Pathophysiology

  In patients with acyanotic atrial septal defect (ASD), the shunt follows the left atrium - right atrium

      - right ventricle
route. If the defect is not small, shunt flow results in dilatations of left atrium, right atrium

      and right ventricle.

  If the ASD is not small, the result is dilatation of the left atrium, right atrium and right ventricle.

  Below is the list of various ECG abnormalities that are reported in various types of ASD.

      These are observed with increased frequency, but not necessarily in all ASD patients.

  The
most frequent ECG abnormalities in ASD are right bundle branch block (RBBB) pattern or

      rsR' pattern in lead C1
. Complete RBBB is observed less frequently.

  In patients with large ASD, presence of tall R or R' in lead C1 suggests development of


      pulmonary hypertension
.

  Size of defect determines the shunt flow which in turn results in most of the ECG abnormalities.

      If the ASD is very small, the ECG may be normal.



Ostium secundum ASD

  Complete RBBB, RBBB pattern or rsR' pattern in lead C1.

  Normal axis or right axis deviation due to right ventricular diastolic overload.

  Right atrial abnormality (may not be observed in children).

  Prolongation of the PR interval: first degree atrioventricular block (less frequent than ostium primum ASD).

 
Crochetage sign : notched R wave in inferior limb leads (may disappear after closure of the defect).

  If the defect is very large, severe atrial dilatation results in atrial flutter of fibrillation in adults.

  In adult patients with ASD, closure of the defect
does not decrease the incidence of atrial fibrillation.


Ostium primum ASD

  rsR' pattern in lead C1 (V1).

  Left axis deviation (due to absence of the left anterior fascicle).

      Left axis deviation persists even after closure of the defect.

 
Determination of QRS axis is very important in the differential diagnosis of ostium secundum

      and ostium primum ASD.


      Right axis deviation is not observed in ostium primum ASD.

  Left atrial abnormality.

  Complete or incomplete RBBB.

  Prolongation of the PR interval (first degree atrioventricular block).



Sinus venosus ASD

  Right axis deviation.

  Ectopic atrial rhythm may be observed.
Negative P waves in inferior leads (II, III and aVF)

      suggest low atrial rhythm.



ECG abnormalities that are reported to occur after percutaneous or surgical closure of the ASD

  Frequent atrial premature contractions (APC).

  Supraventricular tachycardia (SVT) attacks.

  Varying degrees of atrioventricular (AV) blocks (rarely complete AV block).

      Usually, the blocks are reported to disappear in a few weeks.

  Sick sinus syndrome may be seen after closure of the sinus venosus type ASD.



References

  Chou's Electrocardiography in Clinical Practice.

      Adult and Pediatric. 5th ed. Philadelphia. WB Saunders. 2001.

  J Am Coll Cardiol 1996;27:877.

  Ann Thorac Surg 1999;68:75.

  Arch Intern Med 1968;121:402.

  J Interventional Cardiac Electrophysiology 2000;4:469-474.

  J Am Coll Cardiol 2004;43:1677-1682.

  Acc Curr J Review 2003;12:97-100.

  Am Heart J 1959;58:689.





ECG 1. A 4 years old child with an ostium secundum type ASD of 7 mm in diameter. QRS axis is normal. Signs of right
ventricular hypertrophy are generally observed in adult patients with ASD. Right bundle branch block (complete or incomplete)
is the most frequent ECG sign of ASD.

Dr. Mahmut Gokdemir has donated this ECG to our website.

Click here for a more detailed ECG





ECG 2. This 55 years old woman was operated for ASD 15 years ago.

Click here for a more detailed ECG





ECG 3. This ECG belongs to a patient with moderate mitral stenosis who was operated for ASD (Lutembacher syndrome).
Coronary arteries are normal. Rhythm is atrial fibrillation.

Click here for a more detailed ECG





ECG 4. The ECG above belongs to a 2 years old child who was operated for large VSD four weeks ago.

Dr. Mahmut Gokdemir has donated this ECG to our website.

Click here for a more detailed ECG





ECG 5. The ECG above belongs to an 11 years old child who had undergone operation for ASD, VSD and coarctation of the
aorta. Katz-Wachtel phenomenon (biventricular hypertrophy pattern) is observed.

Dr. Mahmut Gokdemir has donated this ECG to our website.

Click here for a more detailed ECG





ECG 6. Fiftynine years old woman who was operated for ASD 23 years ago.

Click here for a more detailed ECG





ECG 7. The above ECG belongs to a 10 years-old boy who had undegone transvenous closure of the ASD 7 years ago.

Dr. Mahmut Gokdemir has donated this ECG to our website.

Click here for a more detailed ECG





ECG 8. The above ECG, belongs to a 7 years-old boy who had undegone operation for ASD and pulmonary stenosis 3 years ago.

Pediatric cardiologist Dr. Mahmut Gokdemir has donated the above ECG to our website.

Click here for a more detailed ECG





ECG 9. The ECG above belongs to a 3 years-old boy who has ostium secundum type ASD (with a diameter of 10 mm) and
dilated right heart chambers.

Pediatric cardiologist Dr. Mahmut Gokdemir has donated the above ECG to our website.

Click here for a more detailed ECG





ECG 10a. The compact ECG above is from a 46 years-old man with a large ostium secundum type atrial septal defect
and left to right shunt. ECHOcardiography showed a dilated right ventricle and a dilated right atrium.
The QRS width is 94 milliseconds.
Inferior leads show notched R waves: Crochetage sign.




ECG 10b. The compact ECG above belongs to the same patient.
It was recorded 30 days after surgical closure of his large secundum ASD.
Right ventricular volume overload is not present anymore. The QRS width has decreased to 84 milliseconds.
The notched R waves in inferior leads are not so prominent.