Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 191: Morphine is used in:

A. Hypertension
B. Cardiac arrhythmias
C. Acute left ventricular failure (Correct Answer)
D. A-V block

Explanation: **Explanation:** Morphine is a cornerstone in the management of **Acute Left Ventricular Failure (ALVF)** and **Acute Pulmonary Edema**. Its therapeutic benefit is derived from several key pharmacological actions: 1. **Venodilation (Preload Reduction):** Morphine increases venous capacitance, leading to peripheral pooling of blood. This reduces venous return to the heart (preload), thereby decreasing pulmonary congestion and cardiac workload. 2. **Arteriodilation (Afterload Reduction):** At higher doses, it reduces peripheral resistance, making it easier for the failing left ventricle to pump blood. 3. **Anxiolysis:** By relieving the intense anxiety and "air hunger" associated with pulmonary edema, it reduces sympathetic overactivity, further lowering myocardial oxygen demand. 4. **Shift in Respiratory Center Sensitivity:** It reduces the respiratory center's sensitivity to $CO_2$, slowing the breathing rate and making it more efficient. **Analysis of Incorrect Options:** * **A. Hypertension:** Morphine is not an antihypertensive. While it may cause a transient drop in BP via histamine release and vasodilation, it is never used for chronic or acute hypertension management. * **B. Cardiac Arrhythmias:** Morphine has no primary anti-arrhythmic properties. In fact, it can occasionally cause bradycardia via vagal stimulation. * **C. A-V Block:** Morphine increases vagal tone, which can worsen or precipitate heart block. It is contraindicated in patients with pre-existing conduction defects. **High-Yield NEET-PG Pearls:** * **Mnemonic for ALVF management:** **LMNOP** (L-Loop diuretics, M-Morphine, N-Nitrates, O-Oxygen, P-Positioning/Pressure/Inotropes). * **Specific Contraindication:** Avoid morphine in **Right Ventricular Infarction** as these patients are preload-dependent; morphine-induced venodilation can cause a catastrophic drop in cardiac output. * **Antidote:** Always keep **Naloxone** ready to reverse potential respiratory depression.

Question 192: Which antiplatelet drug acts via purinergic receptors and is not largely impacted by CYP2C19 polymorphism?

A. Ticlopidine
B. Prasugrel (Correct Answer)
C. Clopidogrel
D. Abciximab

Explanation: **Explanation:** **Prasugrel** is the correct answer because it is a third-generation thienopyridine that acts as a prodrug, irreversibly inhibiting the **P2Y12 purinergic receptor**. Unlike Clopidogrel, Prasugrel undergoes a more efficient, single-step metabolic activation by CYP3A4 and CYP2B6. It is **not significantly impacted by CYP2C19 polymorphisms**, leading to more predictable antiplatelet effects and faster onset of action. **Analysis of Options:** * **Clopidogrel (Option C):** This is a second-generation thienopyridine. Its activation is heavily dependent on the **CYP2C19** enzyme. Patients who are "poor metabolizers" due to CYP2C19 genetic polymorphism have reduced active metabolite levels, leading to a higher risk of cardiovascular events (e.g., stent thrombosis). * **Ticlopidine (Option A):** A first-generation thienopyridine. While it acts on P2Y12 receptors, it is rarely used today due to severe side effects like **neutropenia** and TTP. It is also a prodrug but is not the preferred answer regarding the specific CYP2C19 clinical context. * **Abciximab (Option D):** This is a monoclonal antibody that acts as a **GP IIb/IIIa receptor antagonist**. It does not act on purinergic (P2Y12) receptors and is administered intravenously. **High-Yield NEET-PG Pearls:** * **Ticagrelor:** A cyclopentyl-triazolo-pyrimidine that is **directly acting** (not a prodrug) and **reversible**. Like Prasugrel, it is not affected by CYP2C19. * **Prasugrel Contraindication:** It is strictly contraindicated in patients with a **history of stroke or TIA** due to a high risk of intracranial hemorrhage. * **Monitoring:** Platelet function is generally not monitored, but the gold standard for research is Light Transmission Aggregometry (LTA).

