Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 631: Which of the following is NOT a contraindication for digitalis therapy?

A. Carditis
B. Increased intracellular calcium (Correct Answer)
C. Atrioventricular block
D. Hepatic failure

Explanation: **Explanation:** Digitalis (Digoxin) works by inhibiting the **Na⁺/K⁺-ATPase pump**, which indirectly leads to an **increase in intracellular calcium** levels. This increase in calcium is the fundamental mechanism responsible for its positive inotropic effect (increased force of contraction). Therefore, increased intracellular calcium is the *intended therapeutic goal*, not a contraindication. **Analysis of Contraindications:** * **Carditis (Option A):** In conditions like acute rheumatic carditis, the myocardium is highly irritable. Digitalis can precipitate severe arrhythmias in an inflamed heart, making it a relative contraindication. * **Atrioventricular (AV) Block (Option C):** Digitalis has potent vagomimetic effects and directly slows conduction through the AV node. In patients with pre-existing heart block, it can worsen the condition, potentially leading to complete heart block. * **Hepatic Failure (Option D):** While Digoxin is primarily excreted renally, **Digitoxin** (another cardiac glycoside) is metabolized by the liver. In the context of general digitalis therapy, hepatic or renal impairment requires extreme caution or avoidance to prevent toxicity due to the drug's narrow therapeutic index. **High-Yield Clinical Pearls for NEET-PG:** * **Hypokalemia** is the most common electrolyte abnormality that predisposes to digitalis toxicity (as K⁺ and Digoxin compete for the same binding site on the Na⁺/K⁺-ATPase pump). * **Hypercalcemia** and **Hypomagnesemia** also increase the risk of digitalis-induced arrhythmias. * **Wolff-Parkinson-White (WPW) Syndrome** is a classic contraindication as digitalis can shorten the refractory period of the accessory pathway, leading to fatal ventricular rates. * **Digibind** (Digoxin-specific antibody fragments) is the antidote for life-threatening toxicity.

Question 632: Niacin should be avoided in patients with which of the following conditions?

A. Peptic ulcer (Correct Answer)
B. Hypertension
C. Alzheimer's disease
D. Parkinsonism

Explanation: **Explanation:** **Niacin (Nicotinic Acid)** is a lipid-lowering agent that inhibits the mobilization of free fatty acids from peripheral adipose tissue. While effective at increasing HDL levels, it has a distinct side-effect profile that dictates its contraindications. **Why Peptic Ulcer is the Correct Answer:** Niacin stimulates the release of **histamine**, which leads to an increase in gastric acid secretion via H2 receptors. This can exacerbate or reactivate a **peptic ulcer**. Therefore, active peptic ulcer disease is a relative contraindication for Niacin therapy. Additionally, Niacin is known to cause significant GI irritation and dyspepsia. **Analysis of Incorrect Options:** * **Hypertension:** Niacin actually causes peripheral vasodilation (mediated by Prostaglandin D2 and E2), which can lead to a slight *decrease* in blood pressure. It is not contraindicated in hypertensive patients. * **Alzheimer’s Disease & Parkinsonism:** Niacin has no known adverse interactions with the pathophysiology or treatment of these neurodegenerative conditions. In fact, some research suggests B-complex vitamins may have a supportive role in neurological health. **High-Yield Clinical Pearls for NEET-PG:** * **Cutaneous Flushing:** The most common side effect, mediated by **Prostaglandins**. It can be prevented by taking **Aspirin** 30 minutes before Niacin. * **Metabolic Effects:** Niacin causes **Hyperuricemia** (can precipitate Gout) and **Hyperglycemia** (should be used cautiously in Diabetics). * **Hepatotoxicity:** It is the most serious side effect, especially with sustained-release formulations. * **Acanthosis Nigricans:** A unique dermatological side effect associated with high-dose Niacin.

Question 633: What is the urgent treatment for procainamide toxicity?

