This EKG comes courtesy of Paramedic Guttman!
67 y/o male with a history of MS c/o chest pain and weakness.
The following rhythm strips are obtained.
1. How would you describe this rhythm?
2. How would you manage this patient?
The rhythm strip begins with an escape rhythm (likely junctional) followed by a very long pause with complete AV block and no escape rhythm. It then converts back to a junctional escape rhythm.
The patient should be treated with pacing if they are symptomatic or if the escape rhythm does not return.
The rhythm begins with a wide complex rhythm at a rate of 60 with absent P waves.
Escape rhythms can be junctional or ventricular. Junctional rhythms are usually at a rate of 45-60. They usually have a narrow QRS complex unless the patient has an underlying bundle branch block. Ventricular escape rhythms are usually at a rate of 30-45 with a wide QRS complex. Our patient has an underlying bundle branch block. The initial rhythm likely represents a junctional escape rhythm.
After the first four beats there is a long pause. Pauses on EKG can be caused by: 1) non-conducted PAC’s (most common cause); 2) sinus node disease (Sinus arrest or SA block); 3) AV block.
In a non-conducted PAC, you will see a P wave that comes earlier than expected with no QRS complex following it. This happens because the PAC occurs so early that when it hits the AV node, it is still refractory. The P wave may come so early that it is buried in the preceding T wave just before the pause. Look back at the last T wave before the pause and see if it looks different than the other T waves on the strip. If it looks different, it might be because there is a P wave buried in that T wave. An example is below.
In sinus node disease, you will see a pause with no P waves. In sinus arrest, the SA node takes a little vacation and doesn’t fire. So there will be a pause with no P waves and the length of the pause will be random. In SA block, the SA node continues to fire but can’t depolarize the atrium. So, again there are absent P waves, however the length of the pause will be a multiple of the normal P-P length. Meaning, if you make believe a P wave happened during the pause at it’s expected location, the next P wave will come on time. An example is attached.
Finally, if the pause is due to AV block (2nd or 3rd degree), there will be P waves coming on time with no QRS complex following. Differentiate 2nd degree from 3rd degree and 2nd degree type I from type II the same way you would in any other AV block.
The following algorithm is useful in diagnosing pauses:
In our patient, there is a long pause. There are P waves present and they do not come earlier than expected. So, they are not PAC’s. Since there are P waves present during the pause, it is not sinus arrest or SA block. So, we are dealing with an AV block. In this case there are P waves only with no QRS complexes at all. So, there is no conduction to the ventricles at all so we are dealing with a 3rd degree AV block. Usually a 3rd degree AV block is accompanied by an escape rhythm. During this long pause, there is no escape rhythm that kicks in. Later on the strip (b), the junctional escape rhythm returns.
Patients with long pauses that are symptomatic or unstable should be treated with transcutaneous (pre-hospital) or transvenous (in-hospital) pacing.
Our patient had a cardiac cath which showed clean coronaries. He then had a permanent pacemaker placed.