High RV threshold
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The Transmission shows all three signs of RV lead dysfunction
- Oversensing of non-physiological signals
- Threshold rise (no signs yet of intermittent loss of capture)
- Impedance changes (while value is still within normal range)
Oversensing of noise artifacts is often the first sign of lead failure. Short bursts of noise may trigger the recording of “Ventricular run” episodes in all pacemakers. Therefore it is important to check these episodes using remote monitoring even though the yield is very limited (<2%). In this case, there is not only noise on the ventricular lead but also on the atrial lead. Noise on the two channels at the same time indicate that there is a lead interaction, most probably proximal (outside of the heart, mostly in the pocket) with the one lead damaging the other and vice versa. As the noise is not high amplitude and there is no clipping, it may be confused with an external source of the noise. The fact that the patient was in rest without manipulation of electrical devices and that there are also the other signs of lead failure, the diagnosis of RV (and RA) lead dysfunction can be made.
When there is a suspicion of RV lead noise through remote monitoring. One of the first steps is to assess the risk for the patient. This patient is programmed in DDD mode and has 100% ventricular pacing, which may indicate that the patient is pacemaker dependent, making signs of RV lead failure a medical emergency. During the “Ventricular run” episode, the noise oversensing causes inhibition and we see no signs of intrinsic R-waves. This confirms the suspicion that the patient is pacemaker dependent and is at risk of syncope (due to pacemaker inhibition during longer periods of noise) or even cardiac arrest (when the RV lead stops capturing).
The patient needs to be contacted in order to enquire about possible triggers for lead noise (e.g. a fall or other types of trauma) and whether the patient has had any symptoms (syncope, lightheadedness, palpitations). The patient then should be told to come into hospital (without driving a car) for cardiac monitoring and to plan lead implantaiton. As the leads are a few years old, it can not be repositioned or easily extracted and a new one needs to be implanted. A contrast injection may be performed to verify that the venous system allows passage of new leads. In case of venous ubstruction, contralateral, epicardial or leadless pacemaker implantation may be required.
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You receive the following transmission from a patient implanted in 2006 for complete AV block. There is an alert for high RV pacing threshold.
Which signs of RV lead dysfunction do we observe? (multiple answers may be correct).CorrectIncorrect