A. Calcium chelation
B. Potassium chloride
C. Nitroprusside
D. Sodium lactate (Correct Answer)

Explanation: **Explanation:** Procainamide is a **Class IA antiarrhythmic** that works by blocking fast sodium channels. Toxicity leads to excessive sodium channel blockade, resulting in a widened QRS complex, prolonged QT interval, and potential induction of Torsades de Pointes or ventricular arrhythmias. **Why Sodium Lactate is the Correct Answer:** The management of Class IA (and Class IC) toxicity mirrors that of Tricyclic Antidepressant (TCA) overdose. **Sodium lactate (or Sodium bicarbonate)** is the treatment of choice because: 1. **Sodium Loading:** It increases the extracellular sodium concentration, which helps overcome the competitive blockade of the sodium channels. 2. **Alkalinization:** Increasing the blood pH decreases the drug's affinity for the sodium channels and reduces the fraction of the ionized (active) drug, thereby mitigating cardiotoxicity. **Analysis of Incorrect Options:** * **A. Calcium chelation:** This would worsen myocardial depression. Calcium gluconate is used in hyperkalemia or calcium channel blocker toxicity, not procainamide overdose. * **B. Potassium chloride:** Class IA drugs already prolong repolarization. Adding potassium can exacerbate the electrophysiological disturbances and increase the risk of heart block. * **C. Nitroprusside:** This is a vasodilator used in hypertensive emergencies. It has no role in reversing sodium channel blockade and could worsen the hypotension often seen in procainamide toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Drug-Induced Lupus Erythematosus (DILE):** Procainamide is the most common cause (associated with **anti-histone antibodies**). * **Metabolite:** Procainamide is metabolized via acetylation to **NAPA** (N-acetylprocainamide), which has Class III properties. * **ECG Marker:** A QRS widening of >50% from baseline is a critical sign of toxicity.

Question 634: Which one of the following provides hemodynamic stability and prolongs survival in congestive heart failure?

A. Lisinopril (Correct Answer)
B. Furosemide
C. Digoxin
D. Milrinone

Explanation: **Explanation** In the management of Congestive Heart Failure (CHF), drugs are classified into two categories: those that provide **symptomatic relief** and those that **prolong survival (decrease mortality)**. **1. Why Lisinopril is Correct:** Lisinopril is an ACE Inhibitor (ACEI). ACEIs are the cornerstone of CHF therapy because they inhibit the Renin-Angiotensin-Aldosterone System (RAAS). By reducing Angiotensin II and Aldosterone levels, they decrease afterload (vasodilation) and preload, which provides hemodynamic stability. Crucially, they prevent and reverse **cardiac remodeling** (pathological structural changes in the heart), which is the primary mechanism by which they **prolong survival** and reduce mortality. **2. Why the other options are Incorrect:** * **Furosemide (Loop Diuretic):** Excellent for rapid symptomatic relief of pulmonary edema and congestion by reducing preload. However, it does **not** improve survival or prevent remodeling. * **Digoxin (Cardiac Glycoside):** Increases contractility (positive inotrope) and controls heart rate in atrial fibrillation. While it reduces the rate of hospitalization, it has a **neutral effect on mortality** (DIG Trial). * **Milrinone (PDE-3 Inhibitor):** An "inodilator" used for acute decompensated heart failure. Long-term use is actually associated with **increased mortality** due to arrhythmias. **High-Yield Clinical Pearls for NEET-PG:** * **Mortality-Reducing Drugs in CHF:** ACEIs/ARBs, Beta-blockers (Carvedilol, Metoprolol succinate, Bisoprolol), Aldosterone Antagonists (Spironolactone), and ARNI (Sacubitril/Valsartan). * **Hydralazine + Isosorbide Dinitrate:** This combination also improves survival, particularly in the African-American population. * **SGLT2 Inhibitors (e.g., Dapagliflozin):** The newest class proven to reduce mortality in both HFrEF and HFpEF.

Question 635: Which of the following beta-blockers possesses intrinsic sympathomimetic properties?

