ACLS Revision: Subtle ECG findings in ACS


  • ST-segment elevation in lead aVR portends a worse prognosis in ACS and often predicts the need for CABG.
  • Hyperacute T-waves are not necessarily tall, and small T-waves can still be hyperacute when paired with a low-amplitude QRS complex.
  • The tall T-waves associated with hyperkalemia are sharp, pointy, symmetric, and have a narrow base.
  • When in doubt, get serial ECGs (every 15 minutes) and use adjunctive information.


Where else is there evidence of STEMI?

Inferior STEMI

There is obvious inferior ST elevation, with reciprocal ST Depression in aVL (inferior STEMI). There is also ST Depression in lead I.  This is good evidence that the inferior STEMI is caused by an RCA occlusion. There is ST depression maximal in lead V2.  Thus, there is a posterior STEMI. There is also ST depression in V5 and V6.

Where else is there evidence of STEMI?


ECG Changes of Hyperkalaemia


Classic teaching of the chronological ECG changes of hyperkalemia include:

  1. Peaked T waves
  2. Prolongation of PR interval
  3. Widening QRS Complex
  4. Loss of P wave
  5. “Sine Wave”
  6. Asystole

The order of ECG changes of hyperkalemia have been defined in the experimental setting, but no uniform order has been documented in animal models (Ettinger, Regan, and Oldewurtel 1974)*. The relationship between serum potassium and cardiac manifestations is even less clear in the clinical setting (Acker et al. 1998)*.

ACLS REVISION: Ever wondered about Torsades de Pointes?

Learning Points:

  • Torsades de Pointes (TdP) is a form of polymorphic ventricular tachycardia associated with a prolonged QT.
  • Although we were unable to ascertain a previous history of long QT syndrome or establish a reason for the current prolonged QT, its presence increased the likelihood of a lethal dysrhythmia.
  • Magnesium sulfate has been use for suppression of TdP, although unsynchronized