This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pediatrics
The presence of left axis detion beyond -30deg in electrocardiogram suggests 
Select and explain. 
A. Fossa ovalis ASD, B. Sinus venosus ASD, C. Ostium primum ASD, D. Coronary sinus ASD
C: Ostium primum ASD
Answer: C: Ostium primum ASD 
Explanation: The electrocardiogram of ostium secundum ASD is characterized by right axis detion and right ventricular hyperophy. The characteristic configuration of the lead Vl is rsR&; seen in almost 90% patients. Presence of left axis detion beyond -30deg suggests ostium primum ASD. Reference: Essential Paediatrics; O.P. Ghai; Page no: 413