QTc interval prolongation and severe apneas associated with a change in infant positioning.

For more than a decade there has been considerable interest in the role of QT interval prolongation in the pathogenesis of sudden infant death syndrome. It has been proposed that the QT interval is a surrogate marker for autonomic instability and can be used to identify infants at risk for significant morbidity and mortality, including sudden infant death syndrome. We present the case of an infant that experienced a significant increase in his QTc, as detected by continuous QTc monitoring in the NICU after repositioning from a supine to prone position.

Centralized resources for nurse practitioners: common early experiences among leaders of six large health systems.

Purpose: This article describes common experiences of institutions that have pioneered the work of integrating nurse practitioners (NPs) into complex hospital environments and addresses effective strategies in achieving a centralized leadership model.

Data Sources: We conducted an informal, written survey and focus group discussions comparing experiences of leaders who were first in the position of centralizing resources and providing leadership for NPs in a hospital-based setting. Experiences were compared and common practices summarized.

Deformation patterns in genotyped patients with hypertrophic cardiomyopathy.

Aims: Echocardiographic strain imaging with two-dimensional speckle tracking is an emerging tool for defining cardiac function and identifying preclinical hypertrophic cardiomyopathy (HCM). In HCM, a reverse septal contour is a strong predictor of mutation positive sarcomeric HCM. The objective of this study was to determine whether left ventricular (LV) deformation patterns can differentiate between genotype positive and negative patients within a large HCM cohort.

Prevalence and spectrum of electroencephalogram-identified epileptiform activity among patients with long QT syndrome.

Background: Congenital long QT syndrome (LQTS) is a heritable cardiac disease whereby patients are at an increased risk for LQTS-triggered syncope, seizures, and sudden cardiac arrest. Seizure episodes are common in LQTS and most often seen in patients with type 2 LQTS (LQT2).

Objective: To determine the prevalence of electroencephalogram (EEG)-identified epileptiform activity among patients with LQTS.

Genotype- and phenotype-guided management of congenital long QT syndrome.

Congenital long QT syndrome (LQTS) is a genetically heterogeneous group of heritable disorders of myocardial repolarization linked by the shared clinical phenotype of QT prolongation on electrocardiogram and an increased risk of potentially life-threatening cardiac arrhythmias. At the molecular level, mutations in 15 distinct LQTS-susceptibility genes that encode ion channel pore-forming α-subunits and accessory β-subunits central to the electromechanical function of the heart have been implicated in its pathogenesis. Over the past 2 decades, our evolving understanding of the electrophysiological mechanisms by which specific genetic substrates perturb the cardiac action potential has translated into vastly improved approaches to the diagnosis, risk stratification, and treatment of patients with LQTS.

Left atrial appendage dysfunction in a patient with premature ventricular contractions - a risk factor for stroke?

A 16-year-old female with ventricular dysfunction and frequent ventricular arrhythmia presented with a cardioembolic stroke. Prior electrophysiology study and ablation was performed for ventricular tachycardia (VT). For remaining ventricular ectopy, the patient was maintained on carvedilol and mexiletine.

Arrhythmia phenotype during fetal life suggests long-QT syndrome genotype: risk stratification of perinatal long-QT syndrome.

Background: Fetal arrhythmias characteristic of long QT syndrome (LQTS) include torsades de pointes (TdP) and/or 2° atrioventricular block, but sinus bradycardia, defined as fetal heart rate<3% for gestational age, is most common. We hypothesized that prenatal rhythm phenotype might predict LQTS genotype and facilitate improved risk stratification and management.

Method And Results: Records of subjects exhibiting fetal LQTS arrhythmias were reviewed.

Mutation E169K in junctophilin-2 causes atrial fibrillation due to impaired RyR2 stabilization.

Objectives: This study sought to study the role of junctophilin-2 (JPH2) in atrial fibrillation (AF).

Background: JPH2 is believed to have an important role in sarcoplasmic reticulum (SR) Ca(2+) handling and modulation of ryanodine receptor Ca(2+) channels (RyR2). Whereas defective RyR2-mediated Ca(2+) release contributes to the pathogenesis of AF, nothing is known about the potential role of JPH2 in atrial arrhythmias.

Stroke or transient ischemic attack in patients with transvenous pacemaker or defibrillator and echocardiographically detected patent foramen ovale.

Background: A patent foramen ovale (PFO) may permit arterial embolization of thrombi that accumulate on the leads of cardiac implantable electronic devices in the right-sided cardiac chambers. We sought to determine whether a PFO increases the risk of stroke/transient ischemic attack (TIA) in patients with endocardial leads.

Methods And Results: We retrospectively evaluated all patients who had endocardial leads implanted between January 1, 2000, and October 25, 2010, at Mayo Clinic Rochester.

Uncompressed high-definition videoconferencing tools for telemedicine and distance learning.

