Heart rate variability in epilepsy: A potential biomarker of sudden unexpected death in epilepsy risk.

OBJECTIVE: Sudden unexpected death in epilepsy (SUDEP) is a tragic and devastating event for which the underlying pathophysiology remains poorly understood; this study investigated whether abnormalities in heart rate variability (HRV) are linked to SUDEP in patients with epilepsy due to mutations in sodium channel (SCN) genes. METHODS: We retrospectively evaluated HRV in epilepsy patients using electroencephalographic studies to study the potential contribution of autonomic dysregulation to SUDEP risk. We extracted HRV data, in wakefulness and sleep, from 80 patients with drug-resistant epilepsy, including 40 patients with mutations in SCN genes and 40 control patients with non-SCN drug-resistant epilepsy. From the SCN group, 10 patients had died of SUDEP. We compared HRV between SUDEP and non-SUDEP groups, specifically studying awake HRV and sleep:awake HRV ratios. RESULTS: The SUDEP patients had the most severe autonomic dysregulation, showing lower awake HRV and either extremely high or extremely low ratios of sleep-to-awake HRV in a subgroup analysis. A secondary analysis comparing the SCN and non-SCN groups indicated that autonomic dysfunction was slightly worse in the SCN epilepsy group. SIGNIFICANCE: These findings suggest that autonomic dysfunction is associated with SUDEP risk in patients with epilepsy due to sodium channel mutations. The relationship of HRV to SUDEP merits further study; HRV may eventually have potential as a biomarker of SUDEP risk, which would allow for more informed counseling of patients and families, and also serve as a useful outcome measure for research aimed at developing therapies and interventions to reduce SUDEP risk.

Uptake of Predictive Genetic Testing and Cardiac Evaluation for Children at Risk for an Inherited Arrhythmia or Cardiomyopathy.

Predictive genetic testing in minors should be considered when clinical intervention is available. Children who carry a pathogenic variant for an inherited arrhythmia or cardiomyopathy require regular cardiac screening and may be prescribed medication and/or be told to modify their physical activity. Medical genetics and pediatric cardiology charts were reviewed to identify factors associated with uptake of genetic testing and cardiac evaluation for children at risk for long QT syndrome, hypertrophic cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy. The data collected included genetic diagnosis, clinical symptoms in the carrier parent, number of children under 18 years of age, age of children, family history of sudden cardiac arrest/death, uptake of cardiac evaluation and if evaluated, phenotype for each child. We identified 97 at risk children from 58 families found to carry a pathogenic variant for one of these conditions. Sixty six percent of the families pursued genetic testing and 73% underwent cardiac screening when it was recommended. Declining predictive genetic testing was significantly associated with genetic specialist recommendation (p < 0.001) and having an asymptomatic carrier father (p = 0.006). Cardiac evaluation was significantly associated with uptake of genetic testing (p = 0.007). This study provides a greater understanding of factors associated with uptake of genetic testing and cardiac evaluation in children at risk of an inherited arrhythmia or cardiomyopathy. It also identifies a need to educate families about the importance of cardiac evaluation even in the absence of genetic testing.

Diagnostic pacing maneuvers for supraventricular tachycardias: part 2.

The approach to supraventricular tachycardia (SVT) diagnosis can be complex because it involves synthesizing baseline electrophysiologic features, features of the SVT, and the response(s) to pacing maneuvers. In this two-part review, we will mainly explore the latter while recognizing that neither of the former can be ignored, for they provide the context in which diagnostic pacing maneuvers must be correctly chosen and interpreted. Part 1 involved a detailed consideration of ventricular overdrive pacing, since this pacing maneuver provides the diagnosis in the majority of cases. In Part 2, other diagnostic pacing maneuvers that might be helpful when ventricular overdrive pacing is not diagnostic or appropriate, including attempts to reset SVT with single atrial or ventricular beats, para-Hisian pacing, apex versus base pacing, and atrial overdrive pacing, are discussed, as are some specific diagnostic SVT challenges encountered in the electrophysiology lab. There is considerable literature on this topic, and this review is by no means meant to be all-encompassing. Rather, we hope to clearly explain and illustrate the physiology, strengths, and weaknesses of what we consider to be the most important and commonly employed diagnostic pacing maneuvers, that is, those that trainees in cardiac electrophysiology should be well familiar with at a minimum.

Caring for the Aging Patient With Adult Congenital Heart Disease: A Review of Cardiac and Noncardiac Comorbidities.

As the demographics of congenital heart disease (CHD) have shifted, there are now more adults living with CHD than children in North America. This presents unprecedented challenges as patients with CHD acquire noncardiac comorbidities and seek care for a variety of reasons, including noncardiac surgery and emergency department (ED) visits. CHD shifts from a one organ problem to a multisystem disease and requires a team of specialists to maintain high-quality longitudinal care. In this review, we summarize the challenges patients with CHD and their providers face as they age. We review the demographics of CHD and health care utilization. We examine the rates of noncardiac comorbidities and the current quality of care received by adult patients with CHD.

