WBR1103
| Author | PageAuthor::William J Gibson |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Behavioral Science/Psychiatry, MainCategory::Pharmacology |
| Sub Category | SubCategory::Cardiology |
| Prompt | [[Prompt::A 38-year-old schizophrenic male is found unconscious and pulseless by healthcare workers at his assisted living facility. Emergency personnel were able to revive the patient by defibrillation and the patient was admitted to the hospital. He was monitored by 24-hour-telemetry, a portion of which is shown below.
The patient has no prior history of cardiac disease. Which of the following medications is most likely responsible for this patient's loss of consciousness?]] |
| Answer A | AnswerA::Lithium |
| Answer A Explanation | [[AnswerAExp::Incorrect: Lithium is a mood-stabilizer used for treating bipolar disorder. Lithium toxicity includes movement disorder (Extrapyramidal symptoms), nephrogenic diabetes insipidus, hypothyroidism, and teratogenicity. Prolonged QT-interval is not considered a feature of lithium toxicity.]] |
| Answer B | AnswerB::Chloropromazine |
| Answer B Explanation | [[AnswerBExp::Incorrect: Chlorpromazine is a typical antipsychotic that can be used to treat schizophrenia. Toxicity of chlorpromazine and other typical antipsychotics includes extrapyramidal side effects (dyskinesias), as well as endocrine side effects such as hyperprolactinemia.]] |
| Answer C | AnswerC::Risperidone |
| Answer C Explanation | AnswerCExp::'''Correct:''' |
| Answer D | AnswerD::Hydrochlorothiazide |
| Answer D Explanation | [[AnswerDExp::Incorrect: While hydrochlorothiazide can cause prolonged QT interval, we have no reason to believe that this patient is on hydrochlorothiazide. Because of this patient’s history of schizophrenia, risperidone is a more appropriate choice.]] |
| Answer E | AnswerE::Haloperidol |
| Answer E Explanation | [[AnswerEExp::Incorrect: Haloperidol is a high potency typical antipsychotic whose mechanism of action involves blocking dopamine D2 receptors. Haloperidol toxicity is typically manifested as extrapyramidal side effects, including tardive dyskinesia. Haloperidol is not associated with QT interval prolongation.]] |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::Educational Objective: Risperidone can cause prolonged QT interval, which predisposes to Torsades de Pointes.
References: First Aid 2014 page 277 (Long QT and Torsades de pointes)
First Aid 2014 page 517 (Antipsychotics) |
| Approved | Approved::No |
| Keyword | WBRKeyword::Arrhythmia, WBRKeyword::EKG, WBRKeyword::ECG |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |