Current State of Cardiac Implantable Electronic Device Remote Monitoring in Pediatrics and Congenital Heart Disease: A PACES-Sponsored Quality Improvement Initiative.

Cardiac implantable electronic device (CIED) remote transmissions are an integral part of longitudinal follow-up in pediatric and adult congenital heart disease (ACHD) patients. To evaluate baseline CIED remote monitoring (RM) data among pediatric and ACHD centers prior to implementation of a Pediatric and Congenital Electrophysiology  Society (PACES)-sponsored quality improvement (QI) project. This is a cross-sectional study of baseline CIED RM. Centers self-reported baseline data: individual center RM compliance was defined as high if there was > 80% achievement and low if < 50%. A total of 22 pediatric centers in the USA and Australia submitted baseline data. Non-physicians were responsible for management of the RM program in most centers: registered nurse (36%), advanced practice provider (27%), combination (23%), and third party (9%). Fifteen centers (68%) reported that > 80% of their CIED patients are enrolled in RM and only two centers reported < 50% participation. 36% reported high compliance of device transmission within 14 days of implant and 77% of centers reported high compliance of CIED patients enrolled in RM. The number of centers achieving high compliance differed by device type: 36% for pacemakers, 50% for ICDs, and 55% for Implantable Cardiac Monitors (ICM). All centers reported at least 50% adherence to recommended follow-up for PM and ICD, with 23% low compliance rate for ICMs. Based on this cross-sectional survey of pediatric and ACHD centers, compliance with CIED RM is sub-optimal. The PACES-sponsored QI initiative will provide resources and support to participating centers and repeat data will be evaluated after PDSA cycles.

Limited Relationship Between Echocardiographic Measures and Electrocardiographic Markers of Left Ventricular Size in Healthy Children.

Pediatric ECG standards have been defined without echocardiographic confirmation of normal anatomy. The Pediatric Heart Network Normal Echocardiogram Z-score Project provides a racially diverse group of healthy children with normal echocardiograms. We hypothesized that ECG and echocardiographic measures of left ventricular (LV) dimensions are sufficiently correlated in healthy children to imply a clinically meaningful relationship. This was a secondary analysis of a previously described cohort including 2170 digital ECGs. The relationship between 6 ECG measures associated with LV size were analyzed with LV Mass (LVMass-z) and left ventricular end-diastolic volume (LVEDV-z) along with 11 additional parameters. Pearson or Spearman correlations were calculated for the 78 ECG-echocardiographic pairs with regression analyses assessing the variance in ECG measures explained by variation in LV dimensions and demographic variables. ECG/echocardiographic measurement correlations were significant and concordant in 41/78 (53%), though many were significant and discordant (13/78). Of the 6 ECG parameters, 5 correlated in the clinically predicted direction for LV Mass-z and LVEDV-z. Even when statistically significant, correlations were weak (0.05-0.24). R2 was higher for demographic variables than for echocardiographic measures or body surface area in all pairs, but remained weak (R2 ≤ 0.17). In a large cohort of healthy children, there was a positive association between echocardiographic measures of LV size and ECG measures of LVH. These correlations were weak and dependent on factors other than echocardiographic or patient derived variables. Thus, our data support deemphasizing the use of solitary, traditional measurement-based ECG markers traditionally thought to be characteristic of LVH as standalone indications for further cardiac evaluation of LVH in children and adolescents.

Ripple mapping in ventricular tachycardia substrate mapping and ablation of nonischemic ventricular tachycardia.

