Long QT Syndrome: Difference between revisions

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{{authors|
|mainauthor= [[user:Pgpostema|P.G. Postema, MD]]
|mainauthor= [[user:Drj|J.S.S.G. de Jong, MD]]
|advisor=
|supervisor=
|coauthor= [[user:Drj|J.S.S.G. de Jong, MD]]
|coauthor= [[user:Pgpostema|P.G. Postema, MD]]
|moderator= [[user:Pgpostema|P.G. Postema, MD]]
|moderator= [[user:Pgpostema|P.G. Postema, MD]]
|editor=  
|editor=  
}}
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The '''Long QT Syndrome (LQTS)''' is characterized on the ECG by prolongation of the [[Conduction#The_QT_interval|heart rate corrected QT interval]]. This was first recognized by Dr. Jervell and Dr. Lange-Nielsen in 1957. They described 4 children with a long QT interval which was accompanied by hearing deficits, sudden cardiac death and an autosomal recessive inheritance.<cite>Lang1957</cite>


The Long QT syndrome may be divided into two distinct forms: congenital Long QT syndrome and acquired Long QT syndrome. These forms may however overlap when QT prolongation due to medication occurs in a patient with congenital Long QT syndrome.
<gallery>
File:acquired_longQT.jpg|A 12-lead ECG of a patient with acquired long QT syndrome. Notice the QT prolongation. The QTc is about 640ms.
File:Lqts1.png|A 12 lead ECG of a patient with genetically proven LQTS1
File:Lqts2.png|A 12 lead ECG of a patient with genetically proven LQTS2
File:Lqts3.png|A 12 lead ECG of a patient with genetically proven LQTS3
</gallery>
===Diagnosis===
*The diagnosis is by measurement of the [[Conduction#The_QT_interval|heart rate-corrected QT interval]] on the ECG, which can be calculated with the [[QTc calculator]].
*Sometimes the QT interval can be difficult to assess. Read the [[Difficult_QT|guidelines for measurement of difficult QT interval]].
*A QTc of > 500ms in patients with Long QT Syndrome is associated with an increased risk for sudden death.<cite>Priori</cite>
*In patients suspected of LQTS (e.g. family members of known LQTS patients) a QTc > 430ms makes it likely that a LQTS gene defect is present.<cite>Hofman</cite>
*Because the QTc can change with age, it is best to take the ECG with the longest QTc interval for risk stratification.<cite>Goldenberg</cite>


Het long QT syndrome betreft een aandoening waarbij, zoals de naam al doet vermoeden, de [[Geleidingstijden_%28PQ%2CQRS%2CQT%29|QT tijd]] op het ECG verlengd is. Dit kan inborn zijn, maar ook verworven. Bij een verlengde QT tijd is de repolariatie vertraagd. Dat wil zeggen dat de hartcellen longr nodig hebben om zich klaar te maken voor de volgende slag. Als er een nieuwe hartslag komt, terwijl nog niet alle hartcellen daar klaar voor zijn, kunnen ernstige ritmestoornissen ontstaan, zoals [[Ritmestoornissen#Torsade de pointes| Torsades de Pointes]] en [[Ritmestoornissen#ventrikelfibrilleren|Ventrikelfibrilleren]].
===Treatment<cite>ACC2006</cite>===
*"Lifestyle modification":
** No competitive sports in all LQTS patients
** No swimming in LQT1 patients
** Avoid nightly noise in LQT2 patients (e.g. no alarm clock)
*Medication: beta-blockers. Beta-blockers even reduce the risk of sudden death in patients in whom a genetic defect has been found, but no QT prolongation is visible on the ECG.
*[[:w:nl:Internal_Cardiac_Defibrillator|ICD]] implantation in combination with beta-blockers in LQTS patients with previous cardiac arrest or [[syncope]] or [[Ventricular Tachycardia|ventricular tachycardia]] while on beta-blockers.


