Cardiovascular Anesthesia — MCQs

Cardiovascular Anesthesia Indian Medical PG Practice Questions and MCQs

Question 11: Which of the following is the most likely reason why fentanyl does not disturb cardiovascular stability as much as morphine?

A. It is water soluble
B. It is lipid soluble
C. It does not stimulate histamine release (Correct Answer)
D. It is long acting

Explanation: **Explanation:** The primary reason **Fentanyl** maintains superior cardiovascular stability compared to **Morphine** is that it **does not stimulate histamine release**. **1. Why the Correct Answer is Right:** Morphine is known to cause non-immunologic (direct) mast cell degranulation, leading to the release of histamine. Histamine causes systemic vasodilation (decreasing systemic vascular resistance) and increases capillary permeability, which can result in significant **hypotension** and compensatory tachycardia. Fentanyl, a synthetic phenylpiperidine derivative, lacks this property. Consequently, it does not cause the vasodilation associated with histamine, making it the preferred opioid for hemodynamically unstable patients or those undergoing cardiac surgery. **2. Why Incorrect Options are Wrong:** * **A & B (Solubility):** Fentanyl is highly **lipid-soluble** (not water-soluble), which allows it to cross the blood-brain barrier rapidly. While lipid solubility dictates its rapid onset and redistribution, it is not the direct mechanism for cardiovascular stability. * **D (Duration of Action):** Fentanyl is a **short-acting** drug due to rapid redistribution, whereas Morphine has a longer duration of action. Duration does not correlate with the immediate hemodynamic profile during induction. **Clinical Pearls for NEET-PG:** * **Hemodynamic Profile:** Fentanyl is considered "cardio-stable" because it does not depress myocardial contractility or cause histamine-induced hypotension. * **Side Effect:** The most common cardiovascular side effect of high-dose Fentanyl is **bradycardia** (via central vagal stimulation), not hypotension. * **Chest Wall Rigidity:** Rapid IV bolus of Fentanyl can cause "Wooden Chest Syndrome," which may interfere with ventilation. * **Potency:** Fentanyl is approximately **100 times** more potent than Morphine.

Question 12: A post-operative cardiac surgical patient developed sudden hypotension, raised central venous pressure, and pulsus paradoxus at the 4th post-operative hour. What is the most probable diagnosis?

A. Excessive mediastinal bleeding
B. Ventricular dysfunction
C. Congestive cardiac failure
D. Cardiac tamponade (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Cardiac tamponade** The clinical triad of **sudden hypotension**, **raised Central Venous Pressure (CVP)**, and **pulsus paradoxus** in a post-operative cardiac surgical patient is the classic presentation of **Cardiac Tamponade**. In the post-operative period, this usually occurs due to the accumulation of blood or clots in the pericardial or mediastinal space. This fluid exerts extrinsic pressure on the heart, restricting diastolic filling. The raised CVP reflects the heart's inability to accept venous return (diastolic collapse), while pulsus paradoxus (an exaggerated drop in systolic BP >10 mmHg during inspiration) occurs due to ventricular interdependence within a fixed space. **Analysis of Incorrect Options:** * **A. Excessive mediastinal bleeding:** While bleeding often precedes tamponade, simple hemorrhage without entrapment typically presents with **low CVP** (hypovolemia) rather than raised CVP. * **B. Ventricular dysfunction:** While this causes hypotension and raised CVP, it does not typically cause **pulsus paradoxus**, which is a hallmark of restrictive/pericardial pathology. * **C. Congestive cardiac failure:** This presents with raised CVP and hypotension, but it is usually a more gradual process and is accompanied by pulmonary edema (crackles) rather than the sudden obstructive signs seen here. **High-Yield Clinical Pearls for NEET-PG:** * **Beck’s Triad:** Hypotension, Jugular Venous Distension (raised CVP), and Muffled Heart Sounds. * **Kussmaul’s Sign:** A paradoxical rise in JVP on inspiration (more common in constrictive pericarditis but can be seen in tamponade). * **Echocardiography:** The gold standard for diagnosis (shows diastolic collapse of the Right Atrium/Right Ventricle). * **Management:** Immediate surgical re-exploration or pericardiocentesis. In post-cardiac surgery, "clotted" tamponade may require reopening the sternotomy.

