ECG Case 065

Chest pain and diaphoresis. BP 80/50. Describe and interpret his ECG

TOP 100 ECG QUIZ LITFL 065

Describe and interpret this ECG

ECG ANSWER and INTERPRETATION

This is a repeat ECG of the previous patient, demonstrating:

This ECG pattern is diagnostic of a right coronary artery occlusion.


Rhythm Strip Explanation

RV-MI-2nd-degree-AV-block
  • Arrows indicate the position of P waves.
  • Black arrows indicate conducted P waves.
  • Red arrows indicate non-conducted P waves — some of these are concealed within the preceding T wave, causing a small bump at the back of the T wave.
  • Complexes cluster together in groups with either 2:1 conduction or as 3:2 Wenckebach cycles, with prolongation of the PR interval prior to the non-conducted P wave.
  • The number above each P wave denotes its position in the sequence.

CLINICAL PEARLS

Bradycardia and AV Block in Inferior STEMI

Up to 20% of patients with inferior STEMI will develop either second- or third degree heart block.

There are two presumed mechanisms for this:

  • The conduction block may develop either as a step-wise progression from 1st degree heart block via Wenckebach to complete heart block (in 50% of cases) or as abrupt onset of second or third-degree heart block (in the remaining 50%).
  • Patients may also manifest signs of sinus node dysfunction, such as sinus bradycardia, sinus pauses, sinoatrial exit block and sinus arrest. Similarly to AV node dysfunction, this may result from increased vagal tone or ischaemia of the SA node (the SA nodal artery is supplied by the RCA in 60% of people).
  • Bradyarrhythmias and AV block in the context of inferior STEMI are usually transient (lasting hours to days), respond well to atropine and do not require permanent pacing.

TOP 100 ECG SERIES


Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

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