Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 51: Bradycardia is most commonly treated with which of the following drugs?

A. Epinephrine
B. Atropine (Correct Answer)
C. A diuretic
D. A potent vasodilator

Explanation: **Explanation:** **Atropine** is the first-line pharmacological treatment for symptomatic bradycardia. It is a **competitive muscarinic antagonist** that works by blocking the action of acetylcholine at the M2 receptors in the Sinoatrial (SA) and Atrioventricular (AV) nodes. By inhibiting parasympathetic (vagal) tone, it increases the firing rate of the SA node and enhances conduction through the AV node, thereby increasing the heart rate. **Analysis of Incorrect Options:** * **Epinephrine:** While Epinephrine has potent $\beta_1$ agonist activity that increases heart rate, it is typically reserved for cardiac arrest or bradycardia refractory to Atropine. It is not the "most common" initial treatment due to its systemic vasoconstrictive effects and high myocardial oxygen demand. * **Diuretics:** These drugs (e.g., Furosemide) reduce fluid volume and are used in heart failure or hypertension. They have no direct effect on increasing the heart rate. * **Potent Vasodilators:** Drugs like Hydralazine or Nitroprusside decrease peripheral resistance. While they may cause a *reflex* tachycardia, they are not used to treat bradycardia and could cause dangerous hypotension in a bradycardic patient. **High-Yield Clinical Pearls for NEET-PG:** * **Dosage:** The standard ACLS dose for bradycardia is **0.5 mg to 1.0 mg** IV every 3–5 minutes (Max: 3 mg). * **Paradoxical Effect:** Low doses of Atropine (<0.5 mg) can cause **paradoxical bradycardia** due to the blockade of presynaptic inhibitory M1 receptors on vagal nerve endings. * **Transplant Note:** Atropine is **ineffective** in heart transplant patients because the transplanted heart is denervated (lacks vagal supply). * **Contraindication:** Use with caution in Type II Second-degree or Third-degree AV blocks with wide QRS complexes; pacing is preferred here.

Question 52: Which of the following antihypertensive drugs has a central sympatholytic action?

A. levodopa
B. carbidopa
C. alpha-methyl dopa (Correct Answer)
D. hydralazine

Explanation: **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.

Question 53: What is the mechanism of action of fibrates in the treatment of hyperlipidemia?

A. Activator of lipoprotein lipase (Correct Answer)
B. PPAR alpha agonist
C. Decreased synthesis of VLDL
D. Inhibitor of CETP

Explanation: **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.

Question 54: All of the following peptides produce vasodilation in most vascular beds EXCEPT?

A. Endothelin (Correct Answer)
B. Bradykinin
C. Vasoactive intestinal peptide
D. Calcitonin gene-related peptide

Explanation: **Explanation:** The correct answer is **Endothelin (Option A)**. **1. Why Endothelin is the correct answer:** Endothelin-1 (ET-1) is the most potent endogenous **vasoconstrictor** known [1]. It acts primarily on **$ET_A$ receptors** located on vascular smooth muscle cells, leading to profound and sustained vasoconstriction [2]. While it can cause transient vasodilation via $ET_B$ receptors on endothelial cells (releasing NO), its dominant physiological effect in most vascular beds is intense constriction [2]. **2. Analysis of Incorrect Options:** * **Bradykinin (Option B):** A potent vasodilator that acts by stimulating the release of Nitric Oxide (NO) and Prostacyclin ($PGI_2$). It also increases capillary permeability. * **Vasoactive Intestinal Peptide (VIP) (Option C):** A neurotransmitter/hormone that induces systemic vasodilation and lowers blood pressure by relaxing vascular smooth muscle [3]. * **Calcitonin Gene-Related Peptide (CGRP) (Option D):** One of the most powerful vasodilators in the body. It plays a significant role in the pathogenesis of migraines by causing vasodilation of intracranial blood vessels. **3. NEET-PG High-Yield Pearls:** * **Endothelin Antagonists:** **Bosentan** (non-selective $ET_A/ET_B$ antagonist) and **Ambrisentan** (selective $ET_A$ antagonist) are used in the treatment of **Pulmonary Arterial Hypertension (PAH)** [2], [3]. * **CGRP Antagonists:** Drugs like **Erenumab** (monoclonal antibody) and **Gepants** (e.g., Rimegepant) are used for migraine prophylaxis and treatment. * **ACE Inhibitors:** These drugs increase levels of Bradykinin (by preventing its breakdown), which contributes to both their antihypertensive effect and the common side effect of a **dry cough**.

Question 55: Which condition is typically associated with the use of decoction?

