Cardiovascular Anesthesia — MCQs

Cardiovascular Anesthesia Indian Medical PG Practice Questions and MCQs

Question 21: Which of the following is most cardiostable?

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

Explanation: ### Explanation **Etomidate** is considered the most cardiostable intravenous induction agent because it has minimal to no effect on myocardial contractility, heart rate, or cardiac output. #### Why Etomidate is the Correct Answer: The primary reason for its stability is its lack of interference with the **autonomic nervous system** and its minimal effect on **baroreceptor reflex** mechanisms. It does not cause histamine release and maintains stable systemic vascular resistance (SVR). This makes it the "gold standard" for induction in patients with compromised cardiac function, such as those with valvular heart disease, congestive heart failure, or severe coronary artery disease. #### Why Other Options are Incorrect: * **Thiopentone Sodium:** A potent venodilator that causes a significant drop in blood pressure due to peripheral pooling of blood and direct myocardial depression. It is contraindicated in hypovolemic or shock states. * **Ketamine:** While it often maintains BP, it is not "stable" in the physiological sense. It is **sympathomimetic**, causing an increase in heart rate, BP, and myocardial oxygen demand. In a failing heart with depleted catecholamines, it can actually act as a direct myocardial depressant. * **Propofol:** Known for causing the most significant drop in blood pressure among induction agents. It causes profound vasodilation (both arterial and venous) and inhibits the baroreceptor reflex, preventing a compensatory tachycardia. #### High-Yield Clinical Pearls for NEET-PG: * **Adrenal Suppression:** The major side effect of Etomidate is dose-dependent inhibition of **11-beta-hydroxylase**, leading to suppressed cortisol synthesis (caution in sepsis). * **Myoclonus:** Etomidate is frequently associated with excitatory movements (myoclonus) during induction. * **Drug of Choice:** Etomidate is the preferred agent for **Rapid Sequence Induction (RSI)** in hemodynamically unstable patients. * **Propofol** is the drug of choice for day-care surgery due to its rapid metabolism and anti-emetic properties.

Question 22: The best chances of recovery after successful cardiopulmonary resuscitation are seen in which cardiac rhythm?

A. Ventricular Tachycardia (Correct Answer)
B. Ventricular Fibrillation
C. Asystole
D. Electromechanical dissociation

Explanation: **Explanation:** The prognosis of cardiac arrest is heavily dependent on the initial presenting rhythm. **Ventricular Tachycardia (VT)**, specifically pulseless VT, carries the best prognosis for recovery and neurologically intact survival. **Why Ventricular Tachycardia is the correct answer:** VT and Ventricular Fibrillation (VF) are "shockable" rhythms. However, VT represents a more organized electrical activity than VF. In VT, the myocardium often retains better metabolic status and a higher likelihood of returning to a perfusing rhythm (ROSC) immediately following defibrillation. Because the heart is often in a "fresher" state of ischemia compared to other rhythms, the chances of successful resuscitation are highest. **Analysis of Incorrect Options:** * **Ventricular Fibrillation (VF):** While also a shockable rhythm with a good prognosis compared to non-shockable rhythms, it represents chaotic electrical activity. The longer a patient stays in VF, the more myocardial energy stores are depleted, eventually deteriorating into asystole. * **Asystole:** This is a "non-shockable" rhythm representing the total absence of electrical and mechanical activity. It usually signifies a prolonged period of ischemia and has the poorest prognosis. * **Electromechanical Dissociation (PEA):** In Pulseless Electrical Activity, there is organized electrical activity but no mechanical contraction. It is often caused by reversible factors (the H’s and T’s), but the survival rates are significantly lower than shockable rhythms like VT. **High-Yield Clinical Pearls for NEET-PG:** * **Chain of Survival:** The most critical factor in VT/VF survival is the **time to defibrillation**. * **Shockable Rhythms:** VT and VF. * **Non-Shockable Rhythms:** Asystole and PEA. * **Drug of Choice:** Epinephrine is the primary vasopressor used in all cardiac arrests; Amiodarone or Lidocaine are used specifically for refractory VT/VF.

Question 23: According to the 2010 ACLS Guidelines by AHA, which of the following pharmacological agents is not used in the management of cardiac arrest?

