Impact and Modifiers of Ventricular Pacing in Patients With Single Ventricle Circulation

BACKGROUND

Palliation of the single ventricle (SV) circulation is associated with a burden of lifelong complications. Previous studies have identified that the need for a permanent ventricular pacing system (PPM_v) may be associated with additional adverse long-term outcomes.

OBJECTIVES

The goal of this study was to quantify the attributable risk of PPM_v in patients with SV, and to identify modifiable risk factors.

METHODS

This international study was sponsored by the Pediatric and Congenital Electrophysiology Society. Centers contributed baseline and longitudinal data for functionally SV patients with PPM_v. Enrollment was at implantation. Controls were matched 1:1 to PPM_v subjects by ventricular morphology and sex, identified within center, and enrolled at matched age. Primary outcome was transplantation or death.

RESULTS

In total, 236 PPM_v subjects and 213 matched controls were identified (22 centers, 9 countries). Median age at enrollment was 5.3 years (quartiles: 1.5-13.2 years), follow-up 6.9 years (3.4-11.6 years). Median percent ventricular pacing (Vp) was 90.8% (25th-75th percentile: 4.3%-100%) in the PPM_v cohort. Across 213 matched pairs, multivariable HR for death/transplant associated with PPM_v was 3.8 (95% CI 1.9-7.6; P < 0.001). Within the PPM_v population, higher Vp (HR: 1.009 per %; P = 0.009), higher QRS z-score (HR: 1.19; P = 0.009) and nonapical lead position (HR: 2.17; P = 0.042) were all associated with death/transplantation.

CONCLUSIONS

PPM_v in patients with SV is associated with increased risk of heart transplantation and death, despite controlling for increased associated morbidity of the PPM_v cohort. Increased Vp, higher QRS z-score, and nonapical ventricular lead position are all associated with higher risk of adverse outcome and may be modifiable risk factors.

Cambridge hybrid closed-loop algorithm in children and adolescents with type 1 diabetes: a multicentre 6-month randomised controlled trial

BACKGROUND

Closed-loop insulin delivery systems have the potential to address suboptimal glucose control in children and adolescents with type 1 diabetes. We compared safety and efficacy of the Cambridge hybrid closed-loop algorithm with usual care over 6 months in this population.

METHODS

In a multicentre, multinational, parallel randomised controlled trial, participants aged 6-18 years using insulin pump therapy were recruited at seven UK and five US paediatric diabetes centres. Key inclusion criteria were diagnosis of type 1 diabetes for at least 12 months, insulin pump therapy for at least 3 months, and screening HbA1c levels between 53 and 86 mmol/mol (7·0-10·0%). Using block randomisation and central randomisation software, we randomly assigned participants to either closed-loop insulin delivery (closed-loop group) or to usual care with insulin pump therapy (control group) for 6 months. Randomisation was stratified at each centre by local baseline HbA1c. The Cambridge closed-loop algorithm running on a smartphone was used with either (1) a modified Medtronic 640G pump, Medtronic Guardian 3 sensor, and Medtronic prototype phone enclosure (FlorenceM configuration), or (2) a Sooil Dana RS pump and Dexcom G6 sensor (CamAPS FX configuration). The primary endpoint was change in HbA1c at 6 months combining data from both configurations. The primary analysis was done in all randomised patients (intention to treat). Trial registration ClinicalTrials.gov, NCT02925299.

FINDINGS

Of 147 people initially screened, 133 participants (mean age 13·0 years [SD 2·8]; 57% female, 43% male) were randomly assigned to either the closed-loop group (n=65) or the control group (n=68). Mean baseline HbA1c was 8·2% (SD 0·7) in the closed-loop group and 8·3% (0·7) in the control group. At 6 months, HbA1c was lower in the closed-loop group than in the control group (between-group difference -3·5 mmol/mol (95% CI -6·5 to -0·5 [-0·32 percentage points, -0·59 to -0·04]; p=0·023). Closed-loop usage was low with FlorenceM due to failing phone enclosures (median 40% [IQR 26-53]), but consistently high with CamAPS FX (93% [88-96]), impacting efficacy. A total of 155 adverse events occurred after randomisation (67 in the closed-loop group, 88 in the control group), including seven severe hypoglycaemia events (four in the closed-loop group, three in the control group), two diabetic ketoacidosis events (both in the closed-loop group), and two non-treatment-related serious adverse events. There were 23 reportable hyperglycaemia events (11 in the closed-loop group, 12 in the control group), which did not meet criteria for diabetic ketoacidosis.

INTERPRETATION

The Cambridge hybrid closed-loop algorithm had an acceptable safety profile, and improved glycaemic control in children and adolescents with type 1 diabetes. To ensure optimal efficacy of the closed-loop system, usage needs to be consistently high, as demonstrated with CamAPS FX.

FUNDING

National Institute of Diabetes and Digestive and Kidney Diseases.