Question 13: Which anesthetic agent is least cardiotoxic?

A. Enflurane
B. Isoflurane (Correct Answer)
C. Sevoflurane
D. Halothane, Trilene, ketamine

Explanation: **Explanation:** The cardiotoxicity of volatile anesthetic agents is primarily measured by their potential to cause myocardial depression and sensitize the myocardium to catecholamines (leading to arrhythmias). **Isoflurane** is considered the least cardiotoxic among the older volatile agents because it maintains cardiac output better than others. While it is a potent vasodilator (reducing systemic vascular resistance), it causes a compensatory increase in heart rate, which preserves the cardiac index. Most importantly, it does not sensitize the myocardium to endogenous or exogenous catecholamines, making it safer in hemodynamically stable patients. **Analysis of Incorrect Options:** * **Halothane:** The most cardiotoxic volatile agent. It significantly sensitizes the myocardium to catecholamines, frequently leading to ventricular arrhythmias. It also causes profound dose-dependent myocardial depression. * **Enflurane:** Causes significant myocardial depression and reduces cardiac output more than isoflurane or sevoflurane. * **Sevoflurane:** While very safe and commonly used, in some comparative studies, isoflurane is noted for having the least effect on myocardial contractility among the ethers. * **Ketamine:** Though it stimulates the sympathetic nervous system (increasing BP and HR), it is a direct myocardial depressant. In critically ill patients with depleted catecholamines, it can cause sudden cardiovascular collapse. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of choice for Cardiac Surgery:** Isoflurane (due to its "cardioprotective" effect and stable cardiac output). * **Arrhythmogenic Potential:** Halothane > Enflurane > Sevoflurane > Isoflurane. * **Coronary Steal Phenomenon:** Historically associated with Isoflurane, though clinically insignificant at standard doses. * **Induction in Pediatrics:** Sevoflurane is preferred over Isoflurane because it is non-pungent and does not cause airway irritation.

Question 14: Which of the following anesthetic agents is known to increase cardiac oxygen demand?

A. Halothane
B. Thiopentone
C. Nitrous oxide (N2O)
D. Ketamine (Correct Answer)

Explanation: **Explanation:** **Ketamine (Correct Answer):** Ketamine is a unique anesthetic agent that acts as a **direct sympathomimetic**. It stimulates the sympathetic nervous system, leading to an increase in circulating catecholamines. This results in the "Ketamine Triad": **increased heart rate, increased blood pressure, and increased cardiac output**. These hemodynamic changes significantly elevate **myocardial oxygen demand**. Consequently, Ketamine is generally contraindicated in patients with ischemic heart disease or severe hypertension. **Incorrect Options:** * **Halothane:** This volatile anesthetic is a potent **myocardial depressant**. It decreases cardiac output and blood pressure, thereby reducing myocardial oxygen demand. However, it is high-yield for its tendency to sensitize the myocardium to catecholamines, leading to arrhythmias. * **Thiopentone:** As a barbiturate, it causes peripheral vasodilation and direct myocardial depression. While it may cause a compensatory reflex tachycardia, its overall effect is a reduction in cerebral and systemic metabolic demands. * **Nitrous oxide (N2O):** N2O has a mild direct myocardial depressant effect, which is usually offset by a slight increase in sympathetic tone. However, it does not significantly increase oxygen demand compared to the potent stimulation caused by Ketamine. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Ketamine is the induction agent of choice in **hypovolemic shock** and **cardiac tamponade** due to its pressor effects. * **Exception:** In cases of severe catecholamine depletion (e.g., end-stage heart failure), Ketamine can actually cause a decrease in BP due to its underlying direct myocardial depressant effect being unmasked. * **Key Contraindication:** Avoid Ketamine in patients with **Ischemic Heart Disease (IHD)** and **Raised Intracranial Pressure (ICP)**.

