Drugs in Cardiac Arrest Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Drugs in Cardiac Arrest. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Drugs in Cardiac Arrest Indian Medical PG Question 1: 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
Drugs in Cardiac Arrest 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.
Drugs in Cardiac Arrest Indian Medical PG Question 2: Patient with pulmonary fibrosis. Which antiarrhythmic drug is contraindicated?
- A. Amiodarone (Correct Answer)
- B. Flecainide
- C. Lidocaine
- D. IV ibutilide
Drugs in Cardiac Arrest Explanation: Amiodarone
- **Amiodarone** is contraindicated in patients with pulmonary fibrosis due to its well-known and potentially severe pulmonary toxicity, which can exacerbate existing lung conditions or induce new ones like **interstitial lung disease**. Dose-related pulmonary toxicity is the most important adverse effect, and potentially fatal pulmonary fibrosis can be observed even at low doses [1].
- Its long half-life means that its toxic effects, including **pulmonary toxicity**, can persist for an extended period even after discontinuation [1], [2].
*Flecainide*
- **Flecainide** is a Class IC antiarrhythmic drug primarily associated with cardiac side effects and is generally not contraindicated in patients with pulmonary fibrosis.
- Its main risks include **proarrhythmia**, especially in patients with structural heart disease, but not pulmonary issues [3].
*IV ibutilide*
- **IV ibutilide** is a Class III antiarrhythmic agent used for rapid conversion of atrial fibrillation/flutter and is not specifically contraindicated in pulmonary fibrosis.
- Its primary concern is the risk of **QT prolongation** and **Torsades de Pointes**, rather than pulmonary complications.
*Lidocaine*
- **Lidocaine** is a Class IB antiarrhythmic typically used for ventricular arrhythmias, especially in the setting of acute myocardial infarction. It is not contraindicated in pulmonary fibrosis.
- Its main side effects are **neurological (e.g., seizures, paresthesias)** at higher doses, not pulmonary complications.
Drugs in Cardiac Arrest Indian Medical PG Question 3: Which of these is least effective as first-line treatment for dangerous hyperkalemia?
- A. Calcium chloride injection
- B. Beta-2 agonist (Salbutamol)
- C. Intravenous sodium bicarbonate (Correct Answer)
- D. Dialysis (Hemodialysis)
Drugs in Cardiac Arrest Explanation: ***Intravenous sodium bicarbonate***
- While it can drive potassium into cells, its effect is often **delayed and unreliable** in acute, dangerous hyperkalemia, especially without concurrent acidosis.
- Its efficacy is most pronounced when hyperkalemia is associated with **metabolic acidosis**, which is not always the primary driving factor of dangerous hyperkalemia.
*Calcium chloride injection*
- This is a **first-line treatment** for dangerous hyperkalemia, as it **stabilizes the cardiac membrane** by antagonizing the direct effects of potassium on myocardial excitability [1].
- It does not lower serum potassium levels but **protects the heart** from life-threatening arrhythmias, buying time for other therapies to reduce potassium [1].
*Beta-2 agonist (Salbutamol)*
- **Beta-2 agonists** like salbutamol are effective in shifting potassium **intracellularly**, thereby lowering serum potassium levels.
- This effect is mediated by stimulating the **Na+/K+-ATPase pump** on cell membranes.
*Dialysis (Hemodialysis)*
- **Hemodialysis** is the **most effective and rapid** method for removing excess potassium from the body, especially in cases of severe or refractory hyperkalemia.
- It provides definitive treatment by directly **filtering potassium** from the blood, and is often considered when other measures fail or in patients with kidney failure.
Drugs in Cardiac Arrest Indian Medical PG Question 4: Which of the following rhythms associated with cardiac arrest is considered shockable?
- A. Pulseless ventricular tachycardia
- B. Asystole
- C. Pulseless electrical activity
- D. Ventricular fibrillation (Correct Answer)
Drugs in Cardiac Arrest Explanation: ***Ventricular fibrillation***
- **Ventricular fibrillation (VF)** is a chaotic, disorganized electrical activity in the ventricles, leading to ineffective myocardial contraction and cardiac arrest [1].
- Due to the presence of electrical activity that can be reset, **defibrillation** (an electrical shock) is the definitive treatment to restore a perfusing rhythm [1].
*Asystole*
- **Asystole** is characterized by the complete absence of electrical and mechanical activity in the heart, appearing as a "flat line" on the ECG.
- Since there is no electrical activity to reorganize, defibrillation is ineffective, and management focuses on **cardiopulmonary resuscitation (CPR)** and medications like epinephrine [2].
*Pulseless electrical activity*
- **Pulseless electrical activity (PEA)** involves an organized electrical rhythm on the ECG but no palpable pulse, indicating inadequate cardiac mechanical activity.
- Defibrillation is not indicated as there is a rhythmic electrical activity, and treatment focuses on identifying and correcting the underlying causes of **cardiac mechanical failure**.