===Diagnose en behandeling===
===Acquired LQTS===
De diagnose wordt gesteld aan de hand van het ECG. Hierbij kijkt men naar het [[Geleidingstijden_%28PQ%2CQRS%2CQT%29|QT-interval]] als mede naar de T-golven (repolarisatie). Soms is de QT tijd lastig te bepalen. Kijk hier voor het meten van de '''[[lastige QT|QT tijd bij afwijkende QT patronen]]'''. Een QTc van > 500ms bij patienten met het long QT syndrome is geassocieerd met een verhoogd risico op cardiale events. Omdat de QTc kan wisselen over de jaren, is het belangrijk ECG's te herhalen over de tijd en de langst gemeten QTc te gebruiken bij risico-inschatting. <cite>Goldenberg</cite>
Acquired LQTS is most often caused by drugs that prolong the QT interval. Combined with risk factors (see table) the risk of [[Torsade_de_Pointes|Torsade de Pointes]] increases.


Voor de behandeling zijn er een aantal mogelijkheden:<cite>ACC2006</cite>
{|
*"Lifestyle modification":
|-
** Geen sport in competitieverband bij alle patiënten met LQTS
|valign="top"|
** Niet zwemmen in geval van LQT1
{| class="wikitable" width="400px"
** Nachtelijk lawaai voorkómen in geval van LQT2 (bijvoorbeeld van telefoon of wekker)
!Common drugs that can cause [[Torsade_de_Pointes|Torsade de Pointes]] include:<cite>Roden</cite>
*medicatie: beta-blokkers. Beta-blokkers verminderen het optreden van plotselinge hartdood in patiënten , waarbij een genetische afwijking is gevonden passend bij LQTS, maar bij wie geen verlengd QT interval op het ECG is te zien.
|-
*[[:w:nl:Internal_Cardiac_Defibrillator|ICD]] implantatie in combinatie met een beta-blokker bij LQTS patiënten met een eerdere hartstilstand of met [[syncope]] of ventrikeltachycardiën ondanks beta-blokkers.
|
<ul>
<li>Sotalol</li>
<li>Amiodarone</li>
<li>Erythromycin</li>
<li>Clarithromycin</li>
</ul>
|-
!Less often used drugs include:
|-
|
<ul>
<li>Cisapride</li>
<li>antibiotics: halofantrine, pentamidine, sparfloxacin</li>
<li>Anti-emetics: domperidon, droperidol</li>
<li>Anti-psychotics: chlorpromazine, haloperidol, mesoridazine, thioridazine, pimozide</li>
<li>Methadon</li>
<li>Disopyramide</li>
<li>Dofetilide</li>
<li>Ibutilide</li>
<li>Procainamide</li>
<li>Quinidine</li>
<li>Bepridil</li>
</ul>
|-
|[http://www.torsades.org Torsades.org] has an extensive list of drugs that can TdP
|}
|valign="top"|
{| class="wikitable" align="right" width="400px"
!Concomittant risk factors for medication induced [[Torsade_de_Pointes|Torsade de Pointes]]:
|-
|
<ul>
<li>Female sex</li>
<li>Hypokalemia</li>
<li>Bradycardia</li>
<li>Recent conversion of [[Atrial Fibrillation|atrial fibrillation]], especially if QT prolonging drugs were used (sotalol, amiodarone)</li>
<li>Cardiac decompensation</li>
<li>Digoxin treatment</li>
<li>High or overdosing or rapid infusion of a QT prolonging drug</li>
<li>Pre-existing QT prolongation</li>
<li>Congenital long QT syndrome</li>
</ul>
|}
|-
|}


