Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 181: Which beta-blocker drug is contraindicated in asthma patients?

A. Metoprolol
B. Atenolol
C. Propranolol (Correct Answer)
D. Acebutolol

Explanation: **Explanation:** The correct answer is **C. Propranolol**. **1. Why Propranolol is the correct answer:** Propranolol is a **non-selective beta-blocker**, meaning it blocks both $\beta_1$ receptors (located primarily in the heart) and $\beta_2$ receptors (located in the bronchial smooth muscle). In patients with asthma or COPD, blocking $\beta_2$ receptors leads to bronchoconstriction and can precipitate a life-threatening acute asthmatic attack. Therefore, non-selective beta-blockers are strictly contraindicated in patients with reactive airway diseases. **2. Why the other options are incorrect:** * **Metoprolol and Atenolol (Options A & B):** These are **cardioselective ($\beta_1$) blockers**. At therapeutic doses, they primarily target the heart and have minimal effect on the $\beta_2$ receptors in the lungs. While they should still be used with caution, they are safer than non-selective agents. * **Acebutolol (Option D):** This is also a cardioselective $\beta_1$ blocker with **Intrinsic Sympathomimetic Activity (ISA)**. Like Metoprolol, it is less likely to cause bronchospasm compared to Propranolol. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Cardioselective ($\beta_1$) Blockers:** *"New Beta Blockers Are Exclusive to My Heart"* (Nebivolol, Betaxolol, Bisoprolol, Atenolol, Esmolol, Metoprolol). * **Esmolol:** The shortest-acting beta-blocker (half-life ~9 mins), administered IV for hypertensive emergencies or supraventricular tachycardia. * **Propranolol:** Highly lipid-soluble, crosses the blood-brain barrier (used for prophylaxis of migraine and essential tremors), and inhibits the peripheral conversion of $T_4$ to $T_3$ (used in thyroid storm). * **Absolute Contraindications for Beta-blockers:** Asthma, Bradycardia, 2nd or 3rd-degree Heart Block, and Cardiogenic Shock.

Question 182: Which of the following is least likely to cause an increase in bradykinin production?

A. Perindopril
B. Benzprindopril
C. Irbesartan (Correct Answer)
D. All of the above

Explanation: The correct answer is **Irbesartan** because of the fundamental difference in the mechanism of action between ACE inhibitors and Angiotensin II Receptor Blockers (ARBs). **1. Why Irbesartan is correct:** Irbesartan is an **ARB**. ARBs act by selectively blocking the $AT_1$ receptor. Unlike ACE inhibitors, they do not inhibit the Angiotensin-Converting Enzyme (ACE). Since ACE is the same enzyme responsible for the degradation of bradykinin (also known as Kininase II) [1], ARBs do not interfere with bradykinin metabolism. Therefore, they do not cause an increase in bradykinin levels. **2. Why the other options are incorrect:** * **Perindopril & Benazepril:** These are **ACE Inhibitors**. ACE inhibitors prevent the conversion of Angiotensin I to Angiotensin II. Simultaneously, they inhibit the breakdown of bradykinin into inactive peptides [2]. This leads to an accumulation of bradykinin in the lungs and tissues. **3. Clinical Pearls for NEET-PG:** * **The "Cough" Connection:** The accumulation of bradykinin (and substance P) in the lungs is the primary reason why ACE inhibitors cause a **dry, irritating cough** in 5-20% of patients [1]. * **Angioedema:** Increased bradykinin levels are also implicated in the rare but life-threatening side effect of angioedema associated with ACE inhibitors [1]. * **Switching Therapy:** If a patient develops a cough on an ACE inhibitor (like Perindopril), the standard clinical practice is to switch them to an ARB (like Irbesartan), as ARBs are "bradykinin-neutral." * **High-Yield Fact:** ACE is also known as **Kininase II**. Inhibition of this enzyme is what leads to the "Kinin-mediated" side effects of ACE inhibitors [1].

Question 183: All of the following drugs cause tachycardia except?

