Drug-Induced QT Prolongation Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Drug-Induced QT Prolongation. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Drug-Induced QT Prolongation Indian Medical PG Question 1: Identify the ECG given below?
- A. Viral myocarditis
- B. Torsades de pointes (Correct Answer)
- C. Cardiac tamponade
- D. Pericarditis
Drug-Induced QT Prolongation Explanation: ***Torsades de pointes***
- The ECG shows a polymorphic ventricular tachycardia where the **QRS complexes appear to twist around the baseline**, a classic feature of Torsades de pointes.
- This condition is often associated with **QT prolongation**, which is evident in some of the strips preceding the tachyarrhythmia.
*Viral myocarditis*
- While viral myocarditis can lead to various ECG abnormalities, it typically doesn't present with this specific **polymorphic ventricular tachycardia** morphology.
- Common ECG findings in myocarditis include non-specific ST-T wave changes, sinus tachycardia, or conduction blocks, rather than the characteristic "twisting" pattern seen here.
*Cardiac tamponade*
- Cardiac tamponade is characterized by **electrical alternans** (alternating QRS amplitude), low voltage, and sinus tachycardia on ECG.
- It does not cause a polymorphic ventricular tachycardia with the appearance of QRS complexes twisting around the baseline.
*Pericarditis*
- Pericarditis typically presents with **diffuse ST-segment elevation** (often concave up) and PR-segment depression.
- It does not manifest as a polymorphic ventricular tachycardia like Torsades de pointes.
Drug-Induced QT Prolongation Indian Medical PG Question 2: A patient with hypertension on Metoprolol, Verapamil was given. This will result in?
- A. Bradycardia with AV Block (Correct Answer)
- B. Atrial fibrillation
- C. Torsades de pointes
- D. Tachycardia
Drug-Induced QT Prolongation Explanation: ***Bradycardia with AV Block***
- Both **Metoprolol** (a beta-blocker) and **Verapamil** (a non-dihydropyridine calcium channel blocker) suppress **AV nodal conduction** and decrease heart rate.
- Their combined use has an additive effect, significantly increasing the risk of profound **bradycardia**, **AV block**, and even **asystole**.
*Atrial fibrillation*
- This is an **arrhythmia** characterized by disorganized electrical activity in the atria, not a direct consequence of this drug combination.
- While these drugs *treat* atrial fibrillation by controlling ventricular rate, they do not induce it.
*Torsades de pointes*
- This is a polymorphic **ventricular tachycardia** associated with **QT prolongation** from certain antiarrhythmics or other medications.
- Neither Metoprolol nor Verapamil are known to cause significant QT prolongation that would lead to Torsades de pointes.
*Tachycardia*
- This combination of **negative chronotropic** (heart rate lowering) drugs is highly unlikely to cause tachycardia due to their direct actions on the heart's electrical system.
- These drugs are specifically used to *reduce* heart rate and blood pressure.
Drug-Induced QT Prolongation Indian Medical PG Question 3: Which antipsychotic has highest risk of QTc prolongation?
- A. Ziprasidone (Correct Answer)
- B. Risperidone
- C. Olanzapine
- D. Aripiprazole
Drug-Induced QT Prolongation Explanation: ***Ziprasidone***
- **Ziprasidone** is known to have the highest risk of **QTc prolongation** among the commonly used atypical antipsychotics.
- This effect is dose-dependent and necessitates careful monitoring, especially in patients with pre-existing cardiac conditions or those on other QTc-prolonging medications.
*Risperidone*
- While **risperidone** can cause **QTc prolongation**, its risk is generally considered to be lower than that of ziprasidone.
- It also carries a significant risk of **hyperprolactinemia** and **extrapyramidal symptoms (EPS)**, which are important distinguishing features.
*Olanzapine*
- **Olanzapine** has a relatively low risk of **QTc prolongation** compared to ziprasidone.
- Its primary concerns include substantial **weight gain** and **metabolic syndrome**, which are less prominent with ziprasidone.
