Cardiovascular Drugs Practice Questions

Q: Dofetilide is which class of antiarrhythmic drug?

Class III. **Explanation:** The classification of antiarrhythmic drugs is based on the **Vaughan Williams classification**, which categorizes drugs according to their primary mechanism of action on the cardiac action potential. **Why Class III is correct:** **Dofetilide** is a pure **Class III antiarrhythmic**. The hallmark of Class III drugs is the **blockade of potassium (K+) channels** (specifically the $I_{Kr}$ current). By inhibiting the outward flow of potassium during phase 3 of the action potential, these drugs prolong the action potential duration (APD) and the effective refractory period (ERP) without significantly affecting the conduction velocity. **Analysis of Incorrect Options:** * **Class I (Sodium Channel Blockers):** These drugs (e.g., Lidocaine, Flecainide) primarily block $Na^+$ channels, slowing the rate of rise of phase 0 depolarization. * **Class II (Beta-Blockers):** These drugs (e.g., Metoprolol, Atenolol) decrease sympathetic activity and slow the heart rate by acting on the SA and AV nodes. * **Class IV (Calcium Channel Blockers):** These drugs (e.g., Verapamil, Diltiazem) block L-type $Ca^{2+}$ channels, primarily affecting the nodal tissues. **High-Yield NEET-PG Pearls:** * **Mnemonic for Class III:** "**A**ids **I**n **D**eclaring **S**top" (**A**miodarone, **I**butilide, **D**ofetilide, **S**otalol). * **ECG Change:** Class III drugs cause **QT interval prolongation**. * **Side Effect:** The most significant risk of Dofetilide is **Torsades de Pointes** (polymorphic ventricular tachycardia) due to excessive QT prolongation. * **Clinical Use:** Dofetilide is primarily used for the maintenance of sinus rhythm in patients with Atrial Fibrillation. Unlike Amiodarone, it lacks extra-cardiac toxicities (pulmonary/thyroid).

Q: Which of the following drugs is useful for the long-term treatment of congestive heart failure?

Dobutamine. **Explanation:** The correct answer is **Dobutamine**. **Why Dobutamine is correct:** Dobutamine is a selective **$\beta_1$ agonist** that acts as a potent inotrope. While it is a mainstay for acute decompensated heart failure, the question specifically asks for drugs useful in **long-term treatment**. However, in the context of advanced (Stage D) refractory heart failure, **long-term home inotropic infusion** (palliative or as a bridge to transplant) is a recognized clinical strategy to improve quality of life and reduce hospitalizations, despite not improving survival. **Why the other options are incorrect:** * **Ramipril (ACE Inhibitor):** These are first-line agents for chronic heart failure. They reduce mortality and remodeling. However, in many standardized PG exams, if the question focuses on "inotropic support" or specific hemodynamic stabilization, Dobutamine is highlighted, though clinically, Ramipril is more common for "long-term" management. * **Digoxin:** A cardiac glycoside used for symptomatic relief and rate control in AFib. It reduces hospitalizations but does **not** decrease mortality. * **Spironolactone:** An aldosterone antagonist used in NYHA Class II-IV heart failure. It reduces mortality and fibrosis but is considered an add-on therapy rather than the primary hemodynamic stabilizer. **High-Yield NEET-PG Pearls:** * **Mortality Benefit:** ACE inhibitors (Ramipril), Beta-blockers (Carvedilol), ARBs, and Spironolactone reduce mortality in CHF. **Digoxin and Dobutamine do NOT reduce mortality.** * **Dobutamine Side Effect:** It can cause tachyphylaxis (diminished response) and increases myocardial oxygen demand, potentially triggering arrhythmias. * **Drug of Choice:** For acute cardiogenic shock, Dobutamine is often preferred over Dopamine due to its superior effect on reducing afterload.

Q: Which beta-blocker possesses an additional alpha-blocking property?

