In a patient of known prolonged congenital QT syndrome and intermittent Torsade-de-pointes, which of the following should be prescribed?
**Core Concept**
Prolonged congenital QT syndrome is a genetic disorder affecting the cardiac repolarization phase, leading to an increased risk of arrhythmias, particularly Torsade-de-pointes. Effective management involves addressing the underlying electrolyte imbalances and using medications that shorten the QT interval.
**Why the Correct Answer is Right**
Magnesium sulfate is prescribed in this scenario because it helps stabilize the cardiac membrane, reducing the risk of Torsade-de-pointes. Magnesium also plays a crucial role in potassium channel function, which is often impaired in patients with prolonged QT syndrome. By correcting magnesium deficiency, the risk of life-threatening arrhythmias is decreased.
**Why Each Wrong Option is Incorrect**
**Option A:** **Beta blockers**, such as propranolol, may actually worsen QT prolongation by blocking beta-1 receptors, which are involved in the regulation of heart rate and contractility. This can further increase the risk of arrhythmias.
**Option B:** **Digoxin** is contraindicated in patients with prolonged QT syndrome because it can further prolong the QT interval by blocking potassium channels and increasing intracellular calcium levels.
**Option C:** **Anti-arrhythmic medications**, such as quinidine and amiodarone, can actually worsen QT prolongation and increase the risk of Torsade-de-pointes. These medications are generally avoided in patients with congenital QT syndrome.
**Clinical Pearl / High-Yield Fact**
Magnesium sulfate is a crucial adjunctive therapy in the management of Torsade-de-pointes and prolonged QT syndrome. It is essential to monitor magnesium levels and correct any deficiencies promptly to prevent life-threatening arrhythmias.
**Correct Answer: C. Magnesium sulfate. Magnesium sulfate is prescribed to stabilize the cardiac membrane and reduce the risk of Torsade-de-pointes in patients with prolonged congenital QT syndrome.**