Difference between revisions of "QT prolongation"

(Differential Diagnosis)
(Drug List)
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===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  
 
**Macrolide
 
**Macrolide
***Azithromycin, erythromycin, clarithromycin
+
***[[Azithromycin]], [[erythromycin]], [[clarithromycin]]
 
**Fluoroquinolone
 
**Fluoroquinolone
***[[Ciprofloxacin]], gatifloxacin (most common), gemifloxacin, levofloxacin, moxifloxacin, ofloxacin
+
***[[Ciprofloxacin]], gatifloxacin (most common), [[gemifloxacin]], [[levofloxacin]], [[moxifloxacin]], [[ofloxacin]]
 
**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
 
**Indapamide
 
**Indapamide
 
*Immune suppressants
 
*Immune suppressants
**Tacrolimus
+
**[[Tacrolimus]]
 
*Opiates
 
*Opiates
**Methadone
+
**[[Methadone]]
 
*Phosphodiesterase inhibitors
 
*Phosphodiesterase inhibitors
**Sildenafil, vardenafil
+
**[[Sildenafil]], vardenafil
 
*Skeletal muscle relaxants
 
*Skeletal muscle relaxants
 
**Tizanidine
 
**Tizanidine

Revision as of 14:41, 22 August 2017

Background

  • Prolonged ventricular repolarisation → increased risk of ventricular arrythmias
  • QT interval is from the beginning of the Q wave to the end of the T wave; it is rate dependent and should become proportionately small with increasing rate rate
  • An abnormal QT is >440-450 ms (males) and >460-470 ms (females); >500 may result in torsades

Clinical Features

  • Most are asymptomatic
  • History may or may not include
    • Syncope, cardiac arrest, family history of long QT or sudden death
    • Medication history should always be obtained especially so to avoid interactions and further QT prolongation.

Differential Diagnosis

Drug List

Evaluation

  • ECG
    • quick/imprecise measure: QT takes up more than half the R-R distance
    • Measure QT interval in lead II or V5-6
    • QTc = QT /√R-R
    • Long QT: QTc >440 (male), >460 (female)
    • >500 = real concern (may result in torsades)

Management

Pause Dependent (precipitated by bradycardia)

Adrenergic Dependent (precipited by tachycardia)

Disposition

  • Highly consider admission, especially for QT >500

See Also

External Links

References