*Aripiprazole*
- **Aripiprazole** is generally associated with a very low risk of **QTc prolongation** and is often considered a safer choice in this regard.
- It is known for its unique partial agonist activity at dopamine D2 and serotonin 5-HT1A receptors, and antagonist activity at 5-HT2A receptors, leading to a different side effect profile.
Drug-Induced QT Prolongation Indian Medical PG Question 4: Features of Torsade de pointes include which of the following?
- A. Prolonged QTc interval (Correct Answer)
- B. Wide QRS complex
- C. Short QRS complex
- D. Short QTc interval
Drug-Induced QT Prolongation Explanation: ***Prolonged QTc interval***
- **Torsade de pointes** (TdP) is a polymorphic ventricular tachycardia characterized by a twisting of the QRS complex around the isoelectric line [1].
- It is almost invariably associated with a **prolonged QTc interval**, which can be congenital or acquired due to drugs or electrolyte imbalances [1],[4].
*Wide QRS complex*
- While TdP does involve **wide QRS complexes**, this is a general characteristic of most ventricular tachycardias and not specific enough to define Torsade de pointes [2].
- The distinctive feature of TdP is the **polymorphic nature** of the wide QRS complexes and their characteristic "twisting" pattern, which is rooted in the underlying repolarization abnormality [1].
*Short QRS complex*
- A **short QRS complex** is characteristic of supraventricular arrhythmias and is not seen in ventricular tachycardias like Torsade de pointes [3].
- Ventricular activation originates in the ventricles, leading to a **wider QRS** due to slower, aberrant conduction [2].
*Short QTc interval*
- A **short QTc interval** is linked to conditions like short QT syndrome, which can also cause arrhythmias but is not responsible for Torsade de pointes.
- TdP exclusively occurs in the setting of **prolonged ventricular repolarization**, reflected by a long QTc [1],[4].
Drug-Induced QT Prolongation Indian Medical PG Question 5: Match the following drugs in Column A with their contraindications in Column B.
| Column A | Column B |
| :-- | :-- |
| 1. Morphine | 1. QT prolongation |
| 2. Amiodarone | 2. Thromboembolism |
| 3. Vigabatrin | 3. Pregnancy |
| 4. Estrogen preparations | 4. Head injury |
- A. A-1, B-3, C-2, D-4
- B. A-4, B-1, C-3, D-2 (Correct Answer)
- C. A-3, B-2, C-4, D-1
- D. A-2, B-4, C-1, D-3
Drug-Induced QT Prolongation Explanation: ***A-4, B-1, C-3, D-2***
- **Morphine** is contraindicated in **head injury** as it can increase intracranial pressure and mask neurological symptoms.
- **Amiodarone** is contraindicated in patients with **QT prolongation** due to its risk of inducing more severe arrhythmias like Torsades de Pointes.
- **Vigabatrin** is contraindicated during **pregnancy** due to its potential for teratogenicity and adverse effects on fetal development.
- **Estrogen preparations** are contraindicated in patients with a history of **thromboembolism** due to their increased risk of blood clot formation.
*A-1, B-3, C-2, D-4*
- This option incorrectly matches **Morphine** with QT prolongation and **Estrogen preparations** with head injury, which are not their primary contraindications.
- It also incorrectly links **Vigabatrin** with thromboembolism and **Amiodarone** with pregnancy.
*A-3, B-2, C-4, D-1*
- This choice incorrectly associates **Morphine** with pregnancy and **Vigabatrin** with head injury, which are not the most critical or direct contraindications.
- It also misaligns **Amiodarone** with thromboembolism and **Estrogen preparations** with QT prolongation.
*A-2, B-4, C-1, D-3*
- This option incorrectly matches **Morphine** with thromboembolism and **Amiodarone** with head injury, which are not their most significant contraindications.
- It also incorrectly links **Vigabatrin** with QT prolongation and **Estrogen preparations** with pregnancy.
