Complete Heart Block

Key points

• Features: syncope · heart failure · regular bradycardia 30–50 bpm · wide pulse pressure · JVP cannon waves · variable intensity of S1.
• ECG: third degree (complete) heart block = no association between P waves and QRS complexes; first degree = PR >0.2 s; Mobitz I (Wenckebach) = progressive PR prolongation then dropped beat; Mobitz II = constant PR but P often not followed by QRS.
• CHB after MI localises to the right coronary artery — the AV node is supplied by the posterior interventricular artery (a branch of the RCA in the majority, otherwise the left circumflex).
• CHB following an INFERIOR MI with normal blood pressure is NOT an indication for pacing — manage conservatively if asymptomatic and haemodynamically stable.
• Temporary pacing IS indicated for: CHB following anterior MI · Mobitz type II following anterior MI · trifascicular block prior to surgery · symptomatic bradycardia not responding to drug treatment.

Decision points in this pathway

• Complete heart block following an INFERIOR MI, blood pressure normal?

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