Question 193: Methyl dopa acts on which of the following receptors?

A. α2 (Correct Answer)
B. α1
C. β1
D. D1

Explanation: **Explanation:** **Mechanism of Action (Why A is correct):** Methyldopa is a centrally acting antihypertensive agent [1]. It is a prodrug that crosses the blood-brain barrier and is converted into **α-methylnorepinephrine** [1]. This active metabolite acts as a potent agonist at **presynaptic α2-adrenergic receptors** in the vasomotor center of the medulla [1]. Stimulation of these receptors inhibits the outflow of sympathetic impulses from the brain to the peripheral vasculature, leading to a decrease in peripheral vascular resistance and blood pressure [1]. **Analysis of Incorrect Options:** * **B (α1):** α1 receptors are primarily located postsynaptically on vascular smooth muscle. Agonism here causes vasoconstriction and increases blood pressure (e.g., Phenylephrine), which is the opposite of Methyldopa’s effect. * **C (β1):** β1 receptors are located in the heart and juxtaglomerular cells [4]. Agonism increases heart rate and renin release. Methyldopa does not directly stimulate these receptors. * **D (D1):** D1 receptors are dopamine receptors found in renal and mesenteric vascular beds. Agonism causes vasodilation (e.g., Fenoldopam), but Methyldopa does not utilize this pathway. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Methyldopa remains a first-line agent for managing **Hypertension in Pregnancy** (along with Labetalol and Hydralazine) due to its long-term safety profile for the fetus [2]. * **Side Effects:** A classic exam favorite is the development of a **Positive Coombs Test** (autoimmune hemolytic anemia) in patients on long-term therapy [3]. * **CNS Effects:** It can cause sedation, depression, and hyperprolactinemia (due to its interference with dopaminergic pathways) [3].

Question 194: What is the best drug for the rhythm disorder shown below?

A. Esmolol
B. Amiodarone (Correct Answer)
C. Vernakalant
D. Lignocaine

Explanation: ***Amiodarone*** - **First-line drug** for hemodynamically stable **monomorphic ventricular tachycardia (VT)**, as shown in the ECG. - **Class III antiarrhythmic** with superior efficacy compared to other agents for **VT termination** and prevention of recurrence. *Esmolol* - **Beta-blocker** primarily used for **rate control** in supraventricular tachycardia and atrial fibrillation. - **Not effective** for terminating ventricular tachycardia and may worsen hemodynamic status in VT. *Vernakalant* - **Specialized agent** for **acute cardioversion** of recent-onset atrial fibrillation (within 48 hours). - **No indication** for ventricular arrhythmias and specifically contraindicated in **ventricular tachycardia**. *Lignocaine* - **Class IB antiarrhythmic** that was previously used for VT but is now considered **second-line**. - **Less effective** than amiodarone for VT termination and has **higher failure rates** in clinical practice.

Question 195: Which of the following drugs should be avoided in a pregnant female with dilated cardiomyopathy?