Question 15: Which of the following opioid analgesics is suitable for haemodynamically unstable patients?

A. Morphine
B. Meperidine
C. Fentanyl (Correct Answer)
D. Pentazocine

Explanation: **Explanation:** The primary goal in managing hemodynamically unstable patients is to maintain heart rate, systemic vascular resistance (SVR), and myocardial contractility. **Why Fentanyl is the Correct Choice:** Fentanyl is a synthetic opioid and the preferred analgesic for hemodynamically unstable patients (e.g., trauma, shock, or cardiac surgery) because it is **cardiovascularly stable**. Unlike many other opioids, it **does not cause histamine release**. Consequently, it does not produce the significant peripheral vasodilation or hypotension often seen with morphine. At clinical doses, it has minimal effect on myocardial contractility. **Why Other Options are Incorrect:** * **Morphine:** It triggers significant **histamine release** from mast cells, leading to peripheral vasodilation and a drop in SVR, which can cause profound hypotension in hypovolemic or unstable patients. * **Meperidine (Pethidine):** It has a direct **myocardial depressant** effect and can cause tachycardia (due to its atropine-like structure), which increases myocardial oxygen demand—a risk in unstable patients. * **Pentazocine:** As an agonist-antagonist, it increases pulmonary artery pressure and cardiac workload by increasing catecholamine levels, making it unsuitable for patients with compromised cardiac function. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Fentanyl is the induction agent of choice for cardiac anesthesia and neurosurgery (due to minimal effect on ICP). * **Side Effect:** The most characteristic side effect of rapid high-dose Fentanyl infusion is **Chest Wall Rigidity** (Wooden Chest Syndrome), managed with muscle relaxants. * **Context:** While Fentanyl is stable, it can cause **bradycardia** via central vagal stimulation, but this is generally less detrimental than the hypotension caused by other opioids.

Question 16: What is the recommended ratio of ventilation to cardiac compression in adult CPR when two rescuers are present?

A. 1:15
B. 2:30 (Correct Answer)
C. 30:2
D. 2:10

Explanation: ### Explanation The correct answer is **2:30** (Option B), representing the ratio of **2 breaths to 30 compressions**. **1. Why 2:30 is Correct:** According to the latest **AHA (American Heart Association)** and **ERC (European Resuscitation Council)** guidelines, the universal compression-to-ventilation ratio for **adults** is **30:2**. This applies to both one-rescuer and two-rescuer scenarios. The primary goal is to minimize interruptions in chest compressions to maintain coronary and cerebral perfusion pressure. While the question asks for the "ratio of ventilation to compression," the standard numerical pairing is 2 breaths for every 30 compressions. **2. Why Other Options are Incorrect:** * **A (1:15):** This ratio was used in older guidelines but is no longer recommended for adults. A 15:2 ratio is currently only used in **two-rescuer pediatric/infant CPR**. * **C (30:2):** While 30:2 is the standard *compression-to-ventilation* ratio, the question specifically asks for the ratio of *ventilation to compression*. Therefore, 2:30 is the mathematically accurate response to the phrasing. * **D (2:10):** This ratio is not part of any standard BLS or ACLS protocol. **3. High-Yield Clinical Pearls for NEET-PG:** * **Compression Depth:** 2–2.4 inches (5–6 cm) in adults. * **Compression Rate:** 100–120 per minute. * **Advanced Airway:** Once an endotracheal tube or supraglottic airway is in place, compressions become **continuous**, and ventilations are given at a rate of **1 breath every 6 seconds** (10 breaths/min). * **Recoil:** Allow complete chest recoil after each compression to permit ventricular filling. * **Switching:** Rescuers should switch roles every 2 minutes (or 5 cycles) to prevent fatigue.

Question 17: Which of the following anesthetic agents is safe in patients with heart failure?