A. Amphetamine
B. Nifedipine
C. Theophylline
D. Clonidine (Correct Answer)

Explanation: **Explanation:** The correct answer is **Clonidine**. To answer this question, one must distinguish between drugs that stimulate the sympathetic nervous system and those that inhibit it. **1. Why Clonidine is the correct answer:** Clonidine is a **centrally acting $\alpha_2$-adrenergic agonist**. By stimulating presynaptic $\alpha_2$ receptors in the vasomotor center of the medulla, it inhibits the outflow of sympathetic impulses from the brain to the peripheral nervous system. This reduction in sympathetic tone leads to a decrease in heart rate (**bradycardia**) and a fall in blood pressure. **2. Analysis of Incorrect Options:** * **Amphetamine:** It is an indirect-acting sympathomimetic that increases the release of norepinephrine and dopamine. This leads to potent stimulation of $\beta_1$ receptors in the heart, causing **tachycardia**. * **Nifedipine:** As a Dihydropyridine (DHP) Calcium Channel Blocker, it causes significant peripheral vasodilation. This drop in blood pressure triggers a **reflex tachycardia** mediated by the baroreceptor reflex. * **Theophylline:** This methylxanthine acts by inhibiting phosphodiesterase (increasing cAMP) and antagonizing adenosine receptors. Both mechanisms lead to direct cardiac stimulation and **tachycardia**. **3. NEET-PG High-Yield Pearls:** * **Clonidine Withdrawal:** Abrupt cessation can cause a "rebound hypertension" crisis due to a sudden surge in catecholamines. * **Reflex Tachycardia:** Common with vasodilators like Hydralazine, Minoxidil, and DHP-CCBs (Nifedipine). It can be prevented by co-administering Beta-blockers. * **Other drugs causing Bradycardia:** Beta-blockers, Verapamil/Diltiazem (Non-DHP CCBs), Digoxin, and Amiodarone.

Question 184: Which of the following Potassium channel openers is used in the management of angina?

A. Nicorandil (Correct Answer)
B. Hydralazine
C. Fasudil
D. Ranolazine

Explanation: **Explanation:** **Nicorandil** is the correct answer because it possesses a unique dual mechanism of action. It acts as both a **Potassium channel opener ($K_{ATP}$ channels)** and a **Nitrate-like venodilator**. By opening ATP-sensitive $K^+$ channels in the vascular smooth muscle, it causes potassium efflux, leading to hyperpolarization and subsequent vasodilation of the arterioles (reducing afterload). Its nitrate moiety increases cGMP, causing venodilation (reducing preload). This dual action improves coronary blood flow and reduces myocardial oxygen demand, making it effective in stable angina. **Analysis of Incorrect Options:** * **Hydralazine:** While it is a vasodilator, it acts primarily as a direct arteriolar dilator (mechanism involves inhibiting $IP_3$-induced $Ca^{2+}$ release). It is used in hypertension and heart failure, but not as a primary anti-anginal agent due to reflex tachycardia. * **Fasudil:** This is a **Rho-kinase inhibitor**. It is primarily used in the management of cerebral vasospasm following subarachnoid hemorrhage, not for angina. * **Ranolazine:** This is a modern anti-anginal drug, but its mechanism is the **inhibition of the late inward sodium current ($I_{Na}$)** in the myocardium. It does not act on potassium channels. **High-Yield Pearls for NEET-PG:** * **Nicorandil Side Effect:** A highly specific and "favorite" exam question is its association with **painful mucosal ulcerations** (oral, anal, or GI ulcers). * **Preconditioning:** Nicorandil mimics "ischemic preconditioning," providing a cardioprotective effect on the myocardium. * **Other K+ Channel Openers:** Minoxidil and Diazoxide (used in hypertension/insulinoma) also open $K^+$ channels but are not used for angina.

Question 185: Sodium nitroprusside acts by activation of which of the following?

