Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 41: Propranolol is useful for all of the following conditions except?

A. Angina
B. Familial tremor
C. Hypertension
D. Paroxysmal AV block (Correct Answer)

Explanation: **Explanation:** Propranolol is a non-selective beta-adrenergic antagonist (beta-blocker). The correct answer is **Paroxysmal AV block** because beta-blockers are strictly **contraindicated** in patients with heart block. **1. Why Paroxysmal AV block is the correct choice:** Propranolol blocks $\beta_1$ receptors in the heart, specifically at the SA and AV nodes. This results in negative chronotropy (decreased heart rate) and negative dromotropy (slowed conduction velocity through the AV node). In a patient with paroxysmal AV block, propranolol would further depress conduction, potentially leading to complete heart block or cardiac arrest. **2. Why the other options are incorrect:** * **Angina:** Propranolol reduces myocardial oxygen demand by decreasing heart rate and contractility, making it a first-line agent for chronic stable angina. * **Familial tremor:** Essential/familial tremors are mediated by peripheral $\beta_2$ receptors. Propranolol crosses the blood-brain barrier and blocks these receptors, effectively reducing tremor amplitude. * **Hypertension:** While no longer first-line for uncomplicated hypertension, beta-blockers reduce blood pressure by decreasing cardiac output and inhibiting renin release from the kidneys. **High-Yield Clinical Pearls for NEET-PG:** * **Membrane Stabilizing Activity (MSA):** Propranolol possesses significant MSA (local anesthetic effect), which contributes to its anti-arrhythmic properties but also makes it toxic in overdose. * **Lipophilicity:** It is highly lipid-soluble, allowing it to enter the CNS (useful for prophylaxis of **migraine** and **performance anxiety**). * **Contraindications:** Always remember the "ABCDE" contraindications for Beta-blockers: **A**sthma/COPD, **B**lock (Heart block), **C**ardiogenic shock, **D**iabetes (masks hypoglycemia), and **E**xtremity vascular disease (Raynaud's).

Question 42: Which of the following drugs can cause Torsades de pointes?

A. Quinidine (Correct Answer)
B. Lignocaine
C. Esmolol
D. Flecainide

Explanation: **Explanation:** **Torsades de Pointes (TdP)** is a specific type of polymorphic ventricular tachycardia associated with a **prolonged QT interval**. **1. Why Quinidine is correct:** Quinidine is a **Class IA antiarrhythmic**. Its primary mechanism involves blocking fast sodium channels, but it also significantly blocks **potassium channels** (delayed rectifier current, $I_{Kr}$). By inhibiting potassium efflux during repolarization, it prolongs the action potential duration (APD) and the QT interval. This creates a window for "early after-depolarizations" (EADs), which trigger TdP. This phenomenon is often referred to as "Quinidine Syncope." **2. Why the other options are incorrect:** * **Lignocaine (Class IB):** These drugs have the shortest dissociation kinetics and actually **shorten** the action potential duration. They do not cause QT prolongation and are therefore not associated with TdP. * **Esmolol (Class II):** As a cardioselective beta-blocker, it decreases SA and AV node conduction. It does not significantly affect the ventricular repolarization phase or the QT interval. * **Flecainide (Class IC):** These are potent sodium channel blockers that significantly prolong the QRS duration (conduction slowing) but have **minimal effect** on the QT interval. Their main risk is "re-entrant" ventricular tachycardia, especially post-MI. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for TdP-causing drugs (ABCDE):** **A**ntiarrhythmics (Class IA & III), **B**e-blockers (Sotalol - exception), **C**ytochrome P450 inhibitors, **D**iuretics (via hypokalemia), **E**rythromycin (Macrolides/Fluoroquinolones/Antipsychotics). * **Class III drugs** (e.g., Sotalol, Dofetilide) have the highest risk of TdP, but **Amiodarone** (despite prolonging QT) rarely causes TdP due to its homogenous effect on ventricular repolarization. * **Treatment of choice** for drug-induced Torsades de pointes is **Intravenous Magnesium Sulfate**.