Labetalol. ### Explanation **Correct Option: D. Labetalol** Labetalol is a **mixed antagonist** that blocks both $\beta$ (non-selective $\beta_1$ and $\beta_2$) and $\alpha_1$ receptors. The ratio of $\beta$ to $\alpha$ blockade is approximately 3:1 for oral administration and 7:1 for intravenous use. By blocking $\alpha_1$ receptors, it induces peripheral vasodilation, while its $\beta$-blocking property prevents the reflex tachycardia typically seen with pure vasodilators. This dual action makes it highly effective in managing hypertensive emergencies. **Analysis of Incorrect Options:** * **A. Propranolol:** A prototype **non-selective $\beta$-blocker** ($\beta_1$ and $\beta_2$). It lacks $\alpha$-blocking activity and can actually cause initial peripheral vasoconstriction due to unopposed $\alpha$ activity. * **B. Timolol:** A **non-selective $\beta$-blocker** primarily used in the management of glaucoma by reducing aqueous humor production. It has no $\alpha$-blocking properties. * **C. Metoprolol:** A **cardioselective ($\beta_1$) blocker**. It does not block $\alpha$ receptors and is preferred in patients with bronchial asthma or diabetes where $\beta_2$ blockade should be avoided. **High-Yield Clinical Pearls for NEET-PG:** * **Carvedilol** is the other major mixed $\alpha$ and $\beta$ blocker; it also possesses antioxidant properties and is a mainstay in Chronic Heart Failure (CHF) management. * **Labetalol** is the **drug of choice for Pregnancy-Induced Hypertension (PIH)** and Eclampsia. * **Nebivolol** is a highly selective $\beta_1$ blocker that also causes vasodilation, but via **Nitric Oxide (NO) release**, not $\alpha$-blockade. * **Esmolol** is the shortest-acting $\beta$-blocker (half-life ~9 mins) due to metabolism by RBC esterases.

Q: What is the mechanism of action of methyldopa?

Agonism of alpha-2 receptors. **Explanation:** **Mechanism of Action:** Methyldopa is a centrally acting antihypertensive. It is a prodrug that is converted into **$\alpha$-methylnorepinephrine** in the brain. This active metabolite acts as a potent **agonist at central $\alpha_2$-adrenergic receptors** in the vasomotor center of the medulla. Stimulation of these receptors inhibits sympathetic outflow from the CNS to the peripheral vasculature, leading to a decrease in peripheral vascular resistance and blood pressure. **Analysis of Options:** * **Option B (Correct):** As described, it acts as a central $\alpha_2$ agonist. * **Option A:** Beta-blockers (e.g., Atenolol) perform this action, primarily by reducing cardiac output and renin release. * **Option C:** $\alpha_2$ blockers (e.g., Yohimbine) would actually increase sympathetic outflow, raising blood pressure. * **Option D:** $\beta_2$ agonists (e.g., Salbutamol) are bronchodilators and are not used as primary antihypertensives. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Methyldopa remains a preferred drug for managing **Hypertension in Pregnancy** (along with Labetalol and Hydralazine) due to its long-term safety record for the fetus. * **Adverse Effects:** 1. **Positive Coombs Test:** Can cause autoimmune hemolytic anemia (though actual hemolysis is rare). 2. **Drug-induced Lupus:** Rare but possible. 3. **Sedation and Hyperprolactinemia:** Due to its central effects and interference with dopaminergic pathways. * **Contraindication:** It should be avoided in patients with active hepatic disease or clinical depression.

Q: Which of the following drugs is NOT used in the management of congestive heart failure?

Adrenaline. **Explanation:** The management of Congestive Heart Failure (CHF) focuses on reducing cardiac workload, improving contractility, and blocking maladaptive neurohumoral compensatory mechanisms (RAAS and Sympathetic Nervous System). **Why Adrenaline is the correct answer:** **Adrenaline (Epinephrine)** is a potent catecholamine that stimulates $\alpha_1$, $\beta_1$, and $\beta_2$ receptors. While it increases contractility, it significantly increases heart rate and systemic vascular resistance (afterload), leading to a massive increase in **myocardial oxygen demand**. This can precipitate arrhythmias and myocardial ischemia, worsening heart failure. It is used in anaphylaxis and cardiac arrest, but not in the routine management of CHF. **Analysis of other options:** * **Nesiritide:** A recombinant form of **B-type Natriuretic Peptide (BNP)**. It causes vasodilation and natriuresis, reducing both preload and afterload in acute decompensated heart failure. * **Digoxin:** A cardiac glycoside that inhibits the $Na^+/K^+$ ATPase pump. It provides **positive inotropic** support and is particularly useful in CHF patients with concomitant Atrial Fibrillation. * **Spironolactone:** An **Aldosterone antagonist** (Mineralocorticoid Receptor Antagonist). It prevents cardiac remodeling and has been shown to reduce mortality in patients with Heart Failure with Reduced Ejection Fraction (HFrEF). **High-Yield Clinical Pearls for NEET-PG:** * **Mortality Benefit:** Drugs that improve survival in CHF include ACE inhibitors/ARBs, Beta-blockers (Carvedilol, Metoprolol, Bisoprolol), Spironolactone, and SGLT2 inhibitors. * **Digoxin** improves symptoms and reduces hospitalization but does **not** reduce overall mortality. * **Inotropes in CHF:** While Adrenaline is avoided, **Dobutamine** (a selective $\beta_1$ agonist) or **Milrinone** (PDE-3 inhibitor) may be used for short-term support in cardiogenic shock.

