Cardiovascular Drugs Practice Questions

Q: Which of the following drugs hyperpolarizes AV nodal tissue, is used in PSVT, and has short-lasting adverse effects?

Adenosine. ### Explanation **Correct Answer: C. Adenosine** **Mechanism and Rationale:** Adenosine is the drug of choice for the acute termination of Paroxysmal Supraventricular Tachycardia (PSVT). It acts by binding to **A1 receptors** on the AV node, which activates G protein-coupled inward-rectifying potassium channels (GIRK). This leads to an **efflux of Potassium (K+)**, causing **hyperpolarization** of the nodal tissue. Simultaneously, it decreases cAMP, inhibiting Calcium (Ca2+) influx. The result is a transient but potent suppression of AV nodal conduction, "resetting" the rhythm. **Why the other options are incorrect:** * **Verapamil (CCB):** While used for PSVT, it works by blocking L-type Calcium channels (decreasing the slope of Phase 0). It does not cause hyperpolarization and has a much longer half-life (hours) compared to Adenosine. * **Digoxin:** It increases vagal tone to slow the AV node but is primarily used for rate control in Atrial Fibrillation. It does not cause hyperpolarization; rather, it can increase intracellular Calcium. * **Propranolol (Beta-blocker):** It slows the heart rate by decreasing the Phase 4 depolarization slope in the SA node. It is used for prophylaxis rather than acute termination of PSVT and lacks the rapid "on-off" effect of Adenosine. **High-Yield Facts for NEET-PG:** * **Ultra-short half-life:** <10 seconds (due to rapid uptake by RBCs and endothelial cells). * **Administration:** Must be given as a **rapid IV bolus** followed by a saline flush, preferably through a central or large peripheral vein. * **Adverse Effects:** Flushing, chest pain, and dyspnea. These are distressing but **short-lasting** (seconds). * **Drug Interactions:** Effects are **potentiated by Dipyridamole** and **antagonized by Theophylline/Caffeine** (adenosine receptor blockers). * **Contraindication:** Bronchial asthma (can cause bronchospasm) and high-grade heart block.

Q: Digoxin increases cardiac contractility by directly engaging in which of the following mechanisms?

Inhibiting myocardial Na+/K+-ATPase. **Explanation:** Digoxin, a cardiac glycoside, increases cardiac contractility (positive inotropy) through a well-defined sequence of ionic shifts. **Mechanism of Action (Why D is correct):** The primary molecular target of Digoxin is the **Na+/K+-ATPase pump** located on the sarcolemma of myocardial cells. By binding to the extracellular alpha subunit of this pump, Digoxin inhibits the active transport of Na+ out of the cell and K+ into the cell. This leads to an **increase in intracellular Na+**. The rise in intracellular Na+ reduces the concentration gradient that drives the **Na+/Ca2+ exchanger (NCX)**. Consequently, the efflux of Ca2+ is diminished, leading to increased intracellular Ca2+ levels. This excess Ca2+ is sequestered into the Sarcoplasmic Reticulum (SR) and released during subsequent action potentials, enhancing actin-myosin cross-bridge formation and force of contraction. **Analysis of Incorrect Options:** * **A. Inhibiting myocardial Na+/Ca2+-ATPase:** There is no such enzyme as Na+/Ca2+-ATPase; the Na+/Ca2+ exchanger (NCX) is a secondary active transporter, not a primary ATPase. * **B. Activating L-type Ca2+ channels:** This is the mechanism for drugs like Bay K 8644. Digoxin does not directly act on these channels. * **C. Inhibiting cardiac phosphodiesterase:** This is the mechanism of **Milrinone and Inamrinone**, which increase cAMP levels to improve contractility. **High-Yield NEET-PG Pearls:** * **ECG Changes:** Digoxin causes the characteristic "reverse tick" or "hockey stick" ST-segment depression (Salvador Dali sign). * **Electrolyte Interactions:** **Hypokalemia** predisposes to Digoxin toxicity because K+ and Digoxin compete for the same binding site on the Na+/K+-ATPase pump. * **Antidote:** Digibind (Digoxin-specific Fab fragments). * **Therapeutic Range:** Narrow (0.5–2 ng/mL). Toxicity often presents with gastrointestinal symptoms and xanthopsia (yellow-green vision).

