Arrhythmias in the Adult with Congenital Heart Disease

Arrhythmias are an important problem in adults with congenital heart disease, whether previously operated upon or not. This article discusses the incidence, pathogenesis, diagnosis and management of arrhythmias in the adult congenital patient. Arrhythmias can be the cause or the effect of hemodynamic deterioration. Complex patients, such as those with transposition of the great arteries, tetralogy of Fallot and single ventricle problems are highly likely to have major arrhythmias during adult life. Early recognition and appropriate management can improve the patient’s life and can even prevent early death. Pacemaker placement should be considered for bradycardia.  Tachyarrhythmia patients may need a combination of drug therapy, catheter ablation, pacemaker for antitachycardia pacing, or reoperation for residual structural issues combined with arrhythmia surgery. Sudden death is another major problem and risk stratification strategies will be discussed. Appropriate and early use of implantable defibrillators can also save lives

Indications for Electrophysiology Study in children

The advent of electrophysiology (EP) testing revolutionized the care of children with arrhythmia. Precise mechanistic and anatomical diagnosis of arrhythmias became possible. The later development of catheter-based ablation transformed the care of these children by allowing many arrhythmias to be cured during the same procedure. Indications for EP testing vary depending on the age of the child, the underlying cardiac anatomy, and the suspected arrhythmia. In the current era, the indications for EPS and for ablation are virtually identical. There are a few situations where EPS is sometimes performed without the use of ablation, and these will be pointed out. This paper will address the common conditions for which EP testing is performed

Cardiac Arrhythmias In Congenital Heart Diseases

Arrhythmias figure prominently among the complications encountered in the varied and diverse population of patients with congenital heart disease, and are the leading cause of morbidity and mortality. The incidence generally increases as the patient ages, with multifactorial predisposing features that may include congenitally malformed or displaced conduction systems, altered hemodynamics, mechanical or hypoxic stress, and residual or postoperative sequelae. The safe and effective management of arrhythmias in congenital heart disease requires a thorough appreciation for conduction system variants, arrhythmia mechanisms, underlying anatomy, and associated physiology. We, therefore, begin this review by presenting the scope of the problem, outlining therapeutic options, and summarizing congenital heart disease-related conduction system anomalies associated with disorders of the sinus node and AV conduction system. Arrhythmias encountered in common forms of congenital heart disease are subsequently discussed. In so doing, we touch upon issues related to risk stratification for sudden death, implantable cardiac devices, catheter ablation, and adjuvant surgical therapy

Cardiac Resynchronization Therapy in Children

Cardiac Resynchronization therapy has become an important management tool in adults with heart failure and dilated cardiomyopathy. The role of CRT in children with CHF is still unclear. Evidence is slowly emerging in the pediatric cardiology literature that CRT may have an important and useful role in certain select populations with CHF. These include patients with complete heart block who develop pacing-induced cardiomyopathy, certain forms of congenital heart disease associated with systemic ventricular failure (even if the systemic ventricle is a morphologic RV) and in patients with idiopathic dilated cardiomyopathy. Studies in children supporting the use of CRT include many case reports, a few studies of CRT in post-operative patients, and one multi-center registry reporting the use of CRT in children. These papers will be summarized

Usefulness of Tilt Testing in Children with Syncope: A Survey of Pediatric Electrophysiologists

The role of tilt table testing as a diagnostic modality in children with unexplained syncope is unclear. We sent a questionnaire to members of the Pediatric and Congenital Electrophysiology Society to assess the current practice pattern. Of the 186 members, 97 (52%) replied. Twenty four percent of the pediatric electrophysiologists have completely stopped doing tilt table tests and of those performing the tests, a majority (76%) did < 10 tests/yr (median=3 tilts/yr, range 0-100/yr). Of those performing the test, 95% rarely or never accepted direct referrals from the general practioners and 62% felt that the frequency of tilt table tests being performed had decreased since they had started practicing. The median usefulness of the test was rated at 3 (range 1-9) on a scale of 1 to 10 with 10 being very useful. A majority (68%) felt they rarely or never altered treatment based on the results of the tilt test. Wide variability was noted in the test protocol including the tilt angle, tilt duration, use of pharmacologic agents and the duration of fasting prior to the test. We therefore conclude that there is significant lack of standardization in tilt table tests performed in children. Tilt table testing, as perceived by pediatric electrophysiologists, is of limited utility and progressively less used in children with syncope

Orthogonal and Symplectic Parabolic Bundles

We investigate orthogonal and symplectic bundles with parabolic structure, over a curve.Comment: 21 page

Moduli of parahoric G-torsors on a compact Riemann surface

Let χ be an irreducible smooth projective algebraic curve of genus g ≥ 2 over the ground field C and let G be a semisimple simply connected algebraic group. The aim of this paper is to introduce the notion of a semistable and stable parahoric torsor under a certain Bruhat-Tits group scheme G, construct the moduli space of semistable parahoric G-torsors and identify the underlying topological space of this moduli space with certain spaces of homomorphisms of Fuchsian groups into a maximal compact subgroup of G. The results give a complete generalization of the earlier results of Mehta and Seshadri on parabolic vector bundles