Les caractéristiques démographiques des patients atteints d'une cardiopathie congénitale ont changé : à l'heure actuelle, en Amérique du Nord, il y a plus d'adultes qui présentent une cardiopathie congénitale que d'enfants. Cela représente un défi sans précédent lorsque ces patients ont des troubles concomitants non cardiaques et doivent subir une chirurgie non cardiaque, par exemple, ou se rendre aux urgences pour toutes sortes de raisons. On ne parle alors plus de l'atteinte d'un seul organe, mais bien d'une maladie multisystémique. Une équipe pluridisciplinaire sera nécessaire pour maintenir des soins longitudinaux de haute qualité.Dans notre article, nous faisons le point sur les défis que les personnes atteintes d'une cardiopathie congénitale et les dispensateurs de soins doivent affronter à mesure que le patient avance en âge. Nous passons en revue les données démographiques sur les cardiopathies congénitales ainsi que celles sur l'utilisation des services de santé. Nous examinons la fréquence des comorbidités non cardiaques, tout comme la qualité des soins que reçoivent actuellement les patients atteints d'une cardiopathie congénitale.

Diagnostic pacing maneuvers for supraventricular tachycardia: part 1.

This two-part manuscript reviews diagnostic pacing maneuvers for supraventricular tachycardia (SVT). Part one will involve a detailed consideration of ventricular overdrive pacing (VOP), since this pacing maneuver provides the diagnosis in the majority of cases. This will include a review of the post-VOP response, fusion during entrainment, the importance of the VOP site, quantitative results of entrainment such as the postpacing interval, differential entrainment, and new criteria derived from features found at the beginning of the VOP train. There is a considerable literature on this topic, and this review is by no means meant to be all-encompassing. Rather, we hope to clearly explain and illustrate the physiology, strengths, and weaknesses of what we consider to be the most important and commonly employed diagnostic pacing maneuvers, that is, those that trainees in cardiac electrophysiology should be well familiar with at a minimum. \

A prospective pediatric clinical trial of digital music players: do they interfere with pacemakers?

BACKGROUND: There has been recent concern in the media about iPod interference with pacemakers. We systematically tested two types of digital music players (DMP) on pacemaker or ICD function in children. METHODS/RESULTS: Patients were monitored by a 6-lead ECG and programmer telemetry. The pacemaker was tested in bipolar and unipolar sensing at normal and maximal sensitivities. The order of DMP tested was randomized. Each DMP was placed on top of the pacemaker pocket, put into "play" mode three times (5 seconds each), with and without programmer wand placed one cm adjacent to DMP. Pacemaker interference was defined as: pacing inhibition, inappropriate pacing, oversensing, or detection of high-rate episodes associated with the use of DMP. Of the 67 patients (mean age 12 +/- 5 years), 62 had pacemakers and five had ICDs; 39 endocardial and 28 epicardial systems. Patients were tested with Sansa (67), iPod 30 GB (51), and other DMPs (43). There was no evidence of interference with pacemaker function by any DMP under any of the study conditions (each performed in triplicate). Reproducible programmer telemetry interference was shown in 11 cases (Medtronic 6/47, St. Jude Medical 5/18, Guidant 0/2) related to use of iPod (6), Sansa (1), or others (4). None of these were associated with any evidence of pacemaker malfunction. CONCLUSION: Interference with pacemaker function could not be shown with iPod or MP3 players. No additional precaution beyond standard is necessary for patients with pacemakers when they are using these players.

Second-degree atrioventricular block (Mobitz Type I) in an adolescent with anorexia nervosa: intrinsic or acquired conduction abnormality.

Anorexia nervosa (AN) can cause both functional and structural cardiac complications, including a variety of different conduction abnormalities. This is the first case report of symptomatic diurnal second-degree atrioventricular (AV) block (Mobitz Type I) in an adolescent with AN. We present a 12-year-old girl with AN, restrictor sub-type who reported cardiac symptoms during weight gain, at the time of the initial diagnosis of AV block. Second-degree AV block (Mobitz Type I) is discussed as a possible complication of the AN, as well as being an intrinsic conduction system disease.

Characterization of a Unique Form of Arrhythmic Cardiomyopathy Caused by Recessive Mutation in LEMD2.

Nuclear envelope proteins have been shown to play an important role in the pathogenesis of inherited dilated cardiomyopathy. Here, we present a remarkable cardiac phenotype caused by a homozygous LEMD2 mutation in patients of the Hutterite population with juvenile cataract. Mutation carriers develop arrhythmic cardiomyopathy with mild impairment of left ventricular systolic function but severe ventricular arrhythmias leading to sudden cardiac death. Affected cardiac tissue from a deceased patient and fibroblasts exhibit elongated nuclei with abnormal condensed heterochromatin at the periphery. The patient fibroblasts demonstrate cellular senescence and reduced proliferation capacity, which may suggest an involvement of LEM domain containing protein 2 in chromatin remodeling processes and premature aging.