Q: Cardioselective beta blockers are contraindicated in which of the following conditions?

II & III degree heart block. **Explanation:** The core pharmacological action of beta-blockers involves the inhibition of $\beta_1$ receptors in the heart, leading to negative inotropic (force), chronotropic (rate), and dromotropic (conduction velocity) effects. **Why Option B is Correct:** In **II and III-degree heart blocks**, the conduction of impulses from the atria to the ventricles is already impaired. Beta-blockers further depress the **Atrioventricular (AV) node** conduction. This can exacerbate the block, potentially leading to complete heart block, severe bradycardia, or asystole. Therefore, they are strictly contraindicated regardless of their selectivity. **Why Other Options are Incorrect:** * **A & C (COPD and Asthma):** While *non-selective* beta-blockers are contraindicated due to $\beta_2$ blockade causing bronchospasm, **cardioselective** ($\beta_1$ specific) blockers (e.g., Metoprolol, Atenolol) can be used with extreme caution in stable COPD or mild asthma if the cardiac benefit outweighs the risk. They are not an absolute contraindication compared to heart block. * **D (Tachycardia):** Beta-blockers are actually a **treatment** for tachycardia (especially sinus tachycardia and supraventricular arrhythmias) because they reduce the heart rate. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Cardioselective ($\beta_1$) blockers:** *"New Beta Blockers Are Very Exclusive"* (Nebivolol, Betaxolol, Bisoprolol, Acebutolol, Atenolol, Valolol, Esmolol, Metoprolol). * **Esmolol** is the shortest-acting beta-blocker (half-life ~9 mins), used IV for hypertensive emergencies. * **Absolute Contraindications:** Severe bradycardia, cardiogenic shock, overt heart failure, and advanced heart block. * **Prinzmetal Angina:** Beta-blockers are contraindicated as they can cause unopposed alpha-mediated coronary vasoconstriction.

Q: Which of the following antihypertensives was once used as an antipsychotic?

Reserpine. **Explanation:** **Reserpine** is the correct answer. It is an alkaloid derived from the plant *Rauwolfia serpentina*. * **Mechanism:** Reserpine irreversibly blocks the **Vesicular Monoamine Transporter (VMAT)**. This prevents the storage of neurotransmitters like norepinephrine, dopamine, and serotonin in synaptic vesicles, leading to their depletion. * **Clinical Use:** By depleting norepinephrine, it acts as an antihypertensive. By depleting dopamine and serotonin in the CNS, it was historically used as an **antipsychotic** to treat schizophrenia. However, its use is now obsolete due to the severe side effect of **suicidal depression**. **Incorrect Options:** * **Atenolol:** A selective $\beta_1$ blocker. It is hydrophilic, does not cross the blood-brain barrier effectively, and has no antipsychotic properties. * **Propranolol:** A non-selective $\beta$ blocker. While it is lipophilic and used for performance anxiety, essential tremors, and prophylaxis of migraine, it has never been used as an antipsychotic. * **Clonidine:** An $\alpha_2$ agonist that decreases sympathetic outflow. It is used in ADHD and opioid withdrawal but lacks antipsychotic efficacy. **High-Yield Pearls for NEET-PG:** 1. **Reserpine-induced Depression:** The observation that reserpine caused depression led to the "Monoamine Hypothesis" of depression. 2. **VMAT Inhibition:** Unlike Cocaine or TCAs (which act on reuptake transporters like NET/DAT), Reserpine acts on the **vesicular** transporter. 3. **Contraindication:** Never give reserpine to a patient with a history of mental depression or peptic ulcer disease (as it increases gastric acid secretion).

Q: Which one of the following drugs is associated with the development of a lupus-like syndrome, especially in patients identified as "slow acetylators"?