INTRODUCTION: Substrate-based ablation for ventricular tachycardia (VT) using Ripple map (RM) is an effective treatment strategy for patients with ischemic cardiomyopathy but has yet to be evaluated in patients with nonischemic cardiomyopathy (NICMO). The aim of this study is to determine the feasibility and effectiveness of an RM-based ablation for NICMO patients. METHODS AND RESULTS: This was a single-center, retrospective study including all NICMO patients undergoing VT ablation at St Vincent Hospital between January 1, 2018 and January 12, 2019. Retrospective RM analysis was performed on those that had a substrate-based ablation to identify the location and number of Ripple channels as well as their proximity to ablation lesions. Thirty-three patients met the inclusion criteria and had a median age of 65 (58, 73.5) with 15.2% of the population being female, and were followed for a median duration of 451 (217.5, 586.5) days. Of these patients, 23 (69.7%) had a substrate-based ablation with a median procedural duration of 196.4 (186.8, 339) min, 1946 (517, 2750) points collected per map, and 277 (141, 554) points were within the scar. Two (8.6%) procedural complications occurred, and 7 (30.4%) patients had VT recurrence during follow-up. RM analysis revealed an average of two Ripple channels and the patients without VT recurrence had ablation performed closer to the Ripple channels: 0 (0, 4.7) versus 14.3 (0, 23.5) cm; p = .02. CONCLUSION: An RM-based substrate ablation can be performed in NICMO patients and ablation within Ripple channels is a predictor of VT freedom.

In-vivo evaluation of catheter integrity with the use of a novel catheter torque tool.

INTRODUCTION: Electrophysiology studies and ablation procedures require strength, steadiness, and dexterity to manipulate catheters. We have previously described a novel catheter torque tool (Peritorq) that improves torqueability and stability and decreases user muscle fatigue. The objective was to evaluate measures of catheter integrity with and without the torque tool in place using multiple diagnostic and ablation catheters in an adult porcine model. METHODS: Diagnostic and ablation catheters were inserted through the femoral or jugular vein into areas of the right atrium, coronary sinus (CS), and right ventricle. Electrical measurements including impedance, sensing, and capture thresholds were obtained with and without the torque tool. Ablation lesions (30 s) were given at different locations using both irrigated and nonirrigated catheters and measurements were recorded with and without the torque tool. RESULTS: Procedures were performed in eight adult pigs. Measurements with and without the torque tool in all locations did not differ significantly using any of the catheters. With the nonirrigated ablation catheter there was a significant difference in maximum (mean 1.7 W, p = .03) and average power (mean 9.1 W, p = .04) delivery at the PS tricuspid valve, but there were no other differences with the irrigated or nonirrigated catheters. Subjective assessment by the operator revealed a substantial improvement in maneuverability, ability to transfer torque, and stability within the cardiac space. CONCLUSION: In an in-vivo environment, a novel catheter torque tool subjectively improved catheter manipulation and did not have a significant impact on the integrity of electrophysiologic catheters. Further study including additional catheters and in-vivo human testing is indicated.

Ambulatory Cardiac Monitoring in Infants with Supraventricular Tachycardia.

Supraventricular tachycardia (SVT) is a frequent cause of tachyarrhythmia in infants < 1 year of age and ambulatory cardiac monitoring is an important tool for diagnosis and follow-up of these patients. We retrospectively reviewed 594 infants (mean age 4.05 months, SD 3.55; 54% M) who underwent ambulatory cardiac monitoring (69% 24 h Holter, 31% extended monitor) through the Pocket ECG system (MediLynx) between January 2016 and July 2020. 170 patients who had the ICD-10 code I47.1 for SVT used at enrollment were analyzed separately. 49 (8.3%) patients had sustained SVT or non-sustained SVT (nSVT) during the study period, including 20 patients (11.8%) who had the ICD-10 code I47.1 at enrollment. Extended ambulatory cardiac monitors detected 61% of all patients with nSVT or SVT and was superior when compared to 24 h Holter (p < 0.0001). In the overall group, the first episode of SVT or nSVT was detected within 24 h of monitoring in 40/49 patients (82%). 48/49 patients (98%) were diagnosed within a week of monitoring and the single remaining patient was diagnosed with nSVT at day 15 of monitoring. There was no significant difference in minimal, maximal, and average heart rate between patients with and without ICD-10 code I47.1 at enrollment or between patients with and without SVT or nSVT. Despite their low yield, ambulatory cardiac monitors are an important diagnostic tool. The ideal length of monitoring in patients with known or suspected SVT has yet to be defined, although all patients in our cohort were identified by day 15 of monitoring.

Utility of Exercise Stress Testing in Pediatric Patients with T-Wave Inversions.

