Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 1091: Which of the following statements is MOST accurate about sotalol?

A. Polymorphic ventricular tachycardia is a common problem
B. It is non selective Beta blocker (Correct Answer)
C. It prolongs the action potential duration throughout the heart.
D. It is primarily excreted by the kidneys.

Explanation: ***It is non selective Beta blocker*** - Sotalol is classified as a **Class III antiarrhythmic** due to its **potassium channel blocking activity**, but it also possesses significant **non-selective beta-adrenergic blocking** properties (both β1 and β2). - This **dual mechanism** makes this the most comprehensive and fundamental description of sotalol's pharmacology. - The **beta-blocking effect** contributes to its antiarrhythmic efficacy, particularly in atrial arrhythmias. *It prolongs the action potential duration throughout the heart* - This statement is **factually correct** - sotalol does prolong APD throughout the heart via **Class III potassium channel blocking activity**. - However, this describes only ONE mechanism of action, whereas the correct answer captures its **non-selective beta-blocking property** which is equally fundamental to its classification. *Polymorphic ventricular tachycardia is a common problem* - **Torsades de Pointes** (polymorphic VT) is indeed a **known and serious adverse effect** of sotalol due to **QT interval prolongation**. - However, the word "common" is somewhat misleading - the incidence is approximately **2-4%**, which while significant, is not considered "common" in clinical terms. - This risk is especially elevated in patients with **electrolyte imbalances**, **bradycardia**, or concurrent use of other **QT-prolonging drugs**. *It is primarily excreted by the kidneys* - This statement is **factually correct** - sotalol undergoes **80-90% renal elimination** as unchanged drug with minimal hepatic metabolism. - **Dose adjustment is required in renal impairment**, making this clinically important. - However, like option 2, this describes a pharmacokinetic property rather than the core pharmacodynamic classification of the drug.

Question 1092: All the following statements regarding adenosine are true except:

A. Dipyridamole potentiates its action
B. Administered by slow I.V. injection (Correct Answer)
C. Administered by rapid I.V. injection
D. Used in the treatment of supraventricular tachycardia

Explanation: ***Administered by slow I.V. injection*** - Adenosine has an **extremely short half-life** (less than 10 seconds), so it must be administered as a **rapid intravenous bolus** to reach the heart effectively before being metabolized. - Slow IV injection would lead to its degradation before therapeutic concentrations are achieved at its target receptors in the heart. - This statement is **FALSE** and therefore the correct answer to this EXCEPT question. *Dipyridamole potentiates its action* - **Dipyridamole** inhibits the cellular reuptake and metabolism of adenosine, increasing its extracellular concentration and thus **potentiating its effects**. - This interaction can lead to exaggerated adenosine-induced bradycardia and hypotension, so lower doses of adenosine should be used. - This statement is **TRUE**. *Used in the treatment of supraventricular tachycardia* - Adenosine is the **drug of choice** for acute termination of **paroxysmal supraventricular tachycardia (PSVT)** involving the AV node. - It works by transiently blocking AV nodal conduction, interrupting the reentrant circuit. - This statement is **TRUE**. *Administered by rapid I.V. injection* - Due to its extremely short half-life, adenosine must be given as a **rapid IV bolus** (typically over 1-2 seconds) followed immediately by a saline flush. - Rapid injection ensures sufficient drug concentration reaches the **AV node** before metabolism. - This statement is **TRUE**.

Question 1093: Which of the following is the most beta-1 selective antagonist?

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

Explanation: ***Nebivolol*** - **Nebivolol** is known for its high **beta-1 selectivity** and additional **nitric oxide-mediated vasodilation** properties. - This high selectivity contributes to a reduced incidence of bronchospasm compared to less selective beta-blockers. *Acebutolol* - **Acebutolol** is a **cardioselective** beta-blocker with **intrinsic sympathomimetic activity (ISA)**, meaning it can partially stimulate beta-receptors. - While selective for beta-1, its selectivity is not as high as nebivolol. *Atenolol* - **Atenolol** is a **cardioselective** beta-blocker that primarily antagonizes beta-1 receptors. - Its selectivity is moderate and generally lower than that of nebivolol. *Metoprolol* - **Metoprolol** is also a **cardioselective** beta-blocker, meaning it preferentially blocks beta-1 receptors at lower doses. - Its beta-1 selectivity is not as pronounced as that of nebivolol, and it can lose selectivity at higher doses.

