Natural history of ventricular premature contractions in children with a structurally normal heart: does origin matter?

Aims: Premature ventricular contractions (PVCs) are thought to be innocent in children with normal hearts, especially if they disappear during exercise. The aim of our study was to study the natural history of PVCs in childhood and whether there is a difference between PVCs originating from the right [premature ventricular contraction with left bundle branch block (PVC-LBBB)] or the left ventricle [premature ventricular contraction with right bundle branch block (PVC-RBBB)].

Methods And Results: We evaluated children with frequent PVCs and anatomically normal hearts (n= 59; 35M/24F) by 12-lead ECG, echocardiography, Holter recording, and an exercise test.

Longitudinal echocardiographic follow-up in children with congenital complete atrioventricular block.

Background: Due to a low heart rate (HR) in children with congenital complete atrioventricular block (CCAVB), a larger stroke volume of the left ventricle (LV) may be expected. If so, end-diastolic (LVEDD) and end-systolic (LVESD) diameters may be enlarged and even dilated cardiomyopathy (DCM) may occur. The aim of this study was to answer the question if children with CCAVB develop LV dilatation.

Sinus node function in children with congenital complete atrioventricular block.

Aims: Children with congenital complete atrioventricular block (CCAVB) often need pacemaker therapy. In these children, it may be preferable to use single-lead VDD pacing, but for VDD pacing a normal sinus node function is required. Our aim was to study sinus node function in children with CCAVB.

Developmental aspects of long QT syndrome type 3 and Brugada syndrome on the basis of a single SCN5A mutation in childhood.

Objectives: The aim was to investigate at what age electrocardiographic characteristics of long QT syndrome type 3 (LQT3) and Brugada syndrome (BS), based on a single SNC5A mutation, appear.

Background: The QT interval (QT) in LQT3 is prolonged during bradycardia. It is not clear yet if this is obvious in young children with a relative fast heart rate (HR).

Ventricular fibrillation without overt cardiomyopathy as first presentation of organic cation transporter 2-deficiency in adolescence.

This case report describes ventricular fibrillation without overt cardiomyopathy as the presenting symptom of primary carnitine deficiency due to organic cation transporter 2 (OCTN2)-deficiency in a 15-year-old girl. Normally this disease presents early in life with hypoketotic hypoglycemia, muscle weakness, and/or cardiomyopathy. The patient fully recovered after carnitine supplementation.

Pharmacological treatment of young children with permanent junctional reciprocating tachycardia.

Our objective was to assess the efficacy of pharmacological treatment in reducing the incidence of permanent junctional reciprocating tachycardia in young children, or to bring the mean heart rate over 24 h to a normal level. We included 21 children with a median age of 0.05 year seen with permanent junctional reciprocating tachycardia over the period 1990 through 2001.

A large family characterised by nocturnal sudden death.

Background: We recently identified a novel mutation in large family characterised by premature nocturnal sudden death. In the present paper we provide an overview of the findings in this family.

Methods: From 1958 onwards, when the first patient presented, we collected clinical data on as many family members as possible.

Cross-stimulation during lead impedance monitoring.

At the age of 4 years, a total cavopulmonary connection was performed in a boy with a complex congenital heart defect. On addition, a DDDR pacemaker was implanted for sick sinus syndrome. Atrial and ventricular leads were epicardially placed at the left atrium and left ventricle.

Possible bradycardic mode of death and successful pacemaker treatment in a large family with features of long QT syndrome type 3 and Brugada syndrome.

Introduction: We recently identified a novel mutation of SCN5A (1795insD) in a large family with features of both long QT syndrome type 3 and the Brugada syndrome. The purpose of this study was to detail the clinical features and efficacy of pacemaker therapy in preventing sudden death in this family.

Methods And Results: The study group consisted of 116 adult family members: 60 carriers (29 males) and 56 noncarriers (28 males) of the mutant gene.

Metabolic responses to moderate exercise in lambs with aortopulmonary shunts.

In a previous study we found, after an overnight fast of 18 hours, a lower arterial glucose concentration and a depressed glycogenolysis in lambs with aortopulmonary left-to-right shunts. During exercise, glucose and free fatty acids (FFA) concentrations normally increase. The aim of this study was to investigate whether the shunt lambs could compensate for a depressed glycogenolysis by increasing gluconeogenesis and by increasing levels of blood substrates such as FFA and glycerol during exercise.

A sodium-channel mutation causes isolated cardiac conduction disease.

Cardiac conduction disorders slow the heart rhythm and cause disability in millions of people worldwide. Inherited mutations in SCN5A, the gene encoding the human cardiac sodium (Na+) channel, have been associated with rapid heart rhythms that occur suddenly and are life-threatening; however, a chief function of the Na+ channel is to initiate cardiac impulse conduction. Here we provide the first functional characterization of an SCN5A mutation that causes a sustained, isolated conduction defect with pathological slowing of the cardiac rhythm.

Perinatal changes in myocardial metabolism in lambs.