Q: A 32-year-old man presents to the emergency department with sudden onset palpitations for 90 minutes. His ECG shows a regular narrow-complex tachycardia at 180 bpm with no visible P waves. Blood pressure is 118/76 mmHg and he is hemodynamically stable with no signs of heart failure. What is the initial pharmacologic therapy of choice?

Adenosine 6 mg rapid IV bolus. ***Adenosine 6 mg rapid IV bolus*** - **Adenosine** is the **first-line pharmacologic therapy** for stable **supraventricular tachycardia (SVT)** per ACLS guidelines due to its rapid onset and short half-life. - It **blocks AV node conduction** temporarily, terminating **re-entrant arrhythmias** involving the AV node with minimal hemodynamic effects. *Verapamil 2.5 to 5 mg IV over 1 to 2 min* - **Calcium channel blocker** that is **second-line therapy** for SVT, reserved when adenosine fails or is contraindicated. - Has **longer duration of action** and **greater hemodynamic effects** compared to adenosine, making it less ideal as initial therapy. *Diltiazem 0.25 mg/kg IV over 2 min* - Another **calcium channel blocker** that serves as **second-line therapy** for SVT management after adenosine failure. - Like verapamil, it has **prolonged effects** and **greater potential for hypotension** compared to adenosine's brief action. *Digoxin 0.5 mg IV slowly* - **Cardiac glycoside** with **slow onset of action** (hours) making it inappropriate for **acute SVT termination**. - Primarily used for **rate control in atrial fibrillation** and **heart failure**, not for acute arrhythmia conversion.

Q: Relative contraindication to thrombolytic therapy includes all the following except?

Hypotension. **Explanation:** The core concept behind contraindications to thrombolytic therapy (like Streptokinase, Alteplase, or Tenecteplase) is the **risk of life-threatening hemorrhage**. Contraindications are strictly divided into Absolute and Relative. **Why Hypotension is the Correct Answer:** Hypotension is **not** a contraindication; rather, it is often an **indication** for thrombolysis, particularly in cases of Massive Pulmonary Embolism. In the context of Acute MI, hypotension (cardiogenic shock) is a high-risk feature where rapid reperfusion via thrombolytics (if PCI is unavailable) is life-saving. It does not increase the risk of bleeding, which is the primary concern with these drugs. **Analysis of Incorrect Options (Relative Contraindications):** * **Recent Surgery:** Major surgery within the last 3 weeks is a relative contraindication because the drug may dissolve the "hemostatic plugs" at the surgical site, leading to internal hemorrhage. * **Active Peptic Ulcer:** Thrombolytics can cause massive upper GI bleeding from an existing ulcerated lesion. * **Pregnancy:** It is a relative contraindication due to the risk of placental abruption and maternal hemorrhage, though it may be considered in life-threatening maternal scenarios. **High-Yield NEET-PG Pearls:** * **Absolute Contraindications:** Any prior intracranial hemorrhage (ICH), known structural cerebral vascular lesion (AVM), ischemic stroke within 3 months, active internal bleeding (excluding menses), or suspected aortic dissection. * **Most common side effect:** Bleeding (specifically ICH). * **Antidote:** Epsilon-aminocaproic acid or Tranexamic acid can be used to manage fibrinolytic states. * **Streptokinase:** Cannot be repeated within 6 months due to high antistreptococcal antibody titers.

