Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Eisenmenger syndrome ?
    ### Response:
    What causes Eisenmenger syndrome? Eisenmenger syndrome is caused by a defect in the heart. Most often, the defect is one called a ventricular septal defect (VSD), a hole between the two pumping chambers (the left and right ventricles) of the heart. Other heart defects that can lead to Eisenmenger syndrome include atrial septal defect (ASD) and patent ductus arteriosus (PDA).
    