===Inborn LQTS===
===Congenital LQTS===
[[Image:lqts1-3.png|thumb| De drie meest voorkomende vormen van het long QT syndrome zijn te herkennen aan '''specifieke ECG afwijkingen''': LQT1 'early onset' T top met brede basis; LQT2 kleine late T top; LQT3 verlengde QT tijd met 'late onset' T golf van normale vorm; LQT8 met alternerende T toppen (LQT8 is zeer zeldzaam).]]
[[Image:lqts1-3.png|thumb|The three most common forms of LQTS can be recognized by the '''characteristic ECG abnormalities''']]:  
Congenitale LQTS is een erfelijke aandoening waarbij de ventriculaire repolarisatie verlengd is, wat zich onder meer uit in een verlengde QT tijd op het ECG. Syncope en plotse hartdood treedt bij LQTS vaak op tijdens een specifieke ventriculaire ritmestoornis: [[Ritmestoornissen#Torsade_de_pointes|torsade de pointes]]. Hierbij draait de hartas continu, tijdens een ventriculaire tachycardie. Torsades de pointes kan overgaan in ventrikelfibrilleren en plotse hartdood.
*LQT1 'early onset' broad based T wave
De prevalentie is ongeveer 1:3000-5000. De symptomen starten vaak in de tienerleeftijd. Niet alle dragers van afwijkende LQTS genen zijn ook ziek. De uiting kan wisselen van extreme QT velenging en regelmatige syncope, tot minimaal verlenge QT tijd, zonder enig symptoom.
*LQT2 small late T wave
*LQT3 prolonged QT interval with 'late onset' T wave with a normal configuration
In congenital LQTS the ventricular repolarisation is prolonged. '''The prevalence is about 1:3000-5000'''.  


Onderzoek heeft aangetoond, dat de inborn vormen berusten op een genetisch defect in de genen die coderen voor ionenstromen die verantwoordelijk zijn voor de repolarisatiefase van een actiepotentiaal. He meest voorkomende defect berust op die van de '''uitwaartse kaliumstroom'''. Dit leidt tot een verlengde repolarisatie en dus een verlengde QT-tijd. Tevens bestaan er ook defecten in de '''natriumkanalen'''. Er is dan met name sprake van een longre inwaartse natriumstroom. Het gevolg is een longre actiepotentiaal als mede een longre QT-tijd.
More than 10 different types of congenital LQTS have been described. However, only LQTS 1-3 are relatively common.<cite>ACC2006</cite>
 
Er zijn inmiddels 8 LQTS genen beschreven met ieder verschillende kenmerken: <cite>ACC2006</cite>


