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" (amazon.com books), page 171.

4 comments:

  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?

    ReplyDelete
    Replies
    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.

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

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

      Delete

Recommended Resources