Question 43: Which of the following is NOT a calcium channel blocker?

A. Verapamil
B. Pirenzepine (Correct Answer)
C. Felodipine
D. Nitrendipine

Explanation: **Explanation:** The correct answer is **Pirenzepine**, as it is a selective **M1 muscarinic receptor antagonist**, not a calcium channel blocker (CCB). Historically used in the treatment of peptic ulcers, it works by reducing gastric acid secretion. **Analysis of Options:** * **Verapamil (Option A):** This is a **Phenylalkylamine**, a non-dihydropyridine CCB. It acts primarily on the myocardium and is used as a Class IV antiarrhythmic and for rate control in atrial fibrillation. * **Felodipine & Nitrendipine (Options C & D):** These belong to the **Dihydropyridine (DHP)** class of CCBs. DHPs are characterized by the suffix "-dipine." They are potent peripheral vasodilators primarily used to treat hypertension and angina. **High-Yield Clinical Pearls for NEET-PG:** * **Classification of CCBs:** 1. **Dihydropyridines:** Nifedipine, Amlodipine, Felodipine, Nitrendipine (Mainly vascular effect). 2. **Phenylalkylamines:** Verapamil (Mainly cardiac effect). 3. **Benzothiazepines:** Diltiazem (Intermediate effect on both heart and vessels). * **Drug of Choice (DOC):** Nimodipine (a DHP) is the DOC for preventing vasospasm in **Subarachnoid Hemorrhage (SAH)** due to its high lipid solubility and cerebrovascular selectivity. * **Side Effects:** A common side effect of DHPs (like Amlodipine) is **ankle edema**, while Verapamil is notorious for causing **constipation** and gingival hyperplasia. * **Contraindication:** Verapamil should be avoided in patients with Heart Failure or AV blocks due to its negative inotropic and dromotropic effects.

Question 44: Which of the following statements best explains the action of nitroglycerine on coronary vessels?

A. It mitigates angina pectoris by increasing total coronary flow.
B. It preferentially dilates conducting arteries without affecting resistance arterioles. (Correct Answer)
C. It preferentially dilates autoregulatory arterioles without affecting the larger arteries.
D. It mainly decreases the afterload.

Explanation: **Explanation:** The primary mechanism of Nitroglycerine (NTG) in relieving angina is not by increasing total coronary blood flow, but by **redistributing** it to ischemic areas. **Why Option B is Correct:** Nitroglycerine acts as a prodrug for Nitric Oxide (NO), which activates guanylyl cyclase to increase cGMP, leading to smooth muscle relaxation. In the coronary circulation, NTG **preferentially dilates large epicardial conducting arteries** and collateral vessels. Crucially, it has minimal effect on the smaller, distal **resistance arterioles**. By dilating the larger vessels and collaterals, it allows blood to bypass obstructions and reach the vulnerable subendocardial layers, which are most prone to ischemia. **Why the Other Options are Incorrect:** * **Option A:** In a patient with coronary artery disease, total coronary flow often remains unchanged. The benefit comes from the redistribution of flow to ischemic zones and a decrease in myocardial oxygen demand. * **Option C:** This is the opposite of NTG’s action. Drugs like **Dipyridamole** dilate autoregulatory resistance arterioles, which can lead to "Coronary Steal Phenomenon" (shunting blood away from ischemic areas). NTG avoids this by sparing the arterioles. * **Option D:** While NTG does cause some arterial dilation at high doses, its **predominant** systemic effect is **venodilation** (decreasing **preload**). Decreasing preload reduces ventricular wall tension and oxygen demand, which is its main systemic anti-anginal mechanism. **High-Yield NEET-PG Pearls:** * **Drug of Choice:** Sublingual NTG is the DOC for acute anginal attacks. * **Tolerance:** Continuous use leads to "Nitrate Tolerance" (depletion of sulfhydryl groups). A 10–12 hour "nitrate-free interval" is required daily. * **Contraindication:** Never co-administer with Sildenafil (PDE-5 inhibitors) due to the risk of severe, fatal hypotension. * **Monday Disease:** Workers in dynamite factories developed tolerance during the week but experienced headaches and tachycardia on Mondays (loss of tolerance over the weekend).