Question 1094: What is the mechanism of action of beta-blockers in the treatment of hypertension?

A. Dilating peripheral blood vessels
B. Increasing sodium and water retention
C. Blocking angiotensin-converting enzyme
D. Decreasing heart rate and contractility (Correct Answer)

Explanation: ***Decreasing heart rate and contractility*** - **Beta-blockers** primarily work by blocking the effects of **catecholamines** (like epinephrine and norepinephrine) on **beta-adrenergic receptors** in the heart. - This leads to a reduction in **heart rate** and the **force of myocardial contraction**, thereby decreasing cardiac output and blood pressure. *Dilating peripheral blood vessels* - This is the primary mechanism of action for **alpha-blockers** and some **calcium channel blockers**, not typical beta-blockers. - While some **beta-blockers** (e.g., carvedilol, labetalol) also have **alpha-blocking activity** that causes vasodilation, it's not their main antihypertensive mechanism. *Increasing sodium and water retention* - This effect is actually a common side effect or a compensatory mechanism seen with some other antihypertensive drugs, but it is **not** the mechanism of action of beta-blockers. - Diuretics, for example, work by **reducing sodium and water retention**. *Blocking angiotensin-converting enzyme* - This describes the mechanism of action of **ACE inhibitors** (e.g., enalapril, lisinopril), which prevent the conversion of **angiotensin I to angiotensin II**. - This leads to vasodilation and reduced aldosterone secretion, which is distinct from how beta-blockers work.

Question 1095: BETA-blockers are contraindicated in which of the following conditions?

A. Hypertension
B. Thyrotoxicosis
C. Variant angina (Correct Answer)
D. None of the options

Explanation: ***Variant angina*** - Beta-blockers can paradoxically worsen **variant angina** by enhancing coronary vasospasm due to unopposed **alpha-receptor stimulation**, especially with non-selective agents. - This condition involves transient, focal coronary artery spasms reducing blood flow, which beta-blockers may exacerbate by inhibiting **beta-2 receptor-mediated vasodilation**. *Hypertension* - Beta-blockers are a **first-line treatment** for hypertension, particularly in patients with co-existing conditions like **angina** or **post-myocardial infarction** [2]. - They reduce blood pressure by decreasing **cardiac output** and inhibiting renin release [2]. *Thyrotoxicosis* - Beta-blockers are highly effective in managing the **symptomatic features** of thyrotoxicosis, such as **tachycardia**, palpitations, and tremor [1]. - They act by blocking the effects of **excess thyroid hormones** on beta-adrenergic receptors and can inhibit peripheral conversion of thyroxine to triiodothyronine [1]. *None of the options* - Since **variant angina** is a clear contraindication, this option is incorrect. - Beta-blockers have specific situations where their use is harmful or ineffective.

Question 1096: Which of the following antihypertensive drugs is avoided in patients with high serum uric acid levels?

