Incessant ventricular tachycardia due to spontaneous automaticity in the Purkinje network inducing reversible left ventricular dysfunction

Cardiomyopathy induced by incessant ventricular tachycardia originating in the vicinity of the His bundle

A 04-year-old boy was referred to our institution with severe, progressive heart failure of 4-months duration associated with a persistent wide QRS tachycardia with left bundle branch block and severe left ventricular dysfunction. Because of incessant wide QRS tachycardia refractory to antiarrhythmic drugs, he was referred for electrophysiological study. The ECG was suggestive of VT arising from the right ventricle near the His area. Electrophysiological study revealed that origin of tachycardia was septum of the right ventricle, near His bundle, however the procedure was not successful and an inadvertent complete atrioventricular conduction block occurred. The same ventricular tachycardia recurred. A second procedure was performed with a retrograd aortic approach to map the left side of the interventricular septum. The earliest endocardial site for ablation was localized in the anterobasal region of left ventricle near His bundle. In this location, one radiofrequency pulse interrupted VT and rendered it not inducible. The echocardiographic evaluation showed partial reversal of left ventricular function in the first 3 months. The diagnosis was idiopathic parahisian left ventricular tachycardia leading to a tachycardia mediated cardiomyopathy, an extremely rare clinical picture in children.

Successful ablation of incessant idiopathic right ventricular tachycardia arising from unusual sites in children

OBJECTIVE

Most idiopathic right ventricular tachycardias originate from the outflow tract. We present a case series of idiopathic incessant ventricular tachycardia arising from unusual sites of the right ventricle in children, which were well resolved by catheter ablation.

METHODS

A retrospective review was performed of all three patients who underwent ablation of idiopathic ventricular tachycardia below the level of the right ventricular outflow tract using three-dimensional mapping in our institute. Result All three patients presented with tachycardia-induced cardiomyopathy due to incessant ventricular tachycardia on first admission. The sites of successful ablation were at the proximal right bundle branch, distal right bundle branch, and apex of the right ventricle, respectively. No complications occurred, and there has been no recurrence of ventricular tachycardia after the final ablation at an average follow-up period of 9 months. All three patients have achieved normalisation of left ventricular size and systolic function.

CONCLUSION

Incessant idiopathic ventricular tachycardia originating from unusual sites of the right ventricle in children, resulting in significant symptoms and impaired ventricular function, can be successfully treated with catheter ablation.

Idiopathic accelerated idioventricular rhythm or ventricular tachycardia originating from the right bundle branch: unusual type of ventricular arrhythmia

BACKGROUND

Accelerated idioventricular rhythm (AIVR) or ventricular tachycardia (VT) originating from the right bundle branch (RBB) is rare and published clinical data on such arrhythmia are scarce. In this study, we will describe the clinical manifestations, diagnosis, and management of a cohort of patients with this novel arrhythmia.

METHODS AND RESULTS

Eight patients (5 men; median age, 25 years) with RBB-AIVR/VT were consecutively enrolled in the study. Pharmacological testing, exercise treadmill testing, electrophysiological study, and catheter ablation were performed in the study patients, and ECG features were characterized. All RBB-AIVR/VTs were of typical left bundle-branch block morphology with atrioventricular dissociation. The arrhythmias, which demonstrated chronotropic variability, were often isorhythmic with sinus rhythm and were accelerated by physical exercise, stress, and intravenous isoprenaline infusion. The rate of RBB-AIVR/VT varied from 45 to 200 beats per minute. Two patients experienced syncope, and 3 had impaired left ventricular function. Metoprolol was proven to be the most effective drug to decelerate the arrhythmia rate and relieve symptoms. Electrophysiology study was performed in 5 patients and the earliest activation with a sharp RBB potential was localized in the mid or distal RBB area. Catheter ablation terminated the arrhythmia with subsequent RBB block morphology during sinus rhythm. During follow-up, patients' symptoms were controlled with normalization of left ventricular function either on metoprolol or by catheter ablation.

CONCLUSIONS

RBB-AIVR/VT is an unusual type of ventricular arrhythmia. It can result in significant symptoms and depressed ventricular function and can be successfully treated with catheter ablation.