Uncompressed high-definition (HD) video image quality is superior to compressed HD video provided in most commercially available videoconferencing products. Uncompressed HD videoconferencing tools provide a more immersive experience because there is no reduction of image information and, in most cases, lower latency. Four open source uncompressed video applications are reviewed that have been tested at the National Library of Medicine: three transmitting uncompressed HD video and one transmitting loosely compressed standard-definition video.

Epilepsy misdiagnosed as long QT syndrome: it can go both ways.

Cardiogenic seizures are common and could be the sentinel event heralding the presence of congenital long QT syndrome (LQTS). Distinguishing a cardiogenic seizure from a neurogenic one is of the utmost importance. Herein, we present the case of a 12-year-old boy with recurrent episodes of syncope and seizures.

Left cardiac sympathetic denervation in long QT syndrome: analysis of therapeutic nonresponders.

Background: Long QT syndrome (LQTS) is a potentially lethal but highly treatable cardiac channelopathy. Treatment options include pharmacotherapy, device therapy, and left cardiac sympathetic denervation (LCSD). Here, we sought to determine the characteristics of LQTS patients who have had ≥1 LQTS-related breakthrough cardiac event (BCE) after LCSD.

Junctophilin-2 is necessary for T-tubule maturation during mouse heart development.

Aims: Transverse tubules (TTs) provide the basic subcellular structures that facilitate excitation-contraction (EC) coupling, the essential process that underlies normal cardiac contractility. Previous studies have shown that TTs develop within the first few weeks of life in mammals but the molecular determinants of this development have remained elusive. This study aims to elucidate the role of junctophilin-2 (JPH2), a junctional membrane complex protein, in the maturation of TTs in cardiomyocytes.

Investigation of monoclonal antibody fragmentation artifacts in non-reducing SDS-PAGE.

Fragmentation of monoclonal antibodies has been routinely observed in non-reducing SDS-PAGE, mainly due to disulfide-bond scrambling catalyzed by free sulfhydryl groups, resulting in a method induced artifact. To minimize this artifact, alkylating agents like iodoacetamide (IAM) and N-ethylmaleimide (NEM) were commonly included in SDS sample buffer to block free sulfhydryls. However, the selection of agents and the applied concentrations differ from study to study.

Maternal mosaicism confounds the neonatal diagnosis of type 1 Timothy syndrome.

The presence of 2 distinct populations of somatic or germline cells within a single individual harboring different genotypes is termed mosaicism. Recent reports suggest that parental mosaicism is involved in the heritability of type 1 Timothy syndrome (TS1), an extremely rare and life-threatening multisystem disorder characterized by severe QT interval prolongation, syndactyly, and several other complications. Although full TS1 is caused by a single missense mutation in the CACNA1C-encoded cardiac calcium channel, mosaic TS1 parents can display isolated syndactyly without additional phenotypic manifestations.

Safety of sports for athletes with implantable cardioverter-defibrillators: results of a prospective, multinational registry.

Background: The risks of sports participation for implantable cardioverter-defibrillator (ICD) patients are unknown.

Methods And Results: Athletes with ICDs (age, 10-60 years) participating in organized (n=328) or high-risk (n=44) sports were recruited. Sports-related and clinical data were obtained by phone interview and medical records.

Impact of genetics on the clinical management of channelopathies.

There are few areas in cardiology in which the impact of genetics and genetic testing on clinical management has been as great as in cardiac channelopathies, arrhythmic disorders of genetic origin related to the ionic control of the cardiac action potential. Among the growing number of diseases identified as channelopathies, 3 are sufficiently prevalent to represent significant clinical and societal problems and to warrant adequate understanding by practicing cardiologists: long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, and Brugada syndrome. This review will focus selectively on the impact of genetic discoveries on clinical management of these 3 diseases.

Exome sequencing and systems biology converge to identify novel mutations in the L-type calcium channel, CACNA1C, linked to autosomal dominant long QT syndrome.

Background: Long QT syndrome (LQTS) is the most common cardiac channelopathy with 15 elucidated LQTS-susceptibility genes. Approximately 20% of LQTS cases remain genetically elusive.

Methods And Results: We combined whole-exome sequencing and bioinformatic/systems biology to identify the pathogenic substrate responsible for nonsyndromic, genotype-negative, autosomal dominant LQTS in a multigenerational pedigree, and we established the spectrum and prevalence of variants in the elucidated gene among a cohort of 102 unrelated patients with "genotype-negative/phenotype-positive" LQTS.

Sudden cardiac arrest in a young patient with hypertrophic cardiomyopathy and zero canonical risk factors: the inherent limitations of risk stratification in hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy is the most common heritable cardiovascular disease and a common cause of sudden cardiac death (SCD) in young adolescents and athletes. Clinical risk stratification for SCD is predicated on the presence of established risk factors; however, this assessment is far from perfect. Herein, we present a 16-year-old male who was resuscitated successfully from his sentinel event of out-of-hospital cardiac arrest.