An ECG may show the “crochetage” pattern (92% specific)—a notch near the apex of the R wave in inferior limb leads
Large notches signify a larger shunt
Other ECG findings
(Incomplete right bundle branch block, very sensitive
1st degree AV block<unk>  flutter or<unk>  fibrillation in ~20% of adults with<unk> s requiring surgery
Right axis deviation (pulmonary hypertension)
Large notches signify a larger shunt
1st degree AV block<unk>  flutter or<unk>  fibrillation in ~20% of adults with<unk> s requiring surgery
Right axis deviation (pulmonary hypertension)
Subcostal view preferred window, due to interatrial septum perpendicular to echo signal (apical four-chamber is parallel to<unk>  echo signal)
Clues to<unk> 
Hypermobile interatrial septum
Abrupt<unk>  irregularity
RA and/or RV volume overload
Pulmonary artery dilation
High pulmonary artery pressures
TTE with Doppler can demonstrate most shunting
Agitated saline with Valsalva maneuver to increase right to left shunting is more diagnostic
Hypermobile interatrial septum
Abrupt<unk>  irregularity
RA and/or RV volume overload
Pulmonary artery dilation
High pulmonary artery pressures
Atrial septal defect
Cyanotic
Ventricular septal defect
Tetralogy of fallot
Tricuspid atresia
Total anomalous pulmonary venous return
Patent ductus arteriosus
Transposition of the great arteries