A. Hypertrophic obstructive cardiomyopathy
B. High output failure
C. Atrial fibrillation with a high ventricular rate (Correct Answer)
D. All of the above

Explanation: 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).

Question 56: Which of the following is not a positive ionotropic agent?

A. Dobutamine
B. Dopamine
C. Diltiazem (Correct Answer)
D. Amrinone

Explanation: **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 57: Timolol can be given in all conditions, except:

A. Myocardial infarction
B. Bronchial asthma (Correct Answer)
C. Peptic ulcer
D. Congestive heart failure

Explanation: **Explanation:** **Timolol** is a potent, **non-selective beta-blocker** (antagonizing both $\beta_1$ and $\beta_2$ receptors). **1. Why Bronchial Asthma is the Correct Answer:** The contraindication in bronchial asthma is due to the blockade of **$\beta_2$ receptors** located in the bronchial smooth muscles [1]. Under normal physiological conditions, $\beta_2$ stimulation causes bronchodilation. By blocking these receptors, Timolol can precipitate severe **bronchospasm** and acute asthmatic attacks [1]. Even topical Timolol (used for glaucoma) can be absorbed systemically and trigger life-threatening bronchoconstriction in susceptible patients [2]. **2. Analysis of Incorrect Options:** * **Myocardial Infarction (MI):** Beta-blockers are a cornerstone of post-MI management [3]. They reduce myocardial oxygen demand, decrease heart rate, and prevent fatal arrhythmias, thereby improving long-term survival. * **Peptic Ulcer:** There is no significant clinical contraindication for using beta-blockers in patients with peptic ulcer disease, as they do not significantly affect gastric acid secretion or mucosal integrity. * **Congestive Heart Failure (CHF):** While acutely decompensated heart failure is a contraindication, specific beta-blockers (like Carvedilol, Metoprolol, and Bisoprolol) are standard therapy for **stable, chronic heart failure** to prevent cardiac remodeling and reduce mortality [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Topical Timolol:** It is the drug of choice for wide-angle glaucoma but must be avoided in patients with asthma or COPD [1][2]. * **Selective Alternatives:** In patients with respiratory issues requiring a beta-blocker, **Betaxolol** (a cardioselective $\beta_1$ blocker) is the preferred topical agent for glaucoma [2]. * **Other Contraindications:** Beta-blockers should also be avoided in **AV blocks (2nd/3rd degree)** and **Prinzmetal angina** (due to unopposed alpha-mediated vasoconstriction).

Question 58: Which of the following drugs does NOT increase nitric oxide?

A. Glycerine trinitrate
B. Hydralazine
C. Sodium nitroprusside
D. Fenoldopam (Correct Answer)

Explanation: **Explanation:** The correct answer is **Fenoldopam** because its mechanism of action is entirely independent of the nitric oxide (NO) pathway. **1. Why Fenoldopam is the correct answer:** Fenoldopam is a selective **Post-synaptic Dopamine-1 (D1) receptor agonist**. It causes vasodilation by increasing intracellular cyclic AMP (cAMP) in vascular smooth muscle cells. It is primarily used in hypertensive emergencies to provide rapid vasodilation while maintaining or improving renal perfusion (via "natriuresis"). It does not involve the release or stimulation of nitric oxide. **2. Why the other options are incorrect:** * **Glycerine Trinitrate (GTN):** This is a prodrug that undergoes enzymatic conversion (primarily by mitochondrial aldehyde dehydrogenase) to release **Nitric Oxide (NO)**, which then activates guanylyl cyclase to increase cGMP. * **Sodium Nitroprusside (SNP):** This is a direct NO donor. It spontaneously releases **Nitric Oxide** into the bloodstream without requiring specific enzymes, making it a potent dilator of both arterioles and venules. * **Hydralazine:** While its full mechanism is complex, it is known to stimulate the release of **Nitric Oxide** from the vascular endothelium, leading to arteriolar vasodilation. **High-Yield Clinical Pearls for NEET-PG:** * **Fenoldopam "Niche":** It is the drug of choice for hypertensive emergencies in patients with **renal insufficiency** because it increases renal blood flow. * **Side Effect:** A unique side effect of Fenoldopam is an **increase in intraocular pressure**; it should be used cautiously in glaucoma patients. * **SNP Toxicity:** Prolonged infusion of Sodium Nitroprusside can lead to **Cyanide and Thiocyanate toxicity** (treated with Sodium Thiosulfate/Nitrites). * **GTN Tolerance:** Continuous use of nitrates leads to "tachyphylaxis" due to the depletion of free sulfhydryl groups.

Question 59: Which vitamin is used in the treatment of hyperlipoproteinemia?

