Left Ventricular Abnormal Substrate in Brugada Syndrome

BACKGROUND

Slow-conductive structural abnormalities located in the epicardium of the right ventricle (RV) underlie Brugada syndrome (BrS). The extent of such substrate in the left ventricle (LV) has not been investigated.

OBJECTIVES

This study sought to characterize the extent of epicardial substrate abnormalities in BrS.

METHODS

We evaluated 22 consecutive patients (mean age 46 ± 11 years, 21 male) referred for recurrent ventricular arrhythmias (mean 10 ± 13 episodes) in the setting of BrS. The patients underwent clinical investigations and wide genetic screening to identify SCN5A mutations and common risk variants. High-density biventricular epicardial mapping was performed to detect prolonged (>70 ms) fragmented electrograms, indicating abnormal substrate area.

RESULTS

All patients presented with abnormal substrate in the epicardial anterior RV (27 ± 11 cm2). Abnormal substrate was also identified on the LV epicardium in 10 patients (45%), 9 at baseline and 1 after ajmaline infusion, covering 15 ± 11 cm2. Of these, 4 had severe LV fascicular blocks. Patients with LV substrate had a longer history of arrhythmia (11.4 ± 6.7 years vs 4.3 ± 4.3 years; P = 0.003), longer PR (217 ± 24 ms vs 171 ± 14 ms; P < 0.001) and HV (60 ± 12 ms vs 46 ± 5 ms; P = 0.005) intervals, and abnormal substrate also extending into the inferior RV (100% vs 33%; P = 0.001). SCN5A mutation was present in 70% of patients with LV substrate (vs 25%; P = 0.035). SCN5A BrS patients with recurrent ventricular arrhythmias present a higher polygenic risk score compared with a nonselected BrS population (median of differences: -0.86; 95% CI: -1.48 to -0.27; P = 0.02).

CONCLUSIONS

A subset of patients with BrS present an abnormal substrate extending onto the LV epicardium and inferior RV that is associated with SCN5A mutations and multigenic variants.

Investigation into the importance of using natural PVCs and pathological models for potential-based ECGI validation

Introduction: Premature ventricular contractions (PVCs) are one of the most commonly targeted pathologies for ECGI validation, often through ventricular stimulation to mimic the ectopic beat. However, it remains unclear if such stimulated beats faithfully reproduce spontaneously occurring PVCs, particularly in the case of the R-on-T phenomenon. The objective of this study was to determine the differences in ECGI accuracy when reconstructing spontaneous PVCs as compared to ventricular-stimulated beats and to explore the impact of pathophysiological perturbation on this reconstruction accuracy. Methods: Langendorff-perfused pig hearts (n = 3) were suspended in a human torso-shaped tank, and local hyperkalemia was induced through perfusion of a high-K⁺ solution (8 mM) into the LAD. Recordings were taken simultaneously from the heart and tank surfaces during ventricular pacing and during spontaneous PVCs (including R-on-T), both at baseline and high K⁺. Epicardial potentials were reconstructed from torso potentials using ECGI. Results: Spontaneously occurring PVCs were better reconstructed than stimulated beats at baseline in terms of electrogram morphology [correlation coefficient (CC) = 0.74 ± 0.05 vs. CC = 0.60 ± 0.10], potential maps (CC = 0.61 ± 0.06 vs. CC = 0.51 ± 0.12), and activation time maps (CC = 0.86 ± 0.07 vs. 0.76 ± 0.10), though there was no difference in the localization error (LE) of epicardial origin (LE = 14 ± 6 vs. 15 ± 11 mm). High K⁺ perfusion reduced the accuracy of ECGI reconstructions in terms of electrogram morphology (CC = 0.68 ± 0.10) and AT maps (CC = 0.70 ± 0.12 and 0.59 ± 0.23) for isolated PVCs and paced beats, respectively. LE trended worse, but the change was not significant (LE = 17 ± 9 and 20 ± 12 mm). Spontaneous PVCs were less well when the R-on-T phenomenon occurred and the activation wavefronts encountered a line of block. Conclusion: This study demonstrates the differences in ECGI accuracy between spontaneous PVCs and ventricular-paced beats. We also observed a reduction in this accuracy near regions of electrically inactive tissue. These results highlight the need for more physiologically realistic experimental models when evaluating the accuracy of ECGI methods. In particular, reconstruction accuracy needs to be further evaluated in the presence of R-on-T or isolated PVCs, particularly when encountering obstacles (functional or anatomical) which cause line of block and re-entry.

Optimizing graft-recipient size matching in adolescent liver transplantation: Don't forget ex situ right posterior sectionectomy

BACKGROUND

Graft-recipient size matching is a major challenge in pediatric liver transplantation, especially for adolescent recipients. Indeed, adolescents have the lowest transplantation rate among pediatric recipients, despite prioritization policies and the use of split grafts. In case of an important graft-recipient size mismatch, ex situ graft reduction with right posterior sectionectomy (RPS) may optimize the available donor pool to benefit adolescent recipients.

METHODS

We present three cases of liver graft reduction with ex situ RPS for adolescent recipients. The surgical strategy was guided by GRWR (graft/recipient weight ratio), GW/RAP (right anteroposterior distance ratio), and CT-scan volumetric and anthropometric evaluation.

RESULTS

Recipients were 12, 13, and 14-year-old and weighed 32, 47, and 35 kg, respectively. All liver grafts were procured from brain-dead donors with a donor/recipient weight ratio >1.5. RPS was performed ex situ, removing 20% of the total liver volume leading to a decrease of the GRWR <4% and the GW/RAP <100 g/cm in each case. All three reduced grafts were successfully transplanted with a static cold storage time ranging from 390 to 510 min without the need for delayed abdominal closure. We did not observe any primary non-function, vascular complication, or delayed graft function with a median follow-up of 6 months. One biliary anastomotic stenosis occurred which required surgical treatment.

CONCLUSION

Ex situ liver graft reduction with RPS allowed for successful transplantation in case of anthropometric graft-recipient size mismatch in adolescent liver transplant candidates. Although the use of split grafts remains the gold standard, RPS should be acknowledged as a way to optimize the donor pool, especially for adolescent recipients.