A. Propranolol
B. Oxprenolol (Correct Answer)
C. Practolol
D. Esmolol

Explanation: **Explanation:** **1. Understanding the Correct Answer: Oxprenolol** Beta-blockers with **Intrinsic Sympathomimetic Activity (ISA)**, also known as partial agonists, have the unique ability to stimulate beta-receptors weakly while simultaneously blocking the effects of more potent endogenous catecholamines (like adrenaline). **Oxprenolol**, along with Pindolol, is a classic example of a non-selective beta-blocker with ISA. These drugs cause less resting bradycardia and less coldness of extremities compared to pure antagonists, making them useful in patients who cannot tolerate profound decreases in heart rate. **2. Analysis of Incorrect Options:** * **A. Propranolol:** This is the prototype non-selective beta-blocker. It is a **pure antagonist** and lacks ISA. It is highly lipid-soluble and possesses significant membrane-stabilizing activity (MSA). * **C. Practolol:** While Practolol does possess ISA and was the first cardioselective beta-blocker, it is **no longer used clinically** due to serious adverse effects, specifically "oculo-muco-cutaneous syndrome." In the context of standard pharmacology exams, Oxprenolol or Pindolol are the preferred answers for ISA. * **D. Esmolol:** This is an ultra-short-acting, cardioselective ($\beta_1$) blocker with no ISA. It is metabolized by RBC esterases and is used intravenously for emergency situations like aortic dissection or supraventricular tachycardia. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for ISA:** "**P**alpitation **P**revented by **O**xprenolol and **P**indolol" (**P**indolol, **P**enbutolol, **O**xprenolol, **P**ractolol). * **Clinical Advantage:** Beta-blockers with ISA are preferred in patients with **bradycardia** or those prone to **bronchospasm**, as they cause less "rebound" bronchoconstriction. * **Contraindication:** They are generally avoided in post-myocardial infarction (MI) patients and stable angina because they do not reduce the resting heart rate sufficiently to decrease myocardial oxygen demand effectively.

Question 636: Which of the following is NOT an antiplatelet drug?

A. Aspirin
B. Clopidogrel
C. Dipyridamole
D. Warfarin (Correct Answer)

Explanation: ### Explanation The key to answering this question lies in distinguishing between **antiplatelet drugs** (which inhibit platelet aggregation) and **anticoagulants** (which inhibit the coagulation cascade). **1. Why Warfarin is the correct answer:** Warfarin is an **anticoagulant**, not an antiplatelet drug. It acts as a **Vitamin K antagonist**, inhibiting the enzyme Vitamin K Epoxide Reductase (VKOR). This prevents the γ-carboxylation of Vitamin K-dependent clotting factors (**II, VII, IX, and X**) and proteins C and S. It is primarily used to prevent venous thromboembolism and systemic embolism in patients with prosthetic valves or atrial fibrillation. **2. Why the other options are incorrect:** * **Aspirin:** An irreversible inhibitor of **COX-1**, preventing the synthesis of Thromboxane A2 (TXA2), a potent platelet aggregator. * **Clopidogrel:** A P2Y12 receptor antagonist. It prevents ADP from binding to its receptor on platelets, thereby inhibiting the activation of the GPIIb/IIIa complex. * **Dipyridamole:** A phosphodiesterase (PDE) inhibitor that increases cAMP levels within platelets, leading to the inhibition of platelet aggregation. It also has vasodilator properties. **3. NEET-PG High-Yield Pearls:** * **Monitoring:** Warfarin is monitored using **PT/INR**, whereas Heparin is monitored using **aPTT**. * **Teratogenicity:** Warfarin is contraindicated in pregnancy (causes **Fetal Warfarin Syndrome**); Heparin is the anticoagulant of choice. * **Resistance:** Clopidogrel is a prodrug activated by **CYP2C19**. Genetic polymorphisms or drugs like Omeprazole can reduce its efficacy. * **Abciximab:** Remember that this is a GPIIb/IIIa antagonist, often tested as the "final common pathway" inhibitor of platelet aggregation.

Question 637: Which of the following enzymes metabolizes nitrates to produce nitric oxide (NO)?

