 Comments recieved from the Web
Comments on the tracings:
The patient has a ventricular pacemaker that is a VVI.0 (non-programmable)
It is interesting that this pacer is still implanted after 13 years.
The rhythm in the first strip appears to be supraventricular tachycardia
at a rate of about 140/min.
The pacer is appropriately sensing the SVT and only begins to pace when
the magnet is placed over the pacer.
Note the imprinted rate in the upper right hand corner which is the measurement
made by the pacemaker transmitter/receiver system. The system also gives
the pulse width of pacer spike but in this case it was not recorded on the
strip we printed. This pulse width information is important thought as pulse
width widening in this pacer is a secondary end point to indicate the elective
replacement point for this pacer.
It is interesting that the SVT terminates during the application of the
pacer magnet.
This suggests that the ventricle is part of the reentrant circuit or that
retrograde conduction to the atrium has terminated the arrhythmia.
There is no sign of atrial activity and the rate of 140/min. seems slow
for atrial flutter with 2:1 block.
Flutter is often detected by a saw toothed appearance
of the baseline.
The choices would seem to be an SVT that terminated by chance when the magnet
was applied, or that the magnet actually terminated the arrhythmia. This
is similar to the case of more rapid ventricular pacing
to terminate a nodal tachycardia.
This could be an example of under drive pace termination of an arrhythmia.
This technique is not very effective but can terminate some of the slower
reentrant arrhythmias.
It is possible that this patient has either AVNRT or A/V reentry with slow
AV nodal conduction to explain the slow rate of the tachycardia and the
termination with ventricular pacing.
Dr. Michael Rosengarten |