24-Hour Monitoring of Intraocular Pressure Fluctuations Using a Contact Lens Sensor: Diagnostic Performance for Glaucoma Progression

Purpose

The purpose of this study was to compare 24-hour intraocular pressure (IOP) related fluctuations monitoring between 2 groups of visual field progression rates in patients with open angle glaucoma (OAG).

Methods

Cross-sectional study performed at Bordeaux University Hospital. Twenty-four-hour monitoring was performed using a contact lens sensor (CLS; Triggerfish; SENSIMED, Etagnières, Switzerland). Progression rate was calculated using a linear regression of the mean deviation (MD) parameter of the visual field test (Octopus; HAAG-STREIT, Switzerland). Patients were allocated into two groups: group 1 with an MD progression rate <-0.5 dB/year and group 2 with an MD progression rate ≥-0.5 dB/year. An automatic signal-processing program was developed and a frequency filtering of the monitoring by wavelet transform analysis was used to compare the output signal between the two groups. A multivariate classifier was performed for prediction of the faster progression group.

Results

Fifty-four eyes of 54 patients were included. The mean progression rate was -1.09 ± 0.60 dB/year in group 1 (n = 22) and -0.12 ± 0.13 dB/year in group 2 (n = 32). Twenty-four-hour magnitude and absolute area under the monitoring curve were significantly higher in group 1 than in group 2 (group 1: 343.1 ± 62.3 millivolts [mVs] and 8.28 ± 2.10 mVs, respectively, group 2: 274.0 ± 75.0 mV and 6.82 ± 2.70 mVs respectively, P < 0.05). Magnitude and area under the wavelet curve for short frequency periods ranging from 60 to 220 minutes were also significantly higher in group 1 (P < 0.05).

Conclusions

The 24-hour IOP related fluctuations characteristics, as assessed by a CLS, may act as a risk factor for progression in OAG. In association with other predictive factors of glaucoma progression, the CLS may help adjust treatment strategy earlier.

Atrial Periodic Source Spectrum from Preoperative Body Surface Potentials Predicts Long-term Recurrence of Atrial Fibrillation

OBJECTIVE

About half of patients experience recurrence of atrial fibrillation (AF) within three to five years after a single catheter ablation procedure. The suboptimality of the long-term outcomes likely results from the inter-patient variability of AF mechanisms, which can be remedied by improved patient screening. We aim to improve the interpretation of body surface potentials (BSPs), such as 12-lead electrocardiograms and 252-lead BSP maps, to aid preoperative patient screening.

METHODS

We developed the Atrial Periodic Source Spectrum (APSS), a novel patient-specific representation based on atrial periodic content, computed on the f-wave segments of patient BSPs, using a second-order blind source separation and a Gaussian Process for regression. With follow-up data, Cox's proportional hazard model was used to select the most relevant feature from preoperative APSSs responsible for AF recurrence.

RESULTS

Over 138 persistent AF patients, the presence of highly periodic content with cycle lengths between 220-230 ms or 350-400 ms indicates higher risks of 4-year post-ablation AF recurrence (log-rank test, p-value ).

CONCLUSION AND SIGNIFICANCE

Preoperative BSPs demonstrate effective prediction in the long-term outcomes, highlighting their potential for patient screening in AF ablation therapy.

Full left/full right liver graft ex situ split during hypothermic oxygenated perfusion

BACKGROUND

Ex vivo split liver transplantation in pediatric recipients has shown inferior results compared with whole grafts. One factor among others contributing to split grafts being considered as marginal is the prolonged static cold storage time related to ex vivo liver splitting. End ischemic hypothermic oxygenated perfusion is a validated strategy to improve outcomes of marginal whole grafts and may thus also benefit split liver grafts.

METHOD

We present the first case of full left/full right split procedure performed during hypothermic oxygenated perfusion.

RESULTS

We present a standardized surgical two-step approach where parenchymal transection was performed during end ischemic hypothermic oxygenated perfusion via the portal vein to shorten static cold storage duration. Both split grafts were successfully transplanted in a 4-year-old pediatric and a 38-year-old adult recipient. Despite high-risk procedure (retransplantation), extended donor criteria including a prolonged cardiac arrest and high donor risk index (2,25), both grafts showed early recovery of hepatic function and low serum transaminase release. At 6 months, both recipients were alive with a normal liver biology and a functioning graft.

CONCLUSION

Although challenging, full left/full right liver split procedure during end ischemic hypothermic oxygenated perfusion can be successfully performed and is a promising strategy to improve post-transplant outcomes.

OUP accepted manuscript

Aims

Mapping data of human ventricular fibrillation (VF) are limited. We performed detailed mapping of the activities underlying the onset of VF and targeted ablation in patients with structural cardiac abnormalities.

Methods and results

We evaluated 54 patients (50 ± 16 years) with VF in the setting of ischaemic (n = 15), hypertrophic (n = 8) or dilated cardiomyopathy (n = 12), or Brugada syndrome (n = 19). Ventricular fibrillation was mapped using body-surface mapping to identify driver (reentrant and focal) areas and invasive Purkinje mapping. Purkinje drivers were defined as Purkinje activities faster than the local ventricular rate. Structural substrate was delineated by electrogram criteria and by imaging. Catheter ablation was performed in 41 patients with recurrent VF. Sixty-one episodes of spontaneous (n = 10) or induced (n = 51) VF were mapped. Ventricular fibrillation was organized for the initial 5.0 ± 3.4 s, exhibiting large wavefronts with similar cycle lengths (CLs) across both ventricles (197 ± 23 vs. 196 ± 22 ms, P = 0.9). Most drivers (81%) originated from areas associated with the structural substrate. The Purkinje system was implicated as a trigger or driver in 43% of patients with cardiomyopathy. The transition to disorganized VF was associated with the acceleration of initial reentrant activities (CL shortening from 187 ± 17 to 175 ± 20 ms, P < 0.001), then spatial dissemination of drivers. Purkinje and substrate ablation resulted in the reduction of VF recurrences from a pre-procedural median of seven episodes [interquartile range (IQR) 4–16] to 0 episode (IQR 0–2) (P < 0.001) at 56 ± 30 months.

