This study aims to investigate the efficacy and safety of oral sotalol alone or combination with other anti-arrhythmic medicines in the treatment of arrhythmias in children. The study will regularly monitor the Holter, electrocardiogram (ECG), Echocardiography (Echo), blood routine, urine routine, serum ion, liver and kidney function, troponin I, hypersensitive troponin T, N-terminal pro-brain natriuretic peptide (NT pro-BNP), etc, before and after receive sotalol therapy. Compare the degree of arrhythmia improvement in patients and the side effects after oral sotalol.

Monitoring the Holter, ECG, Echocardiography , blood routine, urine routine, serum ion, liver and kidney function, troponin I, hypersensitive troponin T, NT pro-BNP beforehand. Eligible patients should stop all anti-arrhythmia drugs and digitalis, tricyclic antidepressants, beta blockers or calcium antagonists for at least 5 half-lives, and then do Holter. Randomly grouped. Judging the results according to the situation before and after oral sotalol.

Inclusion Criteria:

1. Age 0 day to 14 year-old
2. Diagnosis of tachycardia (paroxysmal supraventricular tachycardia, paroxysmal atrial tachycardia, ventricular tachycardia, idiopathic ventricular tachycardia, premature ventricular contraction) and had an episode within 3 months; Premature Ventricular Contractions (PVC) (total 10000 times/d, or>5000 times/d with multiple source PVC, or total > 3000 times/d but with paired PVC+ multiple source PVC, or ventricular tachycardia);
3. Although PVC≤ 10000 times/d, but there are obvious symptoms such as palpitation, chest tightness, fatigue, dizziness and other symptoms that need improvement.
4. Signed informed consent before the trial
5. Good compliance

Exclusion Criteria:

1. Heart failure that is ineffective in conventional treatment;
2. Left ventricular ejection fraction (LVEF) ≤ 50%;
3. Suffering from bronchial asthma;
4. Resting sinus heart rate (HR) in newborns <90 bpm; -8 yrs <80 bpm; ≥ 8 yrs <60 bpm;
5. Corrected QT Interval (QTc) ≥ 450ms;
6. II ° -III ° atrioventricular block (AVB);
7. Severe liver, renal dysfunction, acute myocardial infarction, acute myocarditis, electrolyte imbalance have not been corrected;
8. The child has undergone major surgery in the past 4 weeks;
9. The child has participated in other clinical trials in the past 4 weeks;
10. The child has digestive, nervous, circulatory, kidney or liver disease

Dear Sir/Madam Our study receives a grant from China Ministry of Science and Technology. We cannot decide whether the data could be shared. Hope you can understand.