A. Beta blockers
B. Digoxin
C. ACE inhibitors (Correct Answer)
D. Calcium channel blockers

Explanation: **Explanation:** **ACE inhibitors (ACEIs)** are strictly contraindicated in pregnancy (Category D) due to their significant **teratogenic potential**. While they are first-line agents for dilated cardiomyopathy (DCM) in non-pregnant patients, they must be avoided during pregnancy. Their use, particularly in the second and third trimesters, leads to **fetal renal dysgenesis**, which causes oligohydramnios. This lack of amniotic fluid results in the "Potter sequence" (pulmonary hypoplasia, limb deformities, and cranial facial abnormalities) and fetal skull hypoplasia. **Analysis of Incorrect Options:** * **Beta-blockers:** These are generally considered safe and are often used to manage DCM and arrhythmias in pregnancy. While they may be associated with fetal growth restriction (IUGR) or neonatal hypoglycemia, they are not contraindicated. * **Digoxin:** It is considered safe during pregnancy (Category C) and is the drug of choice for controlling ventricular rate in pregnant patients with heart failure or atrial fibrillation. * **Calcium Channel Blockers (CCBs):** While not first-line for DCM, drugs like Nifedipine are frequently used in pregnancy for hypertension or as tocolytics and are not teratogenic. **High-Yield Clinical Pearls for NEET-PG:** * **Management of DCM in Pregnancy:** The preferred regimen includes **Hydralazine and Nitrates** (as a substitute for ACEIs/ARBs), along with **Digoxin** and **Diuretics** (used cautiously). * **ACEI Fetopathy:** Characterized by renal failure, hypotension, and skull hypoplasia. * **Other Contraindicated Drugs in Pregnancy:** Warfarin (Fetal Warfarin Syndrome), Phenytoin (Fetal Hydantoin Syndrome), Tetracyclines (discolored teeth), and Isotretinoin (severe craniofacial defects).

Question 196: Clevidipine is a type of which drug class?

A. Angiotensin-Converting Enzyme Inhibitor (ACEI)
B. Calcium Channel Blocker (Correct Answer)
C. Alpha Blocker
D. Angiotensin Receptor Blocker (ARB)

Explanation: **Clevidipine** is a third-generation, ultra-short-acting **Dihydropyridine (DHP) Calcium Channel Blocker (CCB)** [1, 2]. It works by inhibiting the L-type calcium channels in vascular smooth muscle, leading to potent peripheral vasodilation and a rapid reduction in blood pressure without affecting myocardial contractility or venous capacitance [1].**Why the other options are incorrect:** * **ACE Inhibitors (e.g., Enalapril):** These inhibit the conversion of Angiotensin I to Angiotensin II. They are characterized by the suffix "-pril" and are not chemically related to DHPs.* **Alpha Blockers (e.g., Prazosin):** These block alpha_1-adrenergic receptors to cause vasodilation [2]. They do not act on calcium channels.* **ARBs (e.g., Telmisartan):** These block the AT_1 receptor directly. They are characterized by the suffix "-sartan."**High-Yield Clinical Pearls for NEET-PG:** * **Pharmacokinetics:** Clevidipine is unique because it is metabolized by **blood and tissue esterases**, making its clearance independent of renal or hepatic function.* **Half-life:** It has an extremely short half-life (approx. **1 minute**), allowing for rapid titration and quick offset of action.* **Clinical Use:** It is primarily used for the management of **Hypertensive Emergencies** and perioperative blood pressure control.* **Formulation:** It is administered as a **lipid emulsion** (similar to Propofol); therefore, it is contraindicated in patients with severe disorders of lipid metabolism (e.g., pathological hyperlipidemia) or allergies to soy/eggs.

Question 197: Which drug is used to treat ventricular arrhythmias caused by digoxin toxicity?