Conclusions

The onset of human VF is sustained by activities originating from Purkinje and structural substrate, before spreading throughout the ventricles to establish disorganized VF. Targeted ablation results in effective reduction of VF burden.

Key question

The initial phase of human ventricular fibrillation (VF) is critical as it involves the primary activities leading to sustained VF and arrhythmic sudden death. The origin of such activities is unknown.

Key finding

Body-surface mapping shows that most drivers (≈80%) during the initial VF phase originate from electrophysiologically defined structural substrates. Repetitive Purkinje activities can be elicited by programmed stimulation and are implicated as drivers in 37% of cardiomyopathy patients.

Take-home message

The onset of human VF is mostly associated with activities from the Purkinje network and structural substrate, before spreading throughout the ventricles to establish sustained VF. Targeted ablation reduces or eliminates VF recurrence.

Excision of Wilms' Tumor With Atrial Extension Under Moderate Hypothermia and Cerebral Perfusion

BACKGROUND

Wilms' tumor is the most common pediatric renal tumor. Almost half of all cases have involvement of the inferior vena cava, which must be addressed at the time of surgical excision. Further extension into the right atrium may pose an immediate vital risk and necessitates special operative techniques that employ cardiopulmonary bypass.

CASE REPORT

We report the case of a child with a left Wilms' tumor with inferior caval and right atrial involvement, which led to significant hemodynamic compromise and urgent surgery. A left nephrectomy and cavoatrial thrombectomy were performed via a sterno-laparotomy. Our strategy employed moderate hypothermic circulatory arrest at 26°C and antegrade cerebral perfusion in order to improve visualization and ensure complete thrombectomy and protection of the abdominal organs.

CONCLUSION

This case emphasizes the advantages of moderate hypothermic circulatory arrest compared to deep hypothermic circulatory arrest and normothemic cardiopulmonary bypass.

A novel method to correct repolarization time estimation from unipolar electrograms distorted by standard filtering

Reliable patient-specific ventricular repolarization times (RTs) can identify regions of functional block or afterdepolarizations, indicating arrhythmogenic cardiac tissue and the risk of sudden cardiac death. Unipolar electrograms (UEs) record electric potentials, and the Wyatt method has been shown to be accurate for estimating RT from a UE. High-pass filtering is an important step in processing UEs, however, it is known to distort the T-wave phase of the UE, which may compromise the accuracy of the Wyatt method. The aim of this study was to examine the effects of high-pass filtering, and improve RT estimates derived from filtered UEs. We first generated a comprehensive set of UEs, corresponding to early and late activation and repolarization, that were then high-pass filtered with settings that mimicked the CARTO filter. We trained a deep neural network (DNN) to output a probabilistic estimation of RT and a measure of confidence, using the filtered synthetic UEs and their true RTs. Unfiltered ex-vivo human UEs were also filtered and the trained DNN used to estimate RT. Even a modest 2 Hz high-pass filter imposes a significant error on RT estimation using the Wyatt method. The DNN outperformed the Wyatt method in 62.75% of cases, and produced a significantly lower absolute error (p=8.99E-13), with a median of 16.91 ms, on 102 ex-vivo UEs. We also applied the DNN to patient UEs from CARTO, from which an RT map was computed. In conclusion, DNNs trained on synthetic UEs improve the RT estimation from filtered UEs, which leads to more reliable repolarization maps that help to identify patient-specific repolarization abnormalities.

Epidemiological changes in cutaneous lymphomas: an analysis of 8593 patients from the French Cutaneous Lymphoma Registry

BACKGROUND

Primary cutaneous lymphomas (PCLs) are a heterogeneous group of T-cell (CTCL) and B-cell (CBCL) malignancies. Little is known about their epidemiology at initial presentation in Europe and about potential changes over time.

OBJECTIVES

The aim of this retrospective study was to analyse the frequency of PCLs in the French Cutaneous Lymphoma Registry (GFELC) and to describe the demography of patients.

METHODS

Patients with a centrally validated diagnosis of primary PCL, diagnosed between 2005 and 2019, were included.

RESULTS

The calculated incidence was unprecedently high at 1·06 per 100 000 person-years. The number of included patients increased yearly. Most PCL subtypes were more frequent in male patients, diagnosed at a median age of 60 years. The relative frequency of rare CTCL remained stable, the proportion of classical mycosis fungoides (MF) decreased, and the frequency of its variants (e.g. folliculotropic MF) increased. Similar patterns were observed for CBCL; for example, the proportion of marginal-zone CBCL increased over time.

CONCLUSIONS

Changes in PCL frequencies may be explained by the emergence of new diagnostic criteria and better description of the entities in the most recent PCL classification. Moreover, we propose that an algorithm should be developed to confirm the diagnosis of PCL by central validation of the cases.

A novel trigger-substrate mechanism based on clinically concealed repolarization abnormalities underlies idiopathic ventricular fibrillation

Background

Sudden cardiac arrest (SCA) is most often due to ventricular fibrillation (VF). When no cause is found during diagnostic follow-up, fibrillation is classified as idiopathic (iVF). We hypothesize that a critical functional substrate-trigger interaction underlies iVF.

Purpose

To study electrophysiological triggers and substrate for iVF in a clinical cohort; and seek mechanistic explanations in explanted pig hearts and computer models mimicking trigger-substrate interactions.

Methods

Repolarization time (RT) isochrones on the epicardium were studied with electrocardiographic imaging (ECGI) in patients with iVF, patients with frequent monomorphic premature ventricular complexes (fmPVC) but no structural disease or SCA, and controls without cardiovascular disease.

RT gradients were created in explanted, Langendorff-perfused pig hearts by local infusion of dofetilide (“dof”, 250 nM, delaying RT) and pinacidil (“pin”, 30 μM, shortening RT) in adjacent regions of the heart. Arrhythmia inducibility was tested by programmed stimulation (8 atrial stimuli [S1] followed by one ventricular stimulus [S2] paced at regions of early or late RT).

A computational ventricular monodomain model was used to study the location-dependency of trigger-substrate interaction; RT gradients were created by local changes in potassium channel conductance.