T-wave inversions (TWI) in inferolateral electrocardiogram (ECG) leads (II, III, aVF, V5-V6) are often suggestive of cardiac pathology in adult patients. They are a common reason of additional testing in pediatric patients. The goal of the study is to determine correlation of exercise stress test T-wave response with diagnosis of cardiac pathology. This is a retrospective review of pediatric patients < 21 years with the finding of baseline TWI in inferior (II, III, avF) and/or lateral (V5-V6) leads on 12-lead ECG. All patients underwent treadmill exercise stress test (EST) and an echocardiogram within 1 year of each other. Demographics, baseline ECG findings, echocardiogram results, and EST data were recorded. T-wave reversion was considered complete if T waves demonstrated normalization during exercise, partial if there was minimal improvement, and no response if there was no change or worsening of inversions. In our cohort of 72 patients with a mean age 14.6 (± 2.9) years and 61% males, 59 (82%) had a structurally normal heart. Thirteen patients had evidence of structural or functional heart disease. Of the 59 patients, 83% had either complete or partial T-wave response. Among the 13 patients with heart disease, two patients had genetic testing consistent with risk for hypertrophic cardiomyopathy and had complete and partial response on EST. Exercise stress testing for TWI in pediatric patients has low sensitivity and specificity for the diagnosis of cardiac disease and routine use in this patient population may not be indicated.

A paediatric cardiology handbook for the digital age.

INTRODUCTION: Paediatric cardiology fellows, tasked with studying a large and dynamic field, may benefit from a quick-access digital resource that reflects contemporary practice. The objective of this study was to evaluate the effectiveness of a paediatric cardiology handbook smartphone app in enhancing the accessibility of information such as guidelines and recommendations for paediatric cardiology fellows. MATERIALS AND METHODS: The Peds Cardiology Handbook app (iOS) was designed using XCode and Swift programming. A pre-app survey and download instructions were sent to the US paediatric cardiology fellows, followed by a post-app survey. Fellows were asked to rate the ease of rapid access to various types of information. Responses were compared pre- and post-app using McNemar's test and Wilcoxon signed-rank test. RESULTS: Two-hundred and thirty paediatric cardiology fellows were contacted; 23% (n = 53) completed both the pre- and post-app surveys and were included for analysis. After using the app, fellows found it easier to quickly access information in eight out of nine domains evaluated (p < 0.05). All fellows found the app easy to use (100%), most felt that the app was well-organised (98%), contained reliable information (92%), and was useful for finding quick answers to clinical questions (87%). DISCUSSION: The Peds Cardiology Handbook iPhone app is a useful, reliable tool that provides quick access to high-yield information, including guidelines and references. Overall, paediatric cardiology fellows found it easier to rapidly access clinically relevant information after using the app. Future studies may be necessary to evaluate long-term use and impact on evidence-based practice.

QTc Prolongation in Pediatric Patients with Diabetic Ketoacidosis.

OBJECTIVE: To investigate the association between diabetic ketoacidosis (DKA) and prolonged QTc interval and to assess for correlation between DKA severity and QTc prolongation. STUDY DESIGN: Retrospective observational study in a pediatric hospital. Patients admitted with DKA diagnosed by laboratory criteria and an electrocardiogram (ECG) performed during a period of acidosis were identified using Looking Glass Clinical Analytics. Data including age, sex, pH, electrolytes, anion gap, and ECG variables were collected. Patients were excluded if they had a prior diagnosis of prolonged QTc or were taking QTc prolonging medications. Severity of DKA was classified as mild (pH 7.24-7.3), moderate (pH 7-7.24), or severe (pH <7). ECGs were read by a pediatric electrophysiologist and QTc interval was manually calculated utilizing the Bazett formula. RESULTS: Ninety-six patients were included (mean age 15.2 ± 4.2 years, pH 7.12 ± 0.12, bicarbonate 8.6 ± 3.7 mmol/L, potassium 5.3 ± 1.1 mEq/L). Mean QTc interval for all patients in DKA was 454 ± 32 msec. Mean QTc in the mild group was 441 ± 22 msec, moderate group 460 ± 36 msec, and severe group 461 ± 34 msec. There was a significant difference in QTc interval across DKA severity groups (P = .05). There was a significant association between higher anion gaps and greater QTc intervals (r = 0.21, P = .04). CONCLUSIONS: Thirty-one percent of pediatric patients with DKA demonstrated QTc prolongation on ECG. Severity of DKA and worsening acidosis were associated with increased prolongation of the QTc. Further study is required to evaluate the clinical impact of these findings.