Question 45: What is the primary rationale for co-administering nifedipine and a beta-blocker?

A. To decrease pedal edema caused by nifedipine
B. To counteract the increased sympathetic activity induced by nifedipine (Correct Answer)
C. For the anti-congestive heart failure action of propranolol
D. To achieve the antiarrhythmic effect of nifedipine

Explanation: ### Explanation **1. Why Option B is Correct:** Nifedipine is a potent **Dihydropyridine (DHP) Calcium Channel Blocker** that acts primarily as a peripheral vasodilator. By causing rapid arteriolar dilation, it triggers a baroreceptor-mediated **reflex tachycardia** and increased sympathetic outflow. This surge in sympathetic activity can increase myocardial oxygen demand, potentially precipitating angina. Beta-blockers (like Atenolol or Metoprolol) are co-administered to blunt this reflex tachycardia and suppress the increased sympathetic tone, thereby enhancing the anti-anginal efficacy and improving patient tolerance. **2. Why Other Options are Incorrect:** * **Option A:** Pedal edema is a common side effect of DHPs due to precapillary vasodilation and increased hydrostatic pressure. Beta-blockers do not significantly reduce this; in fact, **ACE inhibitors or ARBs** are the drugs of choice to counteract DHP-induced edema by causing venodilation. * **Option C:** Propranolol and other beta-blockers are generally avoided in *acute* decompensated heart failure due to their negative inotropic effects. Furthermore, Nifedipine is not a standard treatment for CHF. * **Option D:** Nifedipine has negligible effects on the cardiac conduction system at clinical doses and is **not used as an antiarrhythmic**. Verapamil and Diltiazem (Non-DHPs) are the CCBs used for arrhythmias. **3. High-Yield Clinical Pearls for NEET-PG:** * **The "Perfect Match":** Beta-blockers + DHP CCBs (e.g., Nifedipine/Amlodipine) is a synergistic combination for hypertension and angina. * **The "Dangerous Duo":** Beta-blockers + **Verapamil** (Non-DHP) is generally **contraindicated** as both are negative inotropes and dromotropes, risking severe bradycardia or AV block. * **Short-acting Nifedipine:** Should be avoided in hypertensive emergencies as the rapid drop in BP and subsequent sympathetic surge can trigger myocardial infarction or stroke.

Question 46: Which of the following is NOT a treatment given for acute severe digitalis toxicity?

A. Potassium (Correct Answer)
B. Digibind
C. Lignocaine
D. None of these

Explanation: In digitalis toxicity, the management strategy depends heavily on whether the toxicity is **acute** or **chronic**, and the patient's current serum potassium levels. ### Why Potassium is the Correct Answer In **acute severe digitalis toxicity**, the inhibition of the Na+/K+ ATPase pump is so profound that potassium cannot enter the cells, leading to **hyperkalemia**. Administering supplemental potassium in a patient who is already hyperkalemic is contraindicated as it can precipitate fatal cardiac arrest. While potassium is used to treat digitalis-induced arrhythmias in *chronic* toxicity (where diuretics often cause hypokalemia), it is **NOT** given in acute severe cases where potassium levels are already high. ### Explanation of Other Options * **Digibind (Digoxin Immune Fab):** This is the **specific antidote** and the first-line treatment for severe life-threatening toxicity. It binds to digoxin molecules, making them pharmacologically inactive. * **Lignocaine (Lidocaine):** This is the **drug of choice** for treating digitalis-induced ventricular arrhythmias. It suppresses ventricular irritability without significantly worsening AV block. ### NEET-PG High-Yield Pearls * **Most common arrhythmia:** Ventricular Bigeminy. * **Most characteristic arrhythmia:** Atrial Tachycardia with AV block. * **Electrolyte triggers:** Hypokalemia, hypomagnesemia, and hypercalcemia predispose a patient to toxicity. * **ECG finding:** "Reverse Tick" sign or "Sagging" ST-segment depression. * **Contraindication:** DC cardioversion is avoided in digitalis toxicity as it may precipitate ventricular fibrillation.