Results

Although QTc values were similar, iVF survivors (n=11) displayed significantly steeper RT gradients than controls (n=10) or fmPVC individuals (n=7): 269±111 vs 179±40 vs 171±76 ms/cm respectively (panel A). Unipolar electrograms (EGMs) at the gradients displayed a change in polarity of the local T wave (B). In iVF, PVCs originated more often from regions with early RT than in fmPVC individuals (yellow circles in A; 64% vs 14%).

In the explanted hearts (C), drug infusion resulted in similar RT gradients and polarity changes of EGM T waves (D-E). VF inducibility by pacing of the early RT region (D) increased significantly with steeper RT gradients (baseline: 3/6 hearts inducible, dof+pin: 3/3). Pacing of late RT regions (E) did not induce arrhythmias in baseline (0/6) nor with RT gradients (0/3). For similar pacing intervals at the early RT region, the 12-lead ECG R-on-T morphology was similar but VF only occurred in the presence of RT gradients (F).

In the computer model, the number of inducible pacing intervals critically depended on the stimulus location (G).

Conclusion

Combined, these results demonstrate that R-on-T superposition per se is insufficient to explain arrhythmogenesis. Rather, not only the temporal coupling interval but also the spatial origin of PVCs in relationship to the degree of local repolarization abnormalities are critical elements. In iVF, a substrate of RT gradients (panel H1) with triggers from early RT regions (H2) precipitate reentry (H3). Noninvasive ECGI can uncover these substrate and trigger characteristics in (at least a subset of) iVF survivors.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Netherlands Organization for Scientific Research Veni grant TTW 16772, French National Research Agency (ANR-10-IAHU04-LIRYC)

Automated rhythm-based control of radiofrequency ablation close to the atrioventricular node: Preclinical, animal, and first-in-human testing

BACKGROUND

The risk of heart block during radiofrequency ablation of atrioventricular (AV) nodal reentrant tachycardia and septal accessory pathways is minimized by rapidly ceasing ablation in response to markers of risk, such as atrioventricular dissociation, fast junctional rhythm, PR interval prolongation, or 2 consecutive atrial or ventricular depolarizations. Currently this is done manually.

OBJECTIVES

The objectives of this study were to build and test a control system able to monitor cardiac rhythm and automatically terminate ablation energy when required.

METHODS

The device was built from off-shelf componentry. Preclinical testing involved real-time input of electrogram/electrocardiogram data from 209 ablation procedures (20 patients) over slow (n = 19) and fast (n = 1) AV nodal pathways. The device response speed was compared with the human response speed. The device's ability to prevent heart block was tested in 5 sheep. First-in-human testing was then performed in 12 patients undergoing AV nodal reentrant tachycardia ablation.

RESULTS

Risk conditions necessitating shutoff of ablation (200 total; 111 preclinical and 89 first-in-human) were detected by the device with 100% sensitivity and 94% specificity, automatically terminating ablation while still allowing successful ablation in all patients. Device shutoff of ablation was always faster than human response (median difference 1.24 seconds). In each of 5 sheep, 40 consecutive attempts to cause heart block by ablating over the His bundle were unsuccessful because of automatic shutoff in response to rhythm change.

CONCLUSION

Automated shutoff of ablation close to the AV node in response to markers of the risk of heart block is feasible with high accuracy as well as faster response than human response. The system may improve the safety of ablation near the AV node by preventing heart block.

Critical repolarization gradients determine the induction of reentry-based torsades de pointes arrhythmia in models of long QT syndrome

BACKGROUND

Torsades de pointes arrhythmia is a potentially lethal polymorphic ventricular tachyarrhythmia (pVT) in the setting of long QT syndrome. Arrhythmia susceptibility is influenced by risk factors modifying repolarization.

OBJECTIVE

The purpose of this article was to characterize repolarization duration and heterogeneity in relation to pVT inducibility and maintenance.

METHODS

Sotalol was infused regionally or globally in isolated Langendorff blood-perfused pig hearts (N = 7) to create repolarization time (RT) heterogeneities. Programmed stimulation and epicardial activation and repolarization mapping were performed. The role of RT (heterogeneities) was studied in more detail using a computer model of the human heart.

RESULTS

pVTs (n = 11) were inducible at a critical combination of RT and RT heterogeneities. The pVT cycle lengths were similar in the short and long RT regions. Short-lasting pVTs were maintained by focal activity while longer-lasting pVTs by reentry wandering along the interface between the 2 regions. Local restitution curves from the long and short RT regions crossed. This was associated with T-wave inversion at coupling intervals at either side of the crossing point. These experimental observations were confirmed by the computer simulations.

CONCLUSION

pVTs are inducible within a critical range of RT and RT heterogeneities and are maintained by reentry wandering along the repolarization gradient. Double potentials localize at the core of the reentrant circuit and reflect phase singularities. RT gradient and T waves invert with short-coupled premature beats in the long RT region as a result of the crossing of the restitution curves allowing reentry initiation.

Idiopathic Ventricular Fibrillation: Role of Purkinje System and Microstructural Myocardial Abnormalities

Idiopathic ventricular fibrillation is diagnosed in patients who survived a ventricular fibrillation episode without any identifiable structural or electrical cause after extensive investigations. It is a common cause of sudden death in young adults. The study reviews the diagnostic value of systematic investigations and the new insights provided by detailed electrophysiological mapping. Recent studies have shown the high incidence of microstructural cardiomyopathic areas, which act as the substrate of ventricular fibrillation re-entries. These subclinical alterations require high-density endo- and epicardial mapping to be identified using electrogram criteria. Small areas are involved and located individually in various sites (mostly epicardial). Their characteristics suggest a variety of genetic or acquired pathological processes affecting cellular connectivity or tissue structure, such as cardiomyopathies, myocarditis, or fatty infiltration. Purkinje abnormalities manifesting as triggering ectopy or providing a substrate for re-entry represent a second important cause. The documentation of ephemeral Purkinje ectopy requires continuous electrocardiography monitoring for diagnosis. A variety of diseases affecting Purkinje cell function or conduction are potentially at play in their pathogenesis. Comprehensive investigations can therefore allow the great majority of idiopathic ventricular fibrillation to ultimately receive diagnoses of a cardiac disease, likely underlain by a mosaic of pathologies. Precise phenotypic characterization has significant implications for interpretation of genetic variants, the risk assessment, and individual therapy. Future improvements in imaging or electrophysiological methods may hopefully allow the identification of the subjects at risk and the development of primary prevention strategies.

