CardioNerds ECG Challenge #6

  • Post author:


46 yo M is 2 days S/P minimally-invasive mitral valve repair.

Why is he complaining of intermittent neck discomfort❓


Intermittent cannon A waves account for the intermittent neck discomfort.

Learning Points:

  1. The atrial rhythm is sinus at 81/min.​
  2. The QRS complexes are accelerated junctional at 79/min, a common arrhythmia following heart surgery.​
  3. There is A-V dissociation.​
  4. When the PR interval is particularly short or the P wave follows the QRS (not seen in this tracing) the atria contract coincident with, or after the closure of the atrioventricular valves.  The resultant retrograde atrial propulsion of blood into the valveless SVC causes a pronounced pulsation in the neck veins, called a cannon A wave, that he sensed as neck discomfort.  These cannon A waves come in volleys and then disappear, only to return, until the A-V rhythm associates.​
  5. Although acute pericarditis is present and can cause discomfort, this is not intermittent neck discomfort.

Show Answer

Powered by EKGaction: EKGaction is much more than the usual textbook of EKG and is different from other online programs.  It teaches/reinforces EKG interpretation skills using a method that integrates clinical pearls that makes it easier to commit to memory.  These pearls accompany every case and are called Learning Points and Collateral Tracings.  The multiple indexes make it useful as a reference. It has been perfected over 15 years, teaching at leading cardiology fellowship programs.  It has been shown to improve performance on board exams and it’s fun to use!

Learn more at
CardioNerds ECG Challenge #6