Clinical outcomes and programming strategies of implantable cardioverter-defibrillator devices in paediatric hypertrophic cardiomyopathy: a UK National Cohort Study

AIMS

Sudden cardiac death (SCD) is the most common mode of death in paediatric hypertrophic cardiomyopathy (HCM). This study describes the implant and programming strategies with clinical outcomes following implantable cardioverter-defibrillator (ICD) insertion in a well-characterized national paediatric HCM cohort.

METHODS AND RESULTS

Data from 90 patients undergoing ICD insertion at a median age 13 (±3.5) for primary (n = 67, 74%) or secondary prevention (n = 23, 26%) were collected from a retrospective, longitudinal multi-centre cohort of children (<16 years) with HCM from the UK. Seventy-six (84%) had an endovascular system [14 (18%) dual coil], 3 (3%) epicardial, and 11 (12%) subcutaneous system. Defibrillation threshold (DFT) testing was performed at implant in 68 (76%). Inadequate DFT in four led to implant adjustment in three patients. Over a median follow-up of 54 months (interquartile range 28-111), 25 (28%) patients had 53 appropriate therapies [ICD shock n = 45, anti-tachycardia pacing (ATP) n = 8], incidence rate 4.7 per 100 patient years (95% CI 2.9-7.6). Eight inappropriate therapies occurred in 7 (8%) patients (ICD shock n = 4, ATP n = 4), incidence rate 1.1/100 patient years (95% CI 0.4-2.5). Three patients (3%) died following arrhythmic events, despite a functioning device. Other device complications were seen in 28 patients (31%), including lead-related complications (n = 15) and infection (n = 10). No clinical, device, or programming characteristics predicted time to inappropriate therapy or lead complication.

CONCLUSION

In a large national cohort of paediatric HCM patients with an ICD, device and programming strategies varied widely. No particular strategy was associated with inappropriate therapies, missed/delayed therapies, or lead complications.

A STUDY OF THE IMAGE QUALITY OF COMPUTED TOMOGRAPHY ADAPTIVE STATISTICAL ITERATIVE RECONSTRUCTED BRAIN IMAGES USING SUBJECTIVE AND OBJECTIVE METHODS

The recent reintroduction of iterative reconstruction in computed tomography has facilitated the realisation of major dose saving. The aim of this article was to investigate the possibility of achieving further savings at a site with well-established Adaptive Statistical iterative Reconstruction (ASiR™) (GE Healthcare) brain protocols. An adult patient study was conducted with observers making visual grading assessments using image quality criteria, which were compared with the frequency domain metrics, noise power spectrum and modulation transfer function. Subjective image quality equivalency was found in the 40-70% ASiR™ range, leading to the proposal of ranges for the objective metrics defining acceptable image quality. Based on the findings of both the patient-based and objective studies of the ASiR™/tube-current combinations tested, 60%/305 mA was found to fall within all, but one, of these ranges. Therefore, it is recommended that an ASiR™ level of 60%, with a noise index of 12.20, is a viable alternative to the currently used protocol featuring a 40% ASiR™ level and a noise index of 11.20, potentially representing a 16% dose saving.

Feasibility and outcomes of ajmaline provocation testing for Brugada syndrome in children in a specialist paediatric inherited cardiovascular diseases centre

Objectives

Brugada syndrome (BrS) is an inherited arrhythmia syndrome that causes sudden cardiac death in the young. The class Ia antiarrhythmic ajmaline can be used to provoke the diagnostic ECG pattern. Its use has been established in adults, but little data exist on the ajmaline provocation test in children. This study aims to determine the safety and feasibility of ajmaline provocation testing in a large paediatric cohort in a specialist paediatric inherited cardiac diseases centre.

Methods

98 consecutive ajmaline tests were performed in 95 children between September 2004 and July 2012 for family history of BrS (n=46 (48%)); family history of unexplained sudden cardiac death (n=39 (41%); symptoms with suspicious ECG abnormalities (n=9 (10%)). Three patients were retested with age, due to the possibility of age-related penetrance. ECG parameters were measured at baseline and during maximal ajmaline effect.

Results

The mean patient age was 12.55 years, 43% were female. Nineteen patients (20%) had a positive ajmaline test. There were no arrhythmias or adverse events during testing. Ajmaline provoked significant prolongation of the PR, QRS and QTc in all patients. Mean follow-up was 3.62 years with no adverse outcomes reported in any patients with BrS. There were no predictors of a positive ajmaline provocation test on multivariable analysis. One patient who tested negative at 12 years of age, subsequently tested positive at 15 years of age.

Conclusions

Ajmaline testing appears safe and feasible in children when performed in an appropriate setting by an experienced team. Test positivity may change with age in individuals, suggesting that the test should be repeated in the late teenage years or early adulthood.

Clinical implications of machine-probe combinations on obstetric ultrasound measurements used in pregnancy dating

OBJECTIVE

To investigate the effect of use of different machine-probe combinations on measurement variability and to assess how this variability impacts on accuracy of pregnancy dating.