Natural History of Perianal Fistulising Lesions in Patients With Elderly-onset Crohn's Disease: A Population-based Study

INTRODUCTION

Most studies of elderly-onset Crohn's disease [CD; diagnosed in patients aged 60 or over] have described a mild course. However, data on the natural history of perianal fistulising CD [pfCD] in this population are scarce. In a population-based cohort study, we described the prevalence, natural history, and treatment of pfCD in patients with elderly-onset CD vs patients with paediatric-onset CD.

METHOD

All patients diagnosed with CD at or after the age of 60 between 1988 and 2006, were included [n = 372]. Logistic regression, Cox models, and a nested case-control method were used to identify factors associated with pfCD.

RESULTS

A total of 34 elderly patients [9% of the 372] had pfCD at diagnosis. After a median follow-up of 6 years (interquartile range [IQR]: 3; 10), 59 patients [16%] had pfCD; the same prevalence [16%] was observed in paediatric-onset patients. At last follow-up, anal incontinence was more frequent in elderly patients with pfCD than in elderly patients without pfCD [22% vs 4%, respectively; p < 10-4]. Rectal CD at diagnosis was associated with pfCD: hazard ratio (95% confidence interval [CI] = 2.8 [1.6-5.0]). Although 37% of the patients received immunosuppressants and 17% received anti-tumour necrosis factor agents, 24% [14 out of 59] had a definitive stoma at last follow-up.

CONCLUSION

During the first 6 years of disease, the prevalence of pfCD was similar in elderly and paediatric patients. Rectal involvement was associated with the appearance of pfCD in elderly-onset patients. Around a quarter of patients with elderly-onset CD will have a stoma. Our results suggest that treatment with biologics should be evaluated in these patients.

Electrogram morphology discriminators in implantable cardioverter defibrillators: A comparative evaluation

BACKGROUND

Morphology algorithms are currently recommended as a standalone discriminator in single-chamber implantable cardioverter defibrillators (ICDs). However, these proprietary algorithms differ in both design and nominal programming.

OBJECTIVE

To compare three different algorithms with nominal versus advanced programming in their ability to discriminate between ventricular (VT) and supraventricular tachycardia (SVT).

METHODS

In nine European centers, VT and SVTs were collected from Abbott, Boston Scientific, and Medtronic dual- and triple-chamber ICDs via their respective remote monitoring portals. Percentage morphology matches were recorded for selected episodes which were classified as VT or SVT by means of atrioventricular comparison. The sensitivity and related specificity of each manufacturer discriminator was determined at various values of template match percentage from receiving operating characteristics (ROC) curve analysis.

RESULTS

A total of 534 episodes were retained for the analysis. In ROC analyses, Abbott Far Field MD (area under the curve [AUC]: 0.91; P < .001) and Boston Scientific RhythmID (AUC: 0.95; P < .001) show higher AUC than Medtronic Wavelet (AUC: 0.81; P < .001) when tested for their ability to discriminate VT from SVT. At nominal % match threshold all devices provided high sensitivity in VT identification, (91%, 100%, and 90%, respectively, for Abbott, Boston Scientific, and Medtronic) but contrasted specificities in SVT discrimination (85%, 41%, and 62%, respectively). Abbott and Medtronic's nominal thresholds were similar to the optimal thresholds. Optimization of the % match threshold improved the Boston Scientific specificity to 79% without compromising the sensitivity.

CONCLUSION

Proprietary morphology discriminators show important differences in their ability to discriminate SVT. How much this impact the overall discrimination process remains to be investigated.

Effects of Interpolation on the Inverse Problem of Electrocardiography

Electrocardiographic Imaging (ECGI) aims to reconstruct electrograms from the body surface potential measurements. Bad leads are usually excluded from the inverse problem solution. Alternatively, interpolation can be applied. This study explores how sensitive ECGI is to different bad-lead configurations and interpolation methods. Experimental data from a Langendorff-perfused pig heart suspended in a human-shaped torso-tank was used. Epicardial electrograms were acquired during 30 s (31 beats) of RV pacing using a 108-electrode array, simultaneously with torso potentials from 128 electrodes embedded in the tank surface. Six different bad lead cases were designed based on clinical experience. Inverse problem was solved by applying Tikhonov regularization i) using the complete data, ii) bad-leads-removed data, and iii) interpolated data, with 5 different methods. Our results showed that ECGI accuracy of an interpolation method highly depends on the location of the bad leads. If they are in the high-potential-gradient regions of the torso, a highly accurate interpolation method is needed to achieve an ECGI accuracy close to using complete data. If the BSP reconstruction of the interpolation method is poor in these regions, the reconstructed electrograms also have lower accuracy, suggesting that bad leads should be removed instead of interpolated. The inverse-forward method was found to be the best among all interpolation methods applied in this study in terms of both missing BSP lead reconstruction and ECGI accuracy, even for the bad leads located over the chest.

The Spectrum of Idiopathic Ventricular Fibrillation and J-Wave Syndromes: Novel Mapping Insights

Idiopathic ventricular fibrillation and J-wave syndromes are causes of sudden cardiac death (SCD) without any identified structural cardiac disease after extensive investigations. Recent data show that high-density electrophysiological mapping may ultimately offer diagnoses of subclinical diseases in most patients including those termed "unexplained" SCD. Three major conditions can underlie the occurrence of SCD: (1) localized depolarization abnormalities (due to microstructural myocardial alteration), (2) Purkinje abnormalities manifesting as triggering ectopy and inducible reentry; or (3) repolarization heterogeneities. Each condition may result from a spectrum of pathophysiologic processes with implications for individual therapy.

Localized Structural Alterations Underlying a Subset of Unexplained Sudden Cardiac Death

Supplemental Digital Content is available in the text.

Background:

Sudden cardiac death because of ventricular fibrillation (VF) is commonly unexplained in younger victims. Detailed electrophysiological mapping in such patients has not been reported.

