Torsade de pointes (TdP) is a type of polymorphic ventricular tachycardia with obligatory QTc prolongation, that has the potential to devolve into ventricular fibrillation.

Torsade de Pointes (TdP)

Ventricular fibrillation is the main cause of sudden cardiac death, requiring immediate medical intervention, in which the lower heart chambers contract in a disorganized and excessively fast way which fails to pump oxygenated throughout the body. Symptoms include unconsciousness and collapse, often preceded by symptoms of tachycardia.

Ventricular Fibrillation (V-Fib, VF)

Ventricular tachycardia is an arrhythmia in which the heart's lower chamber beats too quickly, improperly distributing oxygenated blood. It can lead to chest palpitations, low blood pressure, chest pain, shortness of breath, fainting, dizziness and lightheadedness, or even cardiac death via ventricular fibrillation.

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Long QT syndrome refers to the prolongation of a patient's QT interval, at greater than 450 milliseconds for men and greater than 470 milliseconds for women. At intervals above 500 milliseconds, the risk of cardiac events is significantly multiplied as QTc prolongation predisposes individuals to ventricular tachyarrhythmias like TdP, ventricular fibrillation, and resulting death. LQTS may be inherited, or acquired due to drug effects or electrolyte changes.

Long QT Syndrome (LQTS)

An arrhythmia refers to an irregularity in the heartbeat, either due to excessive slowness, excessive quickness, or disorganized beating. Though sometimes harmless and natural, they may also cause issues or even be fatal. Symptoms may include chest palpitations, heart rate changes, chest pain, difficult or discomfort while breathing, anxiety, sweating, fatigue, and unconsciousness.

Arrhythmia

Ventricular Tachycardia. (2021, February 22). John Hopkins Medicine. Retrieved January 22, 2023, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/ventricular-tachycardia

Ventricular Tachycardia

Many drugs may cause QT prolongation, which can lead to TdP and resulting sudden cardiac death. The following drugs are included: 

- Antiarrhythmics: procainamide, quinidine, amiodarone, flecainide, propofenone, disopyramide, dronedarone, sotalol, dofetilide, ibutilide
- Antihistamines: terfenadine, astimazole
- Antipsychotics: quetiapine, haloperidol, clozapine
- Tri- and tetra-cyclic antidepressants: imipramine, doxepin
- Selective serotonin reuptake inhibitors: citalopram, fluoxetine
- Antimicrobials: ciprofloxacin, levofloxacin, moxifloxacin, gatifloxacin, ofloxacin, erythromycin, clarithromycin, azithromycin
-Antifungals: ketokonazole, voriconazole
- Antimalarials: quinine, mefloquine, chloroquine

Drugs Associated with LQTS/QT Prolongation/TdP

Ventricular Tachycardia (V-Tach, VT)

Sinus tachycardia refers to a heartbeat of over 100 beats per minute. While this is typically a response to stress and not a cause for concern, it can sometimes arise without an immediate explanation which may be indicative of other underlying health conditions. Symptoms may include chest palpitations and pain, shortness of breath, fatigue, dizziness, and fainting. While it can generally be managed with a healthy lifestyle, some people may require medication, medical procedures, or therapy to control their sinus tachycardia. 

Sinus Tachycardia

Supraventricular tachycardia, or SVT, refers to a tachycardia or abnormally elevated heart rate that causes the heart to pump before its chambers have filled with oxygenated blood. Women and those who smoke, drink, use caffeine, and/or struggle with anxiety are at increased risk. Symptoms may include chest pain and palpitations, dizziness, shortness of breath, fainting, and cardiac arrest. Though it can often be managed with a healthy lifestyle, SVT sometimes requires treatment with medication or medical procedures.

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