Muscle usage and workload assessment of cardiac ablation procedure with the use of a novel catheter torque tool in a pediatric simulator.

BACKGROUND: Cardiac ablation catheters are small in diameter and pose ergonomic challenges that can affect catheter stability. Significant finger dexterity and strength are necessary to maneuver them safely. We evaluated a novel torque tool to reduce muscle activation when manipulating catheters and improve perceived workload of ablation tasks. The objective was to evaluate measurable success, user perception of workload, and muscle usage when completing a simulated ablation task with and without the use of a catheter torque tool. METHODS: Cardiology attendings and fellows were fitted with surface electromyographic (EMG) sensors on 6 key muscle groups in the left hand and forearm. A standard ablation catheter was inserted into a pediatric cardiac ablation simulator and subjects navigated the catheter tip to 6 specific electrophysiologic targets, including a 1-min simulated radiofrequency ablation lesion. Time to complete the task, number of attempts required to complete the lesion, and EMG activity normalized to percentage of maximum voluntary contraction were collected throughout the task. The task was completed 4 times, twice with and twice without the torque tool, in semi-randomized order. A NASA Task Load Index survey was completed by the participant at the conclusion of each task. RESULTS: Time to complete the task and number of attempts to create a lesion were not altered by the tool. Subjectively, participants reported a significant decrease in physical demand, effort, and frustration, and a significant increase in performance. Muscle activation was decreased in 4 of 6 muscle groups. CONCLUSION: The catheter torque tool may improve the perceived workload of cardiac ablation procedures and reduce muscle fatigue caused by manipulating catheters. This may result in improved catheter stability and increased procedural safety.

Electrocardiograms in Healthy North American Children in the Digital Age.

BACKGROUND: Interpretation of pediatric ECGs is limited by lack of accurate sex- and race-specific normal reference values obtained with modern technology for all ages. We sought to obtain contemporary digital ECG measurements in healthy children from North America, to evaluate the effects of sex and race, and to compare our results to commonly used published datasets. METHODS: Digital ECGs (12-lead) were retrospectively collected for children ≤18 years old with normal echocardiograms at 19 centers in the Pediatric Heart Network. Patients were classified into 36 groups: 6 age, 2 sex, and 3 race (white, black, and other/mixed) categories. Standard intervals and amplitudes were measured; mean±SD and 2nd/98th percentiles were determined by age group, sex, and race. For each parameter, multivariable analysis, stratified by age, was conducted using sex and race as predictors. Parameters were compared with 2 large pediatric ECG data sets. RESULTS: Among ECGs from 2400 children, significant differences were found by sex and race categories. The corrected QT interval in lead II was greater for girls compared with boys for age groups ≥3 years (P≤0.03) and for whites compared with blacks for age groups ≥12 years (P<0.05). The R wave amplitude in V6 was greater for boys compared with girls for age groups ≥12 years (P<0.001), for blacks compared with white or other race categories for age groups ≥3 years (P≤0.006), and greater compared with a commonly used public data set for age groups ≥12 years (P<0.0001). CONCLUSIONS: In this large, diverse cohort of healthy children, most ECG intervals and amplitudes varied by sex and race. These differences have important implications for interpreting pediatric ECGs in the modern era when used for diagnosis or screening, including thresholds for left ventricular hypertrophy.

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.

Rising charges and costs for pediatric catheter ablation.

INTRODUCTION: Catheter ablation has been shown to be effective for pediatric tachyarrhythmias, but the associated charges and costs have not been described in the recent era. Understanding such contemporary trends may identify ways to keep an effective therapy affordable while optimizing clinical outcomes. METHODS: We used the 1997-2009 Kids' Inpatient Databases to examine trends in charges and costs for pediatric catheter ablation and identify determinants of temporal changes. RESULTS: There were 7,130 discharges for catheter ablation in the sample. Mean age at ablation was 12.1 ± 0.2 years. Patients with congenital heart disease (CHD) made up 10% of the sample. Complications occurred in 8% of discharges. Mean total charges rose 219% above inflation (from $23,798 ± 1,072 in 1997 to $75,831 ± 2,065 in 2009). From 2003 to 2009, costs rose 25% (from $20,459 ± 780 in 2003 to $25,628 ± 992 in 2009). Charges for ablation increased markedly relative to surgical procedures, but with a similar slope to other catheter-based interventions. Multivariable analysis revealed that year (P < 0.0001), payer (P = 0.0002), CHD (P < 0.0001), valvular heart disease (P = 0.0004), cardiomyopathy (P = 0.0009), hospital region (P < 0.0001), length of stay (P < 0.0001), and complications (P < 0.0001) predicted increased charges. The same factors also predicted increased costs. Charges and costs varied considerably by region, particularly for high-volume centers (P < 0.0001). CONCLUSIONS: Charges and costs for pediatric catheter ablation increased relative to other procedures and significantly outstripped inflation. Further study of complications, length of stay, and regional differences may help control rising costs while maintaining quality of care.

Cost-effectiveness analysis of genetic testing for familial long QT syndrome in symptomatic index cases.

BACKGROUND: Genetic testing for long QT syndrome (LQTS) has been available in a research setting for the past decade, and a commercial test has recently become available. However, the costs and effectiveness of genetic testing have not been estimated. OBJECTIVES: The purpose of this study was to conduct a cost-effectiveness analysis of genetic testing in the management of patients who have or are suspected to have familial LQTS. METHODS: We examined the incremental cost-effectiveness of genetic testing compared with no genetic testing for symptomatic index cases and how this varied according to changes in assumptions and data inputs. Data were obtained from the published literature and a clinical cohort. RESULTS: We found that genetic testing is more cost-effective than not testing for symptomatic index cases at an estimated cost of 2,500 US dollar per year of life saved. These results were generally robust, although they were sensitive to some data inputs such as the cost of testing and the mortality rate among untreated individuals with LQTS. CONCLUSION: A genetic test for familial LQTS is cost-effective relative to no testing, given our assumptions about the population to be tested and the relevant probabilities and costs. The primary benefit of testing is to more accurately diagnose and treat individuals based on a combination of clinical scores and test results. Future economic analyses of testing for familial LQTS should consider the potential benefits of genetic testing of broader populations, including family members.