Methods:

We evaluated 24 patients (29±13 years) who survived idiopathic VF. First, we used multielectrode body surface recordings to identify the drivers maintaining VF. Then, we analyzed electrograms in the driver regions using endocardial and epicardial catheter mapping during sinus rhythm. Established electrogram criteria were used to identify the presence of structural alterations.

Results:

VF occurred spontaneously in 3 patients and was induced in 16, whereas VF was noninducible in 5. VF mapping demonstrated reentrant and focal activities (87% versus 13%, respectively) in all. The activities were dominant in one ventricle in 9 patients, whereas they had biventricular distribution in others. During sinus rhythm areas of abnormal electrograms were identified in 15/24 patients (62.5%) revealing localized structural alterations: in the right ventricle in 11, the left ventricle in 1, and both in 3. They covered a limited surface (13±6 cm²) representing 5±3% of the total surface and were recorded predominantly on the epicardium. Seventy-six percent of these areas were colocated with VF drivers (P<0.001). In the 9 patients without structural alteration, we observed a high incidence of Purkinje triggers (7/9 versus 4/15, P=0.033). Catheter ablation resulted in arrhythmia-free outcome in 15/18 patients at 17±11 months follow-up.

Conclusions:

This study shows that localized structural alterations underlie a significant subset of previously unexplained sudden cardiac death. In the other subset, Purkinje electrical pathology seems as a dominant mechanism.

Noninvasive Mapping and Electrocardiographic Imaging in Atrial and Ventricular Arrhythmias (CardioInsight)

Electrocardiographic imaging is a mapping technique aiming to noninvasively characterize cardiac electrical activity using signals collected from the torso to reconstruct epicardial potentials. Its efficacy has been demonstrated clinically, from mapping premature ventricular complexes and accessory pathways to of complex arrhythmias. Electrocardiographic imaging uses a standardized workflow. Signals should be checked manually to avoid automatic processing errors. Reentry is confirmed in the presence of local activation covering the arrhythmia cycle length. Focal breakthroughs demonstrate a QS pattern associated with centrifugal activation. Electrocardiographic imaging offers a unique opportunity to better understand the mechanism of cardiac arrhythmias and guide ablation.

Reduction of Effects of Noise on the Inverse Problem of Electrocardiography with Bayesian Estimation

To overcome the ill-posed nature of the inverse problem of electrocardiography (ECG) and stabilize the solutions, regularization is used. Despite several studies on noise, effect of prefiltering of ECG signals on the regularized inverse solutions has not been explored. We used Bayesian estimation for solving the inverse ECG problem with and without applying various prefiltering methods, and evaluated our results using experimental data that came from a Langendorff-perfused pig heart suspended in a human-shaped torso-tank. Epicardial electrograms were recorded during RV pacing using a 108-electrode array, simultaneously with ECGs from 128 electrodes embedded in the tank surface. Leave-one-beat-out protocol was used to obtain the prior probability density function (pdf) of electro-grams and noise statistics. Noise pdf was assumed to be zero mean-Gaussian, with covariance assumptions: a) independent and identically distributed (noi-iid), b) correlated (noi-corr). Reconstructed electrograms and activation times were compared to those directly recorded by the sock for 3 beats selected from the recording. Noi-corr is superior to noi-iid when the training set is a good match to data, but for applications requiring activation time derivation, careful selection of preprocessing methods, in particular to adequately remove high-frequency noise, and an appropriate noise model is needed.

Effects of ECG Signal Processing on the Inverse Problem of Electrocardiography

The inverse problem of electrocardiography is ill-posed. Errors in the model such as signal noise can impact the accuracy of reconstructed cardiac electrical activity. It is currently not known how sensitive the inverse problem is to signal processing techniques. To evaluate this, experimental data from a Langendorff-perfused pig heart (n=1) suspended in a human-shaped torso-tank was used. Different signal processing methods were applied to torso potentials recorded from 128 electrodes embedded in the tank surface. Processing methods were divided into three categories i) high-frequency noise removal ii) baseline drift removal and iii) signal averaging, culminating in n=72 different signal sets. For each signal set, the inverse problem was solved and reconstructed signals were compared to those directly recorded by the sock around the heart. ECG signal processing methods had a dramatic effect on reconstruction accuracy. In particular, removal of baseline drift significantly impacts the magnitude of reconstructed electrograms, while the presence of high-frequency noise impacts the activation time derived from these signals (p<0.05).

Mapping and Ablation of Idiopathic Ventricular Fibrillation

Idiopathic ventricular fibrillation (IVF) is the main cause of unexplained sudden cardiac death, particularly in young patients under the age of 35. IVF is a diagnosis of exclusion in patients who have survived a VF episode without any identifiable structural or metabolic causes despite extensive diagnostic testing. Genetic testing allows identification of a likely causative mutation in up to 27% of unexplained sudden deaths in children and young adults. In the majority of cases, VF is triggered by PVCs that originate from the Purkinje network. Ablation of VF triggers in this setting is associated with high rates of acute success and long-term freedom from VF recurrence. Recent studies demonstrate that a significant subset of IVF defined by negative comprehensive investigations, demonstrate in fact subclinical structural alterations. These localized myocardial alterations are identified by high density electrogram mapping, are of small size and are mainly located in the epicardium. As reentrant VF drivers are often colocated with regions of abnormal electrograms, this localized substrate can be shown to be mechanistically linked with VF. Such areas may represent an important target for ablation.