A. Verapamil
B. Diltiazem
C. Quinidine
D. Phenytoin (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Phenytoin** Phenytoin is the drug of choice for treating ventricular arrhythmias induced by digoxin toxicity. Digoxin toxicity causes an increase in intracellular calcium and automaticity, leading to delayed after-depolarizations (DADs). Phenytoin works by: 1. **Suppressing abnormal automaticity:** It blocks voltage-gated sodium channels (Class Ib action), which decreases the slope of Phase 4 depolarization. 2. **Improving AV conduction:** Unlike other antiarrhythmics, phenytoin can actually improve AV node conduction that has been depressed by digoxin, making it safer in the setting of digitalis-induced heart block. **Why the other options are incorrect:** * **Verapamil & Diltiazem (Options A & B):** These are Non-dihydropyridine Calcium Channel Blockers. They are contraindicated in digoxin toxicity because they further depress the SA and AV nodes, potentially worsening heart block. They can also increase digoxin levels by competing for renal excretion. * **Quinidine (Option C):** This is a Class Ia antiarrhythmic. It is strictly contraindicated because it displaces digoxin from tissue binding sites and reduces its renal clearance, leading to a dangerous rise in plasma digoxin levels (doubling the concentration). **High-Yield Clinical Pearls for NEET-PG:** * **Lidocaine** is an alternative to Phenytoin for digoxin-induced ventricular arrhythmias. * **Digibind (Digoxin Immune Fab)** is the definitive antidote for life-threatening toxicity. * **Hypokalemia** predisposes a patient to digoxin toxicity because potassium and digoxin compete for the same binding site on the Na+/K+ ATPase pump. * **ECG Hallmark:** The "Reverse Tick" sign or Sagging ST-segment (indicates digoxin effect, not necessarily toxicity).

Question 198: All of the following drugs can worsen angina, except:

A. Dipyridamole
B. Oxyphedrine (Correct Answer)
C. Thyroxine
D. Sumatriptan

Explanation: **Explanation:** The core concept behind this question is the **"Coronary Steal Phenomenon"** and the myocardial oxygen supply-demand balance. **Why Oxyphedrine is the correct answer:** Oxyphedrine is a unique drug used in the treatment of angina. It acts as a **partial beta-agonist** and has a direct metabolic effect on the myocardium. Unlike potent vasodilators, it improves myocardial metabolism and increases coronary blood flow without causing "coronary steal." Therefore, it is used to *treat* angina rather than worsen it. **Why the other options are incorrect:** * **Dipyridamole:** This is a potent arteriolar dilator. In patients with coronary artery disease, it dilates healthy vessels, "stealing" blood flow away from the already maximally dilated, ischemic distal vessels (the **Coronary Steal Phenomenon**). This worsens ischemia. * **Thyroxine:** It increases the metabolic rate and upregulates beta-receptors in the heart. This leads to increased heart rate and contractility, significantly raising **myocardial oxygen demand**, which can precipitate an anginal attack. * **Sumatriptan:** As a 5-HT$_{1B/1D}$ agonist used for migraines, it can cause **coronary vasospasm**. It is strictly contraindicated in patients with known ischemic heart disease (Prinzmetal or stable angina). **High-Yield NEET-PG Pearls:** * **Coronary Steal Phenomenon:** Classically associated with Dipyridamole and Hydralazine. * **Drugs causing Vasospasm:** Sumatriptan, Ergotamine, and Cocaine. * **Oxyphedrine:** Often classified as a "myocardial enhancer" or "coronary dilator" that is safe in chronic stable angina. * **Thyrotoxicosis:** Always consider it as a secondary cause of worsening angina or new-onset Atrial Fibrillation in elderly patients.

Question 199: Septicemic shock with multi-organ failure is treated by which of the following medications?

