An Uncommon Case of Incessant Tachycardiainduced Cardiomyopathy in a Child

Abstract

An AXIOM Sensis XP system (Siemens AG, Munich, Germany) was also used during the procedure.Narrow complex tachycardia with a cycle length (CL) of 360 ms was ongoing. The earliest atrial activations were recorded in the left posterolateral wall (ie, at 4 o'clock according to the clinical standard nomenclature by Cosio) with the shortest ventriculoatrial (VA) interval equal to 104 ms. Few sinus complexes were recorded with concentric ventricular activation (Figure 2A). The atrium to His (AH) and His to ventricle intervals were 94 ms and 50 ms, respectively ( Figure 2B). The post-pacing interval was 492 ms with a ventricle-atrium-ventricle (VAV) response during overdrive pacing and entrainment of tachycardia from the right ventricle ( Figure 2C). Ventricular pacing within 40 ms of the His potential advanced the atrium and the atrial activation sequence to the same as that seen during tachycardia ( Figure 2D). The ventricular pacing given earlier terminated the tachycardia without advancing to the atrium ( Figure 2E). The VA interval was not decremental, although the tachycardia CL fluctuated from 310 ms to 360 ms. Because of the incessant tachycardia, we could not pace the atrium in sinus rhythm; however, the short attempts showed that the AH intervals during the sinus complexes and the atrial pacing in tachycardia CL were similar. Orthodromic atrioventricular reentrant tachycardia (AVRT) with concealed slow conductive accessory pathway (AP) was diagnosed. Case presentationA nine-year-old girl was admitted to our clinic having presented with palpitation, dyspnea, and heart failure (New York Heart Association functional classification class II). A 12-lead resting electrocardiogram (ECG) revealed regular narrow complex tachycardia (Figure 1). Echocardiography revealed reduced left ventricular systolic function (ejection fraction was 35%) and normal biatrial diameter. Tachycardia was incessant, lasting more than 50% of monitoring time prior to drug administration. Intravenous adenosine and b-blocker medication were ineffective. The patient was referred for electrophysiology (EP) study and catheter ablation. The procedure was performed with the patient under sedation with intubation. A steerable decapolar catheter (Abbott Laboratories, Chicago, IL, USA) was inserted into the coronary sinus via the subclavian vein, a quadripolar catheter (Abbott Laboratories, Chicago, IL, USA) was positioned in the right ventricle, and an ablation catheter (Marinr ® MC; Medtronic, Minneapolis, MN, USA) was placed in the His position via the right femoral vein during the EP study.ABSTRACT. The case of a pediatric patient with a history of incessant narrow complex tachycardia is presented. The patient underwent successful catheter ablation for an uncommon concealed slow accessory pathway. The mechanism and ablation location are discussed.