Cardiovascular Drugs Practice Questions

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

Quinidine. **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**.

Q: All are toxicities seen with amiodarone therapy except?

Productive cough. Amiodarone is a Class III antiarrhythmic drug known for its long half-life and extensive side-effect profile due to its high iodine content and tendency to accumulate in various tissues. **Why "Productive Cough" is the correct answer:** Amiodarone is notorious for causing **Pulmonary Toxicity**, most commonly presenting as **interstitial lung disease or pulmonary fibrosis**. This typically manifests as a **dry, non-productive cough** and progressive dyspnea. A productive cough is not a characteristic feature of amiodarone-induced lung injury and usually suggests an infectious process. **Analysis of Incorrect Options:** * **Pulmonary Fibrosis:** This is the most serious side effect. It is dose-dependent and results from direct toxicity and an inflammatory response leading to alveolar damage. * **Corneal Microdeposits:** These occur in nearly all patients treated for more than six months. They are usually asymptomatic and do not require discontinuation of the drug, though they can occasionally cause "halo vision." * **Cirrhosis of Liver:** Amiodarone is metabolized in the liver and can cause elevated transaminases. Long-term use can lead to steatohepatitis and, rarely, cirrhosis. **NEET-PG High-Yield Pearls:** * **Thyroid Dysfunction:** Amiodarone can cause both **hypothyroidism** (Wolff-Chaikoff effect) and **hyperthyroidism** (Jod-Basedow phenomenon) due to its 37% iodine content. * **Skin:** Can cause a distinctive **blue-gray skin discoloration** (photodermatitis). * **Monitoring:** Baseline and periodic Chest X-rays, Pulmonary Function Tests (PFTs), Liver Function Tests (LFTs), and Thyroid Function Tests (TFTs) are mandatory for patients on chronic therapy.

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

Nephrotoxicity. **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.

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

All the above. 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.

Q: Which of the following antihypertensive drugs has a central sympatholytic action?

alpha-methyl dopa. **Explanation:** **Alpha-methyl dopa** is the correct answer because it is a classic **centrally acting sympatholytic** agent. It acts as a prodrug that is converted into alpha-methyl norepinephrine in the brain. This metabolite acts as a potent agonist at **presynaptic alpha-2 (α2) adrenergic receptors** in the vasomotor center of the medulla. Stimulation of these receptors inhibits the outflow of sympathetic impulses to the heart and peripheral vasculature, leading to a decrease in peripheral vascular resistance and blood pressure. **Analysis of Incorrect Options:** * **Levodopa:** A precursor of dopamine used in Parkinson’s disease. While it crosses the blood-brain barrier, its primary role is to replenish dopamine levels in the basal ganglia, not to lower blood pressure via sympatholysis. * **Carbidopa:** A peripheral dopa-decarboxylase inhibitor. It does not cross the blood-brain barrier and is co-administered with levodopa to prevent its peripheral conversion to dopamine, thereby reducing systemic side effects. * **Hydralazine:** A **direct-acting peripheral vasodilator** that relaxes arteriolar smooth muscle. It does not have a central mechanism of action and often causes reflex tachycardia. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Alpha-methyl dopa remains a preferred drug for managing **hypertension in pregnancy** (along with Labetalol and Nifedipine). * **Side Effects:** A key adverse effect is a **positive Coomb’s test**, which can rarely lead to autoimmune hemolytic anemia. It can also cause sedation and hyperprolactinemia. * **Other Central Sympatholytics:** Clonidine (α2 agonist) and Moxonidine (Imidazoline receptor agonist) are other drugs in this class.

Q: What is the mechanism of action of fibrates in the treatment of hyperlipidemia?

Activator of lipoprotein lipase. **Explanation:** Fibrates (e.g., Fenofibrate, Gemfibrozil) are the primary class of drugs used for treating **hypertriglyceridemia**. Their primary mechanism of action involves the activation of **Lipoprotein Lipase (LPL)**, the enzyme responsible for the hydrolysis of triglycerides in VLDL and chylomicrons. **Why Option A is correct:** Fibrates act as ligands for the **PPAR-α (Peroxisome Proliferator-Activated Receptor-alpha)** transcription factor. Activation of PPAR-α leads to increased expression of the LPL gene and a decrease in **ApoC-III** (an inhibitor of LPL). This dual action significantly enhances LPL activity, leading to rapid clearance of triglyceride-rich lipoproteins from the plasma. **Analysis of other options:** * **Option B (PPAR alpha agonist):** While fibrates *are* PPAR-α agonists, this is the **molecular target**, not the final functional mechanism that lowers lipids. In many exams, if both are present, "Activation of LPL" is considered the definitive physiological result that explains the drug's effect. * **Option C (Decreased synthesis of VLDL):** Fibrates do decrease VLDL secretion by the liver, but this is a secondary effect compared to the massive increase in peripheral clearance via LPL. * **Option D (Inhibitor of CETP):** This describes the mechanism of drugs like **Anacetrapib** or **Torcetrapib**, which aim to increase HDL levels, not fibrates. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Fibrates are the DOC for severe hypertriglyceridemia (TG >500 mg/dL) to prevent **acute pancreatitis**. * **Side Effects:** Myopathy (risk increases when combined with statins) and gallstones (due to increased biliary cholesterol excretion). * **Contraindication:** Avoid in patients with severe renal or hepatic dysfunction.

Q: Which condition is typically associated with the use of decoction?