Question 47: Which of the following is not an adverse effect of amiodarone?

A. Hyperthyroidism
B. Corneal microdeposits
C. Pulmonary fibrosis
D. Nephrotoxicity (Correct Answer)

Explanation: **Explanation:** Amiodarone is a Class III antiarrhythmic drug known for its high iodine content and exceptionally long half-life (several weeks). It is notorious for causing multi-organ toxicities due to its accumulation in various tissues; however, **nephrotoxicity is not a recognized adverse effect** of the drug. **Why Nephrotoxicity is the correct answer:** Amiodarone is primarily metabolized by the liver (CYP3A4) and excreted via the biliary tract. Unlike many other cardiovascular drugs, it does not require dose adjustment in renal failure and does not cause direct structural or functional damage to the kidneys. **Analysis of incorrect options:** * **Hyperthyroidism (and Hypothyroidism):** Amiodarone is 37% iodine by weight. It can cause hypothyroidism (Wolff-Chaikoff effect) or hyperthyroidism (Jod-Basedow phenomenon). * **Corneal microdeposits:** These occur in nearly all patients on long-term therapy. They are usually asymptomatic and do not require drug discontinuation, though they can cause "halos" around lights. * **Pulmonary fibrosis:** This is the most serious/lethal side effect. It is dose-dependent and results from chronic interstitial pneumonitis. **High-Yield Clinical Pearls for NEET-PG:** * **Skin:** Can cause a distinctive **blue-gray skin discoloration** (Photosensitivity). * **Liver:** Can lead to elevated transaminases and cirrhosis. * **Monitoring:** Baseline and periodic **Chest X-ray, PFTs, LFTs, and Thyroid Function Tests (TFTs)** are mandatory. * **Mechanism:** While Class III (K+ channel blocker), it exhibits properties of all four Vaughan-Williams classes.

Question 48: Which of the following is not an inotropic drug?

A. Amrinone
B. Isoprenaline
C. Amiodarone (Correct Answer)
D. Dopamine

Explanation: **Explanation:** Inotropic drugs are agents that alter the force of muscular contractions, specifically increasing myocardial contractility (positive inotropes). The correct answer is **Amiodarone**, as it is primarily an antiarrhythmic agent, not an inotrope. **Why Amiodarone is the correct answer:** Amiodarone is a **Class III antiarrhythmic** drug. Its primary mechanism involves blocking potassium channels, which prolongs the action potential duration and refractory period. While it has complex effects (including Class I, II, and IV actions), it does not increase cardiac contractility. In fact, due to its weak calcium channel-blocking and beta-blocking properties, it can occasionally exert a **negative inotropic effect**, making it a non-inotropic drug. **Why the other options are incorrect:** * **Amrinone (and Milrinone):** These are **Phosphodiesterase-3 (PDE3) inhibitors**. They increase intracellular cAMP levels in cardiac myocytes, leading to increased calcium influx and positive inotropy. * **Isoprenaline:** A potent **non-selective beta-agonist** ($\beta_1$ and $\beta_2$). By stimulating $\beta_1$ receptors in the heart, it significantly increases both heart rate (chronotropy) and force of contraction (inotropy). * **Dopamine:** At moderate to high doses, dopamine stimulates **$\beta_1$ receptors** directly and induces the release of norepinephrine, resulting in a strong positive inotropic effect. **Clinical Pearls for NEET-PG:** * **Inodilators:** Drugs like Amrinone and Milrinone are called "inodilators" because they provide positive inotropy along with systemic vasodilation. * **Amiodarone Side Effects:** High-yield for exams—includes pulmonary fibrosis, thyroid dysfunction (hypo/hyper), corneal microdeposits, and blue-gray skin discoloration. * **Digoxin:** The classic oral positive inotrope that works by inhibiting the Na+/K+ ATPase pump.

