Question:hard
What is the treatment for torsades de pointes in a patient who has had a prolonged QT interval since birth?
What is the treatment for torsades de pointes in a patient who has had a prolonged QT interval since birth?
Show Hint
Congenital long QT syndrome is managed with beta-blockers; catecholamine drugs like isoproterenol can worsen it.
Updated On: Jul 8, 2026
- Magnesium Sulphate
- Overdrive Pacing
- Isoproterenol
- Metoprolol
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: Read the key phrase in the question.
"Prolonged QT interval since birth" signals congenital long QT syndrome, an inherited channelopathy, not a drug or electrolyte problem picked up later in life.
Step 2: Split the four options by mechanism.
Magnesium sulphate calms the heart membrane in any torsades episode. Overdrive pacing and isoproterenol both work by raising heart rate, which shortens a QT interval that is long because of bradycardia or a pause, the pattern typical of acquired long QT from drugs or electrolyte problems. Metoprolol, a beta-blocker, works by blunting the effect of adrenaline on the heart.
Step 3: Match mechanism to congenital disease.
In congenital long QT syndrome, especially the LQT1 subtype, exercise and emotional stress, meaning adrenaline surges, are the classic triggers for torsades. A drug like isoproterenol that mimics adrenaline would make this worse, not better, so it is unsuitable here even though it is useful in acquired, bradycardia-driven torsades.
Step 4: Confirm the beta-blocker link.
Because adrenaline drive is the problem in congenital LQTS, blocking it with a beta-blocker is the standard preventive treatment recommended for these patients, cutting the risk of future torsades and sudden death.
Step 5: State the answer.
The suitable drug for this patient with lifelong QT prolongation is the beta-blocker $metoprolol$.
\[ \boxed{\text{Metoprolol}} \]
"Prolonged QT interval since birth" signals congenital long QT syndrome, an inherited channelopathy, not a drug or electrolyte problem picked up later in life.
Step 2: Split the four options by mechanism.
Magnesium sulphate calms the heart membrane in any torsades episode. Overdrive pacing and isoproterenol both work by raising heart rate, which shortens a QT interval that is long because of bradycardia or a pause, the pattern typical of acquired long QT from drugs or electrolyte problems. Metoprolol, a beta-blocker, works by blunting the effect of adrenaline on the heart.
Step 3: Match mechanism to congenital disease.
In congenital long QT syndrome, especially the LQT1 subtype, exercise and emotional stress, meaning adrenaline surges, are the classic triggers for torsades. A drug like isoproterenol that mimics adrenaline would make this worse, not better, so it is unsuitable here even though it is useful in acquired, bradycardia-driven torsades.
Step 4: Confirm the beta-blocker link.
Because adrenaline drive is the problem in congenital LQTS, blocking it with a beta-blocker is the standard preventive treatment recommended for these patients, cutting the risk of future torsades and sudden death.
Step 5: State the answer.
The suitable drug for this patient with lifelong QT prolongation is the beta-blocker $metoprolol$.
\[ \boxed{\text{Metoprolol}} \]
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