evaluate if beta 2-adrenergic agonist can have adjuvant effect to patients with infantile-onset Pompe disease under enzyme replacement therapy

Inclusion Criteria:

1. Confirm diagnosis as Pompe disease
2. age 2 years or above
3. under at least 1 year regular recombinant human acid alpha glucosidase, and no dosage/frequency change in recent 3 months
4. Provide inform consent

Exclusion Criteria:

1. chronic heart disease such as arrhythmia, cardiomyopathy, cardiac infarction
2. history of seizure
3. history of diabetes mellitus
4. history of hyperthyroidism
5. hypokalemia
6. pregnant
7. allergy to β-agonists
8. under medications including diuretics, digoxin, beta-blockers, etc