Long QT Syndrome medical and device therapy: Difference between revisions
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==Overview== | ==Overview== | ||
Beta-blockers are first line treatment in LQTs along with electrolyte repletion, and avoidance of triggers (drugs, supplements, loud noises). LQTs is one of the few diseases where genetic testing actually can provide important guidance such as who to put a [[AICD]] (defibrillator) in for primary prevention. <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> | |||
==Withdrawal of Drugs and Supplements== | ==Primary Prevention== | ||
===Withdrawal of Drugs and Supplements=== | |||
Certain medications should be avoided in persons with long QT syndrome, to avoid worsening the condition. These medications include certain [[appetite suppressants]], [[decongestants]], and [[antibiotics]] such as [[erythromycin]]. Illicit drugs such as [[cocaine]] and [[amphetamines]] can be even more dangerous in persons with long QT syndrome. | Certain medications should be avoided in persons with long QT syndrome, to avoid worsening the condition. These medications include certain [[appetite suppressants]], [[decongestants]], and [[antibiotics]] such as [[erythromycin]]. Illicit drugs such as [[cocaine]] and [[amphetamines]] can be even more dangerous in persons with long QT syndrome. | ||
==Correct Electrolyte Disturbances== | ===Correct Electrolyte Disturbances=== | ||
Illness that cause [[hypokalemia]] due to [[vomiting]] and [[diarrhea]] can aggravate long QT syndrome. Medications that can lower the levels of [[potassium]] in the blood should also be avoided. | Illness that cause [[hypokalemia]] due to [[vomiting]] and [[diarrhea]] can aggravate long QT syndrome. Medications that can lower the levels of [[potassium]] in the blood should also be avoided. | ||
== | ===Postassium Administration=== | ||
The use of potassium supplementation is experimental and is not evidence based. The hypothesis is that ff the potassium content in the blood rises, the [[action potential]] shortens and it is for this reason that increasing potassium concentration may minimize the occurrence of arrhythmias. It should work best in [[LQT2]] since the HERG channel is especially sensible to potassium concentration, but potassium supplementation is experimental and not evidence based. | |||
===Beta Blockers=== | ===Beta Blockers=== | ||
Beta blockers are first line therapy in the treatment of Long QT syndrome. | Beta blockers are first line therapy in the treatment of Long QT syndrome. | ||
Arrhythmia suppression involves the use of medications or surgical procedures that attack the underlying cause of the arrhythmias associated with LQTS. Since the cause of arrhythmias in LQTS is after depolarizations, and these after depolarizations are increased in states of adrenergic stimulation, steps can be taken to blunt adrenergic stimulation in these individuals. [[Beta blocker|beta receptor blocking agents]] decrease the risk of stress or catecholamine induced arrhythmias. | Arrhythmia suppression involves the use of medications or surgical procedures that attack the underlying cause of the arrhythmias associated with LQTS. Since the cause of arrhythmias in LQTS is after depolarizations, and these after depolarizations are increased in states of adrenergic stimulation, steps can be taken to blunt adrenergic stimulation in these individuals. [[Beta blocker|beta receptor blocking agents]] decrease the risk of stress or catecholamine induced arrhythmias. | ||
===Mexiletine=== | |||
[[Mexiletine]] is a [[sodium channel]] blocker. In [[LQT3]] the problem is that the sodium channel does not close properly. Mexiletine closes these channels and is believed to be potentially of use when other therapies fail. It should be especially effective in LQT3 but there is limited evidence to support this recommendation. | |||
===AICD Implantation=== | ===AICD Implantation=== | ||
Genotype and QT interval duration are independent predictors of recurrence of life-threatening events during beta-blockers therapy. Specifically the presence of QTc >500ms and [[LQT2]] and [[LQT3]] genotype are associated with the highest incidence of recurrence. In these patients primary prevention with ICD (Implantable Cardioverster Defibrilator) implantaion can be considered.<ref>Priori SG, Napolitano C, Schwartz PJ, Grillo M, Bloise R, Ronchetti E, Moncalvo C, Tulipani C, Veia A, Bottelli G, Nastoli J. Association of long QT syndrome loci and cardiac events among patients treated | |||
with beta-blockers. JAMA. 2004 Sep 15;292(11):1341-4.[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=15367556&query_hl=26&itool=pubmed_docsumPMID: 15367556]</ref> | |||
An [[AICD]] should be implanted if: | An [[AICD]] should be implanted if: | ||
*The QTc is > 550 ms and if it is not [[LQT1]] | *The QTc is > 550 ms and if it is not [[LQT1]] | ||
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*In infants with 2:1 [[AV block]] (controversial) | *In infants with 2:1 [[AV block]] (controversial) | ||