A. Guanylate cyclase (Correct Answer)
B. K+ channels
C. Ca++ channels
D. Cyclic AMP

Explanation: ### Explanation **Correct Option: A. Guanylate cyclase** Sodium nitroprusside (SNP) is a potent, rapid-acting vasodilator. Its mechanism involves the release of **Nitric Oxide (NO)**, either spontaneously or through enzymatic conversion in the vascular smooth muscle. NO then activates the enzyme **soluble guanylate cyclase**, which increases the conversion of GTP to **cyclic GMP (cGMP)**. Elevated cGMP levels lead to dephosphorylation of myosin light chains, resulting in profound relaxation of both arterioles and venules (balanced vasodilator). **Why other options are incorrect:** * **B. K+ channels:** While drugs like Minoxidil, Hydralazine, and Diazoxide act by opening ATP-sensitive K+ channels (causing hyperpolarization), SNP does not primarily target these channels. * **C. Ca++ channels:** Calcium channel blockers (e.g., Nifedipine, Amlodipine) inhibit L-type calcium channels. SNP acts downstream of calcium entry by modulating the contractile apparatus via cGMP. * **D. Cyclic AMP:** Drugs like Dobutamine or Milrinone work via the cAMP pathway. SNP specifically utilizes the cGMP second messenger system. **High-Yield Clinical Pearls for NEET-PG:** * **Balanced Vasodilator:** SNP decreases both **Preload** (venous dilation) and **Afterload** (arterial dilation). * **Clinical Use:** It is the drug of choice for **Hypertensive Emergencies** (though Fenoldopam or Labetalol are often preferred now due to toxicity profiles). * **Toxicity:** SNP contains cyanide groups. Prolonged infusion can lead to **Cyanide poisoning** (treated with Sodium Thiosulfate/Nitrites) and **Thiocyanate toxicity** (presents with psychosis and seizures). * **Light Sensitivity:** SNP is unstable in light; the infusion bottle must be covered with opaque foil.

Question 186: Beta-blockers are contraindicated in which of the following conditions?

A. Decompensated congestive heart failure
B. Asthma
C. Variant angina
D. All of the above (Correct Answer)

Explanation: **Explanation:** Beta-blockers act by antagonizing $\beta_1$, $\beta_2$, and sometimes $\alpha_1$ receptors. While they are cornerstone drugs in chronic stable heart failure, their use is strictly contraindicated in certain acute and specific conditions due to their physiological effects. 1. **Decompensated Congestive Heart Failure (CHF):** In acute decompensation, the heart relies on high sympathetic drive (tachycardia and increased contractility) to maintain cardiac output. Beta-blockers are **negative inotropes**; administering them during this phase can further reduce cardiac output, worsening pulmonary edema and leading to cardiogenic shock. 2. **Asthma:** Non-selective beta-blockers (like Propranolol) block **$\beta_2$ receptors** in the bronchial smooth muscle. This leads to bronchoconstriction and can precipitate a life-threatening asthma attack. Even $\beta_1$-selective blockers should be used with extreme caution. 3. **Variant (Prinzmetal) Angina:** This condition is caused by coronary artery vasospasm. Blocking $\beta_2$ receptors (which mediate vasodilation) leaves **$\alpha_1$ receptors unopposed**, leading to exaggerated vasoconstriction and worsening of the ischemic pain. **High-Yield Clinical Pearls for NEET-PG:** * **Diabetes:** Beta-blockers can mask the warning signs of hypoglycemia (tachycardia/tremors), except for sweating (mediated by cholinergic sympathetic nerves). * **Peripheral Vascular Disease:** They can worsen Raynaud's phenomenon due to unopposed $\alpha$-mediated vasoconstriction. * **Heart Block:** Contraindicated in 2nd or 3rd-degree heart block due to negative dromotropic effects (slowing AV conduction). * **Drug of Choice:** While contraindicated in *acute* failure, **Carvedilol, Metoprolol, and Bisoprolol** are proven to reduce mortality in *chronic* stable heart failure.

Question 187: All of the following drugs are used for the treatment of congestive heart failure except?

