Ablation of tachyarrhythmias in pediatric patients

The "hidden" concealed left-sided accessory pathway: An uncommon cause of SVT in young people

BACKGROUND

Concealed left-sided accessory pathways (CLAP) are a cause of supraventricular tachycardia (SVT) in the young. Most are mapped with right ventricular (RV) apical/outflow pacing. Rarely, alternative means of mapping are required. We review our experience from three pediatric electrophysiology (EP) centers with a rare form of "hidden" CLAP.

METHODS

All patients <21 years undergoing EP study from 2008 to 2014 with a "hidden" CLAP (defined as an accessory pathway [AP] for which RV pacing at cycle lengths [CL] stable for mapping did not demonstrate eccentric retrograde conduction) were included.

EXCLUSION CRITERIA

preexcitation. Demographic, procedural, and follow-up data were collected.

RESULTS

A total of 23 patients met the criteria (median age, 14.3 years [range 7-21], weight, 51 kg [31-99]). 21 (96%) had SVT and one AFIB (4%). APs were adenosine sensitive in 7/20 patients (35%) and VA conduction was decremental in six (26%). CLAP conduction was demonstrable with orthodromic reentrant tachycardia in all patients, with RV extrastimulus testing in seven (30%) and with rapid RV pacing (<CL 300) in three (13%). Left ventricular (LV) pacing demonstrated CLAP conduction in 17/17 (100%) patients in whom it was used. All 23 CLAPs were successfully ablated (100%) via transseptal approach with radiofrequency energy. Specific ablation techniques included: 16 (70%) during LV paced rhythm, four (17%) during orthodromic reciprocating tachycardia (ORT; 3/4 ventricular entrained), and three (13%) with brief rapid RV pacing. There were no complications. At 18 months (range 3-96), there was one recurrence (4%).

CONCLUSIONS

Some CLAPs are only demonstrable with LV pacing, entrained ORT, or rapid RV pacing. LV pacing facilitated preferential AP conduction, allowing for mapping while maintaining stable hemodynamics.

Reducing patient radiation dosage during pediatric SVT ablations using an "ALARA" radiation reduction protocol in the modern fluoroscopic era

BACKGROUND

Ablation for supraventricular tachycardia (SVT) relies upon fluoroscopy (fluoro), which exposes the patient and staff to ionizing radiation. The objective of this work was to present a new "ALARA--As Low As Reasonably Achievable" protocol with alterations to fluoroscopic x-ray parameters to reduce dose without an electroanatomical (EAM) approach.

METHODS

All patients <21 years of age undergoing ablation of SVT at our institution from June 2011 to April 2012 were included. EAM was not utilized in any case. An ALARA protocol of low frame rates (2 or 3 fps), low fluoro dose/frame (10-18 nGy/frame), and other techniques aimed at reducing use of fluoroscopy were employed. Demographics, procedural, and radiation data were analyzed.

RESULTS

Forty-two patients underwent ablation and were studied. Median age was 14.1 years (range 4.8-21.1 years), weight was 51 kg (range 18.2-75 kg), and body surface area was 1.51 m(2) (range 0.72- 1.94 m(2)). Seventeen (41%) had Wolff-Parkinson-White syndrome, 14 (33%) atrioventricular nodal reentrant tachycardia, and 11 (26%) concealed pathways. Median procedural time was 114 minutes (57-246 minutes). Median dose area product (DAP) for posterioanterior and lateral fluoroscopy was 343.2 uGym(2) (range 38.2-3,172 uGym(2)); the median air Kerma product (K) was 45.4 mGy (range 6.7-567.5 mGy). DAP and K are lower than prior data from EAM and fluoroscopy techniques. The acute success rate was 95%; no procedural complications.

CONCLUSIONS

An ALARA protocol for ablation of SVT reduced radiation to below levels previously reported for combined EAM/fluoro approaches. Success rates were excellent with no complications and without the costs of EAM.

Management of intra-atrial reentrant tachycardia

PURPOSE OF REVIEW

Intraatrial reentrant tachycardia (IART), a difficult arrhythmia to manage, is likely to become more prevalent as the population of patients with congenital heart disease grows. While pharmacologic therapy alone often remains inadequate, important advances in nonpharmacologic therapy have occurred recently, enhancing the currently available therapeutic options. This review focuses on advances in electroanatomic mapping and catheter ablation, developments in arrhythmia surgery, and device therapy for IART.

RECENT FINDINGS

While catheter ablation for IART has high early recurrence rates, the lack of late recurrence in long-term follow-up is encouraging. Acute success may be improved with greater appreciation for reentrant circuits with current electroanatomic mapping systems, and with larger lesions that can be achieved with the use of irrigated-tip catheters. Arrhythmia surgery at the time of Fontan revision has good short-term and medium-term results, and is being studied as a prophylactic measure at initial Fontan surgery. Device therapy for IART now includes algorithms to prevent atrial arrhythmias, as well as antitachycardia pacing, which can be used safely and has very high efficacy for certain subgroups.

SUMMARY

Due to recent advances in mapping and ablation technology, coupled with developments in arrhythmia surgery and device therapy, the armamentarium of nonpharmacologic management of IART has become more potent. There are still, however, unique challenges posed by patients with congenital heart disease, and long-term follow-up in large numbers of patients with IART are required for this expanding population of patients.