{| border="1" cellpadding="2" cellspacing="0" bordercolor="#6EB4EB" style="font-size:100%;" class="plainlinks" class="wikitable"
{| border="1" cellpadding="2" cellspacing="0" bordercolor="#6EB4EB" style="font-size:100%;" class="plainlinks" class="wikitable"
|- style="text-align:center;background-color:#6EB4EB;"
|- style="text-align:center;background-color:#6EB4EB;"
| type
| '''Type'''
| chromosoom
| '''Chromosome'''
| gen
| '''Gene'''
| protein
| '''Protein'''
| ionchannel
| '''Ionchannel'''
| frequentie<cite>priori</cite>
| '''Frequency<cite>priori</cite>'''
| SCD incidentie<cite>Shah2005</cite>
| '''SCD incidence<cite>Shah2005</cite>'''
| oververving
| '''Inheritance'''
| ECG kenmerken
| '''ECG characteristics'''
| Trigger
| '''Trigger'''
| Eponiem
| '''Eponyme'''
| [[w:OMIM|OMIM&trade;]] link
| '''[[w:OMIM|OMIM&trade;]] link'''
|-
|-
! LQTS1
! LQTS1
Line 52: Line 116:
| I''ks''
| I''ks''
| ~50%
| ~50%
| 0.30%/jaar
| 0.30%/year
| AD, AR
| AD, AR
| 'early onset' T top met brede basis
| broad base 'early onset' T wave
| inspanning, m.n. zwemmen
| exercise, especially swimming
| JLN1 indien homozygoot, LQTS1 indien heterozygoot
| JLN1 if homozygous, LQTS1 if heterozygous
| {{OMIM2|607542}}  
| {{OMIM2|607542}}  
|-
|-
Line 65: Line 129:
| I''kr''
| I''kr''
| 30-40%
| 30-40%
| 0.60%/jaar
| 0.60%/year
| AD
| AD
| kleine late T top
| small late T wave
| adrenerge prikkels, m.n. nachtelijk lawaai
| adrenergic triggers, especially nightly noise
| JLN2 indien homozygoot, LQTS2 indien heterozygoot
| JLN2 if homozygous, LQTS2 if heterozygous
| {{OMIM2|152427}}
| {{OMIM2|152427}}
|-
|-
Line 75: Line 139:
| 3p21
| 3p21
| SCN5A
| SCN5A
| NA kanaal
| NA channel
|
|
| 5-10%
| 5-10%
| 0.56%/jaar
| 0.56%/year
| AD
| AD
| 'Late onset' T golf van normale vorm
| 'Late onset' T wave with normal configuration
|
|
|
|
Line 86: Line 150:
|-
|-
! LQTS4
! LQTS4
| 4q25
| 4q25-q27
| ANK2
| ANK2
| Ankyrin B
| Ankyrin B
|
| I''Na,K''
| <1%
| <1%
| unknown
|  
| AD
| AD
|
|
Line 99: Line 163:
|-
|-
! LQTS5
! LQTS5
| 21q22
| 21q22.1
| KCNE1
| KCNE1
| minK  
| minK  
Line 112: Line 176:
|-
|-
! LQTS6
! LQTS6
| 21q22
| 21q22.1
| KCNE2
| KCNE2
| MiRP1
| MiRP1
Line 124: Line 188:
| {{OMIM2|603796}}
| {{OMIM2|603796}}
|-
|-
! LQTS7
! LQTS7 = ATS1
| 17q23
| 17q23
| KCNJ2
| KCNJ2
Line 137: Line 201:
| {{OMIM2|600681}}
| {{OMIM2|600681}}
|-
|-
! LQTS8
! LQTS8 = TS1
| 6q8A
| 12p13.3
| CACNA1C
| CACNA1C
|  
| Ca<sub>v</sub>1.2
| I''Ca-L''
| I''Ca-L''
| <1%
| <1%
| unknown
| unknown
|  
|  
| alternerende T golven
| alternating T waves
|
|
| Timothy syndrome
| Timothy syndrome
| {{OMIM2|114205}}
| {{OMIM2|601005}}
|-
|-
! LQTS9
! LQTS9
Line 154: Line 218:
| CAV3
| CAV3
| Caveolin 3
| Caveolin 3
|  
| I''Na''
|  
|  
| unknown
| unknown
Line 166: Line 230:
| 11q23.3
| 11q23.3
| SCN4B
| SCN4B
| Navb4
| Na<sub>v</sub>1.5 b4
|  
|  
| 1 family
| 1 family
Line 175: Line 239:
|  
|  
| {{OMIM2|608256}}
| {{OMIM2|608256}}
|-
! LQTS11
| 7q21-q22
| Akap9
| AKAP
| I''ks''
| 1 family
| unknown
|
|
|
|
| {{OMIM2|611820}}
|}
|}
;LQTS: Long QT syndrome
;LQTS: Long QT syndrome
Line 180: Line 257:
;SCD: Sudden Cardiac Death
;SCD: Sudden Cardiac Death
   