A. Epinephrine
B. Vasopressin
C. Atropine (Correct Answer)
D. Amiodarone

Explanation: **Explanation:** The correct answer is **Atropine**. According to the 2010 AHA ACLS Guidelines, Atropine was officially removed from the Cardiac Arrest Algorithm. **Why Atropine is the correct answer:** Previously, Atropine was used for Pulseless Electrical Activity (PEA) and Asystole. However, clinical evidence demonstrated that its routine use during cardiac arrest does not improve outcomes or survival to hospital discharge. While Atropine remains a first-line drug for **symptomatic bradycardia** (with a pulse), it is no longer indicated for a patient in active cardiac arrest. **Analysis of Incorrect Options:** * **Epinephrine (Option A):** This remains the primary vasopressor used in all cardiac arrest rhythms (VF/pVT, PEA, and Asystole). It is administered every 3–5 minutes to improve coronary and cerebral perfusion pressure via its alpha-adrenergic effects. * **Vasopressin (Option B):** In the 2010 guidelines, a single dose of Vasopressin (40 units IV/IO) was permitted as a substitute for the first or second dose of Epinephrine. (Note: It was later removed in the 2015 update to simplify the algorithm). * **Amiodarone (Option C):** This is the preferred anti-arrhythmic agent for shock-refractory Ventricular Fibrillation (VF) or pulseless Ventricular Tachycardia (pVT). **High-Yield Clinical Pearls for NEET-PG:** * **Asystole/PEA:** The only drugs indicated are Epinephrine and treating reversible causes (H’s and T’s). * **Shockable Rhythms (VF/pVT):** If shocks and Epinephrine fail, use Amiodarone (300mg bolus) or Lidocaine. * **Atropine Dosage:** For symptomatic bradycardia, the dose is 1 mg IV every 3–5 minutes (Max: 3 mg). * **Magnesium Sulfate:** Only indicated during cardiac arrest if **Torsades de Pointes** is suspected.

Question 24: A 40-year-old lady intraoperatively develops a heart rate of 220 bpm and a blood pressure of 70/40 mmHg. The ECG shows a QRS complex of 120 milliseconds. What is the best management?

A. Adenosine 6 mg/12 mg
B. Amiodarone
C. DC cardioversion (Correct Answer)
D. Esmolol

Explanation: ### Explanation The core principle in managing any perioperative tachyarrhythmia is assessing **hemodynamic stability**. **1. Why DC Cardioversion is Correct:** The patient is presenting with **unstable tachycardia**, evidenced by a heart rate of 220 bpm and significant hypotension (BP 70/40 mmHg). According to ACLS guidelines, any patient with a tachyarrhythmia (narrow or wide complex) who shows signs of "shock" or hemodynamic instability (hypotension, altered mental status, chest pain, or acute heart failure) must be treated immediately with **synchronized DC cardioversion**. In this case, the QRS duration of 120 ms (borderline wide) suggests a ventricular origin or SVT with aberrancy, but the instability makes electrical therapy the first-line priority over pharmacological intervention. **2. Why Other Options are Incorrect:** * **Adenosine:** This is the drug of choice for *stable* Narrow Complex Supraventricular Tachycardia (SVT). It is contraindicated here because the patient is hypotensive; delaying cardioversion to attempt chemical conversion increases the risk of cardiac arrest. * **Amiodarone:** This is used for *stable* Wide Complex Tachycardia (Ventricular Tachycardia). While effective, it takes time to work and is inappropriate for an unstable patient. * **Esmolol:** A short-acting beta-blocker used for rate control in stable atrial fibrillation or flutter. It has negative inotropic properties which would further worsen this patient's hypotension. **3. High-Yield Clinical Pearls for NEET-PG:** * **The "Rule of Thumb":** If the patient is **Unstable → Shock** (Synchronized Cardioversion). If the patient is **Stable → Medicate**. * **QRS Width:** Narrow (<120 ms) usually implies supraventricular origin; Wide (≥120 ms) usually implies ventricular origin. * **Synchronized vs. Unsynchronized:** Always use *synchronized* shocks for patients with a pulse (to avoid the R-on-T phenomenon and VF). Use *unsynchronized* (defibrillation) for pulseless VT or VF.

Question 25: What is the most common arrhythmia after sinus tachycardia in an ICU patient?

A. Atrial flutter (Correct Answer)
B. A-V block
C. Non-paroxysmal junctional tachycardia
D. Paroxysmal supraventricular tachycardia

