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Accessories Pathway/ WPW
Image of the heart with an accessory pathway that bypasses
electric activity through the AV node (top). An ECG is also shown
with a delta wave between the P wave and R wave that results from
electric activity through the bypass tract.
Some people with an accessory pathway have a normal ECG at
baseline because the accessory pathway is electrically active only
when there is a fast, racing heartbeat (tachycardia) described
below. Therefore, some people with accessory pathways can have
completely normal ECGs. That is referred to as a concealed
accessory pathway.
Placemant of ECG electrodes is esencial for every
Electrophysiology case. ECG elestrodes should be placed on
anatomicly desired positions, where big muscles and bones with
minimum underskin tissue should be avoided. In first case muscle
tremor can be recorded and in second case small amplitude on the
recording signal will also compromise recording quality and make
appropriate diagnosis difficult. Those are examples of bad ECG
placing:
Pacement of the 12 lead ECG electrodes over the bones or
unprepared very dry skin will produce poor recording quality of
surface ECG:
Placemant of 12 lead ECG electrodes directly over the big group
of muscle like sholders or quadriceps, will result in unclear base
line:
Case #1
In our first case, we can observe sign of delta wave on surface
ECG.
We can also observe prolongation of QRS complex 120 ms (normal
60-100ms) and shrinkage of H-V interval to only 28 ms (normal 35-60
ms)
On all 12 ECG leads, delta waves are clearly visible during the
regular sinus rhythm, HR 60 beats per minute.
In this case, we compare two most common algorithms, and choose
to go with Arruda as better mach to presenting findings.
This algorithm uses polarity of initial delta wave Positive +,
negative - , or isoelectric +/-
Lead I delta +/- or or V1 R/S >1 Yes or No
Lead II delta Yes or No
Lead V1 delta +/- or Yes or No
Acessory pathway location is septal tricuspid annulus or
posterior septal (where the blue errow is pointing)
Pacing from HRA catheter, big delta wave it is cearly
displayed
on surface of the ECG
Replacing HRA catheter for ablation 4mm Blazer catheter, we
start mapping by looking at relations of A -V signal on distal
electrodes of ablation catheter. Placement of catheter is on
posterior septal position, which is not target position.
Artial and ventricular signals are still far apart.
Moving ablation catheter more towards anterior septal side of
right artrium, we come to much better, tighter relation of atrial
and ventricular signal on distal electrode of abltion catheter.
Success is visible on ECG tracing with only 3.3 seconds after first
lesion application (red arrows).
Aftter application of only one 60 seconds lesion (RF energy of
50 Watt's, 52 Celsius), we haad success, with no sign of previus
arrhythmia after waiting period of 45 minutes.
On this slide, on both views, we can see (LAO & RAO)
relation of His bundle represented as green biger ball. Smaler
white ball is reference where we observe first good relations in
almost fused atrial and ventricular signal on maping catheter.
Bigger red ball is our lesion sight, where relation of A-V signal
become even better.
Burst pacing from distal coronary sinus catheter electrodes
shows no sign of accessory pathway patern.
Case # 2
In this case, there is no sign of delta way. Presented surface ECG
is very normal.
There is nothing that can suggest that this patient has
accessory pathway.
On his 12 lead ECG we can observe clear sinus rhythm.
This is a moment when the placemant of His catheter initiate
patient's arrhythmia.
Decramental pacing from proximal electrodes on CS catheter
iniciate tachycardia. It is indicative that distal electrode of CS
catheter show that atrial and ventrcular recordings are almost
fused.
Coronary sinus catheter was avanced deeper in CS and total A and
V signals fusion on distal electrode was obtained. Our next step
was replacing 6F octapolar catheter for 4 F decapolar catheter for
better CS signals recording.
Burst pacing from RV catheter terminated arhythmia.
So far everything sugesting that our accessory pathway is on the
left side of the heart. During tachycardia on 12 lead ECG, pattern
of the left bundle branch block is demonstrated. We also used
D'Avila algorithm witch sugested the position of accessory pathway
on the left atrium on anterior/septal wall. After passing atrial
septum with ablation catheter, we start recording interesting
signal right away after pointed to the rigeon of interest.
After fast colecting just dozen points and partial geometry of
the left atrium, we turn our point of ineters towards location
marked from electrode 4 on CS catheter, where we observe fusion of
A and V signal.
This position was chosen as earliest point by mapping system and
as we can see that recording system gave us the same information.
Relation of the A and V signal on maping distal electrode is
great.
Only 4 seconds of RF applications was enought to isolate this
accessories pathway.The orange arrow shows that A and V sinals are
still fused and the red arrow demonstrates clear separation between
of those two signals wich occured in a split second. The same can
also be seen on CS cath. Signals on electrode 3-4 blue arrow
pointed on the still fused signals and next beat, grey arrow,
pointing on separated A and V signals. RF generator was set 35W 40C
30S.
Ablation catheter was with irrigated tip.
On this LAO view it is visible that 6 of the RF applications
were neccesary to complitley eliminated this accessories pathway.
After last leason, arrhythmia was not induceble and it stay the
same after 45 minutes of waiting period.
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