Complete heart block in a young child presumably due to mycoplasma pneumoniae myocarditis

The case is described of an 18 months old boy with sudden onset complete heart block, heralded by Stokes-Adams attacks. General signs of viral illness preceded and accompanied the syndrome; this, along with angiographic evidence of poorly contracting left ventricle, led to the diagnosis of non bacterial myocarditis. Serologic tests disclosed a significant rise in antibodies against mycoplasma pneumoniae (1/16 to 1/128). The His-bundle electrogram showed a block above the His-bundle, but fairly widespread damage to the conduction system is suspected. The complete heart block proved to be permanent and a fixed rate pacemaker had to be implanted.