A. Etomidate (Correct Answer)
B. Propofol
C. Thiopentone
D. Ketamine

Explanation: **Explanation:** The primary goal in the anesthetic management of heart failure is to maintain hemodynamic stability by avoiding drugs that cause myocardial depression or significant changes in systemic vascular resistance (SVR). **1. Why Etomidate is the Correct Answer:** Etomidate is the induction agent of choice for patients with compromised cardiac function (Heart Failure, Valvular Heart Disease, or Shock). Its unique mechanism involves minimal interference with the sympathetic nervous system and the baroreceptor reflex. It provides **hemodynamic neutrality**, meaning it causes negligible changes in heart rate, stroke volume, and mean arterial pressure. **2. Why the Other Options are Incorrect:** * **Propofol:** It is a potent vasodilator and direct myocardial depressant. It causes a significant drop in SVR and preload, which can lead to severe hypotension in heart failure patients. * **Thiopentone:** Like other barbiturates, it causes dose-dependent peripheral vasodilation and negative inotropy, leading to a decrease in cardiac output. * **Ketamine:** While it stimulates the sympathetic nervous system (increasing HR and BP), it is a **direct myocardial depressant**. In patients with end-stage heart failure who are already "catecholamine-depleted," the stimulatory effect is lost, and the direct depressant effect can lead to cardiovascular collapse. **High-Yield Clinical Pearls for NEET-PG:** * **Etomidate Side Effect:** Adrenocortical suppression (inhibits 11-beta-hydroxylase). Avoid in septic shock. * **Drug of Choice for Hemodynamic Stability:** Etomidate. * **Drug of Choice for Reactive Airway Disease:** Ketamine (Bronchodilator). * **Drug of Choice for Day Care Surgery:** Propofol (Rapid recovery).

Question 18: For the management of intraoperative myocardial ischemia, all of the following are advised except?

A. Heparin (Correct Answer)
B. Intravenous nitroglycerine
C. Calcium channel blocker
D. Atropine

Explanation: **Explanation:** The primary goal in managing **intraoperative myocardial ischemia** is to restore the balance between myocardial oxygen supply and demand. This is achieved by manipulating hemodynamic parameters (heart rate, blood pressure, and preload). **Why Heparin is the Correct Answer (The "Except"):** While Heparin is a cornerstone in the management of *Acute Coronary Syndrome (ACS)* in the ER or ICU, it is **not** a primary treatment for intraoperative ischemia. In the operating room, ischemia is usually "demand-led" (due to tachycardia or hypertension) rather than "supply-led" (due to acute plaque rupture and thrombosis). Administering heparin intraoperatively carries a significant risk of surgical site hemorrhage without addressing the immediate hemodynamic triggers of the ischemia. **Analysis of Incorrect Options:** * **Intravenous Nitroglycerine (NTG):** The first-line treatment. It causes venodilation, which decreases preload and ventricular wall tension, thereby reducing oxygen demand. It also dilates coronary arteries to improve supply. * **Calcium Channel Blockers (CCBs):** Agents like Diltiazem are used to control heart rate and reduce systemic vascular resistance, helping to balance the oxygen equation, especially if beta-blockers are contraindicated. * **Atropine:** While Atropine increases heart rate (which usually worsens ischemia), it is indicated if the ischemia is triggered by **severe bradycardia**, which leads to low cardiac output and reduced coronary perfusion pressure. **High-Yield Clinical Pearls for NEET-PG:** * **Most sensitive monitor:** Transesophageal Echocardiography (TEE) is more sensitive than ECG for detecting wall motion abnormalities (the earliest sign of ischemia). * **ECG Lead:** Lead **V5** is the most sensitive single lead for detecting ischemia (75% sensitivity), while combining **V4, V5, and Lead II** increases sensitivity to >95%. * **Management Priority:** The first step is always to increase oxygen delivery (FiO2 100%) and normalize hemodynamics (Target: Slow, Small, Regular heart).

Question 19: In a patient with severe aortic stenosis, which of the following anesthetic techniques is least preferred?

