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Journal of Atrial Fibrillation – Journal of Atrial Fibrillation & Electrophysiology (JAFIB-EP)
Allied Professionals Blog
Kimberly D. O’Donogue
CRM Educator and Instructor and Content Creator
Academy of Medical Education. Arizona, USA
- 30 October 2023
Atrial Lead Diagnostic
Questions : What is happening in this EGM?
This patient presented to device clinic for a routine follow up interrogation. The patient’s AP% was 1.5%, BP 89%, and PVC count 8.9%. The patient stated “periodically feeling “jolts” that are uncomfortable. The following EGM is the presenting rhythm freeze.
Answer:
Some atrial under sensing is observed (circled in red). The P waves that are not being sensed are followed by a native R wave that is therefore being counted as a PVC. The P wave measurement was < 0.2mV, and the atrial impedance was within range and stable.
The threshold testing was causing visible stim, and the patient was uncomfortable. It was determined that the atrial lead was dislodged, and the patient was sent for a revision. Notice the surface electrogram compared to the atrial bipolar channel. The intracardiac signals are great, but surface never lies!
- 25 September 2023
PMT
Questions : What is happening in this EGM?
Answer:
This is an example of a PMT episode that is successfully terminated with the algorithm AP on PMT (Abbott). The PMT detection rate is 120bpm.
The device detected eight consecutive VP-AS intervals with a rate higher than the PMT detection rate (appx. 120), the device then calculated the stability of the eight VP-AS intervals.
The device averages eight VP-AS intervals and compares that average to each of the individual intervals.
In this example, all VP-AS intervals are within 16 ms of the average, therefore considered stable. When the VP-AS are considered stable, the device modifies the AV delay for the ninth interval to confirm the diagnosis of PMT. If one of the eight intervals varied by >16 ms from the average, the VP-AS intervals are considered unstable and the next eight beats are monitored.
The sensed AV delay is shortened by 50 ms if the programmed Sensed AV (AS-VP) interval is ≥100 ms.
The sensed AV delay is lengthened by 50 ms if the programmed Sensed AV (AS-VP) interval is <100 ms.
The next VP-AS interval is then analyzed. If the VP-AS is unchanged, the P-wave is considered retrograde with suspicion of PMT, (as shown in this example)
If the e next VP-AS was different than >16ms, the P wave is not considered retrograde (no PMT). The algorithm may be repeated after 256 beats.
PMT was suspected, therefore the next ventricular pulse (10th cycle) is inhibited.
An atrial pulse is delivered 330 ms after the detected retrograde P wave.
The atrial pulse is followed by ventricular pacing at the end of the AV delay if needed.
The atrial pulse is inhibited if a P wave is sensed (AS) within a 210 ms alert period following the absolute atrial refractory period.
The AP on PMT treatment algorithm was successful, and normal AP with conduction followed.
- 9 October 2023
Sorin Device Troubleshooting
Questions :
The following EGMs are from a routine Sorin dual chamber pacemaker interrogation. Both EGMs were stored as “V Bursts”.
What is your analysis? The patient has complete heart block. Sensing, threshold, and impedance measurements were all stable.
AP 3%, VP >99%
Answer:
The first recorded episode contains NSVT with appropriate sensing.
The second recording shows noise on both the atrial lead and ventricular lead happening concurrently. The noise on the RV lead is causing ventricular pacing inhibition with two approximately 2 second pauses.
Noise was not reproducible with isometrics or pocket manipulation. There was no prior evidence of lead noise. RV sensitivity was decreased from 1.8mV to 3.0mV to avoid oversensing/pacing inhibition on the RV lead due to the patient being dependent. Asynchronous programming was not considered at this time to maintain AV synchrony given the patient has intact sinus node function, but also to be able to detect future VT episodes.
- 23 October 2023
Underlying Rhythm
Questions : What is happening in this EGM?
Answer:
This is an underlying rhythm freeze for an Abbott dual chamber pacemaker. What is the underlying rhythm? Mobitz II block. Notice the sinus(atrial) rate is approximately 90bpm and the ventricular rate is approximately half that at 48bpm.