Shorter work boot shaft height improves ankle range of motion and decreases the oxygen cost of work.

Work boots featuring design elements implemented to protect the foot and lower limb are common in many industries. However, boot design can have negative unintended consequences such as increases in work related fatigue and injury risk. This study compared joint kinematics and the physiological cost of two commercially available steel-toed work boots with different shaft designs worn throughout a simulated work task. A boot with a lower-cut and scalloped shaft allowed greater sagittal plane range of motion at the ankle joint compared to a boot with a higher-cut straight shaft, particularly in the late stance phase of the gait cycle. This was coupled with a decreased physiological cost of treadmill walking (2.6 and 3.1% improvement in oxygen consumption and walking economy, respectively), likely caused by a more efficient gait pattern. A lower-cut and scalloped shaft could lead to decreases in work-related fatigue and the subsequent risk of injuries in workers. Practitioner summary: Gait kinematics and the physiological cost of work boots with different shaft heights has not previously been investigated. A randomised cross-over study design found that a boot with a lower shaft height and scalloped collar improved ankle range of motion and reduced the physiological cost experienced by the wearers. Abbreviations: ROM: range of motion; FS: full shaft; SS: scalloped shaft; COM: centre of mass; HR: heart rate; RPE: rating of perceived exertion; ES: effect size.

Surgical pericardial adhesions do not preclude minimally invasive epicardial pacemaker lead placement in an infant porcine model.

BACKGROUND: Pericardial adhesions in infants and small children following cardiac surgery can impede access to the epicardium. We previously described minimally invasive epicardial lead placement under direct visualization in an infant porcine model using a single subxiphoid incision. The objective of this study was to assess the acute feasibility of this approach in the presence of postoperative pericardial adhesions. METHODS: Adhesion group piglets underwent left thoracotomy with pericardiotomy followed by a recovery period to develop pericardial adhesions. Control group piglets did not undergo surgery. Both groups underwent minimally invasive epicardial lead placement using a 2-channel access port (PeriPath) inserted through a 1 cm subxiphoid incision. Under direct thoracoscopic visualization, pericardial access was obtained with a 7-French sheath, and a pacing lead was affixed against the ventricular epicardium. Sensed R-wave amplitudes, lead impedances and capture thresholds were measured. RESULTS: Eight piglets underwent successful pericardiectomy and developed adhesions after a median recovery time of 45 days. Epicardial lead placement was successful in adhesion (9.5 ± 2.7 kg, n = 8) and control (5.6 ± 1.5 kg, n = 7) piglets. There were no acute complications. There were no significant differences in capture thresholds or sensing between groups. Procedure times in the adhesion group were longer than in controls, and while lead impedances were significantly higher in the adhesion group, all were within normal range. CONCLUSIONS: Pericardial adhesions do not preclude minimally invasive placement of epicardial leads in an infant porcine model. This minimally invasive approach could potentially be applied to pediatric patients with prior cardiac surgery.

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.

Percutaneous epicardial placement of a prototype miniature pacemaker under direct visualization: An infant porcine chronic survival study.