Wavelength and Fibrosis Affect Phase Singularity Locations During Atrial Fibrillation

The mechanisms underlying atrial fibrillation (AF), the most common sustained cardiac rhythm disturbance, remain elusive. Atrial fibrosis plays an important role in the development of AF and rotor dynamics. Both electrical wavelength (WL) and the degree of atrial fibrosis change as AF progresses. However, their combined effect on rotor core location remains unknown. The aim of this study was to analyze the effects of WL change on rotor core location in both fibrotic and non-fibrotic atria. Three patient specific fibrosis distributions (total fibrosis content: 16.6, 22.8, and 19.2%) obtained from clinical imaging data of persistent AF patients were incorporated in a bilayer atrial computational model. Fibrotic effects were modeled as myocyte-fibroblast coupling + conductivity remodeling; structural remodeling; ionic current changes + conductivity remodeling; and combinations of these methods. To change WL, action potential duration (APD) was varied from 120 to 240ms, representing the range of clinically observed AF cycle length, by modifying the inward rectifier potassium current (IK1) conductance between 80 and 140% of the original value. Phase singularities (PSs) were computed to identify rotor core locations. Our results show that IK1 conductance variation resulted in a decrease of APD and WL across the atria. For large WL in the absence of fibrosis, PSs anchored to regions with high APD gradient at the center of the left atrium (LA) anterior wall and near the junctions of the inferior pulmonary veins (PVs) with the LA. Decreasing the WL induced more PSs, whose distribution became less clustered. With fibrosis, PS locations depended on the fibrosis distribution and the fibrosis implementation method. The proportion of PSs in fibrotic areas and along the borders varied with both WL and fibrosis modeling method: for patient one, this was 4.2-14.9% as IK1 varied for the structural remodeling representation, but 12.3-88.4% using the combination of structural remodeling with myocyte-fibroblast coupling. The degree and distribution of fibrosis and the choice of implementation technique had a larger effect on PS locations than the WL variation. Thus, distinguishing the fibrotic mechanisms present in a patient is important for interpreting clinical fibrosis maps to create personalized models.

TTC7A mutation must be considered in patients with repeated intestinal atresia associated with early inflammatory bowel disease: Two new case reports and a literature review

TTC7A mutations cause multiple neonatal intestinal atresias with early inflammatory bowel disease and severe combined immunodeficiency. There are no treatment protocols for this rare disease. Two new cases are described for which radical early treatment measures - total enterectomy, home parenteral nutrition, immunoglobulin therapy and intravenous antibiotic prophylaxis - have allowed both patients to develop optimally.

Dramatic Increase in Incidence of Ulcerative Colitis and Crohn's Disease (1988-2011): A Population-Based Study of French Adolescents

OBJECTIVES

Few data are available to describe the changes in incidence of pediatric-onset inflammatory bowel disease (IBD). The aim of this study was to describe changes in incidence and phenotypic presentation of pediatric-onset IBD in northern France during a 24-year period.

METHODS

Pediatric-onset IBD (<17 years) was issued from a population-based IBD study in France between 1988 and 2011. Age groups and digestive location were defined according to the Paris classification.

RESULTS

1,350 incident cases were recorded (8.3% of all IBD) including 990 Crohn's disease (CD), 326 ulcerative colitis (UC) and 34 IBD unclassified (IBDU). Median age at diagnosis was similar in CD (14.4 years (Q1=11.8-Q3=16.0)) and UC (14.0 years (11.0-16.0)) and did not change over time. There were significantly more males with CD (females/males=0.82) than UC (females/males=1.25) (P=0.0042). Median time between onset of symptoms and IBD diagnosis was consistently 3 months (1-6). Mean incidence was 4.4/10⁵ for IBD overall (3.2 for CD, 1.1 for UC and 0.1 for IBDU). From 1988-1990 to 2009-2011, a dramatic increase in incidences of both CD and UC were observed in adolescents (10-16 years): for CD from 4.2 to 9.5/10⁵ (+126%; P<0.001) and for UC, from 1.6 to 4.1/10⁵ (+156%; P<0.001). No modification in age or location at diagnosis was observed in either CD or UC.

CONCLUSIONS

In this population-based study, CD and UC incidences increased dramatically in adolescents across a 24-year span, suggesting that one or more strong environmental factors may predispose this population to IBD.

Extra-intestinal Manifestations at Diagnosis in Paediatric- and Elderly-onset Ulcerative Colitis are Associated With a More Severe Disease Outcome: A Population-based Study

BACKGROUND AND AIMS

Data on extra-intestinal manifestations [EIM] and their impact on the disease course of ulcerative colitis [UC] in population-based cohorts are scarce, particularly in paediatric- and elderly-onset UC patients. The aims of this population-based study were to assess: 1] the occurrence of EIM in paediatric- and elderly-onset UC; 2] the factors associated with EIM; and 3] their impact on long-term disease outcome.

METHODS

Paediatric-onset [< 17 years at diagnosis] and elderly-onset UC patients [> 60 years at diagnosis] from a French prospective population-based registry [EPIMAD] were included. Data on EIM and other clinical factors at diagnosis and at maximal follow-up were collected.

RESULTS

In all, 158 paediatric- and 470 elderly-onset patients were included [median age at diagnosis 14.5 and 68.8 years, median follow-up 11.2 and 6.2 years, respectively]. EIM occurred in 8.9% of childhood- and 3% of elderly-onset patients at diagnosis and in 16.7% and 2.2% of individuals during follow-up [p < 0.01], respectively. The most frequent EIM was joint involvement [15.8% of paediatric onset and 2.6% of elderly-onset]. Presence of EIM at diagnosis was associated with more severe disease course [need for immunosuppressants or biologic therapy or colectomy] in both paediatric- and elderly-onset UC (hazard ratio [HR] = 2.0, 95% confidence interval [CI]: 1.0-4.2; and HR = 2.8, 0.9-7.9, respectively). Extensive colitis was another independent risk factor in both age groups.

CONCLUSIONS

Elderly-onset UC patients had lower risk of EIM either at diagnosis or during follow-up than paediatric-onset individuals. EIM at diagnosis predicted more severe disease outcome, including need for immunosuppressive or biologic therapy or surgery, in both paediatric- and elderly-onset UC.

Spatially Coherent Activation Maps for Electrocardiographic Imaging

OBJECTIVE

Cardiac mapping is an important diagnostic step in cardiac electrophysiology. One of its purposes is to generate a map of the depolarization sequence. This map is constructed in clinical routine either by directly analyzing cardiac electrograms (EGMs) recorded invasively or an estimate of these EGMs obtained by a noninvasive technique. Activation maps based on noninvasively estimated EGMs often show artefactual jumps in activation times. To overcome this problem, we present a new method to construct the activation maps from reconstructed unipolar EGMs.

