QT prolongation: Difference between revisions
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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
- Pause Dependent (Aquired)
- Drug induced
- Antidyrhythmics
- Phenothiazines
- TCAs
- Organophosphates
- Antihistamines
- Electrolyte Abnormalities (hypoKalemia, hypoMag, hypoCa)
- Hypokalemia triad
- Long QT, ST depressions, PVCs
- Hypokalemia triad
- Hypothermia
- Diet related (starvation, low protein)
- Severe Bradycardia/AV Block
- Hypothyroid
- Contrast injection
- CVA (intraparenchymal)
- Elevated intracranial pressure and Intracranial hemorrhage
- MI
- Drug induced
- Adrenergic Dependent
- Congenital
- Jarvel/Lange-Nielsen
- (+deafness; AR)
- Romano-Ward synd
- (nl hearing; AD)
- Sporatic
- Mitral valve prolapse
- Jarvel/Lange-Nielsen
- Acquired
- CVA (subarachnoid)
- Autonomic surg (catechol excess: neck dissection, carotid endarterect, truncal vagotomy)
- Congenital
Drug List
- Antiarrhythmics
- Amiodarone, disopyramide, dofetilide, flecainide, ibutilide, mexiletine, procainamide, quinidine, sotalol
- Antibiotics
- Macrolide
- Fluoroquinolone
- Ciprofloxacin, gatifloxacin (most common), gemifloxacin, levofloxacin, moxifloxacin, ofloxacin
- Other
- Pentamidine, telithromycin, trimethoprim-sulfamethoxazole
- Antidepressants
- Amitriptyline, citalopram, doxepin, fluoxetine, nortriptyline, paroxetine, sertraline, venlafaxine
- Antiemetics
- Dolasetron, droperidol, granisetron, ondansetron
- Antifungals
- Antihypertensives
- Antineoplastics
- Lapatinib, nilotinib, sunitinib, tamoxifen
- Antimalarials
- Chloroquine, halofantrine
- Antipsychotics
- Chlorpromazine, clozapine, galantamine, haloperidol, lithium, paliperidone, pimozide, quetiapine, risperidone, thioridazine, ziprasidone
- Antivirals
- Amantadine, atazanavir, foscarnet
- Diuretics
- Indapamide
- Immune suppressants
- Opiates
- Phosphodiesterase inhibitors
- Sildenafil, vardenafil
- Skeletal muscle relaxants
- Tizanidine
- Urinary antispasmodics
- Solifenacin
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)
- Unstable/sustained torsades→ defibrilation (unsynchronized)
- Stable
- Treat underlying prob
- Increase HR (isoproterenol or overdrive pacing)
- Magnesium sulfate IV
- Consider amiodarone
Adrenergic Dependent (precipited by tachycardia)
- Unstable/sustained torsades→ defibrilation (unsynchronized)
- Stable
- Slow HR (beta-blockers)
- May consider magnesium sulfate
Disposition
- Highly consider admission, especially for QT >500