EKG Rhythm Strips 22: Paced Rhythms

Identify the following paced rhythms:

1.

2.
3.

4.




5.






Answers
1.
Demand Atrial Paced
Demand Atrial Paced.   There are no pacemaker spikes on the second and fourth complexes.  The P waves are the patient's own native P waves.  But on the other complexes a pacer spike preceeds each of the P waves.   It is not possible to determine the exact kind of internal pacemaker a patient has based on the rhythm.   This could be an example of an AAI pacemaker in which the atria are paced.  But when the pacemaker senses a native P wave it is inhibited from producing a paced beat.   



2.
Biventricular Paced










Biventricular Paced.   Two pacemaker spikes precede the QRS complex.   One pacemaker spike for each ventricle.  A PVC is also present. 

3.
Demand AV Paced







Demand AV Paced.   On the 1st and 7th complexes there are very small atrial spikes present.  On all the other complexes there are native P waves present with a very long 1st degree block. 
what is the underlying PR interval?  The ventricles are 100% paced.  Probably a DDD pacemaker. 

4.
Ventricular Paced











Ventricular Paced.   There are pacemaker spikes before each QRS complex.  The patient's underlying rhythm is atrial fibrillation.  This could be a VVI pacemaker in which the ventricles are paced but when the pacemaker senses a natural QRS complex it inhibits a paced beat. 

5.
External Paced






External Paced.   The ventricles are being externally paced.  The pacemaker markers at the bottom of the stripe identify the pacing stimulus.   On paced rhythms the QRS complex will be much wider than native QRS complex.  The inital deflection will be negative while the terminal deflection will have an opposite polarity and have ST segment elevation.  What is the pacing rate in this strip?   How do you access for mechanical capture?


Reviewed 3/1/16

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