A. Alcohol dehydrogenase
B. Nitrate reductase
C. Aldehyde dehydrogenase (Correct Answer)
D. Phosphodiesterase-5

Explanation: **Explanation:** The correct answer is **C. Aldehyde dehydrogenase (ALDH-2)**. **Mechanism of Action:** Nitrates (specifically Organic Nitrates like Nitroglycerin/GTN) are prodrugs. To exert their vasodilatory effect, they must undergo bioactivation to release **Nitric Oxide (NO)**. This process occurs primarily in the mitochondria of vascular smooth muscle cells. The enzyme **Mitochondrial Aldehyde Dehydrogenase (ALDH-2)** catalyzes the reduction of nitroglycerin into inorganic nitrite and a denitrated metabolite, eventually releasing NO. NO then activates **Guanylyl Cyclase**, increasing cGMP levels, which leads to dephosphorylation of myosin light chains and subsequent vasodilation. **Analysis of Incorrect Options:** * **A. Alcohol dehydrogenase:** While involved in ethanol metabolism, it does not play a significant role in the bioactivation of organic nitrates. * **B. Nitrate reductase:** This enzyme is primarily found in bacteria and plants; it is not the primary human enzyme responsible for the clinical bioactivation of GTN. * **C. Phosphodiesterase-5 (PDE-5):** This enzyme *breaks down* cGMP. Inhibitors like Sildenafil prevent this breakdown. PDE-5 does not produce NO; rather, it regulates the second messenger produced downstream of NO action. **High-Yield Clinical Pearls for NEET-PG:** * **Nitrate Tolerance:** Continuous use of nitrates leads to a "tachyphylaxis" or tolerance. One major mechanism is the **oxidative inhibition of ALDH-2**, which prevents the activation of the drug. * **Nitrate-Free Interval:** To prevent tolerance, a nitrate-free period of 8–12 hours (usually at night) is recommended. * **Drug Interaction:** Nitrates are strictly contraindicated with **PDE-5 inhibitors** (Sildenafil) as the combination causes a synergistic increase in cGMP, leading to life-threatening hypotension. * **Isosorbide Mononitrate:** Unlike GTN, it has 100% bioavailability and does not undergo significant first-pass metabolism.

Question 638: What is the drug of choice to control supraventricular tachycardia?

A. Adenosine (Correct Answer)
B. Propranolol
C. Verapamil
D. Digoxin

Explanation: **Explanation:** **Adenosine** is the drug of choice (DOC) for the acute termination of Paroxysmal Supraventricular Tachycardia (PSVT), including cases involving accessory pathways (WPW syndrome). **Why Adenosine is the Correct Answer:** Adenosine acts on **A1 receptors** in the AV node, causing activation of Ach-sensitive inward rectifier $K^+$ channels and inhibition of $Ca^{2+}$ current. This results in profound hyperpolarization and a transient "chemical cardioversion" (AV block). Its primary advantages are its **ultra-short half-life (<10 seconds)** and rapid onset, allowing for quick termination of the arrhythmia with minimal prolonged systemic side effects. **Analysis of Incorrect Options:** * **Verapamil (Option C):** A Calcium Channel Blocker that was previously the DOC. While effective, it has a longer half-life and carries a higher risk of causing hypotension and negative inotropy compared to Adenosine. * **Propranolol (Option B):** A Beta-blocker used for rate control in chronic SVT or atrial fibrillation, but it is not the first-line agent for acute conversion of PSVT. * **Digoxin (Option D):** Primarily used for rate control in atrial fibrillation (especially in heart failure patients). It has a very slow onset of action, making it unsuitable for acute emergency management. **High-Yield Clinical Pearls for NEET-PG:** * **Administration:** Must be given as a **rapid IV bolus** followed by a saline flush due to its short half-life. * **Side Effects:** Patients often experience transient chest pain, dyspnea, and a sense of "impending doom." * **Contraindications:** Avoid in **Asthmatics** (can cause bronchospasm via A2B receptors) and high-grade heart block. * **Interactions:** Its effects are antagonized by **Theophylline/Caffeine** (adenosine receptor blockers) and potentiated by **Dipyridamole**.

Question 639: A patient presents to the emergency department following a drug overdose, exhibiting severe tachycardia. The patient was previously on therapy for hypertension and angina. Which of the following medications can cause tachycardia?