Explanation: **Explanation:** In the Intensive Care Unit (ICU) setting, the most frequent rhythm disturbance encountered is **Sinus Tachycardia**, which is usually a physiological response to stress, pain, fever, or hypovolemia. However, when considering pathological supraventricular arrhythmias, **Atrial Flutter** is statistically the most common arrhythmia following sinus tachycardia in critically ill patients. **Why Atrial Flutter is correct:** Atrial flutter is frequently triggered in the ICU due to acute factors such as pulmonary embolism, electrolyte imbalances, acid-base disturbances, or cardiac surgery. It is characterized by a "saw-tooth" pattern on ECG and often presents with a fixed or variable AV block (commonly 2:1). Its high prevalence in the ICU is linked to the high adrenergic state and atrial stretch seen in critically ill patients. **Analysis of Incorrect Options:** * **A-V Block:** While common in patients with myocardial infarction or drug toxicity (e.g., Digoxin), it is a conduction defect rather than a primary tachyarrhythmia and occurs less frequently than atrial flutter in general ICU populations. * **Non-paroxysmal junctional tachycardia:** This is a rare arrhythmia typically associated with digitalis toxicity or post-cardiac surgery in pediatric patients; it is not a common finding in a general adult ICU. * **Paroxysmal Supraventricular Tachycardia (PSVT):** While common in the general population (often due to AVNRT), it occurs less frequently in the acute ICU setting compared to atrial flutter or atrial fibrillation. **High-Yield Clinical Pearls for NEET-PG:** * **Most common arrhythmia overall:** Sinus Tachycardia. * **Most common sustained arrhythmia in the elderly/ICU:** Atrial Fibrillation (Note: If Atrial Fibrillation is not an option, Atrial Flutter is the prioritized answer). * **Drug of choice for hemodynamically stable PSVT:** Adenosine. * **Treatment of choice for unstable Atrial Flutter:** Synchronized Cardioversion.

Question 26: During the surgical removal of an invasive glioma from the base of the skull, cranial nerves IX and X are accidentally cut bilaterally. What would be the immediate change in the patient's hemodynamic condition?

A. Bradycardia with hypertension
B. Bradycardia with hypotension
C. Sinus arrhythmia with hypotension
D. Tachycardia with hypertension (Correct Answer)

Explanation: **Explanation:** The correct answer is **Tachycardia with hypertension** because of the interruption of the **Baroreceptor Reflex** arc. **The Underlying Concept:** The baroreceptors (located in the carotid sinus and aortic arch) are responsible for sensing blood pressure changes and sending inhibitory signals to the vasomotor center in the medulla. * **Afferent Pathway:** The Glossopharyngeal nerve (**CN IX**) carries signals from the carotid sinus, and the Vagus nerve (**CN X**) carries signals from the aortic arch. * **Physiology:** Under normal conditions, these nerves provide tonic inhibition to the sympathetic nervous system. When both CN IX and CN X are cut bilaterally, the brain perceives an "acute loss of pressure" (pseudo-hypotension). This results in the immediate withdrawal of parasympathetic tone and a massive, unopposed **sympathetic surge**, leading to an immediate rise in heart rate (tachycardia) and systemic vascular resistance (hypertension). **Analysis of Incorrect Options:** * **A & B (Bradycardia):** Cutting the Vagus nerve (the primary parasympathetic supply to the heart) removes the "vagal brake," making bradycardia physiologically impossible in this scenario. * **C (Hypotension):** Hypotension would only occur if the sympathetic outflow were blocked. Here, the "off-switch" for the sympathetic system is destroyed, leading to the opposite effect. **High-Yield Clinical Pearls for NEET-PG:** 1. **The Reflex Arc:** Remember: **S**inus (Carotid) → **G**lossopharyngeal (IX) and **A**rch (Aortic) → **V**agus (X). (Mnemonic: **SGA-V**) 2. **Surgical Context:** Bilateral injury is rare but most common in extensive skull base surgeries or radical neck dissections. 3. **Vagal Stimulation vs. Vagal Section:** Stimulation of CN X (e.g., traction on viscera) causes bradycardia; sectioning/cutting CN X causes tachycardia. 4. **Cushing’s Triad:** Do not confuse this with the Cushing reflex (Hypertension + Bradycardia), which is caused by *increased intracranial pressure*, not direct nerve transection.

Question 27: What is the vasopressor of choice in anesthesia for a patient with aortic stenosis who develops hypotension during surgery?