Rapid cardiac ventricular pacing to facilitate embolization of vein of Galen malformations: technical note.

In BriefBabies born with life-threatening brain blood-vessel malformations can be helped with new heart pacemaker technology to temporarily stop the flow of blood in their bodies during surgery, for inducing hypotension to aid in controlled embolization.

Sudden Death After Febrile Seizure Case Report: Cerebral Suppression Precedes Severe Bradycardia.

A 20-month-old girl with a complex chromosomal disorder had first presentation of febrile status epilepticus and was admitted to the hospital. Two days after her initial seizure, she died suddenly and unexpectedly during a video EEG monitoring study. An advanced analysis of the physiologic changes in the hours and minutes leading up to death was undertaken. The electrocardiography over the last 19 minutes of life was reviewed, and the R-R intervals were manually measured. Heart rate variability was assessed through calculation of the SD of the R-R intervals and the root mean square of successive differences over successive 100 beat periods. Instantaneous heart rate, SD of the R-R intervals, the root mean square of successive differences, and oxygen saturation were plotted against time over the last 19 minutes of life. Diffuse cerebral suppression on EEG was observed 10 minutes before death, followed minutes later by severe bradycardia and increased heart rate variability. Although the child did not meet criteria for a diagnosis of epilepsy, the sequence of physiologic changes leading up to death suggests a pathophysiology similar to sudden unexplained death in epilepsy. A comparable pattern of diffuse cerebral suppression preceding parasympathetic overactivity has been suggested in some rare cases of adults who have experienced sudden unexplained death in epilepsy during video EEG monitoring.

Non-invasive Investigations for the Diagnosis of Fontan-Associated Liver Disease in Pediatric and Adult Fontan Patients.

Fontan-associated liver disease (FALD) is a serious complication related to the chronically elevated venous pressure and low cardiac output of this abnormal circulation. However, diagnostic markers for this condition are limited. We hypothesized that specific tests for fibrosis developed for other chronic liver diseases would identify a higher prevalence of FALD than ultrasound and standard laboratory tests and that identified abnormalities would correlate with time post-Fontan. In this cross-sectional study, we assessed 19 children (average age 8.4 ± 4.3 and 5.4 ± 4.1 years post-Fontan) and 8 adults (average age 31.5 ± 8.9 and 21.1 ± 4 years post-Fontan) using standard serum laboratory investigations assessing hepatic integrity and function, the FibroTest, liver ultrasound, and transient elastography (FibroScan). In adult Fontan patients, hemoglobin, C-reactive protein, and gamma-glutamyl transpeptidase were significantly increased, and white blood cell and platelet counts were significantly decreased in comparison to the pediatric cohort. International normalized ratio was mildly elevated in both children and adults. FibroTest results were suggestive of fibrosis regardless of time post-Fontan. FibroScan measurements were significantly correlated with time post-Fontan, but the incidence of ultrasound-detected liver abnormalities was variable. No cases of hepatocellular carcinoma were identified. Abnormalities suggestive of FALD occur in both children and adults post-Fontan. Select laboratory tests, and possibly ultrasound and FibroScan in some patients, appear to have the most promise for the non-invasive detection of FALD.

Epicardial left atrial appendage and biatrial appendage accessory pathways.

BACKGROUND: Acute success rates of accessory pathway ablation for Wolff-Parkinson-White (WPW) syndrome can exceed 95%, with rare failures attributed to anatomically complex epicardial connections. Right atrial appendage to right ventricle pathways have been reported, but their left-sided counterparts have only recently been described. OBJECTIVE: The purpose of this study was to report three unique cases of WPW syndrome in children with left atrial appendage and biatrial appendage connections. RESULTS: Three young patients with high-risk accessory pathways (accessory pathway effective refractory period = 190-240 ms) had unsuccessful endocardial ablations despite aggressive efforts with various catheter techniques. One patient had a left atrial appendage to left ventricular connection; the other two had biatrial appendage pathways connected to their respective ventricular surfaces. The latter two patients had a history of ventricular fibrillation: one experiencing ventricular fibrillation in the electrophysiology laboratory and the other suffering from ventricular fibrillation arrest at home. All three patients were taken to the operating room, where the appendages were noted to be diffusely adherent to their ventricles by fibrofatty connections. Dissection of the appendages led to loss of preexcitation and no further tachycardia. CONCLUSION: Surgical management of atrial appendage accessory pathways should be considered if aggressive attempts at endocardial ablation have failed.