Congenital long QT syndrome

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dc.contributor.authorCrotti, Liaen_ZA
dc.contributor.authorCelano, Giuseppeen_ZA
dc.contributor.authorDagradi, Federicaen_ZA
dc.contributor.authorSchwartz, Peteren_ZA
dc.date.accessioned2015-10-28T06:51:37Z
dc.date.available2015-10-28T06:51:37Z
dc.date.issued2008en_ZA
dc.description.abstractCongenital long QT syndrome (LQTS) is a hereditary cardiac disease characterized by a prolongation of the QT interval at basal ECG and by a high risk of life-threatening arrhythmias. Disease prevalence is estimated at close to 1 in 2,500 live births.The two cardinal manifestations of LQTS are syncopal episodes, that may lead to cardiac arrest and sudden cardiac death, and electrocardiographic abnormalities, including prolongation of the QT interval and T wave abnormalities. The genetic basis of the disease was identified in the mid-nineties and all the LQTS genes identified so far encode cardiac ion channel subunits or proteins involved in modulating ionic currents. Mutations in these genes (KCNQ1, KCNH2, KCNE1, KCNE2, CACNA1c, CAV3, SCN5A, SCN4B) cause the disease by prolonging the duration of the action potential. The most prevalent LQTS variant (LQT1) is caused by mutations in the KCNQ1 gene, with approximately half of the genotyped patients carrying KCNQ1 mutations.Given the characteristic features of LQTS, the typical cases present no diagnostic difficulties for physicians aware of the disease. However, borderline cases are more complex and require the evaluation of various electrocardiographic, clinical, and familial findings, as proposed in specific diagnostic criteria. Additionally, molecular screening is now part of the diagnostic process.Treatment should always begin with beta-blockers, unless there are valid contraindications. If the patient has one more syncope despite a full dose beta-blockade, left cardiac sympathetic denervation (LCSD) should be performed without hesitation and implantable cardioverter defibrillator (ICD) therapy should be considered with the final decision being based on the individual patient characteristics (age, sex, clinical history, genetic subgroup including mutation-specific features in some cases, presence of ECG signs - including 24-hour Holter recordings - indicating high electrical instability).The prognosis of the disease is usually good in patients that are correctly diagnosed and treated. However, there are a few exceptions: patients with Timothy syndrome, patients with Jervell Lange-Nielsen syndrome carrying KCNQ1 mutations and LQT3 patients with 2:1 atrio-ventricular block and very early occurrence of cardiac arrhythmias.en_ZA
dc.identifier.apacitationCrotti, L., Celano, G., Dagradi, F., & Schwartz, P. (2008). Congenital long QT syndrome. <i>Orphanet Journal of Rare Diseases</i>, http://hdl.handle.net/11427/14432en_ZA
dc.identifier.chicagocitationCrotti, Lia, Giuseppe Celano, Federica Dagradi, and Peter Schwartz "Congenital long QT syndrome." <i>Orphanet Journal of Rare Diseases</i> (2008) http://hdl.handle.net/11427/14432en_ZA
dc.identifier.citationCrotti, L., Celano, G., Dagradi, F., & Schwartz, P. J. (2008). Congenital long QT syndrome. Orphanet J Rare Dis, 3(18), 1172-3.en_ZA
dc.identifier.ris TY - Journal Article AU - Crotti, Lia AU - Celano, Giuseppe AU - Dagradi, Federica AU - Schwartz, Peter AB - Congenital long QT syndrome (LQTS) is a hereditary cardiac disease characterized by a prolongation of the QT interval at basal ECG and by a high risk of life-threatening arrhythmias. Disease prevalence is estimated at close to 1 in 2,500 live births.The two cardinal manifestations of LQTS are syncopal episodes, that may lead to cardiac arrest and sudden cardiac death, and electrocardiographic abnormalities, including prolongation of the QT interval and T wave abnormalities. The genetic basis of the disease was identified in the mid-nineties and all the LQTS genes identified so far encode cardiac ion channel subunits or proteins involved in modulating ionic currents. Mutations in these genes (KCNQ1, KCNH2, KCNE1, KCNE2, CACNA1c, CAV3, SCN5A, SCN4B) cause the disease by prolonging the duration of the action potential. The most prevalent LQTS variant (LQT1) is caused by mutations in the KCNQ1 gene, with approximately half of the genotyped patients carrying KCNQ1 mutations.Given the characteristic features of LQTS, the typical cases present no diagnostic difficulties for physicians aware of the disease. However, borderline cases are more complex and require the evaluation of various electrocardiographic, clinical, and familial findings, as proposed in specific diagnostic criteria. Additionally, molecular screening is now part of the diagnostic process.Treatment should always begin with beta-blockers, unless there are valid contraindications. If the patient has one more syncope despite a full dose beta-blockade, left cardiac sympathetic denervation (LCSD) should be performed without hesitation and implantable cardioverter defibrillator (ICD) therapy should be considered with the final decision being based on the individual patient characteristics (age, sex, clinical history, genetic subgroup including mutation-specific features in some cases, presence of ECG signs - including 24-hour Holter recordings - indicating high electrical instability).The prognosis of the disease is usually good in patients that are correctly diagnosed and treated. However, there are a few exceptions: patients with Timothy syndrome, patients with Jervell Lange-Nielsen syndrome carrying KCNQ1 mutations and LQT3 patients with 2:1 atrio-ventricular block and very early occurrence of cardiac arrhythmias. DA - 2008 DB - OpenUCT DO - 10.1186/1750-1172-3-18 DP - University of Cape Town J1 - Orphanet Journal of Rare Diseases LK - https://open.uct.ac.za PB - University of Cape Town PY - 2008 T1 - Congenital long QT syndrome TI - Congenital long QT syndrome UR - http://hdl.handle.net/11427/14432 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/14432
dc.identifier.urihttp://dx.doi.org/10.1186/1750-1172-3-18
dc.identifier.vancouvercitationCrotti L, Celano G, Dagradi F, Schwartz P. Congenital long QT syndrome. Orphanet Journal of Rare Diseases. 2008; http://hdl.handle.net/11427/14432.en_ZA
dc.language.isoengen_ZA
dc.publisherBioMed Central Ltden_ZA
dc.publisher.departmentDivision of Cardiologyen_ZA
dc.publisher.facultyFaculty of Health Sciencesen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an Open Access article distributed under the terms of the Creative Commons Attribution Licenseen_ZA
dc.rights.holder2008 Crotti et al; licensee BioMed Central Ltd.en_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/2.0en_ZA
dc.sourceOrphanet Journal of Rare Diseasesen_ZA
dc.source.urihttp://www.ojrd.com/en_ZA
dc.subject.otherCongenital Heart Diseaseen_ZA
dc.subject.otherGenetic Disordersen_ZA
dc.subject.otherArrhythmiaen_ZA
dc.subject.otherCardiac Arresten_ZA
dc.titleCongenital long QT syndromeen_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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