Question 49: Which of the following drugs are implicated in the development of heart block?

A. Beta blockers
B. Lithium
C. Adenosine
D. All the above (Correct Answer)

Explanation: Heart block occurs when there is a delay or interruption in the conduction of electrical impulses from the atria to the ventricles. This can be induced by drugs that depress the **Sinoatrial (SA) node** or the **Atrioventricular (AV) node**. **Explanation of Options:** * **Beta-blockers (Option A):** These drugs act as negative dromotropes by blocking $\beta_1$ receptors in the heart. This decreases the rate of conduction through the AV node and increases the refractory period, which can lead to various degrees of heart block, especially in patients with pre-existing conduction defects. * **Lithium (Option B):** While primarily used as a mood stabilizer, Lithium is known for its cardiac side effects. It can interfere with sinus node function (causing Sick Sinus Syndrome) and impair AV conduction, leading to bradycardia and heart block. * **Adenosine (Option C):** This drug is the treatment of choice for PSVT. It works by activating $A_1$ receptors, which increases $K^+$ efflux and inhibits $Ca^{2+}$ current. This causes a transient but potent suppression of the AV node, which can manifest as a temporary high-grade heart block. **Conclusion:** Since all three drugs can impair cardiac conduction, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** 1. **Other drugs causing heart block:** Non-dihydropyridine Calcium Channel Blockers (Verapamil, Diltiazem), Digoxin, and Amiodarone. 2. **Digoxin Toxicity:** Classically causes heart block with increased atrial rate (Atrial Tachycardia with AV block). 3. **Management:** Atropine is the initial drug of choice for symptomatic bradycardia/heart block, but it is ineffective in high-grade blocks (Mobitz II or 3rd degree), where a pacemaker is required.

Question 50: Which of the following ACE inhibitors is not a prodrug?

A. Captopril (Correct Answer)
B. Enalapril
C. Ramipril
D. All of the above

Explanation: **Explanation:** The core pharmacological concept here is the distinction between **active drugs** and **prodrugs**. Most Angiotensin-Converting Enzyme (ACE) inhibitors are prodrugs, meaning they are inactive when ingested and must undergo hepatic conversion (ester hydrolysis) into their active "–at" metabolites (e.g., Enalapril to Enalaprilat) to exert their effect. **Why Captopril is correct:** **Captopril** and **Lisinopril** are the only two ACE inhibitors that are **not prodrugs**. They are already in their active form upon administration. Because they do not require hepatic activation, they have a faster onset of action and are preferred in patients with severe liver dysfunction. **Why the other options are incorrect:** * **Enalapril:** It is a prodrug converted in the liver to its active form, **Enalaprilat**. (Note: Enalaprilat is available as an IV formulation for hypertensive emergencies). * **Ramipril:** It is a long-acting prodrug converted to **Ramiprilat**. It is commonly used for its cardioprotective benefits in high-risk patients. * **All of the above:** This is incorrect because only Captopril (and Lisinopril) are active drugs. **High-Yield NEET-PG Pearls:** 1. **Mnemonic:** Remember **"L-C"** (Lisinopril and Captopril) as the "Active" ones. 2. **Excretion:** Most ACE inhibitors are excreted renally. **Fosinopril** and **Moexipril** are unique because they have significant biliary excretion, making them safer in patients with renal impairment. 3. **Side Effects:** The most common side effect is a **dry cough** (due to increased Bradykinin and Substance P). The most serious side effect is **Angioedema**. 4. **Contraindication:** ACE inhibitors are strictly **teratogenic** (cause fetal renal anomalies) and are contraindicated in pregnancy.

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

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