Ablation of a wide complexAblation of a wide complex
tachycardia in a young adulttachycardia in a young adult
Salah Atta, MD
Lecturer of Cardiology
Department of Cardiology, Assiut
A 17 years old male from Kena, a student in
the 3rd year of secondary school presented
to us suffering from recurrent attacks of
rapid regular palpitation which was
associated with marked low cardiac output
On clinical examination:
The patient was clinically free.
Echocardiographic examination also
revealed no abnormality.
The baseline ECG of the patient was
sinus rythm of a rate of 70 B/min with
no evidence of pre-excitation.
ECG during the tachycardia:
Regular wide complex tachycardia of a rate of
150 B/min with the LBBB, LAD.
Standard 6 French quadripolar electrode
catheters were positioned in the high right
atrium and at the right ventricular apex
from the left femoral vein, respectively. A
third similar catheter was placed to record
the His-bundle activation. Coronary sinus
mapping was acheived by placing a 6
French 'USCI' octapolar catheter in the
coronary sinus through the left subclavian
By programmed stimulation the patient’s
clinical tachycardia was induced by atrial
pacing and the following intracardiac
electrograms were recorded.
An atrial flutter (Macrore-entry in the
right atrium with atrial rate: 300/min) with
two to one conduction to the ventricles
with LBBB aberration was evident.
Atrial flutter has an area of narrow
conduction located anatomically in the in
the subeustachian isthmus and bounded by
the inferior vena cava and eustachian ridge
posterioly and the tricuspid valve annulus
anteriorly, both of which form barriers
creating a protected zone in the re-entry
So the plan was to do linear ablation of
the Cavo-tricuspid isthmus.
starting at the ventricular side of the
cavotricuspid isthmus and extending
lesion by lesion to the Cavo-atrial
junction side of the isthmus,
Aiming to achieve bidirectional block
in the isthmus and thus cut the circuit and
prevent re-inducibility of the flutter.
Then a Halo catheter was introduced for
mapping, placed along the tricuspid annulus
for both mapping and pacing.
A 7 french catheter with a 4 mm tip
electrode Cordis D curve ablation catheter
with 2.5 mm interelectrode distance was
used for mapping/ radiofrequency ablation
of the Cavo-tricuspid isthmus in this patient
during pacing from the proximal coronary
sinus to detect the bidirectional conduction.
Eight radiofrequency applications were needed to
achieve bidirectional block as proved by pacing
from both the PCS and the distal Halo cathetr placed
at the low lateral atrial aspect of the anulus and both
showed only unidirectional pattern of conduction
(birectional block in the isthmus). There-after the
tachycardia was no more inducible.