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Ablation of a wide complex Ablation of a wide complex tachycardia in a young adulttachycardia in a young adult

Salah Atta, MD

Lecturer of Cardiology

Department of Cardiology, Assiut University Hospitals

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 manifestations.

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.

EPS procedure: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 vein.

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 circuit.

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.

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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.

Thank you