Drug-Induced QT Prolongation Indian Medical PG Question 6: QT shortening is associated with which electrolyte imbalance?
- A. Hypercalcemia (Correct Answer)
- B. Hypokalemia
- C. Hypocalcemia
- D. Hyperkalemia
Drug-Induced QT Prolongation Explanation: ***Hypercalcemia***
- **Elevated calcium levels** lead to a shortened **plateau phase of the cardiac action potential**, which manifests as a **shortened QT interval** on an ECG.
- This imbalance increases the risk of ventricular arrhythmias, although profound shortening can lead to **QRS widening** with further increase in calcium.
*Hypokalemia*
- **Low potassium** levels typically cause **QT prolongation**, usually due to prominent U waves and T wave flattening.
- It does not cause QT shortening; instead, it is associated with an **increased risk of Torsades de Pointes**.
*Hypocalcemia*
- **Low calcium** levels cause **QT prolongation** by lengthening the **plateau phase of the cardiac action potential**, increasing the duration of ventricular repolarization.
- ECG findings include prolonged ST segment and can increase the risk of arrhythmias, including Torsades de Pointes.
*Hyperkalemia*
- **High potassium** levels primarily cause **peaked T waves**, a **widened QRS complex**, and a **prolonged PR interval**, potentially leading to asystole or ventricular fibrillation.
- It does not cause QT shortening; instead, severe hyperkalemia can lead to **loss of P waves** and a **sine wave pattern**.
Drug-Induced QT Prolongation Indian Medical PG Question 7: Which of the following anti-epileptic drugs has the highest teratogenic potential?
- A. Carbamazepine
- B. Phenytoin
- C. Valproate (Correct Answer)
- D. Lamotrigine
Drug-Induced QT Prolongation Explanation: ***Correct: Valproate***
- **Valproate has the highest teratogenic potential** among all anti-epileptic drugs, with a **10-20% risk of major congenital malformations**
- **Neural tube defects** (spina bifida) occur in **1-2% of exposed pregnancies**, which is 10-20 times higher than the general population
- Other significant risks include **cardiac malformations, craniofacial abnormalities**, and **neurodevelopmental disorders** (autism spectrum disorder, reduced IQ)
- **Fetal valproate syndrome** is a recognized clinical entity
- Current guidelines strongly recommend **avoiding valproate in women of childbearing potential** unless no alternatives exist
*Incorrect: Carbamazepine*
- Has teratogenic risks but significantly **lower than valproate** (2-5% risk of major malformations)
- Associated with **neural tube defects** (0.5-1% risk, lower than valproate)
- Considered a safer alternative when valproate must be avoided
*Incorrect: Phenytoin*
- Causes **fetal hydantoin syndrome** with characteristic features: craniofacial anomalies, nail/digital hypoplasia, growth restriction, and developmental delay
- Teratogenic risk is **moderate** (approximately 5-10% risk of major malformations)
- Risk is significant but **lower than valproate**
*Incorrect: Lamotrigine*
- Considered **one of the safest anti-epileptic drugs** during pregnancy
- Low teratogenic risk with **major malformation rate of 2-3%** (close to baseline population risk)
- Slight increased risk of **oral clefts** at higher doses
- **Preferred choice** for women of childbearing potential requiring anti-epileptic therapy
Drug-Induced QT Prolongation Indian Medical PG Question 8: Identify the diagnosis from the given image
- A. TB
- B. Malakoplakia (Correct Answer)
- C. BCC
- D. Drug induced lesion
Drug-Induced QT Prolongation Explanation: ***Malakoplakia***
- The image displays characteristic **Michaelis-Gutmann bodies**, which are concentrically laminated calcified inclusions found within macrophages (**Von Hansemann cells**). These are pathognomic for malakoplakia.
- **Von Hansemann cells** are large, foamy macrophages with abundant cytoplasm, also visible in the image, mixed with lymphocytes and plasma cells.