*Pulseless ventricular tachycardia*
- While **pulseless ventricular tachycardia (VT)** is a malignant rhythm, the question asks for a rhythm that is *considered shockable* in the context of cardiac arrest.
- In actual cardiac arrest algorithms, **pulseless VT** is treated similarly to **ventricular fibrillation** and is indeed shockable [1]. However, if multiple options are given and only one can be chosen, **VF** and **pulseless VT** are both shockable. Given the options, VF is explicitly and commonly cited as a primary shockable rhythm.
* Correction: **Pulseless ventricular tachycardia** *is* a shockable rhythm and is treated with immediate defibrillation in cardiac arrest. The initial explanation incorrectly implies it's not. This response should be revised to state that both VF and pulseless VT are shockable.
- Both **ventricular fibrillation (VF)** and **pulseless ventricular tachycardia (VT)** are considered shockable rhythms in cardiac arrest algorithms [1].
- Defibrillation is performed to depolarize the cardiac muscle cells simultaneously, allowing the natural pacemaker of the heart to resume control [1].
Drugs in Cardiac Arrest Indian Medical PG Question 5: Which drug is used as an adjunct to epinephrine in refractory ventricular fibrillation/ventricular tachycardia during cardiac arrest?
- A. Atropine
- B. Adenosine
- C. High dose vasopressin
- D. Amiodarone infusion (Correct Answer)
Drugs in Cardiac Arrest Explanation: ***Amiodarone infusion***
- **Amiodarone** is a **Class III antiarrhythmic** drug commonly used in advanced cardiac life support (ACLS) protocols for refractory **ventricular fibrillation (VF)** or **pulseless ventricular tachycardia (VT)** that persists despite defibrillation and epinephrine [1].
- It works by blocking potassium channels, prolonging repolarization and the refractory period, which helps to stabilize the electrical activity of the heart.
*Atropine*
- **Atropine** is an anticholinergic drug primarily used to treat **symptomatic bradycardia** by increasing heart rate.
- It is not indicated for the treatment of **ventricular fibrillation** or **ventricular tachycardia** during cardiac arrest.
*High dose vasopressin*
- **Vasopressin** was previously included in some ACLS algorithms as an alternative to epinephrine for **vasoconstrictive effects**, but recent guidelines do not support its routine use in cardiac arrest.
- While it can cause **vasoconstriction**, there is no evidence that high-dose vasopressin improves outcomes in refractory VF/VT over epinephrine.
*Adenosine*
- **Adenosine** is an antiarrhythmic drug used to treat **supraventricular tachycardias (SVTs)** by transiently blocking the AV node.
- It is not effective for **ventricular fibrillation** or **ventricular tachycardia** and can even be harmful in these rhythms.
Drugs in Cardiac Arrest Indian Medical PG Question 6: As per the recent guidelines of resuscitation, what should be done if asystole is not responding to two consecutive doses of epinephrine?
- A. Administer another dose of epinephrine.
- B. Continue high-quality CPR and consider advanced airway management. (Correct Answer)
- C. Administer vasopressin as a second-line drug.
- D. Defibrillation with 200J.
Drugs in Cardiac Arrest Explanation: ***Continue high-quality CPR and consider advanced airway management.***
- For **asystole** that is unresponsive to initial epinephrine doses, maintaining **high-quality CPR** is the cornerstone of resuscitation efforts, ensuring vital organ perfusion.
- **Advanced airway management** (e.g., endotracheal intubation) should be considered early to secure the airway and facilitate ventilation, optimizing oxygen delivery during CPR.
*Administer another dose of epinephrine.*
- While epinephrine is the primary drug for asystole, repeating doses beyond the initial recommended schedule without other interventions is not indicated if there is no response, as it may not improve outcomes.
- The focus shifts to identifying and treating reversible causes while maintaining high-quality CPR, rather than escalating epinephrine frequency.
*Administer vasopressin as a second-line drug.*
- **Vasopressin** is no longer recommended in adult cardiac arrest resuscitation algorithms, including for asystole, according to current guidelines from organizations like the American Heart Association.
- Its use has not been shown to improve survival to hospital discharge or neurological outcomes compared to epinephrine.
*Defibrillation with 200J.*
- **Defibrillation** is only indicated for shockable rhythms such as **ventricular fibrillation (VF)** or **pulseless ventricular tachycardia (pVT)**.
- Asystole is a **non-shockable rhythm**, meaning there is no electrical activity to defibrillate, and administering a shock is ineffective and can be harmful.
Drugs in Cardiac Arrest Indian Medical PG Question 7: Which local anesthetic is considered the most cardiotoxic?
- A. Procaine
- B. Prilocaine
- C. Ropivacaine
- D. Bupivacaine (Correct Answer)
Drugs in Cardiac Arrest Explanation: ***Bupivacaine***
- **Bupivacaine** is an amide-type local anesthetic associated with significant **cardiotoxicity** due to its high lipid solubility and slow dissociation from cardiac sodium channels.
- This can lead to severe **arrhythmias** and myocardial depression, making it particularly dangerous in systemic overdose.
