This patient’s electrocardiogram shows 3rd degree AV block (the p waves march out independent of the QRS complexes). This patient had Lyme disease carditis, which often presents with AV block; she was from an endemic area in the Northeastern United States. She did not recall a tick bite but was presumed to have had one while at summer camp. The classic erythema migrans rash is not reported in 60% of Lyme carditis cases. She was admitted for cardiac monitoring and IV antibiotic therapy. Some patients require a temporary pacemaker.

For more on recognizing different types of AV block, see Merck Manuals article here

For more on Lyme carditis, go here