Delayed diagnosis of long QT syndrome in a patient with seizures

Introduction: Long QT syndrome accompanied by a seizure episode is often misdiagnosed as primary epilepsy. Although patients with Long QT syndrome who are misdiagnosed and improperly managed are likely to result in fatality, their first clinical manifestations are seizure episodes in many cases. Case presentation: A 17-year-old boy visited the emergency department with poorly controlled seizure during epilepsy treatment was found to have been misdiagnosed with epilepsy when he was 7 years old. His electrocardiography showed a prolonged QT interval. After careful re-evaluation, he was finally diagnosed with Long QT syndrome and recovered without any seizure episodes in the absence of anti-epileptic agents. Discussion and conclusion: Careful initial assessment including repetitive electrocardiography, when abnormal, is required for those who visit the emergency department with a seizure or who show no definite abnormalities in diagnostic work up process.

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Prolonged QTc: "Mind the Gap"

Bangladesh Critical Care Journal ◽

10.3329/bccj.v2i1.19970 ◽

2014 ◽

Vol 2 (1) ◽

pp. 44-45

Author(s):

Ahmad Mursel Anam ◽

Raihan Rabbani ◽

Farzana Shumy ◽

M Mufizul Islam Polash ◽

M Motiul Islam ◽

...

Keyword(s):

Cardiac Arrest ◽

Long Qt Syndrome ◽

Qt Interval ◽

Torsades De Pointes ◽

Junior Doctors ◽

Long Qt ◽

Acquired Long Qt Syndrome ◽

Prolonged Qt Interval ◽

Prolonged Qt ◽

Qt Syndrome

We report a case of drug induced torsades de pointes, following acquired long QT syndrome. The patient got admitted for shock with acute abdomen. The initial prolonged QT-interval was missed, and a torsadogenic drug was introduced post-operatively. Patient developed torsades de pointes followed by cardiac arrest. She was managed well and discharged without complications. The clinical manifestations of long QT syndromes, syncope or cardiac arrest, result from torsades de pointes. As syncope or cardiac arrest have more common differential diagnoses, even the symptomatic long QT syndrome are commonly missed or misdiagnosed. In acquired long QT syndrome with no prior suggestive feature, it is not impossible to miss the prolonged QT-interval on the ECG tracing. We share our experience so that the clinicians, especially the junior doctors, will be more alert on checking the QT-interval even in asymptomatic patients. DOI: http://dx.doi.org/10.3329/bccj.v2i1.19970 Bangladesh Crit Care J March 2014; 2 (1): 44-45

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A wearable remote monitoring system for the identification of subjects with a prolonged QT interval or at risk for drug-induced long QT syndrome

International Journal of Cardiology ◽

10.1016/j.ijcard.2018.03.097 ◽

2018 ◽

Vol 266 ◽

pp. 89-94 ◽

Cited By ~ 17

Author(s):

Silvia Castelletti ◽

Federica Dagradi ◽

Karine Goulene ◽

Aurora I. Danza ◽

Enrico Baldi ◽

...

Keyword(s):

Monitoring System ◽

Long Qt Syndrome ◽

Remote Monitoring ◽

Qt Interval ◽

Long Qt ◽

Drug Induced ◽

Remote Monitoring System ◽

Prolonged Qt Interval ◽

Prolonged Qt ◽

Qt Syndrome

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The Common Long-QT Syndrome Mutation KCNQ1/A341V Causes Unusually Severe Clinical Manifestations in Patients With Different Ethnic Backgrounds

Circulation ◽

10.1161/circulationaha.107.726950 ◽

2007 ◽

Vol 116 (21) ◽

pp. 2366-2375 ◽

Cited By ~ 117

Author(s):

Lia Crotti ◽

Carla Spazzolini ◽

Peter J. Schwartz ◽

Wataru Shimizu ◽

Isabelle Denjoy ◽

...

Keyword(s):

Long Qt Syndrome ◽

Clinical Manifestations ◽

Long Qt ◽

The Common ◽

Qt Syndrome

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Age- and Sex-Related Differences in Clinical Manifestations in Patients With Congenital Long-QT Syndrome

Circulation ◽

10.1161/01.cir.97.22.2237 ◽

1998 ◽

Vol 97 (22) ◽

pp. 2237-2244 ◽

Cited By ~ 295

Author(s):

Emanuela H. Locati ◽

Wojciech Zareba ◽

Arthur J. Moss ◽

Peter J. Schwartz ◽

G. Michael Vincent ◽

...

