On ECG a left axis deviation is generally found in<unk><unk>  ASD, but an RSR pattern (M pattern) in V1 is characteristic. Fixed splitting of the second heart sound (S2) occurs because of equal filling of the left and right atria during all phases of the respiratory cycle. ECG of a patient with<unk><unk>  ASD Patients with atrial<unk><unk> s may have atrial fibrillation, atrial tachycardia, or atrial flutter, but these abnormal heart rhythms are not usually seen until the affected individual grows older. Features also seen on the ECG include right atrial enlargement and varying degrees of atrioventricular block. When a person is suspected of having an ASD based on the findings of an incomplete right bundle branch block with a rSr' or rSR', the frontal plane QRS should be examined. The frontal plane QRS is the most helpful clue to distinguish between an<unk>  secundum ASD and an<unk><unk>  ASD. In<unk><unk> s left axis deviation is seen in most patients with an axis of > -30 degrees and very few patients have right axis deviation. In contrast<unk>  secundum<unk> s have an axis between 0 degrees and 180 degrees with most cases to the right of 100 degrees. In the ECG above, you can see an example of the rSR' pattern in V1 with a R' greater than S with T wave inversion which is commonly seen in volume overload right ventricular hypertrophy.
Ostium primum atrial septal defect
Double aortic arch
Double inlet left ventricle
Interrupted aortic arch
Sinus venosus atrial septal defect
Tricuspid atresia
Double outlet right ventricle
Atrioventricular septal defect