Feature of Torsade de pointes is –
**Core Concept**
Torsade de pointes is a specific type of abnormal heart rhythm, also known as a ventricular tachycardia, characterized by a rapid heart rate and a distinctive "twisting" appearance on an electrocardiogram (ECG). It is often associated with a prolonged QT interval, which is a measure of the time it takes for the heart's electrical system to recover between beats.
**Why the Correct Answer is Right**
Torsade de pointes is a type of polymorphic ventricular tachycardia that occurs when there is a prolonged QT interval, often due to a delay in the repolarization of the ventricles. This can be caused by various factors, including medications that prolong the QT interval, such as certain antipsychotics, antiarrhythmics, and antibiotics. The prolonged QT interval allows for an abnormal re-entrant circuit to form, leading to the characteristic twisting pattern of Torsade de pointes on an ECG.
**Why Each Wrong Option is Incorrect**
**Option A:** While Torsade de pointes is a type of ventricular tachycardia, it is not simply a fast heart rate, as this is a common feature of many types of tachycardias.
**Option B:** While Torsade de pointes can be life-threatening, it is not necessarily a result of a heart attack or myocardial infarction.
**Option C:** While Torsade de pointes can be caused by a prolonged QT interval, it is not the only possible cause of this condition.
**Clinical Pearl / High-Yield Fact**
It's essential to recognize that Torsade de pointes can be caused by various medications, and some patients may be at higher risk due to genetic predispositions or other underlying conditions. Always consider the patient's medication list and medical history when evaluating a patient with a prolonged QT interval.
**Correct Answer: C.**