Atrial septal defects

a type of left to right shunt
2 main types
1. secundum ASD
  1. 50% of ASDs
  2. defect in centre of atrial septum involving foramen ovale
2. partial AVSD (primium ASD, pAVSD)
  1. defect in atrioventricular wall w/
    1. inter-atrial commn btw bottm end of atrial septum and AV valves (primium ASD)
    2. abnormal atrioventricular (AV) valves
      1. left AV valve has 3 leaflets and leaks (regurgitant)
clinical features
1. symptoms
  1. none (commonly)
  2. recurrent chest infections/wheeze
  3. arrythmias (age 40+)
2. physical signs
  1. ejection systolic murmur
    1. best heard @ upper left sternal edge
    2. due to increased flow across pulmonary valve cos of L to R shunt
  2. fixed & widely split S2
    1. right ventricular stroke volume equal on inspiration & expiration
      Anmerkungen:
      - the extra blood returning to right atrium on inspiration is equalised between left and right atria cos of the hole.
  3. partial AVSD
    1. apical pansystolic murmur
      1. due to AV valve regurg
Ix
1. CXR
  1. cardiomegaly
  2. enlarged pulmonary aa
  3. increased pulmonary vascular markings
2. ECG
  1. secundum ASD
    1. partial right bundle branch block
      1. can also be normal in kids
    2. right axis deviation
      1. due to right ventricular enlargement
  2. partial AVSD
    1. superior QRS
      1. mainly -ve in AVF
      2. due to defect in middle of heart where AVN normally is
        displaced AVN conducts impulse to ventricles superiorly hence abnormal axis
3. Echo
  1. mainstay of ix
  2. will show anatomy
Mx
1. needs treating if ASD large enough to -> right ventricular dilatation
  1. secundum ASD
    1. cardiac catherisation w/ insertion of occlusion device
  2. partial AVSD
    1. surgery
  3. done @ 3-5 years old
    1. prevent future heart failure & arrythmias

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Atrial septal defects

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