3. • Crochetage sign was first described in 1959
• Is defined as notch on the R-wave in inferior limb leads
• Is seen in patients with ostium secundum or sinus venosus ASD
• It has high specificity (92–100%), when present in all three inferior
leads
• Its incidence increases with greater left to right shunt or larger
anatomical defect
• Post-operatively, early disappearance of this pattern occurs in around
one third of patients
