Objective:To review experience of the surgical treatment for large ventricular septal defect(VSD)with pulmonary hypertension(PH)in infants less than 5kg.Methods:From January 2003 to May 2006

45cases of large ventricular septal defects in weighting less than 5kg were operated.Their age ranged from 1month to 11months.Among then

15cases were aged from 1 to 3months

14cases from 3 to 6months and 16cases over 6months

the mean weight was 4.1±0.4(2.5~5.0)kg.All the cases had single incidence of VSD

and among them

the perimembranous type was in 36 patients

the conal septal defect in 9

six patients were associated with atrial septal defect(ASD)

three with patent ductus arteriosus(PDA)

three with ASD and PDA

and one with PDA and coarctation of the aorta(COA).All were repaired by cardiopulmonary bypass(CPB)under general anesthesia.Results:There was no death after operation.There were 18cases of postoperative complications

with the incidence rate as 40%.And the complications included low cardiac output syndrome(2cases)

arrhythmia(3cases)

pneumonia(5cases)

pleural effusion(1case)and atelectasis(7cases).In the early phase after operation

all cases were checked by color ultrasound and found that heart function and valve closure were all normal except 2cases with slight residue difflunce

All patients were discharged after full recovery.Conclusions:Infants with large VSD

having lower weight and being quite young should be operated on as early as possible.During the operation

extracorporeal circulation lesion should be alleviated

viscera functions protected

and after operation

the control of respiratory duct strengthened

and low cardiac output and high pressure of pulmonary artery prevented

which are the keys to decrease the complications and mortality.