 hours post return from theatre – very common for patient to be unsettled on first night
- Inotropes: usually not required
- Haemodynamics: age adjusted, in neonates: SBP >60 mmHg, MAP >40 mmHg (increasing over time), CVP 8-12 mmHg
- Respiratory: normoxaemia, normocapnea
- Fluid restriction: 1 ml/kg/hr, early feeding
- Haemostasis
Specific problems:
Problems are unusual
Pericardial effusion/tamponade: 2-5%
Cardiac arrhythmias – SVT, AV block: approx 2%
Embolisation of device: 2-6%
Outcome:
Very good long term survival >95%
Minimal difference between surgical vs percutaneous closure
References
[1] Nelson’s Textbook of Pediatrics 18th Edition
[2] UpToDate 2010. Management and Outcome of Isolated Atrial Septal Defects in Children. Vick, W, Bezold, L, Fulton, D, Triedman, J, Kim, M
[3] J Am Coll Cardiol 1193; 22:851. Predictive Factors for Spontaneous Closure of Atrial Septal Defects Diagnosed in the First 3 Months of Life. Radzik, D, Davignon, A, van Doesburg, N, et al
[4] UpToDate 2007. Devices for Percutaneous Closure of a Secundum Atrial Septal Defect. Weigers, S, St John Sutton, M, Graham Jr, T, Triedman, J, Connolly, H, Yeon, S
[5] F1000 Medicine Reports 2010, 2:8. Recent Advances in Closure of Atrial Septal Defects and Patent Foramen Ovale. Qureshi, A, Latson, L
[6] Heart 1999; 82:300-306. Transcatheter Closure of Atrial Septal Defect and Interatrial Communications with a New Self Expanding Nitinol Double Disc Device (Amplatzer Septal Occluder): Multicentre UK Experience. Chan, K, Godman, M, Walsh, K, Wilson, N, Redington, A, Gibbs, J
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