A. Nitroglycerine
B. Spironolactone
C. Nesiritide
D. Trimetazidine (Correct Answer)

Explanation: **Explanation:** The goal of treating Congestive Heart Failure (CHF) is to reduce preload, reduce afterload, and improve cardiac remodeling. **Trimetazidine** is the correct answer because it is not indicated for the management of heart failure; rather, it is a **metabolic modulator** used primarily as an add-on therapy for **Stable Angina Pectoris**. It works by inhibiting the enzyme 3-ketoacyl-CoA thiolase (3-KAT), shifting myocardial metabolism from fatty acid oxidation to glucose oxidation, which is more oxygen-efficient during ischemia. **Analysis of Incorrect Options:** * **Nitroglycerine (Option A):** A potent vasodilator (primarily venodilator). In acute heart failure, it reduces **preload** and pulmonary congestion, making it a mainstay for symptomatic relief. * **Spironolactone (Option B):** An Aldosterone Antagonist (MRA). It is a "disease-modifying" drug in CHF (NYHA Class II-IV) that reduces cardiac fibrosis and mortality by blocking the harmful effects of aldosterone. * **Nesiritide (Option C):** A recombinant form of **Brain Natriuretic Peptide (BNP)**. It causes vasodilation and natriuresis, used intravenously in patients with acutely decompensated heart failure to reduce dyspnea. **High-Yield Clinical Pearls for NEET-PG:** * **Drugs reducing mortality in CHF:** ACE inhibitors/ARBs, Beta-blockers (Carvedilol, Metoprolol, Bisoprolol), Spironolactone, and SGLT2 inhibitors (Dapagliflozin). * **Trimetazidine Side Effects:** Can cause **Parkinsonian symptoms** (tremors, rigidity) and should be avoided in patients with Parkinson’s disease. * **Nesiritide** is contraindicated in patients with cardiogenic shock or systolic BP < 90 mmHg.

Question 188: In which of the following conditions are beta-blockers contraindicated?

A. Acute congestive heart failure (Correct Answer)
B. Hypertension
C. Chronic congestive heart failure
D. Arrhythmia

Explanation: ### Explanation **Correct Option: A. Acute Congestive Heart Failure (CHF)** Beta-blockers are contraindicated in **Acute CHF** because they possess **negative inotropic** properties. In an acute decompensated state, the heart relies on sympathetic stimulation (increased heart rate and contractility) to maintain cardiac output. Administering a beta-blocker at this stage can further depress myocardial contractility, leading to a rapid decline in cardiac output, worsening pulmonary edema, and potential cardiogenic shock. **Analysis of Incorrect Options:** * **B. Hypertension:** Beta-blockers (like Atenolol or Metoprolol) are used as second-line agents in hypertension, especially in patients with co-morbidities like post-MI or stable angina. * **C. Chronic CHF:** While contraindicated in *acute* failure, beta-blockers (specifically **Bisoprolol, Carvedilol, and Metoprolol succinate**) are the gold standard for *stable, chronic* heart failure. They prevent cardiac remodeling and reduce mortality by protecting the heart from chronic catecholamine toxicity. * **D. Arrhythmia:** Beta-blockers are Class II anti-arrhythmics. They are the drugs of choice for controlling ventricular rate in atrial fibrillation and managing supraventricular tachycardias (SVT). **High-Yield NEET-PG Pearls:** 1. **The "ABC" of Beta-blockers in Chronic CHF:** Only three are proven to reduce mortality: **A**tenolol is NOT one of them; they are **B**isoprolol, **C**arvedilol, and **M**etoprolol succinate. 2. **Other Absolute Contraindications:** Severe Bradycardia, 2nd or 3rd-degree Heart Block, and **Prinzmetal (Variant) Angina** (due to unopposed alpha-mediated vasoconstriction). 3. **Asthma/COPD:** Non-selective beta-blockers (e.g., Propranolol) are contraindicated due to bronchospasm risk. Use cardioselective ($\beta_1$) blockers if necessary.

Question 189: Which of the following drugs is contraindicated in bilateral renal artery stenosis?