INTRODUCTION: Pacemaker implantation in infants typically consists of surgical epicardial lead placement with an abdominal generator. Here, we describe the chronic performance of our minimally invasive prototype miniature pacemaker implanted under direct visualization in an immature porcine model. METHODS: Twelve piglets underwent miniature pacemaker implantation. A self-anchoring two-channel access port was inserted into a 1 cm incision in the subxiphoid space, and a thoracoscope was inserted into the main channel to visualize the thoracic cavity under insufflation. The pacemaker leadlet was inserted through a sheath via secondary channel and affixed against the epicardium using a helical side-biting electrode. The miniature pacemaker was tucked into the incision, which was sutured closed. Ventricular sensing, leadlet impedance, and capture thresholds were measured biweekly. A limited necropsy was performed after euthanasia. RESULTS: Nine piglets were followed for a median of 78 (IQR 52-82) days and gained 6.6 ± 3.2 kg. Three animals were censored from the analysis due to complications unrelated to the procedure. Capture thresholds rose above maximal output after a median of 67 (IQR 40-69) days. At termination, there was a significant decrease in R-wave amplitude (P = .03) and rise in capture thresholds at 0.4 ms (P = .01) and 1.0 ms pulse widths (P = .02). There was no significant change in leadlet impedance (P = .74). There were no wound infections. CONCLUSIONS: There were no infections following minimally invasive implantation of our prototype miniature pacemaker. Improvements to epicardial fixation are necessary to address diminished leadlet efficacy over time.

Serial follow-up of corrected QT interval in Rett syndrome.

AIM: To identify factors associated with baseline prolonged corrected QT (QTc) and higher risk of QTc prolongation during follow-up in patients with Rett syndrome (RTT). METHOD: A retrospective review of patients receiving an electrocardiogram (ECG) between June 2012 and June 2018 was performed. Age, methyl-CpG binding protein 2 gene (MECP2) mutation, RTT Severity Scale (RSSS) score, breathing abnormalities, seizure frequency, medications, and ECG parameters were collected. Prolonged QTc was defined as greater than or equal to 460ms. Comparisons at baseline and during follow-up were made. RESULTS: In total, 129 unique patients (all female) had 349 ECGs. At baseline, 12 (9.3%) had a prolonged QTc (median 474ms, interquartile range 470-486ms) and were more likely to have moderate/severe breathing abnormalities (66.7% vs 24.8%; p=0.005) and take selective serotonin reuptake inhibitors (SSRIs) (41.7% vs 15.4%; p=0.04). There was no difference in age, RSSS score, seizures, or mutation. Twenty-six developed prolonged QTc during a median follow-up of 1 year 7 months (interquartile range 0-3y 6mo). QTc prolongation was associated with p.(Thr158Met) mutation versus the remaining six common mutations (hazard ratio 4.1, 95% confidence interval 1.4-12.0; p=0.01) but not with age, RSSS score, seizures, breathing abnormalities, or SSRIs. INTERPRETATION: Breathing abnormalities and SSRIs were associated with baseline QTc prolongation and those with p.(Thr158Met) mutation were more likely to develop prolonged QTc over time. Identification of patients with prolonged QTc warrants increased clinical monitoring. WHAT THIS PAPER ADDS: Breathing abnormalities and selective serotonin reuptake inhibitors are associated with prolonged baseline corrected QT (QTc). Development of QTc prolongation is associated with the p.(Thr158Met) mutation.

Speckle Tracking Echocardiography in Pediatric Patients with Premature Ventricular Contractions.

Premature ventricular contractions (PVCs) in pediatric patients without structural heart disease and normal left ventricular systolic function rarely require therapy, though it is unknown whether these patients have subclinical cardiac dysfunction. Speckle tracking echocardiography is an additional means of evaluating cardiac function in asymptomatic pediatric PVC patients with normal standard measures of left ventricular (LV) function. Asymptomatic pediatric patients (< 21 years) without congenital heart disease, LV ejection fraction (LVEF) ≥ 55% and PVC burden ≥ 5% on 24-h Holter monitor were included. Demographic information, exercise stress test results, standard echocardiographic measures of LV systolic function and PVC morphology by 12-lead ECG were collected. Peak global systolic longitudinal strain (GLS) from apical four-chamber view was analyzed offline. 29 patients were identified (mean age 11.7 ± 5.8 years, 49.2 ± 25.3 kg, 59% male). Mean PVC burden was 12.0 ± 7.0% (range 5-37.5%). 14/29 (48%) had exercise stress testing with evidence of PVCs; 9/14 (64%) had PVC suppression at a mean heart rate (HR) of 160 ± 23 bpm and 5/14 (36%) did not suppress at a mean maximum HR of 188 ± 9 bpm. All patients had normal strain values by speckle tracking echocardiography (mean LV GLS - 22.5 ± 2.0%, LV global circumferential strain - 25.3 ± 3.9 and RV GLS - 24.1 ± 3.0%). There was no correlation between PVC burden and cardiac function parameters. Asymptomatic pediatric patients without structural heart disease, preserved LVEF/shortening fraction and PVC burden ≥ 5% demonstrated normal cardiac function including strain patterns indicating no evidence of subclinical cardiac dysfunction. Larger scale studies and longitudinal evaluation of left ventricular function using speckle tracking echocardiography is warranted in this population.