*Procaine*
- **Procaine** is an ester-type local anesthetic with a relatively low potential for cardiotoxicity.
- Its rapid metabolism by **plasma pseudocholinesterase** limits systemic exposure and reduces the risk of cardiac effects.
*Prilocaine*
- **Prilocaine** is an amide-type local anesthetic that is generally less cardiotoxic than bupivacaine.
- Its primary concern is the potential to cause **methemoglobinemia** at higher doses, a side effect not directly related to cardiotoxicity.
*Ropivacaine*
- **Ropivacaine** is an amide-type local anesthetic developed as an alternative to bupivacaine with a reduced cardiotoxicity profile.
- It exhibits a more favorable **therapeutic index** for cardiac effects due to its chemical structure and faster dissociation from cardiac sodium channels.
Drugs in Cardiac Arrest Indian Medical PG Question 8: In ACLS, which antiarrhythmic drug can be given following ventricular fibrillation after cardiac arrest other than epinephrine?
- A. Amiodarone (Correct Answer)
- B. Dopamine
- C. Adenosine
- D. Atropine
Drugs in Cardiac Arrest Explanation: ***Amiodarone***
- **Amiodarone** is a Class III antiarrhythmic agent recommended in ACLS for **refractory ventricular fibrillation (VF)** or pulseless ventricular tachycardia (pVT) after initial defibrillation and epinephrine.
- It works by blocking potassium channels, prolonging repolarization, and increasing the **refractory period** in the heart.
*Dopamine*
- **Dopamine** is a **vasopressor** used to improve **hemodynamics** in patients with symptomatic hypotension, not primarily as an antiarrhythmic for VF.
- Its effects include increasing heart rate, myocardial contractility, and blood pressure.
*Adenosine*
- **Adenosine** is a drug of choice for **supraventricular tachycardia (SVT)** to interrupt reentry pathways in the AV node.
- It is not indicated for ventricular fibrillation, as it would be ineffective in this rhythm.
*Atropine*
- **Atropine** is an **anticholinergic agent** used to treat **symptomatic bradycardia** by increasing heart rate.
- It has no role in the management of ventricular fibrillation.
Drugs in Cardiac Arrest Indian Medical PG Question 9: Identify the diagnosis based on the provided ECG image.
- A. VT
- B. PSVT (Correct Answer)
- C. AT
- D. Ventricular fibrillation
Drugs in Cardiac Arrest Explanation: ***PSVT***
- The ECG shows a **narrow complex tachycardia** with a regular rhythm and a high heart rate, characteristic of **paroxysmal supraventricular tachycardia (PSVT)**.
- P waves are often **buried within the QRS complex** or T waves, or may be retrograde, which can be seen as small deflections or changes in the baseline in some leads.
*VT*
- **Ventricular tachycardia** is characterized by a **wide QRS complex** (>0.12 seconds), which is not observed in this ECG.
- While VT can be regular, the primary distinguishing feature is the QRS duration.
*AT*
- **Atrial tachycardia (AT)** is another form of supraventricular tachycardia, but it typically shows **distinct P waves** with an abnormal morphology, often separate from the T wave, which are not clearly visible or consistently distinct in this tracing.
- While it can present with narrow complex tachycardia, the mechanism differs from re-entrant PSVT.
*Ventricular fibrillation*
- **Ventricular fibrillation** is characterized by **chaotic, irregular electrical activity** with no distinguishable P waves, QRS complexes, or T waves, representing disorganized ventricular depolarization.
- The ECG in the image shows a consistent, regular rhythm with identifiable, albeit narrow, QRS complexes.
Drugs in Cardiac Arrest Indian Medical PG Question 10: According to the Maastricht classification, Category 3 is?
- A. dead on arrival to hospital
- B. awaiting cardiac arrest after withdrawal of support (Correct Answer)
- C. resuscitation attempted without success
- D. cardiac arrest while brain dead
Drugs in Cardiac Arrest Explanation:
***awaiting cardiac arrest after withdrawal of support***
- Under the **Maastricht classification**, Category 3 describes patients who are **expected to die** following the planned withdrawal of life-sustaining treatment. These patients are potential donors after circulatory death (DCD). [1], [2]
*dead on arrival to hospital*
- This scenario aligns with **Maastricht Category 1** (Uncontrolled DCD), where death occurs outside the hospital setting without prior intervention.
- Patients in this category often have unpredictable warm ischemia times, making organ procurement challenging for some organs.
*resuscitation attempted without success*
- This situation aligns with **Maastricht Category 2** (Uncontrolled DCD), referring to patients declared dead after unsuccessful resuscitation efforts in the emergency department or hospital.
- The period of observed death following resuscitation attempts is crucial for determining organ viability.
*cardiac arrest while brain dead*
- This describes a patient who is **brain dead** but still has some circulatory function, which eventually ceases. This is typically associated with organ donation after brain death (DBD), not the DCD categories defined by Maastricht. [1], [3]
- In brain death, the **neurological criteria for death** are met, regardless of circulatory status at the time of diagnosis. [2], [4]
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