CardiovascularPending review

Bradyarrhythmias and Heart Block

Failure or delay of impulse generation or conduction anywhere from the sinus node to the ventricles slows or interrupts the heart's electrical cascade, so the exact pattern of block on the ECG predicts how much of the atrial rhythm still reaches the ventricles, and therefore how dangerous it is.

In a nutshell

Bradyarrhythmias arise from failure of impulse generation or conduction anywhere from the sinus node to the ventricles. The degree of AV block on the ECG predicts both how much atrial activity reaches the ventricles and how reliable any escape rhythm will be, which is why Mobitz II and complete heart block are managed far more urgently than first-degree block.

Classic presentation

An older patient presents with dizziness or sudden syncope without warning, found to have a slow pulse and complete AV dissociation on ECG.

Key points

First-degree block and Mobitz I are usually benign; Mobitz II and complete heart block carry a real risk of progression to asystole.

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Educational content pending clinical review. Not medical advice.