An infant phantom for pediatric pericardial access and electrophysiology training.

Background: Cardiac procedures in infants and children require a high level of skill and dexterity owing to small stature and anatomy. Lower incidence of procedure volume in this population results in fewer clinical opportunities for learning. Simulators have grown in popularity for education and training, though most existing simulators are often cost-prohibitive or model adult anatomy. Objective: Develop a low-cost simulator for practicing the skills to perform percutaneous pericardial access and cardiac ablation procedures in pediatric patients. Methods: We describe 2 simulators for practicing cardiac procedures in pediatric patients, with a total cost of less than $500. Both simulators are housed within an infant-size doll. The first simulator is composed of an infant-size heart and a skin-like covering to practice percutaneous pericardial access to the heart. Participants obtained sheath access to the heart under direct visualization. The second simulator houses a child-size heart with 7 touch-activated targets to practice manipulating a catheter through a small heart. This can be performed under direct visualization and with 3-dimensional mapping via CARTO. Participants manipulated a catheter to map the heart by touching the 6 positive targets, avoiding the negative target. Results: Physicians-in-training improved their time to complete the task between the first and second attempts. Physicians experienced with the tools took less time to complete the task than physicians-in-training. Conclusion: This inexpensive simulator is anatomically realistic and can be used to practice manipulating procedure tools and develop competency for pediatric cardiac procedures.

Can the 12-lead ECG distinguish RVOT from aortic cusp PVCs in pediatric patients?

BACKGROUND: The ability to differentiate right ventricular outflow tract (RVOT) from coronary cusp (CC) site of origin (SOO) by 12-lead ECG in pediatric patients may impact efficacy and procedural time. The objective of this study was to predict RVOT versus CC SOO by ECG in pediatric patients. METHODS: Pediatric patients (<21 years) without structural heart disease with RVOT or CC premature ventricular contraction (PVC) ablations performed (2014-2018) were evaluated through multi-institution retrospective review. Demographics, ECG PVC parameters, ablation site, recurrence, and repeat procedures were collected. RESULTS: Thirty-seven patients were evaluated (mean age 14.6 years, weight 60.6 kg): 11 CC and 26 RVOT PVC SOO. CC PVCs were less likely to exhibit left bundle branch block (64% vs 100%, P = .005), had larger R-wave amplitude in V1 (0.27 vs 0.11 mV, P = .03), larger R/S ratio in V1 (0.37 vs 0.09, P = .003), and had precordial transition in V3 or earlier (73% vs 15%, P = .002). A composite score was created with the following variables: isodiphasic or positive QRS in V1, R/S ratio in V1 > 0.05, S wave in V1 < 0.9 mV, and precordial transition at or before V3. Composite score ≥ 2 was associated with a CC SOO (OR 42.0, P = .001, and AUC 0.86). CONCLUSIONS: 12-lead ECG of PVCs from the CC was associated with larger V1 R-wave amplitude, larger R/S ratio in V1, and precordial transition at or before V3. A composite score may help predict PVC/VT arising from the CC.

Off the pedal: Fluoroless transseptal puncture in pediatric supraventricular tachycardia ablation.

BACKGROUND: Fluoroless transseptal (TS) puncture may represent the final step toward elimination of fluoroscopy in pediatric supraventricular tachycardia ablation in normal hearts. We aimed to demonstrate the safety and feasibility of fluoroless TS puncture in pediatric patients and compare procedural timing with the fluoroscopic approach. METHODS: We performed a retrospective cohort analysis of all TS procedures performed without fluoroscopy at our institution; fluoroless TS procedures were performed under intracardiac echocardiography (ICE) guidance after the creation of a 3D electroanatomic map and identification of fossa ovalis (FO) on 3D map. TS procedure times reported are the time from sheath insertion (8.5F short sheath for ICE catheter and SL-1 for TS needle) to the time of confirmed left atrial access. Prior TS procedures performed by the same operator utilizing a combination of ICE and fluoroscopy and by a second operator utilizing fluoroscopic guidance alone were used for comparison. RESULTS: Fluoroless TS puncture was performed in nine patients (mean age 13.8 years); the site of TS puncture was within 2 mm of the FO identified on the EA map. The mean TS procedure time was 22.2 minutes (range 10-45). There was no significant difference in TS procedure times between the three groups. There were no complications related to any TS procedure. CONCLUSION: Fluoroless TS procedures utilizing ICE can safely be performed in pediatric patients without adding substantial procedural times compared with those utilizing fluoroscopic guidance.

Ablation of the vanishing PVC, facilitated by quantitative morphology-matching software.