A. Propofol induction
B. Etomidate induction
C. Spinal anesthesia with 15 mg bupivacaine (Correct Answer)
D. Epidural anesthesia with 2% lidocaine

Explanation: In **Severe Aortic Stenosis (AS)**, the cardiac output is "fixed" due to the narrowed valve. The hemodynamic goals are to maintain **Normal Sinus Rhythm**, **High-Normal Afterload (SVR)**, and **Adequate Preload**. ### Why Spinal Anesthesia is Least Preferred Spinal anesthesia (Option C) is generally **contraindicated** in severe AS. A dose of 15 mg bupivacaine typically results in a rapid, dense sympathetic blockade. This causes a sudden, profound drop in **Systemic Vascular Resistance (SVR)**. Because the stenotic valve limits the increase in cardiac output, the body cannot compensate for this hypotension. This leads to decreased coronary perfusion pressure, myocardial ischemia, and potentially fatal cardiac arrest. ### Analysis of Other Options * **A. Propofol induction:** While propofol causes vasodilation and myocardial depression, it can be used with extreme caution and slow titration. However, it is less dangerous than the rapid onset of a high-level spinal block. * **B. Etomidate induction:** This is often the **induction agent of choice** for AS because it is cardiostable and maintains SVR and heart rate. * **D. Epidural anesthesia:** Unlike spinal anesthesia, an epidural allows for a **gradual, titrated** onset of sympathetic block. With careful dosing, SVR can be maintained more effectively than with a "single-shot" spinal. ### High-Yield Clinical Pearls for NEET-PG * **The "Death Spiral" of AS:** Hypotension → Decreased Coronary Perfusion → Myocardial Ischemia → Decreased Contractility → Further Hypotension. * **Heart Rate Goal:** Maintain a slow-to-normal heart rate (60–80 bpm). Tachycardia is poorly tolerated as it decreases diastolic filling time and increases oxygen demand. * **Atrial Kick:** Maintenance of Sinus Rhythm is vital; the "atrial kick" contributes up to 40% of stroke volume in AS patients. * **Vasopressor of Choice:** Phenylephrine (increases SVR without increasing heart rate).

Question 20: Which of the following induction agents produces cardiac stability in patients with coronary artery disease?

A. Ketamine
B. Etomidate (Correct Answer)
C. Propofol
D. Midazolam

Explanation: **Explanation:** **Etomidate** is the induction agent of choice for patients with coronary artery disease (CAD) or compromised cardiovascular reserve because it provides the greatest **hemodynamic stability**. It has minimal to no effect on heart rate, mean arterial pressure, or cardiac output. Crucially, it maintains the balance between myocardial oxygen supply and demand, making it ideal for patients where tachycardia or hypotension could trigger ischemia. **Analysis of Incorrect Options:** * **Ketamine (A):** It is a direct myocardial depressant but acts as a **sympathomimetic** by inhibiting catecholamine reuptake. This leads to increased heart rate, blood pressure, and myocardial oxygen consumption, which can precipitate angina or myocardial infarction in CAD patients. * **Propofol (C):** It causes significant **hypotension** due to profound vasodilation (decreased systemic vascular resistance) and direct myocardial depression. This drop in perfusion pressure can compromise coronary blood flow. * **Midazolam (D):** While relatively safe, it can cause a modest decrease in systemic vascular resistance and blood pressure, especially when combined with opioids. It is not as "cardio-stable" as Etomidate. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Etomidate acts via the GABA-A receptor. * **Major Side Effect:** **Adrenocortical suppression** (inhibits 11-beta-hydroxylase), which is its most tested disadvantage. * **Myoclonus:** Common during induction with Etomidate (can be reduced by pre-treatment with opioids). * **Drug of Choice:** For patients with shock, trauma, or severe valvular heart disease.

Practice by Chapter

Cardiovascular Physiology

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Anesthesia for Coronary Artery Disease

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Valvular Heart Disease Management

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Congenital Heart Disease in Adults

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Cardiopulmonary Bypass Principles

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Myocardial Protection Strategies

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Inotropes and Vasopressors

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Vasodilators in Cardiac Anesthesia

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Transesophageal Echocardiography

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Off-Pump Cardiac Surgery

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Management of Cardiac Pacemakers and ICDs

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