Background: Lactate accounts for a third of myocardial oxygen consumption before and in the first 2 weeks after birth. It is unknown how the remainder of myocardial oxygen is consumed. Glucose is thought to be important before birth, whereas long-chain fatty acids (LC-FA) are the prime substrate for the adult.

Lower arterial glucose concentrations in lambs with aortopulmonary shunts after an 18-hour fast.

Spontaneously occurring hypoglycemia has been described in children with severe acute congestive heart failure. Hypoglycemia may be the result of an increase in glucose utilization in tissues, a decrease in glucose production, or a decrease in the dietary intake of nutrients. To determine whether hypoglycemia may also occur in congenital heart disease with volume overloading, we investigated glucose metabolism during and after an 18-hour fast in nine lambs with an aortopulmonary left-to-right shunt and nine control lambs.

Novel KCNQ1 and HERG missense mutations in Dutch long-QT families.

Congenital long QT syndrome (cLQTS) is electrocardiographically characterized by a prolonged QT interval and polymorphic ventricular arrhythmias (torsade de pointes). These cardiac arrhythmias may result in recurrent syncopes, seizure, or sudden death. LQTS can occur either as an autosomal dominant (Romano Ward) or as an autosomal recessive disorder (Jervell and Lange-Nielsen syndrome).

Myocardial lactate metabolism in fetal and newborn lambs.

Background: Around birth, myocardial substrate supply changes from carbohydrates before birth to primarily fatty acids after birth. Parallel to these changes, the myocardium is expected to switch from the use of primarily lactate before birth to fatty acids thereafter. However, myocardial lactate uptake and oxidation around birth has not been measured in vivo.

Lactate kinetics at rest and during exercise in lambs with aortopulmonary shunts.

In a previous study [G. C. M.

Comparison of longevity, pacing, and sensing characteristics of steroid-eluting epicardial versus conventional endocardial pacing leads in children.

Objective: Because of either cardiac anatomy or small size, pacing in children often occurs by means of epicardial leads. The disadvantage of epicardial leads is the shorter longevity of these leads compared with endocardial leads. During short-term follow-up, improved stimulation thresholds were found for the newer steroid-eluting epicardial leads.

The right auricle tunnel as intercaval tunnel in total cavopulmonary connection may prevent atrial flutter.

Objective: Total cavopulmonary connection (TCPC) is a routine operation for palliation of children with cardiac anomalies in whom biventricular repair is impossible. The original technique consists of the creation of a semi-prosthetic intercaval tunnel. A substantial proportion of these patients develop atrial flutter.

Increased myocardial lactate oxidation in lambs with aortopulmonary shunts at rest and during exercise.

Free fatty acids are the major fuels for the myocardium, but during a higher load carbohydrates are preferred. Previously, we demonstrated that myocardial net lactate uptake was higher in lambs with aortopulmonary shunts than in control lambs. To determine whether this was caused by an increased lactate uptake and oxidation or by a decreased lactate release, we studied myocardial lactate and glucose metabolism with 13C-labeled substrates in 36 lambs in a fasting, conscious state.

Determination of organ substrate oxidation in vivo by measurement of 13CO2 concentration in blood.

Substrate oxidation by various organs in animals as well as in humans is usually studied by experiments in which radioactively labeled substrates are used and the production of 14CO2 is measured. In vivo, substrate oxidation by an organ has, up to now, not been determined by means of stable isotopes. Problems in the determination of the concentration of 13CO2 in blood may have impeded the use of 13C-labeled substrates.

Sotalol for atrial tachycardias after surgery for congenital heart disease.

Atrial tachycardias, in particular atrial flutter after surgery for congenital heart disease, is associated with a high mortality. Treatment with various antiarrhythmic drugs and/or antitachycardia pacemakers is not very successful. Sotalol, a Class III drug, has shown to be a promising drug in adults with atrial tachycardias.

Effectiveness of sotalol for atrial flutter in children after surgery for congenital heart disease.

This study describes the efficacy of oral sotalol in the treatment and prevention of atrial flutter in children after surgery for congenital heart disease. In 11 of 13 children (85%), conversion to sinus rhythm was achieved, and in 8 of 11 within 24 hours.

Quantification of the beta-adrenoceptor ligand S-1'-[18F]fluorocarazolol in plasma of humans, rats and sheep.

Myocardial and pulmonary beta-adrenoceptors can be imaged with 2-(S)-(-)-(9H-carbazol-4-yl-oxy)-3-[1-(fluoromethyl)ethyl]amino-2- propanol (S-1'-[18F]fluorocarazolol, I). Quantification of unmodified fluorocarazolol in plasma is necessary for analysis of PET images in terms of receptor densities. We have determined I and its radioactive metabolites in rat, sheep and human plasma, using (1) solid-phase extraction (C18) followed by reversed-phase HPLC and (2) direct injection of untreated plasma samples on an internal-surface reversed-phase (ISRP) column.

Late cardiotoxicity after treatment for a malignant bone tumor.

Cardiac function was assessed in long-term survivors of malignant bone tumors who were treated according to Rosen's T5 or T10 protocol, both including doxorubicin. Thirty-one patients, age 10-45 years (median age 17.8 years) were evaluated 2.