A. Adrenaline
B. Ephedrine
C. Phenylephrine
D. Norepinephrine (Correct Answer)

Explanation: **Explanation:** **Norepinephrine** is the first-line vasopressor for the management of septic shock (as per the Surviving Sepsis Campaign guidelines). In septic shock, there is profound peripheral vasodilation (distributive shock). Norepinephrine acts primarily as a potent **$\alpha_1$ agonist**, causing intense vasoconstriction which increases Systemic Vascular Resistance (SVR) and Mean Arterial Pressure (MAP). It also has modest **$\beta_1$ activity**, providing some inotropic support to maintain cardiac output without causing the excessive tachycardia often seen with other catecholamines. **Why other options are incorrect:** * **Adrenaline (Epinephrine):** While it is a potent vasopressor, it is generally reserved as a second-line agent. It can cause significant tachycardia and increase serum lactate levels, which may complicate the clinical monitoring of sepsis. It is the drug of choice for **Anaphylactic shock**. * **Ephedrine:** This is a mixed-acting sympathomimetic with a slow onset and long duration. It is primarily used for anesthesia-induced hypotension but is too weak and unpredictable for the management of multi-organ failure in septic shock. * **Phenylephrine:** A pure $\alpha_1$ agonist. It increases SVR but can cause reflex bradycardia and may decrease stroke volume. It is used only if norepinephrine triggers serious arrhythmias or if cardiac output is known to be high. **High-Yield Clinical Pearls for NEET-PG:** * **Target MAP:** The goal in septic shock is to maintain a **MAP $\geq$ 65 mmHg**. * **Dopamine:** No longer preferred over Norepinephrine due to a higher risk of arrhythmias and increased mortality in cardiogenic/septic shock. * **Vasopressin:** Often added to Norepinephrine ("catecholamine-sparing") if the target MAP is not achieved. * **Drug of Choice (DOC) Summary:** * Septic Shock: Norepinephrine * Anaphylactic Shock: Adrenaline (1:1000 IM) * Cardiogenic Shock: Dobutamine (Inotrope) or Norepinephrine (if hypotensive)

Question 200: Quinidine exerts its action on the heart by which mechanism?

A. Calcium channel blockade
B. Sodium channel blockade (Correct Answer)
C. Potassium channel opening
D. Chloride channel opening

Explanation: **Explanation:** **Mechanism of Action (The Correct Answer):** Quinidine is a prototype **Class IA antiarrhythmic drug**. Its primary mechanism of action is the **blockade of voltage-gated sodium (Na+) channels** (specifically in the open state). By inhibiting the influx of sodium during Phase 0 of the cardiac action potential, it decreases the rate of rise ($V_{max}$), slows conduction velocity, and reduces excitability. Additionally, Class IA drugs also block potassium channels, which prolongs the action potential duration (APD) and the effective refractory period (ERP). **Analysis of Incorrect Options:** * **Option A (Calcium channel blockade):** This is the mechanism of **Class IV** antiarrhythmics (e.g., Verapamil, Diltiazem). While quinidine has some alpha-blocking properties, its primary cardiac effect is not on calcium channels. * **Option C (Potassium channel opening):** Quinidine actually **blocks** potassium channels (contributing to QT prolongation). Potassium channel openers (like Minoxidil or Nicorandil) are used as vasodilators, not as Class I antiarrhythmics. * **Option D (Chloride channel opening):** Chloride channels are not the primary target for standard antiarrhythmic therapy. Drugs acting on chloride channels (like Benzodiazepines via GABA receptors) are used in neurology/psychiatry. **High-Yield Clinical Pearls for NEET-PG:** * **ECG Changes:** Quinidine causes widening of the QRS complex (due to Na+ block) and prolongation of the QT interval (due to K+ block). * **Adverse Effects:** Look for **Cinchonism** (tinnitus, dizziness, headache) and **Torsades de Pointes** (due to prolonged QT). * **Drug Interaction:** Quinidine reduces the renal clearance of **Digoxin**, leading to digoxin toxicity. * **Vagal Effect:** It has an atropine-like (antimuscarinic) effect, which can paradoxically increase AV conduction; hence, it is often given with AV nodal blockers.

Practice by Chapter

Antihypertensive Agents

Practice Questions

Drugs for Heart Failure

Practice Questions

Antiarrhythmic Drugs

Practice Questions

Antianginal Agents

Practice Questions

Lipid-Lowering Drugs

Practice Questions

Anticoagulants and Antiplatelet Drugs

Practice Questions

Thrombolytic Agents

Practice Questions

Drugs Used in Pulmonary Hypertension

Practice Questions

Drugs Used in Shock

Practice Questions

Cardiovascular Effects of Non-Cardiovascular Drugs

Practice Questions

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