Long QT syndrome (LQTs) is a rare congenital disorder of the heart's electrical activity. Patients with LQTs are at increased risk of developing fatal ventricular arrhythmias. Elevated levels of sympathetic stimulation can exacerbate this risk. Successful behavior management is indispensable in the treatment of patients with LQTs. However, many drugs involved in pharmacologic behavior management are known to adversely affect the QT interval. Therefore, careful selection of a sedative drug is essential in avoiding such incidences. A 10-year-old boy with a known diagnosis of LQTs required restorative treatment due to dental caries at the permanent molar. He required sedation since treatment was painful and dental phobia can trigger sympathetic stimulation, creating a dangerous situation for patients with LQTs. Therefore, the treatment was performed over two sessions under moderate sedation involving propofol combined with nitrous oxide. Restorative treatment was successful without any complications under sedation with a target-controlled infusion (TCI) of propofol. There was no significant QT prolongation during pulpal treatment. Propofol TCI may be a good candidate for sedation in patients with LQTs.
Arrhythmias, Cardiac ; Child ; Congenital, Hereditary, and Neonatal Diseases and Abnormalities ; Conscious Sedation* ; Dental Anxiety ; Dental Caries ; Diagnosis ; Humans ; Incidence ; Long QT Syndrome* ; Male ; Molar ; Nitrous Oxide ; Propofol*

Long QT syndrome (LQTs) is a rare congenital disorder of the heart's electrical activity. Patients with LQTs are at increased risk of developing fatal ventricular arrhythmias. Elevated levels of sympathetic stimulation can exacerbate this risk. Successful behavior management is indispensable in the treatment of patients with LQTs. However, many drugs involved in pharmacologic behavior management are known to adversely affect the QT interval. Therefore, careful selection of a sedative drug is essential in avoiding such incidences. A 10-year-old boy with a known diagnosis of LQTs required restorative treatment due to dental caries at the permanent molar. He required sedation since treatment was painful and dental phobia can trigger sympathetic stimulation, creating a dangerous situation for patients with LQTs. Therefore, the treatment was performed over two sessions under moderate sedation involving propofol combined with nitrous oxide. Restorative treatment was successful without any complications under sedation with a target-controlled infusion (TCI) of propofol. There was no significant QT prolongation during pulpal treatment. Propofol TCI may be a good candidate for sedation in patients with LQTs.
Arrhythmias, Cardiac ; Child ; Congenital, Hereditary, and Neonatal Diseases and Abnormalities ; Conscious Sedation* ; Dental Anxiety ; Dental Caries ; Diagnosis ; Humans ; Incidence ; Long QT Syndrome* ; Male ; Molar ; Nitrous Oxide ; Propofol*

Long QT interval is an important finding that is often missed by electrocardiogram interpreters. Long QT syndrome (inherited and acquired) is a potentially lethal cardiac channelopathy that is frequently mistaken for epilepsy. We present a case of long QT syndrome with multiple cardiac arrests presenting as syncope and seizures. The long QTc interval was aggravated by hypomagnesaemia and drugs, including clarithromycin and levofloxacin. Multiple drugs can cause prolongation of the QT interval, and all physicians should bear this in mind when prescribing these drugs.
Adult ; Defibrillators, Implantable ; Electrocardiography ; Heart Rate ; Humans ; Long QT Syndrome ; complications ; congenital ; diagnosis ; therapy ; Male ; Risk Factors ; Seizures ; complications

OBJECTIVETo construct the sodium channel gene SCN5A-delQKP1507-1509 mutation associated with congenital long QT syndrome, and its eukaryotic expression vector, and to examine the expression of mutation protein in human embryonic kidney (HEK) 293 cells.

METHODSEukaryotic expression vector PEGFP-delQKP-hH1 for SCN5A-delQKP1507-1509 mutation was constructed by rapid site-directed mutagenesis. HEK293 cells were transfected with the wild or mutant vector using lipofectamine, and then subjected to confocal microscopy. The transfected cells were immunostained to visualize intracellular expression of the mutant molecules.

RESULTSDirect sequence and electrophoresis analysis revealed 9 basic group absences at position 1507-1509. The delQKP1507-1509 mutation eukaryotic expression vector was expressed in HEK293 cells. Immunostaining of transfected cells showed the expression of both wild type and mutant molecules on the plasma membrane and there was no difference in the amount of protein, which suggested that the mutant delQKP1507-1509 did not impair normal protein expression in HEK293 cells.

CONCLUSIONSSuccessful construction of mutant SCN5AdelQKP1507-1509 eukaryotic expression vector and expression of SCN5A protein in HEK293 cells provides a basis for further study on the functional effects of congenital long QT syndrome as a cause of SCN5A mutation.

