Radiofrequency catheter ablation of right ventricular outflow tract tachycardia in a preschooler

Vagal Termination of Ventricular Tachycardia in a Pediatric Patient

Ventricular tachycardia is a rare clinical entity in pediatric patients and typically requires chemical and/or electrical intervention to convert into a sustained sinus rhythm. However, for certain forms originating from the right ventricular outflow tract, conversion with adenosine and vagal maneuvers has been demonstrated in adult patients. In this case, we suggest that pediatric patients with right ventricular outflow tract ventricular tachycardia who are hemodynamically stable may benefit from a trial of vagal maneuvers.

Catheter ablation for right ventricular outflow tract ventricular tachycardia induced by fever in a 7-year-old girl

We report a 7-year old girl with ventricular tachycardia exacerbated by fever. She experienced her first symptom of palpitations during an influenza infection, and electrocardiogram showed wide QRS tachycardia of a left bundle branch block inferior axis pattern. We performed an electrophysiological study (EPS) for diagnosis, but the wide QRS tachycardia could not be induced. The wide QRS tachycardia recurred during upper respiratory tract infection with fever and ceased with lidocaine administration. Wide QRS tachycardia is characteristic of ventricular tachycardia (VT) exacerbated by fever. VT was not able to be induced at a normal temperature on EPS; however, when her temperature exceeded 38 degrees C, VT was easily induced and was accompanied by decreased blood pressure. Radiofrequency catheter ablation was performed in the right ventricular outflow tract (RVOT) just under the pulmonic valve, with a fractionated potential 29 ms before onset of V1 QRS. VT was terminated approximately 4 s after RF application, and then VT could not be induced with or without high fever. This is the first report of successful ablation treatment in RVOT VT exacerbated by fever in a young child.

Right ventricular outflow tract tachycardia in children

OBJECTIVE

To assess the clinical spectrum of right ventricular outflow tract tachycardia and its management in children.

STUDY DESIGN

Five centers identified patients for retrospective review. Patients (age <18 years) demonstrating ventricular tachycardia with an inferior axis and left bundle branch block were included. Patients with structural heart disease, myocarditis, cardiomyopathy, or long QT syndrome were excluded. Demographics, clinical presentation, investigations, and treatment were analyzed. Holter data were used to quantify ectopy.

RESULTS

Patients (n = 48) were referred for evaluation of incidental findings (39/48), near syncope or syncope (7/48), or other (2/48). Investigations included magnetic resonance imaging (51%), endomyocardial biopsy (25%), and angiography (23%). Medical treatment was initiated in 26 of the 48 patients. The most common indications for treatment were frequent ectopy and symptoms. Medical treatment (P <.007) and observation alone (P <.02) were both associated with a reduction in ectopy. Symptoms persisted in 3 of 13 patients who were treated medically and in all untreated patients. At follow-up, there were no deaths and no difference in ectopy (P <.46) between patients who were treated medically and patients who were observed. Ablation was attempted in 6 of the 48 patients (successful in 4/6).

CONCLUSION

The clinical spectrum and management of right ventricular outflow tract tachycardia in children are diverse. Both medical therapy and observation alone were associated with a reduction in ectopy.

Radiofrequency catheter ablation of ventricular tachycardia in children and young adults with congenital heart disease

OBJECTIVES

The aim of this study was to expand data on outcomes for radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) in young patients and to identify obstacles to success.

BACKGROUND

Ablation of VT is performed infrequently in young patients. Published experience has been limited to case reports and small descriptive series.

METHODS

A retrospective review of 97 consecutive VT ablation procedures involving 62 patients at a single institution from 1990 to 2003 was undertaken. All intention-to-treat procedures were analyzed.

RESULTS

Mean age was 13.9 +/- 9.4 years. Procedures were categorized according to VT mechanism as follows: idiopathic right ventricle (n = 37); idiopathic left ventricle (n = 24); congenital heart disease (n = 20); or other structural disease (n = 16). Acute success was achieved in 58 (60%) of 97 procedures. Of the 39 failures, 33 were aborted cases due to inability to induce sufficient ectopy for mapping in 12, high-risk location near the His bundle or coronary artery in 11, unstable VT in 7, and anatomic obstacles in 3. Recurrence rate after acutely successful RFCA was 34% (20/58 procedures) at a mean follow-up of 3.8 +/- 2.0 years. Ultimately, long-term success was achieved in 38 (61%) of 62 patients after a mean of 1.6 +/- 0.9 procedures, with the highest success rate (87%) for idiopathic left ventricular tachycardia.

CONCLUSIONS

When analyzed on a strict intention-to-treat basis, a long-term success rate of 61% is observed with ablation of VT in young patients. Inability to induce stable VT for precision mapping and certain high-risk VT locations can be significant obstacles to success.

Pediatric Cardiac Electrophysiology

The rapid development of invasive cardiac electrophysi ologic procedures, including the insertion of rate-responsive pacemakers, radiofrequency catheter ablation (RFA), and the implantation of cardiac defibrillators has given pediatric cardiac electrophysiologists better techniques to treat in fants and children with arrhythmias. Expertise on the basic pathophysiologic mechanisms of arrhythmias is a requisite in performing invasive intracardiac electrophysiologic pro cedures. Techniques for invasive cardiac electrophysiologic procedures (EPS) in pediatric patients are similar to those for diagnostic cardiac catheterization. The choice of anes thesia is determined by institutional preference, patient's age, anticipated sites of intravascular access, and type of procedure. The goal is to avoid agents that depress myocar dial contractility or affect cardiac conduction or refractori ness. EPS equipment includes multielectrode catheters, a multichannel recording system, an electrical stimulator, and a fluoroscopy unit. EPS require the ability to induce, termi nate, and modify cardiac arrhythmias. The objectives of the EPS include definition of the mechanisms of observed and induced cardiac arrhythmias, determination of risk for sudden cardiac arrhythmic death, investigation of antiar rhythmic drug efficacy, and ablation of tachyarrhythmia sub strates. This is accomplished by evaluating electrophysi ologic properties, such as automaticity, conduction, and refractoriness; by initiating and terminating tachycardias; by mapping sequence of activation; and by evaluating patients for various forms of therapy and judging the response to therapy. Though generally quite low, the associated morbid ity and mortality in performing EP study and RFA in pediatric patients varies considerably, depending on the patient's age and size, diagnosis, associated cardiac defects, and prepro cedure condition.