P485Successful epicardial ablation of ventricular tachycardia electric storm in an 8 years-old boy with idiopathic left ventricle aneurysm - CASE REPORT

Abstract

This 8 year-old boy had no personal or family history of cardiac disease, he suddenly complained of chest pain and palpitations, then fell unconscious and pulseless. CPR was immediately started before emergency rescue squad intervention which identified pulseless VT (220 bpm). Sinus rhythm was restored after 2 external defibrillator shocks and amiodarone bolus infusion. Transthoracic echocardiography showed dilated left ventricle mildly hypokinetic with an ejection fraction of 40% and marked hypokinesia of the inferior and lateral segments. No myocardial hypertrophy was observed. Coronary arteries were in normal position. On the following days, sustained monomorphic VT arising from the apico-lateral segment of the left ventricle (LV) was incessant despite general anesthesia, hypothermia and antiarrhythmic drug such as amiodarone alone or in association. Slightly slowed down or interrupted by external defibrillator shocks, the VT was not compromising the hemodynamic, extra corporal membrane oxygenation was not required before practicing catheter ablation. Aortic retrograde approach was the initial chosen strategy. Several EKG and EGM criteria were corresponding with an epicardial exit or substrate with the earliest endocardial activation (-70ms) located at the apico-lateral wall of the LV. VT was interrupted only by long duration high power (40 to 50 W) 4 mm irrigated RF application but easily re-induced by programmed ventricular stimulation at a slower rate (170 bpm), demonstrating the failure of this endocardial approach. A sub-xyphoidian pericardial percutaneous puncture was then performed providing a left lateral approach through a Biosense Mobicath steerable sheath. Epicardial mapping demonstrated a large area (20 cm2) of late abnormal ventricular activation (LAVA) opposite of the endocardial ablation site. The LAVA area was isolated by 30 Watts RF application until the tachycardia was not inducible any more. Prior to RF application, left coronary artery angiography coupled to the 3D navigation system (Carto Univu) allowed to preclude coronary injury. Ablation ended up with no VT inducible. Cardiac Magnetic resonance imaging (MRI) clearly depicted an aneurysm as an area of circumscript wall thinning showing regional dyskinesia. Because of non-reversible lesion of the left ventricle, Implantable Cardioverter Defibrillator (ICD) was implanted epicardially in secondary prevention. Conclusion: Left ventricle aneurysm (LVA) is a rare condition. It can be acquired or congenital and it's sometimes diagnosed prenatally. In the pediatric population acquired LVA can be seen after myocardial ischemia mostly due to Kawasaki disease. Life-threatening arrhythmia and sudden death can be its first manifestation. By definition LVA is a transmural lesion. Endocardial ablation can be ineffective. This case report demonstrated the interest of epicardial ablation in this condition and it emphasized its feasibility in very young patient by experimented team.