   
Nog voordat deze genen bekend waren, waren er al enkele syndromen beschreven, die gepaard gingen met een long QT tijd.  
Long before the genes involved were known, two syndromes  associated with a prolonged QT interval on the ECG had been described.
* Anton Jervell and Fred Lange-Nielsen uit Oslo beschreven in 1957 een autosomaal recessief overervend syndrome dat gepaard ging met QT verlenging, doofheid en plotselinge hartdood. Sindsdien heet dit syndrome '''Jervell-Lange-Nielsen syndrome'''. <cite>Lang1957</cite>
* Anton Jervell and Fred Lange-Nielsen from Oslo described in 1957 an autosomaal recessive syndrome that was associated with QT interval prolongation, deafness and sudden death: the now called '''Jervell-Lange-Nielsen syndrome'''. <cite>Lang1957</cite>
* '''Romano-Ward syndrome''' is een long QT syndrome met normale gehoorfunctie en erft i.t.t. de anderen autosomaal dominant over. Inmiddels is bekend dat ook deze syndromen berusten op afwijkingen in bovenstaande genen.
* '''Romano-Ward syndrome''' is a long QT syndrome with normal auditory function and autosomal dominant inheritance.  
* In a genotype–phenotype study by Moss et al. that studied type-1 LQTS, it was found that mutations located in the transmembrane portion of the ion channel protein and the degree of ion channel dysfunction caused by the mutations are important independent risk factors influencing the clinical course of this disorder.<cite>moss</cite>
* In a genotype–phenotype study by Moss et al. that studied type-1 LQTS, it was found that mutations located in the transmembrane portion of the ion channel protein and the degree of ion channel dysfunction caused by the mutations are important independent risk factors influencing the clinical course of this disorder.<cite>moss</cite>


===Verworven LQTS===
==External links==
Verworven long QT syndrome wordt veroorzaakt meestal veroorzaakt door medicijnen. In combinatie met een aantal risicofactoren neemt het risico op ritmestoornissen toe, met name ook weer [[Ritmestoornissen#Torsade_de_pointes|Torsade de Pointes]].
#[http://www.torsades.org Torsades.org has a list of QT prolonging drugs]
 
#[http://qtdrugs.org QTdrugs.org, another list of QT prolonging drugs]
{| class="wikitable" align="right" width="400px"
#[http://www.sads.org Sudden Arrhythmia Death Syndrome Foundation]. LQTS patient group.
!Medicijnen die [[Ritmestoornissen#Torsade_de_pointes|Torsade de Pointes]] kunnen veroorzaken:<cite>Roden</cite>
|-
|
<ul>
<li>Sotalol</li>
<li>Amiodarone</li>
<li>Erythromycine</li>
<li>Clarithromycine</li>
</ul>
|-
!Minder vaak gebruikte medicijnen:
|-
|
<ul>
<li>Cisapride</li>
<li>antibiotica: halofantrine, pentamidine, sparfloxacin</li>
<li>Anti-emetica: domperidon, droperidol</li>
<li>Anti-psychotica: chlorpromazine, haloperidol, mesoridazine, thioridazine, pimozide</li>
<li>Methadon</li>
<li>Disopyramide</li>
<li>Dofetilide</li>
<li>Ibutilide</li>
<li>Procainamide</li>
<li>Quinidine</li>
<li>Bepridil</li>
</ul>
|-
|Zie ook [http://www.torsades.org Torsades.org] voor een uitgebreide lijst
|}
 
{{clr}}
 
{| class="wikitable" align="right" width="400px"
!Risicofactoren voor medicijngeïnduceerde [[Ritmestoornissen#Torsade_de_pointes|Torsade de Pointes]]:
|-
|
<ul>
<li>Vrouwelijk geslacht</li>
<li>Hypokaliemie</li>
<li>Bradycardie</li>
<li>Recente conversie van [[Ritmestoornissen#Torsade_de_pointes|boezemfibrilleren]], in het bijzonder als er een QT-verlengend medicijn is gebruikt (sotalol, amiodarone)</li>
<li>Decompensatio cordis</li>
<li>Digitalis behandeling</li>
<li>Hoge of overdosering of snelle intraveneuze toediening van één van bovengenoemde medicamenten</li>
<li>Bestaande QT verlenging vóórdat het medicament werd toegediend</li>
<li>Subklinisch long QT syndrome</li>
<li>Bepaalde ion-kanaal polymorphismen</li>
</ul>
|}
 
