Atrial septal defect is the most common congenital heart disease in the adults.
It has the characteristic electrocardiogram of incomplete right bundle branch block
which has been found to be of greatest diagnostic value in all atrial septal
defects. It has been known that in the great majority of cases, the rSR' pattern in
V1 and V2 did not mean any disturbance of conduction of the right bundle branch
itself, but rather a selective hypertrophy and dilation of the basal portion of the
fight ventricle. It has been observed that the R' wave disappeared or decreased in
amplitude after the closure of the atrial septal defect.
This series comprised thirty-seven patients with atrial septal devect who
underwent the open heart surgery after cardiac catheterization at Severance
Hospital during the past 10 years. Each had been followed for a period of six
months to eight years. The EKG studies were made both pre-operatively and at the
follow-up examination, with regard to rhythm, the nature and duration of the P wave
and the QRS complex, and the direction of the mean QRS axis in the frontal plane.
An attempt was made to correlate the electrocardiographic findings with the
hemodynamic data in these cases.
1. Nineteen of the thirty-seven patients were male and eighteen female. Their
ages ranged from 6 years to 53 years; the mean age was 22.8 years.
2. There was statistically significant difference in the amplitude of the P wave
in V1 and S wave in V6 between the pre- and post-operative values. The duration of
the P wave in lead Ⅱ and QRS comples in V1 as well as the amplitude of R wave in
V6 did not show any change post-operatively.
3. The right axis deviation(more than +110' rightward) was present in 14 of 27
patients pre-operatively. The post-operative change of the mean QRS axis towards
the left was significant in all cases except four.
4. The slurring of the S wave in V6 disappeared immediately after the closure of
the atrial septal defect. It is suggested that the atrial septal defect. It is
suggested that the pre-operatively wide S wave might be caused by the dilatation of
the outflow tract of right ventricle secondary to increased right ventricular
5. Twenty-two of the twenty-seven patients(81.5%) revealed rSR' pattern in V1
pre-operatively. Post-operatively this type of complex persisted in 19 patients
with significant reduction of R' amplitude. In the other three patients this R'
wave completely disappeared.
6. Only one case of atrial fibrillation was noted pre-operatively in a 53
year-old man. The post-operative arrhythmia and conduction disturbance were present
in 7 of 37 patients(18.9%). These consisted of A-V junctional rhythm in two;
complete right bundle branch block in two; atrial fibrillation in one; atrial
flutter in one; A-V dissociation in one. These changes occurred immediately after
operation and disappeared within two days except one case of complete RBBB, which
persisted until 6 months later.
7. Comparing with the patients with normal QRS axis in frontal plane, patients
with right axis deviation showed higher right ventricular systolic pressure and
smaller left-to-right shunt.