Better medical management, together with a number of newer surgical techniques, has enable more girls with congenital heart disease to reach childbearing age. Congenital heart lesions now constitute at least half of all cases of heart disease encountered during pregnancy. Pregnancy is characterized by marked increase in stroke volume and cardic output during the antepartum period. The hemodynamic demands of pregnancy dangerously stress the impaired cardiovascular reserve. We experienced that a case of cardiac arrest in a preeclamptic patient with unrecognized heart failure during induction of the general anesthesia for cesarean section. We found out later that she had an operation because of patent ductus arteriosus at the age of 15 and then already had mitral valve regurgitation and LVH findings in the echocardiogram. We suggested that heart failure was enhanced by the hyperdynamic cardiovascular changes of normal pregnancy and further aggrevated by preeclampsia and anemia.