Ultrasound-guided axillary venous access for pediatric and adult congenital lead implantation.

BACKGROUND: Axillary venous access with ultrasound guidance for pediatric transvenous lead implantation may reduce risks for pneumothorax and hemothorax. The objective was to retrospectively evaluate ultrasound-guided axillary vein access as an alternative to the subclavian approach. METHODS: The technique consists of ultrasonographic identification of the axillary vein at the deltopectoral groove after initial contrast venography. A micropuncture kit is used for initial ultrasound-guided percutaneous access with fluoroscopic confirmation of wire position. Pocket creation is performed, and sheath insertion and lead implantation proceed as usual. Demographic, procedural, and radiation exposure data were collected and analyzed. RESULTS: Sixteen patients (median age = 13 years, 8-50 years; median weight = 56 kg, 29-77 kg) underwent lead implantation; two additional patients required fluoroscopy due to poor acoustic windows (89% success). Fifteen of 21 leads (71%) were ventricular; 50% of implants were pacemakers, and 31% were dual chamber. Median time to venous access was 13 min (interquartile range (IQR) = 9.25-20.25) and median implant procedure time was 156 min (IQR = 112-172). Median fluoroscopy time was 18.0 min (IQR = 11.9-29.6), median air kerma was 9.0 mGy (IQR = 3.0-28.5), and median dose-area product was 30.2 Gy-cm2 (IQR = 16.1-234.5). One patient required generator pocket revision 2 days postprocedure without lead dislodgement. There were no other complications encountered. CONCLUSIONS: Transvenous pacemaker and implantable cardioverter-defibrillator lead implantation in the pediatric and adult congenital population through ultrasound-guided axillary venous access is safe and efficacious. This technique may provide a low-risk alternative for vascular access for pediatric implantation procedures.

Risk Factors for Development of Ectopic Atrial Tachycardia in Post-operative Congenital Heart Disease.

Ectopic atrial tachycardia (EAT) is common in surgically repaired congenital heart disease (CHD) and carries the potential for significant hemodynamic compromise. Our objective was to determine the incidence, and risk factors of EAT after CHD surgery. Prospective study of patients that underwent surgery for CHD from February to October 2016 was performed. Demographic, perioperative and electrophysiologic data were collected. Sustained EAT (> 30 s) was documented by telemetry or electrocardiogram and confirmed by a pediatric electrophysiologist. All patients were followed through index hospitalization. During the study period, 17/204 (8%) of patients developed EAT with median time-to-event of 14 days. 15/17 (88%) received anti-arrhythmic therapy for sustained EAT. By univariate analysis, younger age (5 vs. 284 days, P < .001), lower weight (3.2 vs. 7.5 kg, P < .001), single ventricle physiology (P = .05), longer cardiopulmonary bypass time (176 vs. 94 min, P < .001), need for delayed sternal closure (P < .001), and higher STAT category (P < .001) were associated with EAT. Incidence among single ventricle patients was 7/44 (16%), and of those 7/13 (54%) were < 30 days of age. Multivariable Cox regression analysis confirmed age at surgery < 30 days (hazard ratio = 11.7, P = .002) and use of milrinone (hazard ratio = 4.4, P = .007) as independent predictors of EAT. Post-operative EAT is frequent following surgery for CHD especially in neonates. Further study is warranted, specifically in the single ventricle population, given the high potential risk for arrhythmia-induced hemodynamic compromise in this vulnerable population.

Facial feature tracking: a psychophysiological measure to assess exercise intensity?