{{clr}}
 
===Externe links===
#LongQT.org [http://www.longqt.org/images/Long%20QT%20Syn%20Feb-2002.pdf Powerpoint presentatie over long QT syndrome]
#[http://www.torsades.org Torsades.org met een lijst met QT verlengende medicatie]
#[http://qtdrugs.org QTdrugs.org, met een lijst van QT verlengende medicatie]
#[http://www.cardiogenetica.nl Cardiogenetica.nl]
#[http://www.sads.org Sudden Arrhythmia Death Syndrome Foundation]. Een Amerikaanse vereniging o.a. voor LQTS patiënten.
#[http://www.fsm.it/cardmoc/ Inherited Arrhythmias Database]
#[http://www.fsm.it/cardmoc/ Inherited Arrhythmias Database]


===Referenties===
==Referenties==
<biblio>
<biblio>
#Schwartz2001 pmid=11136691
#Schwartz2001 pmid=11136691
Line 259: Line 278:
#moss pmid=17470695
#moss pmid=17470695
#priori pmid=12736279
#priori pmid=12736279
#Hofman pmid=17090615
#Roden pmid=18184962
</biblio>
</biblio>
<analytics uacct="UA-807577-6"></analytics>

Latest revision as of 19:47, 27 August 2020

Author(s) J.S.S.G. de Jong, MD
Moderator P.G. Postema, MD
Supervisor
some notes about authorship

The Long QT Syndrome (LQTS) is characterized on the ECG by prolongation of the heart rate corrected QT interval. This was first recognized by Dr. Jervell and Dr. Lange-Nielsen in 1957. They described 4 children with a long QT interval which was accompanied by hearing deficits, sudden cardiac death and an autosomal recessive inheritance.[1]

The Long QT syndrome may be divided into two distinct forms: congenital Long QT syndrome and acquired Long QT syndrome. These forms may however overlap when QT prolongation due to medication occurs in a patient with congenital Long QT syndrome.

Diagnosis

  • The diagnosis is by measurement of the heart rate-corrected QT interval on the ECG, which can be calculated with the QTc calculator.
  • Sometimes the QT interval can be difficult to assess. Read the guidelines for measurement of difficult QT interval.
  • A QTc of > 500ms in patients with Long QT Syndrome is associated with an increased risk for sudden death.[2]
  • In patients suspected of LQTS (e.g. family members of known LQTS patients) a QTc > 430ms makes it likely that a LQTS gene defect is present.[3]
  • Because the QTc can change with age, it is best to take the ECG with the longest QTc interval for risk stratification.[4]

Treatment[5]

  • "Lifestyle modification":
    • No competitive sports in all LQTS patients
    • No swimming in LQT1 patients
    • Avoid nightly noise in LQT2 patients (e.g. no alarm clock)
  • Medication: beta-blockers. Beta-blockers even reduce the risk of sudden death in patients in whom a genetic defect has been found, but no QT prolongation is visible on the ECG.
  • ICD implantation in combination with beta-blockers in LQTS patients with previous cardiac arrest or syncope or ventricular tachycardia while on beta-blockers.

Acquired LQTS

Acquired LQTS is most often caused by drugs that prolong the QT interval. Combined with risk factors (see table) the risk of Torsade de Pointes increases.