Keyword(s):

Long Qt Syndrome ◽

Clinical Manifestations ◽

Long Qt ◽

Qt Syndrome ◽

Age And Sex ◽

Congenital Long Qt Syndrome

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Faculty Opinions recommendation of The common long-QT syndrome mutation KCNQ1/A341V causes unusually severe clinical manifestations in patients with different ethnic backgrounds: toward a mutation-specific risk stratification.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1097645.553746 ◽

2008 ◽

Author(s):

Richard NW Hauer

Keyword(s):

Risk Stratification ◽

Long Qt Syndrome ◽

Clinical Manifestations ◽

Long Qt ◽

Specific Risk ◽

The Common ◽

Qt Syndrome

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Clinical and electrophysiological characterization of a novel mutation (F193L) in the KCNQ1 gene associated with long QT syndrome

Clinical Science ◽

10.1042/cs1040377 ◽

2003 ◽

Vol 104 (4) ◽

pp. 377-382 ◽

Cited By ~ 6

Author(s):

Masato YAMAGUCHI ◽

Masami SHIMIZU ◽

Hidekazu INO ◽

Hidenobu TERAI ◽

Kenshi HAYASHI ◽

...

Keyword(s):

Long Qt Syndrome ◽

Novel Mutation ◽

Expression System ◽

Clinical Manifestations ◽

Delayed Rectifier ◽

Polymorphism Analysis ◽

Long Qt ◽

Α Subunit ◽

Kcnq1 Gene ◽

Qt Syndrome

KCNQ1 is a gene encoding an α subunit of voltage-gated cardiac K+ channels, with properties similar to the slowly activating delayed rectifier K+ current, and one of the genes causing long QT syndrome (LQTS). However, genotype–phenotype correlations of the KCNQ1 gene mutations are not fully understood. The aims of this study were to identify a mutation in the KCNQ1 gene in patients with LQTS, and to characterize the clinical manifestations and electrophysiological properties of the mutation. We screened and identified mutations by PCR, single-strand conformational polymorphism analysis and DNA sequencing. We identified a novel mutation [Phe193Leu (F193L)] in the KCNQ1 gene in one family with LQTS. The patients with this mutation showed a mildly affected phenotype. The proband was a 17-year-old girl who had a prolonged QT interval. Her elder brother, father and paternal grandmother also had the mutation. None of them had any history of syncope. Sudden death was not found in this family. Next, we studied the electrophysiological characteristics of the F193L mutation in the KCNQ1 gene using the expression system in Xenopus oocytes and the two-microelectrode voltage-clamp technique. Co-expression of F193L KCNQ1 with the K+ channel minK suppressed peak (by 23.3%) and tail (by 38.2%) currents compared with those obtained by the combination of wild-type (WT) KCNQ1 and minK. Time constants of current activation in F193L KCNQ1 and F193L KCNQ1+minK were significantly slower than those of WT KCNQ1 and WT KCNQ1+minK. This electrophysiological study indicates that F193L causes less severe KCNQ1 current suppression, and thereby this mutation may result in a mildly affected phenotype.

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Compound heterozygosity for mutations Asp611→Tyr in KCNQ1 and Asp609→Gly in KCNH2 associated with severe long QT syndrome

Clinical Science ◽

10.1042/cs20040220 ◽

2005 ◽

Vol 108 (2) ◽

pp. 143-150 ◽

Cited By ~ 17

Author(s):

Masato YAMAGUCHI ◽

Masami SHIMIZU ◽

Hidekazu INO ◽

Hidenobu TERAI ◽

Kenshi HAYASHI ◽

...

Keyword(s):

Long Qt Syndrome ◽

Clinical Manifestations ◽

Torsades De Pointes ◽

Dominant Negative ◽

Missense Mutations ◽

Wild Type ◽

Long Qt ◽

Mild Phenotype ◽

Electrophysiological Properties ◽

Qt Syndrome

LQTS (long QT syndrome) is an inherited cardiac disorder characterized by prolongation of QT interval, torsades de pointes and sudden death. We have identified two heterozygous missense mutations in the KCNQ1 and KCNH2 (also known as HERG) genes [Asp611→Tyr (D611Y) in KCNQ1 and Asp609→Gly (D609G) in KCNH2] in a 2-year-old boy with LQTS. The aim of the present study was to characterize the contributions of the mutations in the KCNQ1 and KCNH2 genes relative to the clinical manifestations and electrophysiological properties of LQTS. Six of 11 carriers of D611Y in KCNQ1 had long QT intervals. D609G in KCNH2 was detected only in the proband. Studies on the electrophysiological alterations due to the two missense mutations revealed that the D611Y mutation in KCNQ1 did not show a significant suppression of the currents compared with wild-type, but the time constants of current activation in the mutants were increased compared with that in the wild-type. In contrast, the D609G mutation in KCNH2 showed a dominant-negative suppression. Our results suggest that the mild phenotype produced by the D611Y mutation in KCNQ1 became more serious by addition of the D609G mutation in KCNH2 in the proband.

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