A. Vitamin B1
B. Vitamin B6
C. Niacin/Nicotinic acid (Correct Answer)
D. Vitamin B12

Explanation: Explanation: **Correct Option: C (Niacin/Nicotinic acid)** Niacin (Vitamin B3) is a water-soluble vitamin that, when used in pharmacological doses (grams per day), acts as a potent lipid-lowering agent [1]. It inhibits the enzyme **hormone-sensitive lipase** in adipose tissue, reducing the breakdown of triglycerides into free fatty acids (FFAs). Since FFAs are the primary substrate for hepatic VLDL synthesis, Niacin effectively lowers VLDL and LDL levels [2]. Most importantly, it is the **most effective drug for increasing HDL levels** (by decreasing its fractional clearance). **Incorrect Options:** * **Vitamin B1 (Thiamine):** Primarily used to treat Beriberi and Wernicke-Korsakoff syndrome; it has no role in lipid metabolism. * **Vitamin B6 (Pyridoxine):** Used to prevent peripheral neuropathy (e.g., with Isoniazid therapy) and in sideroblastic anemia; it does not affect lipoprotein levels. * **Vitamin B12 (Cyanocobalamin):** Essential for DNA synthesis and neurological function; its deficiency leads to megaloblastic anemia and subacute combined degeneration of the spinal cord. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects:** The most common side effect is **cutaneous flushing** (mediated by Prostaglandin D2/E2). This can be prevented by pre-treating with **Aspirin**. * **Metabolic Concerns:** Niacin can cause **hyperuricemia** (precipitating gout) and **hyperglycemia** (use with caution in diabetics) [1]. It may also cause acanthosis nigricans. * **Drug of Choice:** While statins are first-line for LDL reduction, Niacin is historically significant for patients with low HDL or elevated Lipoprotein(a) [2].

Question 60: A 65-year-old male had a myocardial infarction one year ago. The same patient now presents with hypertension. Which of the following drugs is best suited for this patient?

A. Clonidine
B. Thiazide
C. Propranolol
D. Lisinopril (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Lisinopril** The primary goal in managing hypertension in a patient with a history of Myocardial Infarction (MI) is **cardioprotection** and prevention of **ventricular remodeling**. **ACE Inhibitors (like Lisinopril)** are the drugs of choice in post-MI patients because they: 1. **Inhibit Ventricular Remodeling:** They prevent the structural changes (hypertrophy and fibrosis) in the myocardium that occur after an MI, thereby reducing the risk of heart failure. 2. **Reduce Mortality:** Large clinical trials have consistently shown that ACE inhibitors improve long-term survival rates in post-MI patients. 3. **Renoprotection:** They are also beneficial if the patient has co-morbidities like diabetes or chronic kidney disease. --- ### Why other options are incorrect: * **A. Clonidine:** This is a centrally acting alpha-2 agonist. It is generally a second or third-line agent for hypertension and has no proven benefit in post-MI remodeling or mortality reduction. * **B. Thiazide:** While excellent for primary hypertension, they do not provide the specific cardioprotective "anti-remodeling" benefits required for a post-MI patient. * **C. Propranolol:** Although Beta-blockers are indicated post-MI, Propranolol is a **non-selective** beta-blocker. In modern practice, **cardioselective** beta-blockers (e.g., Metoprolol, Atenolol) or vasodilatory beta-blockers (e.g., Carvedilol) are preferred. Lisinopril remains a more fundamental "first-choice" for preventing remodeling. --- ### NEET-PG High-Yield Pearls: * **Drugs that reduce mortality post-MI:** ACE inhibitors/ARBs, Beta-blockers, Aldosterone antagonists (e.g., Spironolactone), and Statins. * **Drug of Choice (DOC) for HTN with Diabetes:** ACE inhibitors (due to nephroprotective effects). * **Common Side Effect of Lisinopril:** Dry cough (due to increased Bradykinin levels); if this occurs, switch the patient to an **ARB (e.g., Losartan)**. * **Contraindication:** ACE inhibitors are strictly contraindicated in **pregnancy** (teratogenic) and **bilateral renal artery stenosis**.

Practice by Chapter

Antihypertensive Agents

Practice Questions

Drugs for Heart Failure

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Antiarrhythmic Drugs

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Antianginal Agents

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Lipid-Lowering Drugs

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Anticoagulants and Antiplatelet Drugs

Practice Questions

Thrombolytic Agents

Practice Questions

Drugs Used in Pulmonary Hypertension

Practice Questions

Drugs Used in Shock

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Cardiovascular Effects of Non-Cardiovascular Drugs

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