QT prolongation: Difference between revisions

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==Differential Diagnosis==
==Differential Diagnosis==
*Pause Dependent (Aquired)
*Pause Dependent (Acquired)
**Drug induced
**Drug induced
***Antidyrhythmics
***[[Antiarrhythmics]]
***Phenothiazines
***[[Phenothiazines]]
***[[TCAs]]
***[[TCAs]]
***[[Organophosphates]]
***[[Organophosphates]]
***Antihistamines
***[[Antihistamines]]
**[[Electrolyte Abnormalities]] ([[hypoKalemia]], [[hypoMag]], [[hypoCa]])
**[[Electrolyte Abnormalities]] ([[hypoKalemia]], [[hypoMag]], [[hypoCa]])
***Hypokalemia triad
***[[Hypokalemia]] triad
****Long QT, ST depressions, PVCs
****Long QT, ST depressions, PVCs
**[[Hypothermia]]
**[[Hypothermia]]
**Diet related (starvation, low protein)
**Diet related (starvation, low protein)
**[[Severe Bradycardia]]/AV Block
**[[Severe Bradycardia]]/[[AV Block]]
**[[Hypothyroid]]
**[[Hypothyroid]]
**Contrast injection
**Contrast injection
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***Jarvel/Lange-Nielsen
***Jarvel/Lange-Nielsen
****(+deafness; AR)
****(+deafness; AR)
***Romano-Ward synd
***Romano-Ward syndrome
****(nl hearing; AD)
****(normal hearing; AD)
***Sporatic
***Sporadic
***Mitral valve prolapse
***[[Mitral valve prolapse]]
**Acquired
**Acquired
***[[CVA]] (subarachnoid)
***[[CVA]] (subarachnoid)
***Autonomic surg (catechol excess: neck dissection, carotid endarterect, truncal vagotomy)
***Autonomic surgery (catechol excess: neck dissection, carotid endarterectomy, truncal vagotomy)


===Drug List===
===Drug List===
*Antiarrhythmics
*[[Antiarrhythmics]]
**[[Amiodarone]], disopyramide, dofetilide, [[flecainide]], ibutilide, mexiletine, [[procainamide]], [[quinidine]], [[sotalol]]
**[[Amiodarone]], disopyramide, dofetilide, [[flecainide]], ibutilide, mexiletine, [[procainamide]], [[quinidine]], [[sotalol]]
*[[Antibiotics]]  
*[[Antibiotics]]  
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**Other
**Other
***[[Pentamidine]], telithromycin, [[trimethoprim-sulfamethoxazole]]
***[[Pentamidine]], telithromycin, [[trimethoprim-sulfamethoxazole]]
*[[Antidepressants]]
*Antidepressants
**[[Amitriptyline]], citalopram, [[doxepin]], fluoxetine, [[nortriptyline]], paroxetine, sertraline, [[venlafaxine]]
**[[Amitriptyline]], citalopram, [[doxepin]], [[fluoxetine]], [[nortriptyline]], paroxetine, sertraline, [[venlafaxine]]
*[[Antiemetics]]
*[[Antiemetics]]
**Dolasetron, [[droperidol]], granisetron, [[ondansetron]]
**Dolasetron, [[droperidol]], granisetron, [[ondansetron]]
*Antifungals
*[[Antifungals]]
**[[Fluconazole]], [[itraconazole]], [[ketoconazole]], [[voriconazole]]
**[[Fluconazole]], [[itraconazole]], [[ketoconazole]], [[voriconazole]]
*Antihypertensives
*[[Antihypertensives]]
**[[Nicardipine]]
**[[Nicardipine]]
*Antineoplastics
*Antineoplastics
**Lapatinib, nilotinib, sunitinib, tamoxifen
**Lapatinib, nilotinib, sunitinib, tamoxifen
*Antimalarials
*[[Antimalarials]]
**[[Chloroquine]], halofantrine
**[[Chloroquine]], halofantrine
*Antipsychotics
*[[Antipsychotics]]
**[[Chlorpromazine]], [[clozapine]], galantamine, [[haloperidol]], [[lithium]], paliperidone, pimozide, [[quetiapine]], [[risperidone]], thioridazine, [[ziprasidone]]
**[[Chlorpromazine]], [[clozapine]], galantamine, [[haloperidol]], [[lithium]], paliperidone, pimozide, [[quetiapine]], [[risperidone]], thioridazine, [[ziprasidone]]
*Antivirals
*[[Antivirals]]
**[[Amantadine]], atazanavir, [[foscarnet]]
**[[Amantadine]], atazanavir, [[foscarnet]]
*[[Diuretics]]
*[[Diuretics]]
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**[[Methadone]]
**[[Methadone]]
*Phosphodiesterase inhibitors
*Phosphodiesterase inhibitors
**[[Sildenafil]], vardenafil
**[[Sildenafil]], [https://nizagara-online.net/vardenafil/ Vardenafil]
*Skeletal muscle relaxants
*Skeletal muscle relaxants
**Tizanidine
**[[Tizanidine]]
*Urinary antispasmodics
*Urinary antispasmodics
**Solifenacin
**Solifenacin

Revision as of 04:30, 25 February 2020

Background

  • Prolonged ventricular repolarisation → increased risk of ventricular arrythmias
    • Males >440-450 ms
    • Females >500 ms
    • Rule of thumb: Normal QT interveal is less than half of preceding RR interval
  • QT interval is from the beginning of the Q wave to the end of the T wave
    • Rate dependent and should become proportionately shorter with increasing heart rate

Clinical Features

  • Most are asymptomatic
  • History may include:
  • Medication history may include QT prolonging medications

Differential Diagnosis

Drug List

Evaluation

Workup

  • ECG
  • CBC
  • Chem 10

Diagnosis

Acquired QT prolongation
  • ECG
    • On visual inspection, QT takes up more than half the R-R distance
    • Measure QT interval in lead II or V5-6
    • QTc = QT /√R-R

Management

Pause Dependent (precipitated by bradycardia)

Adrenergic Dependent (precipited by tachycardia)

Disposition

  • Consider admission, especially for QT >500 or if symptomatic
  • May require consultation for discontinuation of QT prolonging medications
  • Avoid prescribing medications that may contribute to prolonged QT

See Also

External Links

References