Emergency Room Visit:
An 83-year-old male presented to the emergency room in spring 2024 with complaints of palpitations, dizziness, fatigue, and mild chest pain. A Merlin on Demand remote device transmission was sent in from the ED, and a subsequent follow up in-person device check from a local device representative happened shortly after the transmission was received. The following EGM is the presenting rhythm freeze at the time of the Merlin on Demand transmission. The device is a dual chamber ICD with a system implant date of summer 2016.
What is your analysis of this EGM?
- Is there a P-wave?
- Is there a relationship between P waves and the QRS complex?
- What is the QRS morphology?
- What is the rate?
- What is the rhythm?
Answer:
When looking solely at the intracardiac and not a 12-lead, it is difficult to assess if p waves are present. In this EGM it looks like the p waves and R waves are right on top of each other, which could also be far R. This gives us the answer to the second question as unable to determine based on this EGM. The QRS morphology looks wide on the RV coil-can configuration, similar to a paced complex. The rate is ventricular at approximately 619ms/97bpm. This rhythm was determined to be a slow VT, or accelerated idioventricular rhythm as it is below 100bpm. It is sustained and meets the diagnostic criteria for VT (>/= 3 consecutive ventricular bpm, wide QRS, and AV dissociation).
The following image is the diagnositics summary. What do you notice?
Answer:
Notice the PVC burden of 38% along with the ventricular heart rate histogram showing a high percentage of V rates in the 90-100 bpm range.
Once it was confirmed that this was slow VT, the rounding Electrophysiologist decided to try non-invasive pacing stimulus (NIPS) through the device programmer to see if the rhythm would convert. The following screen capture was taken after the rhythm was converted with NIPS. Notice the patient is AP/VP at the programmed LRL of 50bpm. The patient was scheduled for a VT ablation.
Next Steps:
Once it was confirmed that this was slow VT, the rounding Electrophysiologist decided to try non-invasive pacing stimulus (NIPS) through the device programmer to see if the rhythm would convert. The following screen capture was taken after the rhythm was converted with NIPS. Notice the patient is AP/VP at the programmed LRL of 50bpm. The patient was scheduled for a VT ablation.
Why was the patient scheduled for a VT ablation when ATP converted the rhythm?
Answer:
The lowest tachy therapy zone that can be programmed in this particular device is 101bpm. The VT was approximately 97bpm which would not meet the detection criteria for therapy. The patient had a successful ablation and has had no reoccurrence of this arrhythmia.
Thank you to Gisselle Beltran Valdez from Abbott CRM for assistance with this case study.