Class I
1, high grade II or III AV block combined with symptomatic bradycardia, abnormal ventricular function or low cardiac output (Class C)
2, Children with abnormal sinus node function combined with age-inappropriate bradycardia; definition of bradycardia is based on the child’s age and expected heart rate (Class B)
3, postoperative high II or III degree AV block without a trend of remission or at least 7 days after cardiac surgery (Class B)
4, congenital grade III AV block with wide QRS escape rhythm, complex ventricular ectopic rhythm or abnormal ventricular function (Class B)
5. Ventricular rate <55 beats/min in infants with congenital III degree AV block; ventricular rate <70 beats/min in those with combined congenital heart disease (Class C)
Class IIa
1, congenital heart disease with sinus bradycardia for prevention of recurrent intra-atrial folding tachycardia; sinus node abnormalities can be primary or secondary to antiarrhythmic therapy (Class C)
2, children older than 1 year with congenital third-degree AV block with a mean heart rate <50 beats/min or with sudden RR long intervals lasting 2 to 3 times the basic cardiac cycle, or with clinical symptoms due to cardiac tachyarrhythmias (Class B)
3.Children with sinus bradycardia combined with complex congenital heart disease have a resting heart rate <40 beats/min or a long heartbeat interval >3 seconds (Class C)
4.Children with congenital heart disease have hemodynamic abnormalities due to sinus bradycardia and atrioventricular contraction asynchrony (Class C)
5. Transient complete atrioventricular block after congenital heart disease with residual bundle branch block occurs with unexplained syncope, and other causes are excluded (Class B)
Class IIb
1. Transient postoperative atrioventricular block of degree III converted to sinus rhythm with double bundle branch block (Class C)
2.Children or adolescents with congenital III degree AV block, heart rate in acceptable range, narrow QRS wave, normal ventricular function, no clinical symptoms (Class B)
3, asymptomatic sinus bradycardia after biventricular repair of congenital heart disease, with heart rate <40 beats/min at rest or with long intervals >3 seconds (Class C)
Class III
1.Postoperative transient atrioventricular block with restoration of normal atrioventricular conduction without any clinical symptoms (Class B)
2, asymptomatic double bundle branch block after congenital heart disease, with or without first degree AV block, without previous transient complete AV block (Class C)
3, asymptomatic II degree type I AV block (grade C)
4, asymptomatic sinus bradycardia with a maximum RR interval <3 seconds and a minimum heart rate >40 beats/min (Class C)