A. Hydralazine
B. Enalapril (Correct Answer)
C. Methyldopa
D. Dopamine

Explanation: **Explanation:** **Correct Option: B. Enalapril** Enalapril is an ACE inhibitor (ACEi). In patients with **bilateral renal artery stenosis (RAS)**, the renal perfusion pressure is significantly reduced. To maintain an adequate Glomerular Filtration Rate (GFR), the kidney relies on the renin-angiotensin-aldosterone system (RAAS). Specifically, **Angiotensin II** causes preferential **vasoconstriction of the efferent arteriole**, which builds up the intraglomerular pressure necessary for filtration. When an ACE inhibitor like Enalapril is administered, it inhibits the production of Angiotensin II, leading to efferent arteriolar vasodilation. This causes a precipitous drop in intraglomerular pressure, resulting in **acute renal failure**. Therefore, ACE inhibitors and ARBs are strictly contraindicated in bilateral RAS (or unilateral RAS in a solitary functioning kidney). **Incorrect Options:** * **A. Hydralazine:** A direct vasodilator primarily used in pregnancy-induced hypertension. It does not interfere with the RAAS-mediated autoregulation of GFR. * **C. Methyldopa:** A centrally acting alpha-2 agonist. It is safe for renal hemodynamics and is a preferred drug in pregnancy. * **D. Dopamine:** At low doses, dopamine causes renal vasodilation (via D1 receptors) and generally increases renal blood flow, rather than causing a drop in GFR. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Clue:** Suspect bilateral RAS if a patient’s serum creatinine rises by **>30%** after starting an ACE inhibitor or ARB. * **Drug of Choice:** Calcium Channel Blockers (CCBs) are generally considered safe for managing hypertension in patients with bilateral RAS. * **Auscultation:** The presence of an abdominal bruit is a classic clinical sign of renal artery stenosis.

Question 190: Which of the following statements about Ivabradine is FALSE?

A. It acts by inhibiting the funny current (If).
B. It is used in the long-term prophylaxis of stable angina.
C. It causes tachycardia. (Correct Answer)
D. It may lead to visual field defects.

Explanation: **Explanation:** **Ivabradine** is a unique heart-rate-lowering agent. The correct answer is **C**, as Ivabradine causes **bradycardia**, not tachycardia. 1. **Why Option C is False:** Ivabradine selectively inhibits the **$I_f$ (funny) current** in the sinoatrial (SA) node. This current is responsible for the spontaneous diastolic depolarization that determines heart rate. By blocking these channels, Ivabradine slows the firing rate of the SA node, leading to a reduction in heart rate (**bradycardia**). It is specifically used when a patient cannot tolerate beta-blockers or when the heart rate remains >70 bpm despite optimal therapy. 2. **Analysis of Other Options:** * **Option A:** This is **true**. Ivabradine is a pure $I_f$ channel blocker. * **Option B:** This is **true**. By reducing the heart rate, it decreases myocardial oxygen demand without affecting contractility or blood pressure, making it effective for the **prophylaxis of stable angina**. * **Option D:** This is **true**. $I_f$ channels are structurally similar to **$I_h$ channels** in the retina. Inhibition of these retinal channels can cause transient luminous phenomena (phosphenes) or blurred vision, which are characteristic side effects. **High-Yield Clinical Pearls for NEET-PG:** * **Indication:** Stable Angina and Chronic Heart Failure (NYHA Class II-IV) with EF ≤35%. * **Requirement:** The patient must be in **Sinus Rhythm** for the drug to work (it is ineffective in Atrial Fibrillation). * **Benefit:** Unlike beta-blockers, it has no effect on ventricular repolarization, myocardial contractility, or airway resistance (safe in asthma). * **Side Effects:** Bradycardia, Phosphenes (visual brightness), and Hypertension.

Practice by Chapter

Antihypertensive Agents

Practice Questions

Drugs for Heart Failure

Practice Questions

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

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Drugs Used in Pulmonary Hypertension

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Drugs Used in Shock

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Cardiovascular Effects of Non-Cardiovascular Drugs

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