RYT Sung, MC Yam, KL Kwok, CK Li

Objective To study the incidence, morphological types, natural course and surgical implications of ventricular septal defects (VSD) in 680 patients seen at the Prince of Wales Hospital (PWH) between 1985 and 1994.

Patients and methods Two groups of patients with VSD were followed up clinically and regular echocardiography was performed to document any change of morphology. The two groups consisted of: (1) 349 babies born in PWH or its catchment areas who were diagnosed as having an isolated VSD or VSD in combination with a small patent ductus arteriosus or foramen ovale by echocardiography. (2) 331 children who were born outside the catchment area of PWH but were referred to PWH because of migration or other various causes.

The incidence of VSD was calculated from the number of group one patients and the total live births within the catchment area during the study period. Classifications of VSD were compared between the groups. The Kaplan-Meier method of life table estimation was used to calculate the probability of spontaneous closure within group 1 patients.

Results The distribution of perimembranous, subarterial and muscular VSD in group 1 are 78%, 15% and 7% respectively. The corresponding figures in group 2 are 62%, 34% and 4%. 60% of muscular VSD and 18% of perimembranous VSD closed spontaneously with the first two years of life. 45 patients had surgical repair of VSD during the follow up period. The post operative mortality was 4.4%. 9 patients died of congestive heart failure or concurrent chest infection. 5 patients developed Eisenmenger syndrome. Most of the deaths and Eisenmenger syndrome occurred in babies with chromosome abnormalities.

Conclusion The incidence of VSD in Hong Kong is similar to reports from the West. Subarterial VSD is more common (15%) but not as high as reported from Japan and Taiwan. Muscular VSD is much less common. Most children who required surgical closure had operation within the first two years of life and the mortality in children without chromosome abnormality is very low.