ABSTRACT
AV block, and so the P waves may be abnormal or even absent. • In a patient with a recent onset of third-degree AV block, always consider the possibility of Lyme disease. This is transmitted by the spirochaete Borrelia burgdorferi and, in the second stage of the illness, can lead to first-degree, second-degree or third-degree AV block. The AV block can resolve entirely in response to antibiotics, although the patient may require support with a temporary pacemaker during treatment. • In congenital third-degree AV block, which is
uncommon, the block is usually at the level of the AV node and is often associated with maternal anti-Ro or anti-La antibodies.
