Sunday, August 11, 2013

What does this tracing show? (contributed by K. Wang)

I don't have the clinical presentation, but the ECG is diagnostic on its own:

See question and answer below

What does this tracing show? Choose one from the list below.
   a) Hyperkalemia
   b) Hyperkalemia and hypocalcemia
   c) Hyperacute ischemic changes
   d) Normal varient

Answer: b) Hyperkalemia and hypocalcemia

Discussion: T waves are tall, tented and pointed, indicating hyperkalemia. That T waves are "pushed out" by a long ST segment especially noticeable in V5&6, characteristic of hypocalcemia, too. The serum K was 6.6 mEq and the serum Ca was 5.3 mg/dL in a patient with chronic renal failure, which is known to cause these combination of electrolyte problems. It is not hyperacute ischemic changes because the tall T waves are tented (the base of the T wave becomes narrow and pointed). There is some asymmetry of the T-waves, especially in V3 and Lead II, suggestive of normal variant, but the T-waves are far too "tented" and narrow-based for simple normal variant.  The differential Dx of tall T waves are well outlined in the book "Atlas of Electrocardiography" ( books), page 171.


  1. why would a K of 6.6 not present with longer PR segments or signs of QRS widening( these appear to be normal)? Does the hypocalcemia "hide" these other common hyperkalemia findings?

    1. K. Wang replies: The earliest ECG manifestation of hyperkalemia is tall, tented T waves. QRS widening is rather a late manifestation. K of 6.6 may not be high enough to cause QRS widenong. It will if it goes higher.
      K. Wang.

    2. Are not the tall T waves normally proportional to the tall QRSs in the same leads?

    3. K. Wang says: "Not necessarily. Sometimes yes, sometimes, no." I would agree with that.


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