BACKGROUND: Ablation of cardiac arrhythmias in children and teenagers often necessitates the use of anesthesia, which can suppress ventricular arrhythmias (VAs), making it difficult to map the site of origin using activation time (AT). Pace mapping, a technique employed to assist with VA origin localization, depends on subjective comparison of paced and targeted QRS morphology. We assessed the utility of a quantitative approach to paced QRS to VA morphology matching using the PaSo software (Carto 3, Biosense Webster), to localize the VA site of origin. METHODS: Twenty-four patients underwent 26 procedures for frequent VAs, 29 for targeted VA. If AT mapping was precluded due to infrequent VA, pace mapping was executed using the PaSo software, after regionalization based on targeted VA QRS morphology. RESULTS: Subjects were aged 1-32 (mean 14 ± 6) years; 10 were male. Heart disease was present in six patients. PVC frequency prior to onset of anesthesia was 15 ± 16/min, decreasing to 0-1 PVC/min in 17 cases prior to ablation. Arrhythmia localization was performed by AT mapping + PaSo (12) or PaSo only (17). Pace mapping exhibited an intraventricular gradient of percent QRS morphology match. Highest achieved QRS match averaged 96 ± 2%. Successful ablation (> 1-month follow-up) was achieved in 24/29 targeted VAs, 11/12 ablated using AT and pace mapping, and 13/17 VA ablated using pace mapping only, P  =  0.29. CONCLUSIONS: (1) Spontaneous VA frequency was markedly reduced following anesthesia, despite catecholamine administration. (2) Notwithstanding the ability to perform AT mapping, successful ablation can still be performed using pace mapping only, facilitated by the PaSo software.

Acute Cardiac MRI Assessment of Radiofrequency Ablation Lesions for Pediatric Ventricular Arrhythmia: Feasibility and Clinical Correlation.

BACKGROUND: Arrhythmia ablation with current techniques is not universally successful. Inadequate ablation lesion formation may be responsible for some arrhythmia recurrences. Periprocedural visualization of ablation lesions may identify inadequate lesions and gaps to guide further ablation and reduce risk of arrhythmia recurrence. METHODS: This feasibility study assessed acute postprocedure ablation lesions by MRI, and correlated these findings with clinical outcomes. Ten pediatric patients who underwent ventricular tachycardia ablation were transferred immediately postablation to a 1.5T MRI scanner and late gadolinium enhancement (LGE) imaging was performed to characterize ablation lesions. Immediate and mid-term arrhythmia recurrences were assessed. RESULTS: Patient characteristics include median age 14 years (1-18 years), median weight 52 kg (11-81 kg), normal cardiac anatomy (n = 6), d-transposition of great arteries post arterial switch repair (n = 2), anomalous coronary artery origin post repair (n = 1), and cardiac rhabdomyoma (n = 1). All patients underwent radiofrequency catheter ablation of ventricular arrhythmia with acute procedural success. LGE was identified at the reported ablation site in 9/10 patients, all arrhythmia-free at median 7 months follow-up. LGE was not visible in 1 patient who had recurrence of frequent premature ventricular contractions within 2 hours, confirmed on Holter at 1 and 21 months post procedure. CONCLUSIONS: Ventricular ablation lesion visibility by MRI in the acute post procedure setting is feasible. Lesions identifiable with MRI may correlate with clinical outcomes. Acute MRI identification of gaps or inadequate lesions may provide the unique temporal opportunity for additional ablation therapy to decrease arrhythmia recurrence.

Getting to zero: impact of electroanatomical mapping on fluoroscopy use in pediatric catheter ablation.

PURPOSE: Over the past several years, alternative imaging techniques including electroanatomic mapping systems such as CARTO®3 (C3) have been developed to improve anatomic resolution and potentially limit radiation exposure in electrophysiology (EP) procedures. We retrospectively examined the effect of the introduction of C3 on patient radiation exposure during EP studies and ablation procedures at a children's hospital. METHODS: All patients that underwent EP and ablation procedures between January 2012 and August 2015 were included; demographic information, fluoroscopy time (FT), total radiation dose (RAD), and dose-area product (DAP) were collected. Patients were stratified by time period (before vs. after C3 introduction) in three groups: (1) normal heart, (2) congenital heart disease (CHD), and (3) those requiring trans-septal (TS) access. The normal heart group was further separated by arrhythmia diagnosis (accessory pathway (AP), AV nodal reentry tachycardia (AVNRT), atrial, or ventricular arrhythmia). Mean values were compared using a single sample t test, as well as analysis of covariance to control for age, weight, and arrhythmia diagnosis. RESULTS: Mean FT decreased after introduction of C3 in patients in all three patient groups (p < 0.01). When separated by arrhythmia diagnosis, FT decreased in the AP and AVNRT groups (p < 0.0001). After controlling for age, weight, and arrhythmia diagnosis, there was a statistically significant decrease in FT in all three groups and in both RAD and DAP in the normal heart group. Zero fluoroscopy was achieved in 50/159 (31 %) and ≤1 min of FT in 71/159 (45 %) of cases. CONCLUSIONS: We have shown a significant decrease in multiple measures of radiation after introduction of C3. Continued refinements are needed to further decrease radiation utilization and achieve the goal of zero fluoroscopy.