LQT9: Difference between revisions
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==Overview== | ==Overview== | ||
LQT9 subtype is a variant of long QT syndrome, which causes abnormalities in a membrane protein called [[caveolin]]. | |||
==LQT9== | ==LQT9== | ||
{| class="wikitable" | {| class="wikitable" | ||
| '''Type | | '''Type''' ||'''Mutation''' | ||
|- | |- | ||
| [[LQT9]] | | [[LQT9]] || [[Caveolin 3]] | ||
|} | |} | ||
This newly discovered variant is caused by mutations in the membrane structural protein,[[caveolin]]<nowiki>-3</nowiki>. Caveolins form specific membrane domains called [[caveolae]] in which among others the Na<sub>V</sub>1.5 [[voltage-gated sodium channel]] sits. Similar to LQT3, these particular mutations increase so-called 'late' sodium current which impairs cellular [[repolarization]]. | |||
===History and Symptoms=== | |||
*[[Seizures]] - due to [[oxygen]] deprivation that occurs during [[arrhythmia]]. | |||
*[[Fainting]] - fainting or [[syncope]] is the most common symptom LQTS. | |||
* A prodrome may occur before losing consciousness, which may consist of [[lightheadedness]], heart [[palpitations]], [[blurred vision]] or [[weakness]]. | |||
*[[Sudden death]] - a fatal [[arrhythmia]] that is not quickly intervened on, may cause sudden death. | |||
===Therapy=== | |||
*[[Beta-blockers]] are the first line treatment in LQTS, even in asymptomatic carriers, as they reduce the incidence of [[syncope]] and [[sudden cardiac death]]. | |||
*Other [[medications]] to control non-malignant [[arrhythmias]]. | |||
*[[Electrolytes]] should be repleted as neccesary. | |||
*Avoidance of triggers (drugs, supplements, loud noises, exercise). | |||
* LQTs is one of the few diseases where genetic testing can provide important guidance, such as in whom to place an [[AICD]] (defibrillator) for the primary prevention of cardiac events. <ref>Compton SJ, Lux RL, Ramsey MR, Strelich KR, Sanguinetti MC, Green LS, Keating MT, Mason JW. Genetically defined therapy of inherited long-QT syndrome. Correction of abnormal repolarization by potassium. Circulation. 1996 Sep 1;94(5):1018-22. PMID 8790040</ref> | |||
*Placement of a [[pacemaker]] may be indicated. | |||
*Left [[Stellate ganglion|stellectomy]] is not a cure, but is a second line therapy to reduce the risk of [[sudden cardiac death]] and is indicated if the patient does not tolerate [[beta blockers]], as well as in young patients under the age of 12 where [[beta blockers]] are not deemed protective enough and [[AICD]] is not appropriate. | |||
*Patients with [[long QT syndrome]] should undergo secondary prevention with [[AICD]] implantation if they sustain an aborted [[cardiac arrest]] or [[sudden cardiac death]]. | |||
==References== | ==References== | ||
Latest revision as of 11:13, 9 October 2012
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Long QT Syndrome Microchapters |
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LQT9 On the Web |
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American Roentgen Ray Society Images of LQT9 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]
Overview
LQT9 subtype is a variant of long QT syndrome, which causes abnormalities in a membrane protein called caveolin.
LQT9
| Type | Mutation |
| LQT9 | Caveolin 3 |
This newly discovered variant is caused by mutations in the membrane structural protein,caveolin-3. Caveolins form specific membrane domains called caveolae in which among others the NaV1.5 voltage-gated sodium channel sits. Similar to LQT3, these particular mutations increase so-called 'late' sodium current which impairs cellular repolarization.
History and Symptoms
- Seizures - due to oxygen deprivation that occurs during arrhythmia.
- Fainting - fainting or syncope is the most common symptom LQTS.
- A prodrome may occur before losing consciousness, which may consist of lightheadedness, heart palpitations, blurred vision or weakness.
- Sudden death - a fatal arrhythmia that is not quickly intervened on, may cause sudden death.
Therapy
- Beta-blockers are the first line treatment in LQTS, even in asymptomatic carriers, as they reduce the incidence of syncope and sudden cardiac death.
- Other medications to control non-malignant arrhythmias.
- Electrolytes should be repleted as neccesary.
- Avoidance of triggers (drugs, supplements, loud noises, exercise).
- LQTs is one of the few diseases where genetic testing can provide important guidance, such as in whom to place an AICD (defibrillator) for the primary prevention of cardiac events. [1]
- Placement of a pacemaker may be indicated.
- Left stellectomy is not a cure, but is a second line therapy to reduce the risk of sudden cardiac death and is indicated if the patient does not tolerate beta blockers, as well as in young patients under the age of 12 where beta blockers are not deemed protective enough and AICD is not appropriate.
- Patients with long QT syndrome should undergo secondary prevention with AICD implantation if they sustain an aborted cardiac arrest or sudden cardiac death.
References
- ↑ Compton SJ, Lux RL, Ramsey MR, Strelich KR, Sanguinetti MC, Green LS, Keating MT, Mason JW. Genetically defined therapy of inherited long-QT syndrome. Correction of abnormal repolarization by potassium. Circulation. 1996 Sep 1;94(5):1018-22. PMID 8790040