Common drugs that can cause Torsade de Pointes include:[6]
  • Sotalol
  • Amiodarone
  • Erythromycin
  • Clarithromycin
Less often used drugs include:
  • Cisapride
  • antibiotics: halofantrine, pentamidine, sparfloxacin
  • Anti-emetics: domperidon, droperidol
  • Anti-psychotics: chlorpromazine, haloperidol, mesoridazine, thioridazine, pimozide
  • Methadon
  • Disopyramide
  • Dofetilide
  • Ibutilide
  • Procainamide
  • Quinidine
  • Bepridil
Torsades.org has an extensive list of drugs that can TdP
Concomittant risk factors for medication induced Torsade de Pointes:
  • Female sex
  • Hypokalemia
  • Bradycardia
  • Recent conversion of atrial fibrillation, especially if QT prolonging drugs were used (sotalol, amiodarone)
  • Cardiac decompensation
  • Digoxin treatment
  • High or overdosing or rapid infusion of a QT prolonging drug
  • Pre-existing QT prolongation
  • Congenital long QT syndrome

Congenital LQTS

The three most common forms of LQTS can be recognized by the characteristic ECG abnormalities

:

  • LQT1 'early onset' broad based T wave
  • LQT2 small late T wave
  • LQT3 prolonged QT interval with 'late onset' T wave with a normal configuration

In congenital LQTS the ventricular repolarisation is prolonged. The prevalence is about 1:3000-5000.

More than 10 different types of congenital LQTS have been described. However, only LQTS 1-3 are relatively common.[5]

Type Chromosome Gene Protein Ionchannel Frequency[7] SCD incidence[8] Inheritance ECG characteristics Trigger Eponyme OMIM™ link
LQTS1 11p15 KCNQ1 KvLQT1 Iks ~50% 0.30%/year AD, AR broad base 'early onset' T wave exercise, especially swimming JLN1 if homozygous, LQTS1 if heterozygous 607542
LQTS2 7q35 KCNH2 hERG Ikr 30-40% 0.60%/year AD small late T wave adrenergic triggers, especially nightly noise JLN2 if homozygous, LQTS2 if heterozygous 152427
LQTS3 3p21 SCN5A NA channel 5-10% 0.56%/year AD 'Late onset' T wave with normal configuration 600163
LQTS4 4q25-q27 ANK2 Ankyrin B INa,K <1% AD 106410
LQTS5 21q22.1 KCNE1 minK Iks <1% unknown AD/AR 176261
LQTS6 21q22.1 KCNE2 MiRP1 Ikr <1% unknown AD 603796
LQTS7 = ATS1 17q23 KCNJ2 Kir 2.1 IK1 <1% unknown AD Anderson-Tawil syndrome 600681
LQTS8 = TS1 12p13.3 CACNA1C Cav1.2 ICa-L <1% unknown alternating T waves Timothy syndrome 601005
LQTS9 3p25.3 CAV3 Caveolin 3 INa unknown 601253
LQTS10 11q23.3 SCN4B Nav1.5 b4 1 family unknown 608256
LQTS11 7q21-q22 Akap9 AKAP Iks 1 family unknown 611820
LQTS
Long QT syndrome
JLN
Jervell and Lange-Nielsen syndrome
SCD
Sudden Cardiac Death

Long before the genes involved were known, two syndromes associated with a prolonged QT interval on the ECG had been described.

  • Anton Jervell and Fred Lange-Nielsen from Oslo described in 1957 an autosomaal recessive syndrome that was associated with QT interval prolongation, deafness and sudden death: the now called Jervell-Lange-Nielsen syndrome. [1]
  • Romano-Ward syndrome is a long QT syndrome with normal auditory function and autosomal dominant inheritance.
  • In a genotype–phenotype study by Moss et al. that studied type-1 LQTS, it was found that mutations located in the transmembrane portion of the ion channel protein and the degree of ion channel dysfunction caused by the mutations are important independent risk factors influencing the clinical course of this disorder.[9]

External links

  1. Torsades.org has a list of QT prolonging drugs
  2. QTdrugs.org, another list of QT prolonging drugs
  3. Sudden Arrhythmia Death Syndrome Foundation. LQTS patient group.
  4. Inherited Arrhythmias Database

Referenties

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All Medline abstracts: PubMed | HubMed