Assessment of a novel radiation reduction protocol for pediatric and adult congenital device implantation.

PURPOSE: Device implantation requires fluoroscopic guidance, which carries inherent risks of ionizing radiation. We evaluated the impact of a low-dose fluoroscopic protocol on radiation exposure during device implantation. METHODS: All patients who underwent pacemaker or ICD implantation with new transvenous leads from July 2011 to January 2018 were included. A novel ALARA protocol consisting of ultra-low frame rates (2-3 frames/s), low dose/frame (6-18 mGy/frame), and use of the "air-gap" technique in patients < 20 kg was employed. Demographics, procedural data, and radiation exposure levels were collected and analyzed. RESULTS: Thirty patients underwent device implantation without additional catheterization, electrophysiology study, or ablation procedure (median age 15 years; range 5-50) with a total of 43 leads placed. Forty-seven percent of patients had a primary rhythm disturbance, 33% had cardiomyopathy, and 20% had congenital heart disease. Fifty percent were pacemakers (53% dual-chamber, 27% ventricle, 20% atrial) and 50% of devices implanted were ICDs (87% single-chamber). All implants were acutely successful with acceptable atrial and ventricular sensing and capture thresholds. The median fluoroscopy time was 11.5 min (inter-quartile range (IQR) 8.0-18.2), median air kerma dose 4.0 mGy (IQR 2.5-19.5), and median dose-area product 27.8 µGy/m2 (IQR 17.1-106.5). Median implant procedure time was 133 min. One patient required revision secondary to device migration without lead derangement 2 days post-procedure. CONCLUSIONS: Use of a novel fluoroscopic protocol may help decrease radiation exposure to patients and staff without affecting efficacy or risk. These data may represent benchmarks against which future device implantation procedures can be compared.

Sports Participation in Genotype Positive Children With Long QT Syndrome.

OBJECTIVE: The study sought to examine the prevalence and outcomes of sports participation (both competitive and recreational) in our single-center LQTS genotype positive pediatric population. BACKGROUND: The risks of sports participation in patients with long QT syndrome (LQTS) are not clearly elucidated. METHODS: A retrospective review was performed on genotype positive patients referred for the evaluation and management of LQTS between 1998 and 2013 at the Children's Hospital of Philadelphia. Pediatric patients participating in competitive or recreational sports were included in the analysis and their charts were reviewed for documented LQTS events during follow-up. RESULTS: The cohort of genotype-positive LQTS patients included 212 patients, and 103 patients (49%, female n = 53, average follow-up 7.1 ± 4.0 years, average QTc 468 ± 42 ms) participated in sports. A total of 105 LQTS disease-causing mutations were identified: KCNQ1 n = 60 (58%), KCNH2 n = 36 (35%), SCN5A n = 6 (6%), KCNE1 n = 1 (1%), and KCNE2 n = 2 (2%). All patients were treated with beta-blockade, with noncompliance in 1 patient and intolerance in 1 patient. Twenty-six patients participated in competitive sports (26%, female n = 15, average follow-up 6.9 ± 4.1 years, average QTc 461 ± 35 ms). Seventy-seven patients (75%, female n = 35, average follow-up 7.3 ± 3.9 years, average QTc 470 ± 43 ms) participated in recreational sports. No patients had LQTS symptoms during sports participation. Five appropriate implantable cardioverter-defibrillator shocks occurred in 2 patients, though none were related to sports participation. CONCLUSIONS: In this series no cardiac events and no deaths were observed in treatment-compliant LQTS children while participating in sports in 755 patient-years of follow-up.

Implantable cardioverter-defibrillator lead failure in children and young adults: a matter of lead diameter or lead design?

OBJECTIVES: This study aimed to investigate the impact of lead diameter and design on implantable cardioverter-defibrillator (ICD) lead survival in children and young adults. BACKGROUND: Recent reports have called attention to high rates of lead failure in adults with small-diameter ICD leads, but data in the pediatric population is limited. METHODS: We reviewed lead performance in consecutive subjects ≤30 years with transvenous right ventricular ICD leads implanted at our center between January 1995 and October 2011. Lead failure was defined as fracture, perforation, or sensing failure necessitating revision. RESULTS: A total of 120 ICD leads were implanted in 101 patients at a mean age of 15.5 ± 4.9 years. There were 47 small-diameter (≤8-F) and 73 standard-diameter (>8-F) leads. During a median follow-up of 28.7 months (interquartile range: 14.4 to 59.2 months), there were 25 lead failures (21% prevalence), with an incidence of 5.6%/year (95% confidence interval: 3.4 to 7.8). Sprint Fidelis (SF) (Medtronic, Inc., Minneapolis, Minnesota) leads had lower 3-year (69% vs. 92%, p < 0.01) and 5-year (44% vs. 86%, p < 0.01) survival probabilities than standard-diameter leads. In multivariate Cox regression, SF design conferred the greatest hazard ratio for lead failure (hazard ratio: 4.42, 95% confidence interval: 1.73 to 11.29, p < 0.01). Age and linear growth were not significantly associated with lead failure. CONCLUSIONS: In this single-center pediatric study that evaluated lead diameter, lead design, and patient factors, the SF design conferred the highest risk of lead failure, suggesting that design rather than diameter is the critical issue in ICD lead performance.

