The congenital 3rd degree AVB is rare: 1/20,000 to 1/50,000 births.

It is

-         either associated with congenital heart disease: ASD,  common atrioventricular canal, single ventricle, atrioventricular discordance

-         either secondary to the transplacental passage of  anti SS-A/Ro and SS-B/La antibodies from a mother affected by a collagenosis (mainly: systemic lupus erythematosus, Sj÷gren syndrome), which causes fetal myocarditis and fibrosis of conduction tissue.

There is also a rare genetic form (transmission: autosomal recessive or dominant). 

Later in life, AVB may be secondary to  open heart surgery, myocarditis (Kawasaki or Chagas disease), typhoid, a muscular pathology (Steinert's disease), a mitochondrial cytopathy (Kearns-Sayres), a heart tumor  (Bourneville sclerosis).

In the absence of associated heart disease, the indications of a pacemaker are as follows:

-         syncope (blackouts)or their equivalent

-         a frequency of QRS < 50/min if < 2 years; < 45/min from 2 to 5 years and < 40/min from 5 to 10 years 

-         an enlarged QRS;

-         repolarization disorders;

-         a junctional block;

-         ventricular extrasystoles;

-         absence of junctional acceleration following an effort

-         significant dilatation of the left ventricle

Before the age of 2 to 5 years, epicardial stimulation  in VVI with intra-abdominal positioning of the pacemaker is preferred. Leads insertion routes are subxiphoid, sternal or thoracic. 

Transesophageal stimulation can be used in emergency (neonatal period) pending the installation of a permanent pacemaker. In the older child, a type DDD endocardial probe is placed as in adults. The child with a congenital AVB must be regularly monitored  as dilated cardiomyopathy can appear gradually, although the pacemaker is perfectly working.

Anesthetic implications: 

It is wise to prepare a continuous infusion of isoproterenol (0.1-0.2 µg/kg/min) and to prefer agents that do not induce slowing of the heart rate (ketamine, isoflurane, sevoflurane, for example). The response to atropine is generally poor (less than 20% increase of heart rate ). It is useful to insert a  central venous catheter and an invasive arterial line if the child is hemodynamically unstable preoperatively. 

In the absence of associated anatomical pathology, inhalation anesthesia can be used. In case of cardiopathy, consider the hemodynamic adjustements that are required by the specific malformation. In an emergency situation, a temporary  pacemaker can be inserted percutaneously (epicardial pacing through sub-xiphoid route: risk of false contact and burning, direct muscular stimulation), by the esophageal route or intravenously through a central venous access.

References:

•        Batisse A., Fermont L., Lévy M. 
  Troubles du rythme et de la conduction. 
  In Cardiologie pédiatrique pratique, 4ème éd. Doin, 2013, p 220-22.
•        Bennie RE, Dierdorf SF, Hubbard JE.
  Perioperative management of children with third degree heart block undergoing pacemaker placement: a ten year review.
  Pediatr Anesth 1997; 7: 301-4.
•        Castilla M, Jerez M, Llacer M, Martinez S. 
  Anaesthetic management in a neonate with congenital heart block. 
  Pediatr Anesth 2004, 14:172-5.
•        Razka T, Rifai N, Delapintiere A, Magnenant E Vaksmann G, Bonnevalle M, Lequien P, Storme L.
  Electro-stimulation in preterm neonates with congenital auriculo-ventricular block. Report of three cases.
  Eur J Pediatr 2004; 163: 85-8
•        Kussman BD, Madril DR, Thiagarajan RR, Walsh EP, Laussen PC. 
  Anesthetic management of the neonate with congenital complete heart block: a 16-year review. 
  Pediatr Anesth 2005; 15:1059-66.
•        Sreevastava DK, Setlur R, Sharma VK, Padmini HS, Puri B, Bhargava AK.
  Anesthetic management of an infant with lupus and congenital complete heart block.
  Pediatr Anesth 2006; 16: 216-7.
•        Kiran U, Dutta A, Mehra A, Das SN, Zuber K.
  Neonatal lupus erythematosus with complete congenital heart block and severe respiratory distress: anesthetic management for urgent pacemaker implantation.
  Acta Anaesthesiol Scand 2006; 50:1315-6.
•        Tunaoglu FS, Yildirim A, Vurali D.
  Isolated congenital heart block.
  Tex Heart Inst J 2010; 37: 579-83. 

Update: November 2016