EKG – 3 – Complete Heart Block

A woman presents to Mirebalais with shortness of breath and generalized weakness.  On presentation, patient is dyspneic with bilateral crackles and lower extremity edema.

Vitals per triage sheet:  BP 151/118, FC 155, FR 48, O2 sat 98% on nonrebreather mask, Temp 35.8C

I have also attached a short video of her monitored rhythm.

WHAT DOES HER EKG SHOW? And what is usual about her monitored rhythm and vitals obtained at triage?

ANSWER: This is another example of a THIRD DEGREE or COMPLETE HEART BLOCK

AXIS:  Normal axis  (I+, II+, III+)
RATE: around 40bpm
RHYTHM:  regular with p-waves without dropped QRS complexes
Interval:  QRS narrow around .1s (2.5 small boxes)
SIZE:  unremarkable
ST SEGMENTs: unremarkable

Like the EKG from 2 weeks ago, this EKG shows complete “dissociation,” or no communication between the atrial and ventricles.  Again, since there are p waves without QRS waves, this must be a second degree or third degree block.  WHENEVER YOU SEE P WAVES WITHOUT QRS, IT MUST BE A 2ND OR 3RD DEGREE BLOCK.   Because the PR intervals ARE NOT always the same, this cannot be a mobitz type II block (type 2 second degree block) which will always have the same PR intervals when present.  Could this be a mobitz type I in which the PR interval gradually lengths until a QRS complex is dropped?  NO!  In this EKG, there is no pattern to QRS intervals, and again, if you look closely, you can see that the p waves are going independently without relation to the QRS.

Whenever you see a patient that is bradycardic in the high 30s and lower 40s, remember to consider a heart block, and especially a complete heart block, as that is the rate at which the ventricles will beat if not guided by the atria.  Remember, every heart cell has the ability to be a pacemaker, it’s just fastest one that takes the lead!

Interestingly in this case, the QRS is narrow, suggesting that this is a complete heart block with a junctional escape rhythm.

If the patient is bradycardic, why did the triage sheet show a heart rate in the 150s and why is the monitor reading a heart rate bouncing between the 80s – 110s?  If you look closely at the video you can see the p waves on the monitor.  On the monitor they appear peaked and likely are being counted as QRS complexes, therefore giving a false heart rate reading.  Likely the triage nurse saw a heart rate of 155 on the monitor and wrote that on the triage sheet.  This demonstrates the importance of analyzing the monitored rhythm, not just looking at the number displayed.  If we had just looked at the number and not analyzed the rhythm (or not placed the patient on a monitor!) and if we had not obtained an EKG (which should always be obtained in a patient presenting with shortness of breath), we could easily have missed that she was bradycardic and actually thought she was tachycardic.

How was this patient treated?  Caring for such a patient given the available resources is very difficult.  While her blood pressure was not low, she was too weak and unstable to be transported to a hospital where she could receive a pacemaker even if such a place was available.  Had she become unstable due to her low heart rate, currently in Mirebalais we do not have the ability to transcutaneously pace her, which would be the preferred temporary treatment until she could be transported to a hospital where a pacemaker could be placed.  Instead the patient was placed on BIPAP and given furosemide with some improvement and was admitted to the internal medicine service.



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