Impact of cardiac devices on the quality of life in pediatric patients.

BACKGROUND: Cardiac rhythm devices are increasingly used in the pediatric population, although their impact on quality of life (QOL) is poorly understood. The purpose of this study was to compare (QOL) scores among pediatric device patients, healthy controls, and congenital heart disease (CHD) patients and determine the key drivers of QOL in pediatric device patients. METHODS AND RESULTS: Multicenter, cross-sectional study at 8 pediatric centers of subjects aged 8 to 18 years with either a pacemaker or defibrillator was carried out. Patient-parent pairs completed the Pediatric Quality of Life Inventory and Pediatric Cardiac Quality of Life Inventory. QOL outcomes in device patients were compared with healthy controls and patients with various forms of CHD. Structural equation modeling was used to test for differences in Pediatric Cardiac Quality of Life Inventory scores among (1) device type, (2) presence of CHD, and (3) hypothesized key drivers of QOL. One hundred seventy-three patient-parent pairs (40 defibrillators/133 pacemakers) were included. Compared with healthy controls, patients with devices and their parents reported significantly lower Pediatric Quality of Life Inventory scoring. Similarly, compared with patients with mild forms of CHD, parents and patients with devices reported significantly lower Pediatric Cardiac Quality of Life Inventory scores and were similar to patients with more severe CHD. Key drivers of patient QOL were presence of implantable cardioverter-defibrillator and CHD. For patients, self-perception was a key driver of lower QOL, whereas for parents behavioral issues were associated with lower QOL. CONCLUSIONS: Patient QOL is significantly affected by the presence of cardiac rhythm devices. Whether these effects can be mitigated through the use of psychotherapy needs to be assessed.

Junctional tachycardia in a child with Lyme carditis.

A 3-year-old girl presented with fatigue, fever, and rash. Tachycardia was noted and an ECG showed junctional tachycardia. Lyme titers were positive and the arrhythmia resolved with intravenous ceftriaxone.

Predictors for hemodynamic improvement with temporary pacing after pediatric cardiac surgery.

OBJECTIVES: Temporary epicardial pacing wires are commonly placed during pediatric cardiac surgery. Data are sparse on postoperative pacing in this population. The objective of this study was to determine the frequency of use and identify predictors for the use of temporary epicardial pacing wires. METHODS: Perioperative data were prospectively collected on all patients who underwent cardiac surgery at our institution (n = 162). RESULTS: A total of 117 (72%) patients had temporary epicardial pacing wires placed. Postoperatively, 23 (20%) of 117 patients had hemodynamic improvement with the use of temporary epicardial pacing wires. Indications for pacing were slow junctional rhythm (11/23 [48%]), junctional ectopic tachycardia (7/23 [31%]), pace termination of supraventricular tachycardia (3/23 [13%]) and atrial flutter (1/23 [4%]), and complete heart block (1/23 [4%]). By using univariate analysis, single-ventricle anatomy, heterotaxy, the Fontan procedure, use of circulatory arrest, intraoperative arrhythmia, pacing in the operating room, and use of vasoactive medications were predictors for hemodynamic improvement with the use of temporary epicardial pacing wires (P < .05). On multivariate analysis, the Fontan procedure, circulatory arrest, and intraoperative arrhythmias were independent predictors (P < .01). When excluding all patients with any of these 3 risk factors, only 2% were paced. Patients with clinically significant pacing had longer chest tube drainage (P < .01) and intensive care unit length of stay (P < .01). There were no complications associated with temporary epicardial pacing wires. CONCLUSIONS: The Fontan procedure, use of circulatory arrest, and intraoperative arrhythmias were associated with hemodynamic improvement with postoperative pacing and might represent indications for empiric intraoperative placement of temporary epicardial pacing wires. Patients without these risk factors were less likely to require pacing. Temporary epicardial pacing wires were safe and useful in the management of arrhythmias after pediatric cardiac surgery.

Survival of transvenous ICD leads in young patients.

BACKGROUND: In adults, transvenous implantable cardioverter defibrillator (ICD) lead failure rates are significant, and their occurrence increases with time from implant. There are limited data in children. The goal of this study was to assess lead survival in young patients undergoing ICD implantation at a single center. METHODS: Records of patients under 21 years old with transvenous ICD leads implanted at our center from June 1997 to August 2007 were retrospectively reviewed. Age, weight, height, diagnosis, lead and generator model, venous access technique, generator position, pacing thresholds, lead impedance, and R wave size were recorded. "Lead failure" was defined as any lead problem requiring surgical intervention to restore proper function to the ICD system. RESULTS: Seventy-one transvenous leads were included (70 patients). Average age at implant was 14.8 years (range 5.7-19.5). All the devices were implanted by a single operator (HMS). Venous access was obtained via cephalic cutdown in 66/71. Mean follow-up time was 2.8 years (range 0.2-7.8 years, median 2.3 years). There were no infections requiring explantation. There were four lead failures. Three were lead fractures, occurring 12, 13, and 19 months after implant. The fourth lead failed when an arrhythmia was not appropriately detected, and a second dedicated rate-sensing lead was thus implanted. Univariate analysis did not identify any variable to be a significant predictor of lead failure. Kaplan-Meier survival analysis demonstrated 5-year lead survival at 89.6%. CONCLUSIONS: ICD lead survival in children, when performed by an experienced operator, is similar to that found in adults.