*TB*
- Tuberculosis (TB) typically presents with **granulomatous inflammation** characterized by caseating necrosis, epithelioid macrophages, Langhans giant cells, and lymphocytes [2]. These features are not apparent in the image.
- While TB can involve macrophages, the distinct Michaelis-Gutmann bodies seen here are not a feature of tuberculous granulomas [1].
*BCC*
- Basal cell carcinoma (BCC) is a malignant epithelial tumor characterized by nests of basaloid cells with peripheral palisading, clear clefts, and often stromal retraction. This biopsy shows inflammatory cells and calcified inclusions, not epithelial malignancy.
- BCC would show atypical epithelial cells and features of a neoplastic process, which are distinctly different from the inflammatory infiltrate and inclusion bodies in the image.
*Drug induced lesion*
- Drug-induced lesions are highly variable and context-dependent, but they do not typically present with the specific histopathological features of Michaelis-Gutmann bodies within macrophages.
- The image depicts a specific and recognizable inflammatory pattern with unique inclusions, which points to a distinct disease entity rather than a non-specific drug reaction.
**References:**
[1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 198-200.
[2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 360.
Drug-Induced QT Prolongation Indian Medical PG Question 9: Alkaline diuresis in drug poisoning is not done in?
- A. Aspirin
- B. Morphine (Correct Answer)
- C. Phenobarbitone
- D. Methotrexate
Drug-Induced QT Prolongation Explanation: ***Morphine***
- **Morphine** is an **alkaline drug**, so its elimination is actually enhanced by **acidification of the urine**, not alkalinization.
- Alkaline diuresis would decrease the ionization of morphine in the renal tubules, leading to **increased reabsorption** and reduced excretion.
*Aspirin*
- **Aspirin (acetylsalicylic acid)** is an **acidic drug**, and **alkaline diuresis** is effective in increasing its excretion by trapping the ionized form in the renal tubules.
- This process prevents reabsorption and promotes clearance, which is a standard treatment for aspirin overdose.
*Methotrexate*
- **Methotrexate** is a **weak organic acid**, and **alkaline diuresis** is crucial in reducing its toxicity, especially in high-dose therapy.
- By increasing urine pH, the renal elimination of methotrexate is significantly enhanced, preventing kidney damage and systemic accumulation.
*Phenobarbitone*
- **Phenobarbitone** is a **weak acid**, and **alkaline diuresis** is a well-established method to increase its renal excretion in cases of overdose.
- Alkalinization of the urine promotes the ionization of phenobarbitone, reducing its reabsorption by the renal tubules and accelerating its elimination.
Drug-Induced QT Prolongation Indian Medical PG Question 10: Which one of the following antihypertensive drugs is NOT safe during pregnancy?
- A. Labetalol
- B. ACE-inhibitors (Correct Answer)
- C. Nifedipine
- D. Alpha-methyl dopa
Drug-Induced QT Prolongation Explanation: ***ACE-inhibitors*** - **ACE inhibitors** (e.g., enalapril, lisinopril) are **contraindicated** in pregnancy due to their association with severe fetal abnormalities, including **renal agenesis**, **oligohydramnios**, and **fetal death** [1], [2]. - They should be discontinued as soon as pregnancy is confirmed or suspected due to their known **teratogenic effects** [1], [2].*Labetalol* - **Labetalol**, a combined alpha- and beta-blocker, is considered one of the **first-line agents** for managing hypertension in pregnancy. - It has a good safety profile for both the mother and the fetus and is commonly used in conditions like **preeclampsia**.*Nifedipine* - **Nifedipine**, a calcium channel blocker, is also a **safe and effective** option for treating hypertension during pregnancy. - It is frequently used for managing **chronic hypertension** and **preeclampsia** due to its rapid onset of action and tolerability.*Alpha-methyl dopa* - **Alpha-methyl dopa** (methyldopa) is considered one of the **safest and most extensively studied** antihypertensive medications for use in pregnancy. - It is often the **first-choice agent** for chronic hypertension during pregnancy due to its long-standing track record of safety for the fetus.
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