The primary aim of this study was to determine whether facial feature tracking reliably measures changes in facial movement across varying exercise intensities. Fifteen cyclists completed three, incremental intensity, cycling trials to exhaustion while their faces were recorded with video cameras. Facial feature tracking was found to be a moderately reliable measure of facial movement during incremental intensity cycling (intra-class correlation coefficient = 0.65-0.68). Facial movement (whole face (WF), upper face (UF), lower face (LF) and head movement (HM)) increased with exercise intensity, from lactate threshold one (LT1) until attainment of maximal aerobic power (MAP) (WF 3464 ± 3364mm, P < 0.005; UF 1961 ± 1779mm, P = 0.002; LF 1608 ± 1404mm, P = 0.002; HM 849 ± 642mm, P < 0.001). UF movement was greater than LF movement at all exercise intensities (UF minus LF at: LT1, 1048 ± 383mm; LT2, 1208 ± 611mm; MAP, 1401 ± 712mm; P < 0.001). Significant medium to large non-linear relationships were found between facial movement and power output (r2 = 0.24-0.31), HR (r2 = 0.26-0.33), [La-] (r2 = 0.33-0.44) and RPE (r2 = 0.38-0.45). The findings demonstrate the potential utility of facial feature tracking as a non-invasive, psychophysiological measure to potentially assess exercise intensity.

Immune Recognition of the Epidemic Cystic Fibrosis Pathogen Burkholderia dolosa.

Burkholderia dolosa caused an outbreak in the cystic fibrosis (CF) clinic at Boston Children's Hospital from 1998 to 2005 and led to the infection of over 40 patients, many of whom died due to complications from infection by this organism. To assess whether B. dolosa significantly contributes to disease or is recognized by the host immune response, mice were infected with a sequenced outbreak B. dolosa strain, AU0158, and responses were compared to those to the well-studied CF pathogen Pseudomonas aeruginosa In parallel, mice were also infected with a polar flagellin mutant of B. dolosa to examine the role of flagella in B. dolosa lung colonization. The results showed a higher persistence in the host by B. dolosa strains, and yet, neutrophil recruitment and cytokine production were lower than those with P. aeruginosa The ability of host immune cells to recognize B. dolosa was then assessed, B. dolosa induced a robust cytokine response in cultured cells, and this effect was dependent on the flagella only when bacteria were dead. Together, these results suggest that B. dolosa can be recognized by host cells in vitro but may avoid or suppress the host immune response in vivo through unknown mechanisms. B. dolosa was then compared to other Burkholderia species and found to induce similar levels of cytokine production despite being internalized by macrophages more than Burkholderia cenocepacia strains. These data suggest that B. dolosa AU0158 may act differently with host cells and is recognized differently by immune systems than are other Burkholderia strains or species.

Single-incision percutaneous pericardial ICD lead placement in a piglet model.

INTRODUCTION: Our group has demonstrated the feasibility of percutaneous pericardial ICD lead placement in a piglet model utilizing direct visualization from a lateral thoracoscopic approach. Development of a novel delivery tool that incorporates visualization allows for the procedure to be performed with a 1 cm subxiphoid incision. METHODS AND RESULTS: A 1 cm incision is made in the subxiphoid area and a novel self-anchoring delivery tool is inserted. A rigid thoracoscope and needle are inserted into two crossed working channels of the tool. After needle visualization, pericardial needle access, followed by sheath access is obtained. A modified side-biting ICD lead is inserted and fixated to the ventricular epicardial surface. The lead is connected to an ICD generator and lead testing followed by defibrillation threshold testing (DFT) is performed. Single-incision ICD lead placement was performed in 6 piglets without acute complications. Median time from subxiphoid incision to DFT testing was 64 minutes; median time from thoracoscope insertion to lead fixation was 16.5 minutes (range 9-30). All had adequate ventricular sensing and pacing at implant and underwent successful defibrillation (range 3-5 J). Survival period ranged from 1 to 16 weeks. Two piglets had survival periods of 12 and 16 weeks with mean weight gain of 7 kg; both had successful repeat DFT at 10 J. All survival animals had stable lead impedances and R-wave amplitudes throughout the survival period. CONCLUSION: Percutaneous pericardial placement of an ICD lead using our novel access tool can be safely performed through a 1 cm incision without complications.