*In [[JLNS]] (LQTS with deafness) given its malignant propensity (controversial) | *In [[JLNS]] (LQTS with deafness) given its malignant propensity (controversial) | ||
===Sympathetic Denervation=== | ===Sympathetic Denervation=== | ||
Videoscopic Left Cardiac Sympathetic Denervation Surgery is not a cure, but reduces the risk of [[sudden cardiac death]] and is indicated if: | Videoscopic Left Cardiac Sympathetic Denervation Surgery (left [[Stellate ganglion|stellectomy]]) is not a cure, but reduces the risk of [[sudden cardiac death]] and is indicated if: | ||
*The patient does not tolerate [[beta blockers]] or breaks through [[beta blockers]] | *The patient does not tolerate [[beta blockers]] or breaks through [[beta blockers]] | ||
*The patient [[faints]] while on [[beta blockers]] | *The patient [[faints]] while on [[beta blockers]] | ||
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==Secondary Prevention== | ==Secondary Prevention== | ||
Patients with [[Long QT syndrome]] should undergo secondary prevention with [[AICD]] implantation if they sustain an aborted [[cardiac arrest]] or[[sudden cardiac death]]. | 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== | ||
Revision as of 03:40, 2 October 2012
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]
Overview
Beta-blockers are first line treatment in LQTs along with electrolyte repletion, and avoidance of triggers (drugs, supplements, loud noises). LQTs is one of the few diseases where genetic testing actually can provide important guidance such as who to put a AICD (defibrillator) in for primary prevention. [1]
Primary Prevention
Withdrawal of Drugs and Supplements
Certain medications should be avoided in persons with long QT syndrome, to avoid worsening the condition. These medications include certain appetite suppressants, decongestants, and antibiotics such as erythromycin. Illicit drugs such as cocaine and amphetamines can be even more dangerous in persons with long QT syndrome.
Correct Electrolyte Disturbances
Illness that cause hypokalemia due to vomiting and diarrhea can aggravate long QT syndrome. Medications that can lower the levels of potassium in the blood should also be avoided.
Postassium Administration
The use of potassium supplementation is experimental and is not evidence based. The hypothesis is that ff the potassium content in the blood rises, the action potential shortens and it is for this reason that increasing potassium concentration may minimize the occurrence of arrhythmias. It should work best in LQT2 since the HERG channel is especially sensible to potassium concentration, but potassium supplementation is experimental and not evidence based.
Beta Blockers
Beta blockers are first line therapy in the treatment of Long QT syndrome.
Arrhythmia suppression involves the use of medications or surgical procedures that attack the underlying cause of the arrhythmias associated with LQTS. Since the cause of arrhythmias in LQTS is after depolarizations, and these after depolarizations are increased in states of adrenergic stimulation, steps can be taken to blunt adrenergic stimulation in these individuals. beta receptor blocking agents decrease the risk of stress or catecholamine induced arrhythmias.
Mexiletine
Mexiletine is a sodium channel blocker. In LQT3 the problem is that the sodium channel does not close properly. Mexiletine closes these channels and is believed to be potentially of use when other therapies fail. It should be especially effective in LQT3 but there is limited evidence to support this recommendation.
AICD Implantation
Genotype and QT interval duration are independent predictors of recurrence of life-threatening events during beta-blockers therapy. Specifically the presence of QTc >500ms and LQT2 and LQT3 genotype are associated with the highest incidence of recurrence. In these patients primary prevention with ICD (Implantable Cardioverster Defibrilator) implantaion can be considered.[2]
An AICD should be implanted if:
- The QTc is > 550 ms and if it is not LQT1
- LQT2 in women and the QTc is > 500 ms, with or without symptoms
- In infants with 2:1 AV block (controversial)
- In JLNS (LQTS with deafness) given its malignant propensity (controversial)
Sympathetic Denervation
Videoscopic Left Cardiac Sympathetic Denervation Surgery (left stellectomy) is not a cure, but reduces the risk of sudden cardiac death and is indicated if:
- The patient does not tolerate beta blockers or breaks through beta blockers
- The patient faints while on beta blockers
- There is a history of VF terminating AICD shocks
- In young patients under the age of 12 where beta blockers are not deemed protective enough and where the morbidity of an AICD seems excessive.
Secondary Prevention
Patients with Long QT syndrome should undergo secondary prevention with AICD implantation if they sustain an aborted cardiac arrest orsudden 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
- ↑ Priori SG, Napolitano C, Schwartz PJ, Grillo M, Bloise R, Ronchetti E, Moncalvo C, Tulipani C, Veia A, Bottelli G, Nastoli J. Association of long QT syndrome loci and cardiac events among patients treated with beta-blockers. JAMA. 2004 Sep 15;292(11):1341-4.15367556