Case Studies In Small Animal

Cardiovascular Medicine

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Case 35

ECGs

Because Dante's events were due to his AV nodal disease, it was decided to implant a pacemaker in him.

Prior to temporary pacemaker lead placement

Prior to anesthetic induction Dante was still having periods of high grade second degree AV block. However, once he was brought into the cardiac catheterization laboratory he was in a steady sinus rhythm with no evidence of an AV nodal conduction abnormality, as seen above. However, his heart rate was relatively slow at approximately 50 beats/minute. Consequently, it was decided to place the temporary pacing lead in his right atrium first and to pace his atrium at a faster rate to see if his AV nodal refractory period was normal.

 

During atrial pacing

As you can now see above, he has sharp spikes when the generator fires followed by a P wave and that only every other P wave is conducted through to produce a QRS complex (he has a 2:1 second degree AV block). This confirmed that his AV node had not somehow miraculously recovered. The temporary lead was then placed in his right ventricle, as seen below. A permanent pacemaker was then implanted. He was reexamined 1 month later and was doing very well.

 

During ventricular pacing (temporary lead)

Mark D. Kittleson, D.V.M., Ph.D. All rights reserved.