A. Hydrochlorothiazide (Correct Answer)
B. Enalapril
C. Prazosin
D. Atenolol

Explanation: ***Hydrochlorothiazide (Correct Answer)*** - **Thiazide diuretics** like hydrochlorothiazide inhibit the sodium-chloride cotransporter in the **distal convoluted tubule**, leading to increased sodium, chloride, and water excretion - These drugs **reduce renal excretion of uric acid** by competing for secretion in the proximal tubule, leading to **hyperuricemia** - Can precipitate or exacerbate **gout attacks** in susceptible patients - Should be **avoided or used with caution** in patients with elevated serum uric acid levels *Enalapril (Incorrect)* - **ACE inhibitor** that blocks conversion of angiotensin I to angiotensin II - Causes vasodilation and reduces aldosterone secretion - Does **not significantly affect uric acid metabolism** - Safe for use in patients with hyperuricemia *Prazosin (Incorrect)* - **Alpha-1 adrenergic blocker** causing vasodilation by blocking alpha-1 receptors in vascular smooth muscle - Mechanism does **not interfere with uric acid excretion or production** - Safe option for patients with elevated serum uric acid *Atenolol (Incorrect)* - **Beta-1 selective adrenergic blocker** that reduces heart rate, cardiac output, and renin release - Does **not have clinically significant impact** on renal uric acid handling - Can be used in patients with hyperuricemia

Question 1097: Nitrates decrease myocardial oxygen consumption by all of the following mechanisms except which of the following?

A. By dilation of the capacitance vessels
B. By direct reduction of oxygen consumption of the myocardial cell
C. By increasing the left ventricular end diastolic pressure (Correct Answer)
D. By decreasing the size of the heart

Explanation: ***By increasing the left ventricular end diastolic pressure*** - This is the **EXCEPT** answer - nitrates do NOT work by this mechanism. - Nitrates primarily decrease **preload** by venous dilation, which leads to a **decrease** in left ventricular end-diastolic pressure (LVEDP), not an increase. - An **increased LVEDP** would raise myocardial wall tension and oxygen demand, which is **contrary** to the therapeutic effect of nitrates. - This is the only option that does NOT represent a mechanism by which nitrates reduce myocardial oxygen consumption. *By dilation of the capacitance vessels* - Nitrates cause **venodilation** (dilation of capacitance vessels), leading to venous pooling and reduced venous return. - This decreases **preload**, lowering left ventricular end-diastolic volume and pressure. - Reduced preload decreases **myocardial wall tension** and oxygen consumption (Laplace's law). *By direct reduction of oxygen consumption of the myocardial cell* - While primarily acting through hemodynamic effects, nitrates can have **some direct myocardial effects** through NO-mediated pathways. - However, this is NOT their primary mechanism - the major oxygen-sparing effects come from reducing **preload** and **afterload**. - This mechanism is less significant compared to their hemodynamic effects. *By decreasing the size of the heart* - By reducing both **preload** (venous dilation) and **afterload** (arterial dilation), nitrates decrease ventricular volume. - Smaller ventricular size reduces **myocardial wall stress** according to the **Law of Laplace** (Wall stress ∝ Pressure × Radius). - This translates to decreased myocardial oxygen consumption.

Question 1098: Which of the following is the best inotrope agent for use in right heart failure secondary to pulmonary hypertension?

A. Milrinone (Correct Answer)
B. Dobutamine
C. Digoxin
D. Dopamine

Explanation: ***Milrinone*** - Milrinone is a **phosphodiesterase-3 inhibitor** that increases myocardial contractility and causes **pulmonary and systemic vasodilation**. - Its vasodilatory effect is particularly beneficial in **pulmonary hypertension** as it can help reduce **pulmonary vascular resistance (PVR)**, a critical factor in right heart failure. - The combination of **positive inotropy** and **selective pulmonary vasodilation** makes it the optimal choice for right ventricular failure secondary to pulmonary hypertension. *Dobutamine* - Dobutamine is a **beta-1 agonist** that primarily increases myocardial contractility with some beta-2 mediated vasodilation. - While it improves cardiac output, its lesser effect on **pulmonary vascular resistance** compared to milrinone makes it less ideal for right heart failure specifically complicated by pulmonary hypertension. *Digoxin* - Digoxin is a **cardiac glycoside** that increases contractility but has a slow onset of action and a narrow therapeutic window, making it less suitable for acute management. - It does not significantly reduce **pulmonary vascular resistance** and is primarily used for chronic heart failure or rate control in atrial fibrillation. *Dopamine* - Dopamine is a **catecholamine** with dose-dependent effects: at moderate doses (5-10 mcg/kg/min), it acts as a **beta-1 agonist** providing inotropic support. - However, at higher doses it causes **alpha-adrenergic vasoconstriction** which can **increase pulmonary vascular resistance**, potentially worsening right heart failure in pulmonary hypertension. - Unlike milrinone, it lacks specific pulmonary vasodilatory properties beneficial for reducing RV afterload.