METHODS

On top of the standard estimation of local activation time from unipolar intrinsic deflections, we propose to mutually compare the EGMs in order to estimate the delays in activation for neighboring recording locations. We then describe a workflow to construct a spatially coherent activation map from local activation times and delay estimates in order to create more accurate maps. The method is optimized using simulated data and evaluated on clinical data from 12 different activation sequences.

RESULTS

We found that the standard methodology created lines of artificially strong activation time gradient. The proposed workflow enhanced these maps significantly.

CONCLUSION

Estimating delays between neighbors is an interesting option for activation map computation in electrocardiographic imaging.

Impact of previous cyst-enterostomy on patients’ outcome following resection of bile duct cysts

AIM: To analyze the impact of previous cyst-enterostomy of patients underwent congenital bile duct cysts (BDC) resection.

METHODS: A multicenter European retrospective study between 1974 and 2011 were conducted by the French Surgical Association. Only Todani subtypes I and IVb were included. Diagnostic imaging studies and operative and pathology reports underwent central revision. Patients with and without a previous history of cyst-enterostomy (CE) were compared.

RESULTS: Among 243 patients with Todani types I and IVb BDC, 16 had undergone previous CE (6.5%). Patients with a prior history of CE experienced a greater incidence of preoperative cholangitis (75% vs 22.9%, P < 0.0001), had more complicated presentations (75% vs 40.5%, P = 0.007), and were more likely to have synchronous biliary cancer (31.3% vs 6.2%, P = 0.004) than patients without a prior CE. Overall morbidity (75% vs 33.5%; P < 0.0008), severe complications (43.8% vs 11.9%; P = 0.0026) and reoperation rates (37.5% vs 8.8%; P = 0.0032) were also significantly greater in patients with previous CE, and their Mayo Risk Score, during a median follow-up of 37.5 mo (range: 4-372 mo) indicated significantly more patients with fair and poor results (46.1% vs 15.6%; P = 0.0136).

CONCLUSION: This is the large series to show that previous CE is associated with poorer short- and long-term results after Todani types I and IVb BDC resection.

Congenital bile duct cyst (BDC) is a more indolent disease in children compared to adults, except for Todani type IV-A BDC: results of the European multicenter study of the French Surgical Association

AIM

To compare clinical presentation, operative management and short- and long-term outcomes of congenital bile duct cysts (BDC) in adults with children.

METHODS

Retrospective multi-institutional Association Francaise de Chirurgie study of Todani types I+IVB and IVA BDC.

RESULTS

During the 37-year period to 2011, 33 centers included 314 patients (98 children; 216 adults). The adult population included more high-risk patients, with more active, more frequent prior treatment (47.7% vs 11.2%; p < 0.0001), more complicated presentation (50.5% vs 35.7%; p = 0.015), more synchronous biliary cancer (11.6% vs 0%; p = 0.0118) and more major surgery (23.6% vs 2%; p < 0.0001), but this latter feature was only true for type I+IVB BDC. Compared to children, the postoperative morbidity (48.1% vs 20.4%; p < 0.0001), the need for repeat procedures and the status at follow-up were worse in adults (27% vs 8.8%; p = 0.0009). However, severe postoperative morbidity and fair or poor status at follow-up were not statistically different for type IVA BDC, irrespective of patients' age. Synchronous cancer, prior HBP surgery and Todani type IVA BDC were independent predictive factors of poor or fair long-term outcome.

CONCLUSION

BDC is a more indolent disease in children compared to adults, except for Todani type IV-A BDC.

Intermittent drivers anchoring to structural heterogeneities as a major pathophysiological mechanism of human persistent atrial fibrillation

The mechanisms responsible for perpetuation of human persistent atrial fibrillation (AF) are controversial and probably vary between individuals. A wide spectrum of mechanisms have been described in experimental studies, ranging from a single localized stable (focal/reentrant) source, to multiple sources, up to diffuse bi-atrial wavelets. We characterized AF drivers in patients with persistent AF (lasting less than 1 year) using novel high resolution mapping, imaging and modelling approaches with the objective of evaluating their relationship to atrial structural heterogeneities. Using panoramic non-invasive mapping in humans, focal or reentrant sources driving AF waves were identified, originating from multiple distinct regions and exhibiting short lifespans and periodic recurrences in the same locations. The reentrant driver regions harboured long, fractionated electrograms covering most of the fibrillatory cycle lengths with varying beat-to-beat sequences suggestive of unstable trajectories attached to slow conducting heterogeneous tissue. MRI atrial imaging demonstrated that such drivers preferentially clustered at the borders of fibrotic atrial regions. In patient-specific computer simulations, sustained AF was shown to be driven by meandering transitory reentries attached to fibrosis borders expressing specific metrics in density and extent. Finally, random microstructural alterations devoid of cellular electrical changes were modelled, showing that a percolation mechanism could also explain atrial reentries and complex fractionated electrograms. These data from clinical, imaging and computational studies strongly suggest that intermittent and spatially unstable drivers anchoring to structural heterogeneities are a major pathophysiological mechanism in human persistent atrial fibrillation.

Body Surface Electrocardiographic Mapping for Non-invasive Identification of Arrhythmic Sources

The authors describe a novel three-dimensional, 252-lead electrocardiography (ECG) and computed tomography (CT)-based non-invasive cardiac imaging and mapping modality. This technique images potentials, electrograms and activation sequences (isochrones) on the epicardial surface of the heart. This tool has been investigated in the normal cardiac electrophysiology and various tachyarrhythmic, conduction and anomalous depo-repolarisation disorders. The clinical application of this system includes a wide range of electrical disorders like atrial arrhythmias (premature atrial beat, atrial tachycardia, atrial fibrillation), ventricular arrhythmias (premature ventricular beat, ventricular tachycardia) and ventricular pre-excitation (Wolff-Parkinson-White syndrome). In addition, the system has been used in exploring abnormalities of the His-Purkinje conduction like the bundle branch block and intraventricular conduction disturbance and thereby useful in electrically treating the associated heart failure (cardiac resynchronisation). It has a potential role in furthering our understanding of abnormalities of ventricular action potential (depolarisation [Brugada syndrome and repolarisation], long QT and early repolarisation syndromes) and in evaluating the impact of drugs on His-Purkinje conduction and cardiac action potential.