Blotting, Western ; HEK293 Cells ; Humans ; Long QT Syndrome ; congenital ; genetics ; Mutagenesis, Site-Directed ; NAV1.5 Voltage-Gated Sodium Channel ; analysis ; genetics ; physiology

PURPOSE: The use of implantable cardioverter defibrillators (ICDs) to prevent sudden cardiac death is increasing in children and adolescents. This study investigated the use of ICDs in children with congenital heart disease. METHODS: This retrospective study was conducted on the clinical characteristics and effectiveness of ICD implantation at the department of pediatrics of a single tertiary center between 2007 and 2011. RESULTS: Fifteen patients underwent ICD implantation. Their mean age at the time of implantation was 14.5+/-5.4 years (range, 2 to 22 years). The follow-up duration was 28.9+/-20.4 months. The cause of ICD implantation was cardiac arrest in 7, sustained ventricular tachycardia in 6, and syncope in 2 patients. The underlying disorders were as follows: ionic channelopathy in 6 patients (long QT type 3 in 4, catecholaminergic polymorphic ventricular tachycardia [CPVT] in 1, and J wave syndrome in 1), cardiomyopathy in 5 patients, and postoperative congenital heart disease in 4 patients. ICD coils were implanted in the pericardial space in 2 children (ages 2 and 6 years). Five patients received appropriate ICD shock therapy, and 2 patients received inappropriate shocks due to supraventricular tachycardia. During follow-up, 2 patients required lead dysfunction-related revision. One patient with CPVT suffered from an ICD storm that was resolved using sympathetic denervation surgery. CONCLUSION: The overall ICD outcome was acceptable in most pediatric patients. Early diagnosis and timely ICD implantation are recommended for preventing sudden death in high-risk children and patients with congenital heart disease.
Adolescent ; Cardiomyopathies ; Channelopathies ; Child ; Convulsive Therapy ; Death, Sudden ; Death, Sudden, Cardiac ; Defibrillators ; Defibrillators, Implantable ; Early Diagnosis ; Follow-Up Studies ; Heart ; Heart Arrest ; Heart Defects, Congenital ; Heart Diseases ; Humans ; Korea ; Long QT Syndrome ; Pediatrics ; Retrospective Studies ; Shock ; Sympathectomy ; Syncope ; Tachycardia, Supraventricular ; Tachycardia, Ventricular

OBJECTIVETo perform mutation analysis in a family with long QT syndrome.

METHODSThe medical record of the affected child and his parents were collected. The locus of gene associated with the long QT syndrome was mapped by linkage analysis. Mutation analysis was done by PCR-single strand conformation polymorphism (SSCP) and direct sequencing.

RESULTSA mutation (L539fs/47) and a SNP (L564L) were found in exon 7 of the KCNH2 gene of the proband. The mutation was from the father.

CONCLUSIONA novel mutation of L539fs/47 in the KCNH2 gene was identified in the LQTS family, which might be the disease-causing mutation for the family.

Base Sequence ; ERG1 Potassium Channel ; Ether-A-Go-Go Potassium Channels ; genetics ; Female ; Frameshift Mutation ; Humans ; Long QT Syndrome ; congenital ; genetics ; Male ; Molecular Sequence Data ; Pedigree ; Polymorphism, Single Nucleotide ; Young Adult

OBJECTIVEThe congenital long QT syndrome (LQTs) is a hereditary disorder in which most affected family members have delayed ventricular repolarization manifested on the electrocardiogram (ECG) as QT interval prolongation. The disorder is associated with an increased propensity to arrhythmogenic syncope, polymorphous ventricular tachycardia (torsade de pointes), and sudden arrhythmic death. LQTs is due to mutations involving principally the myocyte ion-channels, and this monogenetic disorder has an autosomal inheritance pattern. This study investigated the gene mutation of a Chinese family of LQTs with multiple phenotypes including dilated cardiomyopathy (DCM) and cardiac conduction defects, thus to understand the molecular pathogenesis of the diseases.

METHODSA three-generation Chinese LQTs family with multiple phenotypes was investigated. Blood sample was collected from the 8 family members and 100 unassociated normal individuals. Polymerase chain reaction (PCR)-DNA direct sequencing was performed to screen all exons and their flanking introns of SCN5A gene for mutation analysis. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) was used to exclude polymorphism.

RESULTSPCR amplification and subsequent direct sequencing of SCN5A from proband revealed a heterozygous deletion of nine base pairs (CAGAAGCCC) in exon 26, corresponding to the three amino acid residues Gln1507-Lys1508-Pro1509 (QKP). This mutation is localized in the linker region between DIII-DIV of SCN5A. The same mutation was found in another patient (her grandmother) and excluded in the remaining living subjects in this family. This mutation was confirmed using SSCP in 100 unassociated healthy individuals. Similar analysis excluded possible mutations that would lead to amino acid changes in KCNQ1, KCNH2 and LAMIN A/C commonly associated with LQTs and DCM with conduction disorders, no new mutations that would lead to amino acid changes was found.

CONCLUSIONThe result of the present study suggests that SCN5A mutation delQKP1507-1509 exists in patients with LQTs. The delQKP1507-1509 of SCN5A is a novel mutation in Chinese people. The same mutation was previously reported in a French family with only a single LQTs phenotype. Further studies on functional expression of SCN5A mutation delQKP1507-1509 will be helpful to understand the mechanism of the multiple phenotypes.