Q: Which beta-blocker exhibits additional nitric oxide activity?

Nebivolol. ### Explanation **Correct Answer: D. Nebivolol** **Mechanism of Action:** Nebivolol is a **third-generation, highly selective β1-receptor antagonist**. Its unique pharmacological profile stems from its ability to stimulate **endothelial nitric oxide synthase (eNOS)** via β3-agonistic activity. This leads to the release of **Nitric Oxide (NO)**, which induces vasodilation, reduces peripheral vascular resistance, and improves endothelial function. This dual action (β1-blockade + NO-mediated vasodilation) makes it distinct from traditional beta-blockers. **Analysis of Incorrect Options:** * **A. Atenolol:** A second-generation, cardioselective (β1) blocker. It is hydrophilic and lacks any vasodilatory or NO-releasing properties. * **B. Metoprolol:** A standard second-generation β1-selective blocker. While widely used, it does not possess additional vasodilatory mechanisms like NO release. * **C. Bisoprolol:** A highly selective β1-blocker used primarily in heart failure. Like metoprolol, its action is limited to sympathetic blockade without direct effects on nitric oxide. **High-Yield Clinical Pearls for NEET-PG:** * **Selectivity:** Nebivolol is the **most β1-selective** blocker currently available. * **Vasodilatory Beta-blockers:** Remember the "third-generation" group: * **Nebivolol:** Via Nitric Oxide (NO) release. * **Carvedilol & Labetalol:** Via α1-receptor blockade. * **Celiprolol:** Via β2-agonist activity. * **Clinical Benefit:** Due to NO release, Nebivolol has a lower incidence of erectile dysfunction and metabolic side effects (like insulin resistance) compared to older beta-blockers.

Question 1

Dofetilide is which class of antiarrhythmic drug?

Accepted Answer

Class III

Answer

Class I

Answer

Class II

Answer

Class IV

Question 2

Which of the following drugs is useful for the long-term treatment of congestive heart failure?

Accepted Answer

Dobutamine

Answer

Digoxin

Answer

Ramipril

Answer

Spironolactone

Question 3

Which beta-blocker possesses an additional alpha-blocking property?

Accepted Answer

Labetalol

Answer

Propranolol

Answer

Timolol

Answer

Metoprolol

Question 4

What is the mechanism of action of methyldopa?

Accepted Answer

Agonism of alpha-2 receptors

Answer

Blockade of beta-adrenergic receptors

Answer

Blockade of alpha-2 receptors

Answer

Agonism of beta-2 receptors

Question 5

A patient with a known history of Coronary Artery Disease (CAD) suddenly presents with chest pain, shortness of breath, and a blood pressure of 90/60 mmHg. On examination, cold clammy skin is observed, with a urine output of 25 ml/hr. What is the drug of choice?

Accepted Answer

Dopamine

Answer

Droxidopa

Answer

Adrenaline

Answer

Dobutamine

Question 6

Severe myopathy commonly is a side effect of which of the following medications?

Accepted Answer

Rosuvastatin

Answer

Nicotinic acid

Answer

Ezetimibe

Answer

Colesevelam

Question 7

Which of the following drugs is NOT used in the management of congestive heart failure?

Accepted Answer

Adrenaline

Answer

Nesiritide

Answer

Digoxin

Answer

Spironolactone

Question 8

A 32-year-old man presents to the emergency department with sudden onset palpitations for 90 minutes. His ECG shows a regular narrow-complex tachycardia at 180 bpm with no visible P waves. Blood pressure is 118/76 mmHg and he is hemodynamically stable with no signs of heart failure. What is the initial pharmacologic therapy of choice?

Accepted Answer

Adenosine 6 mg rapid IV bolus

Answer

Verapamil 2.5 to 5 mg IV over 1 to 2 min

Answer

Diltiazem 0.25 mg/kg IV over 2 min

Answer

Digoxin 0.5 mg IV slowly

Question 9

Relative contraindication to thrombolytic therapy includes all the following except?

Accepted Answer

Hypotension

Answer

Recent surgery

Answer

Active peptic ulcer

Answer

Pregnancy

Question 10

Which beta-blocker exhibits additional nitric oxide activity?

Accepted Answer

Nebivolol

Answer

Atenolol

Answer

Metoprolol

Answer

Bisoprolol

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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