A. Guanethidine
B. Isosorbide dinitrate (Correct Answer)
C. Propranolol
D. Verapamil

Explanation: The correct answer is **Isosorbide dinitrate (Option B)**. **Mechanism of Action:** Isosorbide dinitrate is a nitrate that acts as a potent vasodilator. It primarily causes venodilation (reducing preload) and, at higher doses, arterial dilation (reducing afterload) [1]. This sudden drop in systemic blood pressure triggers a **baroreceptor-mediated reflex increase in sympathetic outflow**, leading to **reflex tachycardia** [3]. This is a classic compensatory mechanism seen with rapidly acting vasodilators. **Analysis of Incorrect Options:** * **Guanethidine (A):** This is an adrenergic neuron blocker that inhibits the release of norepinephrine. It typically causes bradycardia and orthostatic hypotension, not tachycardia. * **Propranolol (C):** A non-selective beta-blocker ($ \beta_1$ and $\beta_2$). By blocking $\beta_1$ receptors in the heart, it decreases the heart rate (**bradycardia**) and myocardial contractility [4]. * **Verapamil (D):** A non-dihydropyridine calcium channel blocker (CCB) with significant negative chronotropic and inotropic effects. It acts directly on the SA and AV nodes to cause **bradycardia**; its interaction with beta-blockers can further worsen this effect [4]. **High-Yield NEET-PG Pearls:** * **Reflex Tachycardia:** Common with Nitrates, Hydralazine, and Dihydropyridine CCBs (e.g., Nifedipine) [1], [2]. * **Clinical Correlation:** To prevent reflex tachycardia and "steal phenomenon," nitrates are often co-administered with beta-blockers (like Propranolol) in angina patients. * **Contraindication:** Avoid using Nitrates in patients taking Sildenafil (PDE-5 inhibitors) due to the risk of life-threatening hypotension [1]. * **Drug of Choice:** For nitrate-induced tachycardia, the drug of choice is a beta-blocker.

Question 640: Which drug decreases lipoprotein (a)?

A. Fibrates
B. Niacin (Correct Answer)
C. Statins
D. All of the above

Explanation: ### Explanation **Correct Answer: B. Niacin** **Mechanism and Rationale:** Lipoprotein (a) [Lp(a)] is a low-density lipoprotein-like particle that is genetically determined and considered an independent risk factor for atherosclerotic cardiovascular disease (ASCVD). **Niacin (Nicotinic acid/Vitamin B3)** is the most potent agent among traditional lipid-lowering drugs for reducing Lp(a) levels, typically decreasing it by 20–30%. It achieves this by inhibiting the synthesis of apolipoprotein (a) in the liver and reducing the assembly of Lp(a) particles. **Analysis of Other Options:** * **A. Fibrates:** These primarily target triglycerides by activating PPAR-α. While they significantly lower VLDL and increase HDL, they have **no significant effect** on Lp(a) levels. * **C. Statins:** These are the first-line drugs for LDL reduction via HMG-CoA reductase inhibition. Interestingly, statins have **no effect or may even slightly increase** Lp(a) levels in some patients. * **D. All of the above:** Incorrect, as only Niacin significantly lowers Lp(a) among the listed options. **High-Yield Clinical Pearls for NEET-PG:** * **Lp(a) Significance:** It is structurally similar to plasminogen but lacks fibrinolytic activity; thus, it is both **pro-atherogenic and pro-thrombotic**. * **Niacin Side Effects:** The most common side effect is **cutaneous flushing** (mediated by Prostaglandin D2/E2; prevented by Aspirin). It can also cause hyperuricemia (gout) and hyperglycemia. * **Newer Agents:** While Niacin is the traditional answer, **PCSK9 inhibitors** (e.g., Evolocumab, Alirocumab) also significantly decrease Lp(a) levels. * **Most Potent Drugs:** Niacin is the most effective drug for increasing HDL, while Statins are most effective for decreasing LDL, and Fibrates are most effective for decreasing Triglycerides.

Practice by Chapter

Antihypertensive Agents

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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

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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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