Procainamide. ### Explanation **Correct Option: D. Procainamide** Procainamide is a Class IA antiarrhythmic drug notorious for causing **Drug-Induced Lupus Erythematosus (DILE)**. The underlying mechanism involves its metabolism via the **N-acetyltransferase (NAT)** enzyme. In the liver, procainamide is acetylated to N-acetylprocainamide (NAPA). Patients who are **"slow acetylators"** have a genetic deficiency of this enzyme, leading to the accumulation of the parent drug. This excess drug undergoes alternative oxidative metabolism, forming reactive metabolites that trigger an autoimmune response, typically manifesting as joint pain, fever, and pleuritis. **Analysis of Incorrect Options:** * **A. Amiodarone:** Known for causing pulmonary fibrosis, thyroid dysfunction (hypo/hyperthyroidism), and corneal microdeposits, but not a lupus-like syndrome. * **B. Clonidine:** An alpha-2 agonist used for hypertension; its primary side effects include sedation, dry mouth, and rebound hypertension upon abrupt withdrawal. * **C. Nitroglycerin:** A vasodilator used in angina; common side effects include throbbing headache, flushing, and orthostatic hypotension. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for DILE drugs:** "**S**hip **H**as **P**ushed **M**e" (**S**ulfonamides, **H**ydralazine, **I**soniazid, **P**rocainamide, **P**henytoin, **M**ethyldopa). * **Serology:** DILE is characterized by the presence of **Anti-Histone Antibodies** (95% sensitivity). Unlike systemic lupus (SLE), Anti-dsDNA antibodies are usually absent. * **Prognosis:** Symptoms typically resolve upon discontinuation of the offending drug. * **Procainamide specific:** It has the highest risk of inducing ANA (Antinuclear Antibody) positivity, occurring in up to 80% of patients over time.

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

Irbesartan. 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].

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

All of the above. **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.

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

Acute congestive heart failure. ### 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.

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

Enalapril. **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.

Q: Which of the following statements about Ivabradine is FALSE?

It causes tachycardia.. **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.

Question 1

Which of the following drugs hyperpolarizes AV nodal tissue, is used in PSVT, and has short-lasting adverse effects?

Accepted Answer

Adenosine

Answer

Verapamil

Answer

Digoxin

Answer

Propranolol

Question 2

Digoxin increases cardiac contractility by directly engaging in which of the following mechanisms?

Accepted Answer

Inhibiting myocardial Na+/K+-ATPase

Answer

Inhibiting myocardial Na+/Ca2+-ATPase

Answer

Activating L-type Ca2+ channels

Answer

Inhibiting cardiac phosphodiesterase

Question 3

Cardioselective beta blockers are contraindicated in which of the following conditions?

Accepted Answer

II & III degree heart block

Answer

COPD

Answer

Asthma

Answer

Tachycardia

Question 4

Which of the following antihypertensives was once used as an antipsychotic?

Accepted Answer

Reserpine

Answer

Atenolol

Answer

Propranolol

Answer

Clonidine

Question 5

Which one of the following drugs is associated with the development of a lupus-like syndrome, especially in patients identified as "slow acetylators"?

Accepted Answer

Procainamide

Answer

Amiodarone

Answer

Clonidine

Answer

Nitroglycerin

Question 6

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

Accepted Answer

Irbesartan

Answer

Perindopril

Answer

Benzprindopril

Answer

All of the above

Question 7

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

Accepted Answer

All of the above

Answer

Decompensated congestive heart failure

Answer

Asthma

Answer

Variant angina

Question 8

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

Accepted Answer

Acute congestive heart failure

Answer

Hypertension

Answer

Chronic congestive heart failure

Answer

Arrhythmia

Question 9

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

Accepted Answer

Enalapril

Answer

Hydralazine

Answer

Methyldopa

Answer

Dopamine

Question 10

Which of the following statements about Ivabradine is FALSE?

Accepted Answer

It causes tachycardia.

Answer

It acts by inhibiting the funny current (If).

Answer

It is used in the long-term prophylaxis of stable angina.

Answer

It may lead to visual field defects.

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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