Entrainment to distinguish orthodromic reciprocating tachycardia from atrioventricular nodal reentry tachycardia in children.

BACKGROUND: Studies in adults suggest that after entrainment from the right ventricle, a post-pacing interval (PPI) minus tachycardia cycle length (TCL), when corrected for atrioventricular node delay (cPPI-TCL), is useful to distinguish atrioventricular nodal reentry tachycardia (AVNRT) from orthodromic reciprocating tachycardia (ORT), but this has not been evaluated in children. METHODS: In 100 children undergoing catheter ablation, entrainment of ORT or AVNRT was performed from the right ventricular apex. The atrial-His (AH) interval was measured on the return cycle (post-AH) and during tachycardia just prior to pacing (pre-AH). The cPPI-TCL was calculated as (PPI-TCL) - (post-AH - pre-AH). In the first 50 children, the best cutoff was identified and then validated in the next 50 children. RESULTS: In the first 50 children, cPPI-TCL was longer in AVNRT compared with ORT (122 +/- 19 ms vs 63 +/- 23 ms, P < 0.001). Furthermore, cPPI-TCL exceeded 95 ms in all AVNRT patients, but was less than < 95 ms in 28 of 29 ORT patients. In the next 50 children, a cPPI-TCL < 95 ms was 100% specific for ORT; a cPPI-TCL > 95 ms was 95% specific for AVNRT. There was even greater separation of cPPI-TCL values comparing AVNRT with ORT utilizing a septal accessory pathway. CONCLUSIONS: The cPPI-TCL is a useful technique to distinguish AVNRT from ORT in children. Our data suggest that in children a cPPI-TCL < 95 ms excludes AVNRT, while a value > 95 ms is rarely observed in ORT. This technique is particularly useful to distinguish AVNRT from ORT utilizing a septal accessory pathway. (PACE 2010; 469-474).

Verapamil sensitive ventricular tachycardia associated with a cardiac hemangioma in the right ventricular outflow tract.

Primary tumors of the heart are rare, but they are often associated with refractory arrhythmias. Vascular tumors of the heart comprise a small minority of primary cardiac tumors. In patients with structurally normal hearts, ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT) can be sensitive to adenosine, vagal maneuvers, and calcium channel blockers. In this report, we describe a case of ventricular tachycardia originating from within a hemangioma in the RVOT that was ultimately controlled with verapamil.

Elevated impedance during cardioversion in neonates with atrial flutter.

Direct-current cardioversion is a common treatment modality for acute termination of atrial flutter in neonates. Studies in children have demonstrated that cardioversion is often successful with as little as 0.25-0.5 J/kg with the current biphasic devices. We hypothesize that during cardioversion of atrial flutter in neonates, however, the impedance may be high and more energy may be required for successful cardioversion. A retrospective chart review of our institutional experience from 2005 through 2008 was performed. Neonates with atrial flutter requiring cardioversion who had strips available for review were included. Six patients met the inclusion criteria. The median age at the time of cardioversion was 2.6 h (range, 1.3-336 h) and the mean weight was 3.22 +/- 0.4 kg (SD). The mean electrical impedance of the successful shocks was elevated, at 234 +/- 136 Omega. The mean energy delivered for successful cardioversion was 0.9 +/- 0.3 J/kg, and the current was 1 A in all patients. In conclusion, the shock impedance was elevated in the neonates studied during cardioversion of atrial flutter. Low current was sufficient for successful cardioversion. Further studies are needed in this specific population.

An epicardial pacing safety net: an alternative technique for pacing in the young.

Epicardial pacing is the standard approach for permanent pacing in small children and patients with functionally univentricular physiology. The longevity of epicardial leads, however, is compromised by increased occurrences of exit block and lead fractures. We report our experience with a technique of placing a second ventricular lead, and attaching it to the atrial port of a dual chamber pacemaker to prevent the need for early re-operation in the event of failure of the primary epicardial lead. A retrospective review showed that, over the period from 2001 through 2007, epicardial ventricular pacemakers had been placed in 88 patients. In 6 of these, we had placed 2 ventricular leads, their median weight being 8.0 kilograms, with a range from 4.2 to 31.8 kilograms. Fracture of a lead occurred in 1 of the patients (17%) 8 months after placement, requiring reprogramming to pace from the atrial port. This possibility avoided the need for repeated emergent surgery. At a median follow-up of 1.5 years, with a range from 0.3 to 4.4 years, there have been no complications. During the same time period, overall failure of epicardial leads at our institution was 13%. Placement of a second ventricular epicardial pacing lead, attached to the atrial port of a dual chamber pacemaker, therefore, may provide a safe and effective means of ventricular pacing in the setting of epicardial lead failure, and may obviate the need for repeat, potentially urgent, pacemaker surgery.