Question 1099: Which of the following is a K+ channel opener?

A. Ranolazine
B. Nicorandil (Correct Answer)
C. Verapamil
D. Lignocaine

Explanation: ***Nicorandil*** - **Nicorandil** opens ATP-sensitive K+ channels, causing hyperpolarization of vascular smooth muscle cells. - This K+ channel opening leads to **vasodilation** in both arteries and veins, reducing preload and afterload. *Ranolazine* - **Ranolazine** is a selective inhibitor of the late sodium current in cardiac myocytes. - Its primary action is to reduce **intracellular sodium** and subsequent calcium overload, rather than opening K+ channels. *Verapamil* - **Verapamil** is a **non-dihydropyridine calcium channel blocker**. - It works by inhibiting the influx of calcium into cardiac and smooth muscle cells, thus decreasing contractility and causing vasodilation, not by opening K+ channels. *Lignocaine* - **Lignocaine** (lidocaine) is a **sodium channel blocker** primarily used as a local anesthetic and antiarrhythmic. - It stabilizes neuronal and cardiac cell membranes by preventing sodium influx, which differs from K+ channel modulation.

Question 1100: Which one of the following was traditionally considered the drug of choice for ventricular tachycardia in myocardial infarction?

A. Xylocaine (Correct Answer)
B. Digitalis
C. Quinidine
D. Disopyramide

Explanation: ***Xylocaine/Lidocaine*** - **Lidocaine (Xylocaine)** is a **Class IB antiarrhythmic drug** [2] that was historically the drug of choice for suppressing ventricular arrhythmias, including ventricular tachycardia, in the setting of **myocardial ischemia and infarction** [1]. - It works by **blocking sodium channels** and shortening the action potential duration, thereby reducing excitability and automaticity in ischemic myocardial tissue [1]. - **Current guidelines**: Lidocaine is now considered a **second-line agent**, with **amiodarone** being the preferred first-line antiarrhythmic for hemodynamically stable VT in acute MI, and electrical cardioversion for unstable VT. *Digitalis* - **Digitalis** (e.g., digoxin) is primarily used for **supraventricular arrhythmias** like atrial fibrillation or flutter, and for heart failure due to its positive inotropic effect. - It can **aggravate ventricular arrhythmias** in the setting of acute myocardial infarction and is generally contraindicated for ventricular tachycardia. *Quinidine* - **Quinidine** is a **Class IA antiarrhythmic drug** that prolongs the action potential and is effective against a variety of arrhythmias. - However, it can cause **hypotension** and has a **proarrhythmic effect**, increasing the risk of Torsades de Pointes, making it less favorable as a first-line agent, especially in acute MI. *Disopyramide* - **Disopyramide** is also a **Class IA antiarrhythmic drug** with similar mechanisms to quinidine. - It has significant **negative inotropic effects** and can worsen heart failure [3], which is a common complication in acute myocardial infarction, making it less suitable.

Practice by Chapter

Antihypertensive Agents

Practice Questions

Drugs for Heart Failure

Practice Questions

Antiarrhythmic Drugs

Practice Questions

Antianginal Agents

Practice Questions

Lipid-Lowering Drugs

Practice Questions

Anticoagulants and Antiplatelet Drugs

Practice Questions

Thrombolytic Agents

Practice Questions

Drugs Used in Pulmonary Hypertension

Practice Questions

Drugs Used in Shock

Practice Questions

Cardiovascular Effects of Non-Cardiovascular Drugs

Practice Questions

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