Second Degree Atrioventricular Block 2:1

With 2:1 atrioventricular block, it is impossible to know whether it is Mobitz I (nodal) or Mobitz II (infranodal) based on the surface ECG; therefore, 2:1 AV block is simply referred to as “2:1 AV block.” When the QRS is narrow, as in this case, Mobitz I is more likely; however, it is prudent to assume the worst scenario (i.e., Mobitz II).



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