Adolescent ; Adult ; Asian Continental Ancestry Group ; genetics ; DNA Mutational Analysis ; ERG1 Potassium Channel ; Ether-A-Go-Go Potassium Channels ; genetics ; Female ; Humans ; KCNQ1 Potassium Channel ; genetics ; Long QT Syndrome ; classification ; congenital ; genetics ; Male ; Middle Aged ; Mutation ; NAV1.5 Voltage-Gated Sodium Channel ; Pedigree ; Phenotype ; Sodium Channels ; genetics

OBJECTIVETo identify the gene mutation in a Chinese family with congenital long QT syndrome (LQTS) and predict the changes of the secondary structure of the protein.

METHODSPolymerase chain reaction and DNA sequencing were used to screen for KCNH2 mutation in the proband. After the mutation was identified, KCNH2 gene of the family members was screened by multiplex PCR with site-specific primers. Network analysis software was used to predict the secondary structure of the KCNH2 protein.

RESULTSA novel heterozygous missense mutation of F463L(GenBank accession no.EU218526) located at the transmembrane domain S2 of KCNH2 was detected. The mutation did not result in the change of the transmembrane domain, but altered the hydrophobicity and secondary structure of the protein.

CONCLUSIONThe novel mutation identified in this study has enriched the GenBank data of ion channel gene mutation in LQTS. The changes of the secondary structure caused by the gene mutation were analyzed by Mfold and TMHMM software, which may help to understand LQTS.

Adult ; Amino Acid Sequence ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; DNA Mutational Analysis ; ERG1 Potassium Channel ; Ether-A-Go-Go Potassium Channels ; chemistry ; genetics ; Female ; Humans ; Hydrophobic and Hydrophilic Interactions ; Long QT Syndrome ; congenital ; genetics ; Male ; Molecular Sequence Data ; Mutation, Missense ; Pedigree ; Protein Structure, Secondary ; Protein Structure, Tertiary

OBJECTIVETo investigate the functional expression of HERG mutation A561V detected in a Chinese congenital long QT syndrome family.

METHODSThe mutation gene A561V was cloned into eukaryotic expressive vector pcDNA3 by quick site-directed mutagenesis PCR and restriction enzymes. The wild-type HERG, heterozygous type HERG and HERG mutation A561V were respectively cotransfected with pRK5-GFP into HEK293 cells by Suprefact transfection regent. The protein expression was measured by immunofluorescence method and Western blot. The electrophysiological characteristics of transfected cells were determined by whole cell patch-clamp technique.

RESULTSDirect sequence analyses revealed a C to T transition at position 1682. A561V mutation was correctly combined to eukaryotic expressive vector pcDNA3 and expressed in HEK293 cells. The protein expression of mutation and heterozygosis were located in cytoplasm and cellular membrane. 155 kDa and 135 kDa protein bands were detected in wild type HERG channel while only 135 kDa protein band was shown in heterozygous and mutational channels. Significant HERG tail-current was recorded in wild type HERG channel but not in mutation and heterozygosis channels.

CONCLUSIONThis study evidenced a functional dominant-negative current suppression in HEK293 cells transfected with HERG mutation A561V.

Cell Line ; DNA Mutational Analysis ; ERG1 Potassium Channel ; Ether-A-Go-Go Potassium Channels ; genetics ; Gene Expression ; Humans ; Long QT Syndrome ; congenital ; genetics ; Mutation ; Patch-Clamp Techniques ; Transfection

OBJECTIVETo investigate the molecular pathology in families with long QT syndrome (LQTS) including Jervell-Longe-Nielsen syndrome (JLNS) and Romano-ward syndrome (RWS) and Brugada syndrome (BS) in Chinese population.

METHODSPolymerase chain reaction and DNA sequencing were used to screen for KCNQ1, KCNH2, KCNE1, and SCN5A mutation.

RESULTSWe identified a novel mutation N1774S in the SCN5A gene of the BS family, a novel mutation G314S in a RWS family which had also been found in Europe, North America, and Japan, and a single nucleotide polymorphisms (SNPs) G643S in the KCNQ1 of the JLNS family. In this JLNS family, another heterozygous novel mutation in exon 2a was found in KCNQ1 of the patients.

CONCLUSIONNew mutations were found in our experiment, which expand the spectrum of KCNQ1 and SCN5A mutations that cause LQTS and BS.

Adolescent ; Adult ; Base Sequence ; ERG1 Potassium Channel ; Ether-A-Go-Go Potassium Channels ; genetics ; Female ; Humans ; Jervell-Lange Nielsen Syndrome ; genetics ; KCNQ1 Potassium Channel ; genetics ; Long QT Syndrome ; congenital ; genetics ; Male ; Middle Aged ; Molecular Sequence Data ; Muscle Proteins ; genetics ; Mutation ; NAV1.5 Voltage-Gated Sodium Channel ; Pedigree ; Potassium Channels, Voltage-Gated ; genetics ; Romano-Ward Syndrome ; genetics ; Sodium Channels ; genetics