The patients with atrial septal defect generally have no symptoms in the childhood, and have nonspecific symptoms such as dyspnea on exertion, fatigue, and palpitation even in the late period of adult. Thus delayed diagnosis for whom surgical correction was undoubtedly needed remains to be resolved. Accordingly, the simple and noninvasive method such as electrocardiography in patients with atrial septal defect having the nonspecific symptoms or having no symptoms warrants to be developed. This study was performed to see whether the crochetage pattern on R wave in inferior limb leads is effective for the electrocardiographic diagnosis of atrial septal defect and relates to the magnitude of left to right shunt.

Our subjects were 129 patients diagnosed as the atrial septal defect by the echocardiography and cardiac catheterization from January 1992 to June 1998. We selected 57 persons, as control group, who showed the normal findings under the echocardiography and also showed the incomplete right bundle branch block on the electrocardiography. We compared the frequency of the crochetage pattern in inferior limb leads between the two groups. Also we compared the frequency of the crochetage pattern before operation and after operation according to the quantity of the left to right shunt in the operated 40 patients with atrial septal defect.

1) The crochetage pattern was observed in 61.2% in patients with atrial septal defect and its frequency was greater than that of the control group (38.6%, p=0.005). 2) The crochetage pattern was disappeared by the operation in 16/29 patients (55.2%, p=0.001). 3) The frequency of disappearance of the crochetage pattern after operation differed significantly according to shunt severity: 72.2% for a Qp/Qs≥3.0 group, 18.2% for a Qp/Qs<3.0 group (p=0.015).

The crochetage pattern on R wave in inferior limb leads was helpful to the electrocardiographic diagnosis of the atrial septal defect. The disappearance of the crochetage pattern after operation was correlated with shunt severity.