Atrial fibrillation with a high ventricular rate. The question refers to **Digoxin** (often historically or colloquially linked to digitalis decoctions). Digoxin is a cardiac glycoside primarily used for its positive inotropic and negative chronotropic effects. **Why Option C is Correct:** In **Atrial Fibrillation (AFib)**, the atria generate rapid, disorganized electrical impulses. Digoxin is a drug of choice for **rate control** in AFib because it increases vagal tone (parasympathomimetic effect) [1], which slows conduction through the **Atrioventricular (AV) node**. This increases the refractory period of the AV node, effectively reducing the number of impulses reaching the ventricles and lowering the heart rate [1]. **Why Other Options are Incorrect:** * **A. Hypertrophic Obstructive Cardiomyopathy (HOCM):** Digoxin is **contraindicated** here. Its positive inotropic effect increases myocardial contractility, which can worsen the outflow tract obstruction and increase the pressure gradient across the subaortic area. * **B. High Output Failure:** This condition (caused by anemia, thyrotoxicosis, or Beriberi) is due to increased metabolic demand rather than primary pump failure. Digoxin is generally ineffective because the underlying pathology is not a deficit in contractility. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Inhibits Na+/K+ ATPase pump $\rightarrow$ increases intracellular Na+ $\rightarrow$ decreases Na+/Ca2+ exchange $\rightarrow$ increases intracellular Ca2+ (Inotropy). * **ECG Changes:** Characterized by the "reverse tick" sign or **Sagging ST-segment depression** [1]. * **Toxicity:** Hypokalemia predisposes to digoxin toxicity. The most common arrhythmia in toxicity is **Atrial Tachycardia with AV block**, while the most specific is **Bidirectional Ventricular Tachycardia** [1]. * **Antidote:** Digibind (Digoxin-specific antibody fragments).

Q: Which of the following is not a positive ionotropic agent?

Diltiazem. **Explanation:** The term **positive inotrope** refers to agents that increase the force of myocardial contraction. The correct answer is **Diltiazem** because it is a **negative inotrope**. **1. Why Diltiazem is the correct answer:** Diltiazem is a non-dihydropyridine **Calcium Channel Blocker (CCB)**. It works by blocking L-type calcium channels in the myocardium and cardiac conduction tissue. Since intracellular calcium is essential for the actin-myosin cross-bridge formation, blocking these channels reduces the force of contraction (negative inotropy). It is primarily used for rate control in atrial fibrillation and for hypertension. **2. Analysis of incorrect options:** * **Dobutamine:** A selective **$\beta_1$ agonist**. It increases cAMP levels in cardiac myocytes, leading to increased calcium influx and strong positive inotropic effects. It is a drug of choice for cardiogenic shock. * **Dopamine:** At moderate doses (5–10 µg/kg/min), it stimulates **$\beta_1$ receptors**, increasing cardiac contractility. At higher doses, it also acts on $\alpha_1$ receptors to cause vasoconstriction. * **Amrinone (and Milrinone):** These are **Phosphodiesterase-3 (PDE-3) inhibitors**. They prevent the breakdown of cAMP in the heart, increasing contractility (inotropy) and causing vasodilation (lusitropy), often referred to as "Inodilators." **Clinical Pearls for NEET-PG:** * **Inodilators:** Milrinone and Amrinone (increase CO while decreasing afterload). * **Digitalis:** A positive inotrope that works by inhibiting the $Na^+/K^+$ ATPase pump, indirectly increasing intracellular calcium. * **Contraindication:** Non-dihydropyridine CCBs (Diltiazem, Verapamil) are generally avoided in patients with Systolic Heart Failure (HFrEF) due to their negative inotropic effects.

Question 1

Which of the following drugs can cause Torsades de pointes?

Accepted Answer

Quinidine

Answer

Lignocaine

Answer

Esmolol

Answer

Flecainide

Question 2

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

Accepted Answer

It preferentially dilates conducting arteries without affecting resistance arterioles.

Answer

It mitigates angina pectoris by increasing total coronary flow.

Answer

It preferentially dilates autoregulatory arterioles without affecting the larger arteries.

Answer

It mainly decreases the afterload.

Question 3

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

Accepted Answer

To counteract the increased sympathetic activity induced by nifedipine

Answer

To decrease pedal edema caused by nifedipine

Answer

For the anti-congestive heart failure action of propranolol

Answer

To achieve the antiarrhythmic effect of nifedipine

Question 4

All are toxicities seen with amiodarone therapy except?

Accepted Answer

Productive cough

Answer

Pulmonary fibrosis

Answer

Corneal microdeposits

Answer

Cirrhosis of liver

Question 5

Which of the following is not an adverse effect of amiodarone?

Accepted Answer

Nephrotoxicity

Answer

Hyperthyroidism

Answer

Corneal microdeposits

Answer

Pulmonary fibrosis

Question 6

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

Accepted Answer

All the above

Answer

Beta blockers

Answer

Lithium

Answer

Adenosine

Question 7

Which of the following antihypertensive drugs has a central sympatholytic action?

Accepted Answer

alpha-methyl dopa

Answer

levodopa

Answer

carbidopa

Answer

hydralazine

Question 8

What is the mechanism of action of fibrates in the treatment of hyperlipidemia?

Accepted Answer

Activator of lipoprotein lipase

Answer

PPAR alpha agonist

Answer

Decreased synthesis of VLDL

Answer

Inhibitor of CETP

Question 9

Which condition is typically associated with the use of decoction?

Accepted Answer

Atrial fibrillation with a high ventricular rate

Answer

Hypertrophic obstructive cardiomyopathy

Answer

High output failure

Answer

All of the above

Question 10

Which of the following is not a positive ionotropic agent?

Accepted Answer

Diltiazem

Answer

Dobutamine

Answer

Dopamine

Answer

Amrinone

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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