Comment on the diagnosis of the ECG tracing shown below.: (A) First degree AV block, intranodal, (B) Second degree AV block type1, intranodal, (C) Second degree AV block type 2, infranodal, (D) Third degree AV block
Answer is C. Symmetry in PR interval before and after the missed beat --> Indicating Second degree AV block type 2: infranodal. In Second degree AV block type 1 --> Serial lengthening of PR interval before and after the missed beat. In Third degree AV block --> complete dissociation b/w atria and ventricles.