METHODS

Sixteen different ultrasound machine-probe combinations were used for lateral measurement of targets spaced 10 and 40 mm apart and axial measurement of targets spaced 10 and 50 mm apart in an ultrasound phantom, and differences between the measured and true values were determined. The mean of the 40-mm lateral measurements was used to estimate gestational age using standard obstetric dating tables for crown-rump length (CRL) and femur length (FL) and the mean of the 50-mm axial measurements was used to estimate gestational age using the obstetric dating tables for biparietal diameter (BPD).

RESULTS

As absolute measurements became larger, differences observed using different machine-probe combinations exceeded those due to intraobserver variability. Maximum dating differences for first-trimester CRL of 2 days (based on a measured CRL range of 39-42 mm), second-trimester BPD of 4 days (based on a measured BPD range of 49-52 mm) and FL of 9 days (based on a measured FL range of 39-42 mm) were observed when measurements were transposed to the equivalent gestational age using standard charts.

CONCLUSION

Differences between measured and true values of biometric measurements reflect both machine-probe and intraobserver variability. Incremental first-trimester CRL growth with time is rapid, but second-trimester FL growth is much less so, leaving this lateral measurement more prone to both observer and machine-probe errors. The only axial growth measurement commonly performed is BPD where the measurement differences were intermediate between those of CRL and FL. The differences that can be ascribed to different equipment combinations are in many cases greater than those expected in clinical practice and are of potential importance in determining how fetal biometry is used for dating pregnancies.

Decreased milk drinking causing flecainide toxicity in an older child

Flecainide is a class IC antiarrhythmic agent, used frequently in all age groups for the treatment of tachyarrhythmias. Flecainide blocks the voltage-gated sodium channel in the myocardium, leading to prolongation of depolarisation resulting in slowed conduction velocity. Within a paediatric population, flecainide is indicated primarily for supraventricular tachycardia resulting from atrioventricular nodal re-entry and accessory pathway mediated re-entry. It can be considered for use in patients with atrial tachycardia, fascicular ventricular tachycardia, benign right ventricular outflow tract tachycardia and paroxysmal atrial fibrillation. It is well documented to cause paradoxical proarryhthmia in children, with evidence that milk can reduce absorption in infants. The authors present the case of an older child whose flecainide levels were persistently subtherapeutic until he reduced his milk intake. At this time he developed symptoms of severe flecainide toxicity associated with increased levels.

Thermographic imaging during nasal peanut challenge may be useful in the diagnosis of peanut allergy

BACKGROUND

Double-blinded challenges are widely used for diagnosing food allergy but are time-consuming and cause severe reactions. Outcome relies on subjective interpretation of symptoms, which leads to variations in outcome between observers. Facial thermography combined with nasal peanut challenge was evaluated as a novel objective indicator of clinical allergy.

METHODS

Sixteen children with positive blinded peanut challenge underwent nasal challenge with 10 μg peanut protein or placebo. Mean skin temperatures were recorded from the mouth and nose using infrared thermography over 18 min.

RESULTS

The area under curve of nasal skin temperature was significantly elevated after peanut vs placebo (18.2 vs 4.8°Cmin). The maximum increase in temperature was also significantly greater after peanut: mean difference +0.9°C.

CONCLUSION

This feasibility study shows thermography can detect inflammation caused by nasal challenges whilst employing one thousand-fold less peanut than an oral challenge. This novel technique could be developed to provide a rapid, safe and objective clinical allergy test.

Successful cardiac transplantation in Barth syndrome--single-centre experience of four patients

We describe four patients with Barth syndrome who have undergone successful orthotopic heart transplantation. Patients are one, seven, 12.5 and 14.7 yr post-transplantation. One episode of severe infection occurred. Renal dysfunction and coronary allograft vasculopathy do not appear accelerated over non-Barth patients. Despite withholding purine synthesis inhibitors, these patients have not demonstrated an increased rate of rejection.

Heat distribution and heat transport in bone during radiofrequency catheter ablation

BACKGROUND

To assess the feasibility of percutaneous radiofrequency ablation in large bone tumours, the heat distribution in cortical bone and marrow around inserted electrodes was measured.

METHODS

Fresh bovine cadaver tibial bones were locally heated through drill holes for a maximum of half an hour using water-cooled single radiofrequency electrodes (Radionics Instruments Inc) by pulsed energy. Temperatures were measured in the marrow canal as well as in cortical bone by thermocouples at various distances from the inserted probes.

RESULTS

Perpendicular to the probe, hyperthermia of more than 50 degrees C could be created in bone marrow in a sphere of approximately 3 cm, and of approximately 1 cm in cortical bone.

CONCLUSION

As irreversible cellular damage can be expected when increasing the temperature to 50 degrees C for a duration of 6 min, this method may be effective for the minimal invasive ablation of neoplasms within human bone in cigar-shaped regions of approximately 3-cm diameter.