A. Ephedrine
B. Dopamine
C. Dobutamine
D. Phenylephrine (Correct Answer)

Explanation: **Explanation:** The primary hemodynamic goal in managing a patient with **Aortic Stenosis (AS)** is to maintain a "slow, small, and tight" profile. This means maintaining a normal sinus rhythm, adequate preload, and **high systemic vascular resistance (SVR)**. **Why Phenylephrine is the Correct Choice:** In AS, the left ventricle (LV) is hypertrophied and highly dependent on coronary perfusion pressure to meet its high oxygen demands. Coronary perfusion pressure is determined by the gradient between the aortic diastolic pressure and the LV end-diastolic pressure. **Phenylephrine**, a pure alpha-1 agonist, increases SVR and aortic diastolic pressure without increasing the heart rate. This maintains coronary perfusion while avoiding tachycardia, which is detrimental in AS because it shortens diastole (reducing coronary filling time) and increases myocardial oxygen demand. **Why the Other Options are Incorrect:** * **Ephedrine:** This is a sympathomimetic with both alpha and beta activity. Its beta-1 effect causes tachycardia, which decreases diastolic filling time and increases myocardial oxygen consumption, potentially leading to ischemia in a stenotic heart. * **Dobutamine:** A potent beta-1 agonist (inodilator). It increases heart rate and decreases SVR, both of which are contraindicated in severe AS as they can lead to a precipitous drop in coronary perfusion. * **Dopamine:** At medium to high doses, it increases heart rate and myocardial contractility. Similar to ephedrine, the risk of tachycardia makes it less ideal than a pure alpha agonist. **High-Yield Clinical Pearls for NEET-PG:** * **AS Hemodynamic Goals:** Maintain Preload (High), SVR (High), Heart Rate (Low/Normal 60-80 bpm), and Sinus Rhythm (Crucial for atrial kick, which contributes up to 40% of LV filling in AS). * **Avoid:** Tachycardia, Bradycardia, and Vasodilation (Spinal anesthesia is generally avoided or used with extreme caution due to rapid sympathectomy). * **Fixed Cardiac Output:** AS is a fixed-output state; the heart cannot increase stroke volume in response to vasodilation.

Question 28: All of the following are indicated in the management of a patient with the given ECG findings, except?

A. CPR for 60-90 seconds
B. Epinephrine
C. Vasopressin
D. Sodium bicarbonate (Correct Answer)

Explanation: ***Sodium bicarbonate*** - **NOT routinely indicated** in ventricular fibrillation cardiac arrest management unless specific conditions like **hyperkalemia** or **tricyclic antidepressant overdose** are present. - Can worsen **intracellular acidosis** and cause **hyperosmolarity**, potentially reducing the effectiveness of resuscitation efforts. *CPR for 60-90 seconds* - In older **ACLS protocols**, CPR for 60-90 seconds was recommended before attempting defibrillation in **witnessed VF arrest**. - Provides **coronary perfusion pressure** and **cerebral blood flow** to optimize the chance of successful defibrillation. *Epinephrine* - **Alpha-adrenergic effects** increase coronary and cerebral perfusion pressure during CPR in **VF/VT cardiac arrest**. - Standard dose is **1 mg IV/IO** every 3-5 minutes during cardiac arrest resuscitation. *Vasopressin* - **Vasoconstrictor** that increases coronary and cerebral perfusion pressure, similar to epinephrine in cardiac arrest. - Can be used as an alternative to epinephrine in **VF/VT cardiac arrest** with dose of **40 units IV/IO**.

Question 29: After effective cardiopulmonary resuscitation, what physiological change is observed?

A. Constriction of pupil (Correct Answer)
B. Dilation of pupil
C. Elevation of blood pressure
D. None of the above

Explanation: **Explanation:** The primary goal of cardiopulmonary resuscitation (CPR) is to restore the delivery of oxygenated blood to vital organs, most importantly the brain. The pupillary response is a critical clinical indicator of cerebral perfusion and brainstem function during and after resuscitation. **Why Option A is Correct:** During cardiac arrest, the lack of blood flow to the brain leads to cerebral hypoxia, causing the pupils to become fixed and dilated (mydriasis) due to the loss of parasympathetic tone. **Effective CPR** restores oxygenated blood flow to the Edinger-Westphal nucleus in the midbrain. When cerebral perfusion is adequate, the parasympathetic nervous system reactivates, leading to **pupillary constriction (miosis)**. This is often the first clinical sign that resuscitative efforts are providing sufficient cardiac output to maintain brain viability. **Why Other Options are Incorrect:** * **Option B (Dilation):** Mydriasis is a sign of sympathetic overactivity or, more commonly in this context, severe cerebral hypoxia/ischemia. Persistent dilation during CPR suggests poor prognosis or inadequate chest compressions. * **Option C (Elevation of BP):** While effective CPR generates a pulse and some blood pressure, "elevation" of blood pressure (hypertension) is not a standard physiological hallmark of the resuscitation process itself. Blood pressure remains significantly lower than baseline during manual compressions. **High-Yield Clinical Pearls for NEET-PG:** * **Pupillary reflex:** The most sensitive indicator of the adequacy of cerebral circulation during CPR. * **End-Tidal CO2 (EtCO2):** The most reliable *monitor* for CPR quality. A sudden increase in EtCO2 (to >35-40 mmHg) is the earliest sign of **ROSC** (Return of Spontaneous Circulation). * **Compression Depth:** 5–6 cm in adults at a rate of 100–120 bpm. * **Epinephrine:** Administered to increase coronary perfusion pressure via alpha-1 mediated vasoconstriction.

Question 30: What is the anesthetic of choice for cardiac anesthesia?

A. Isoflurane (Correct Answer)
B. Ketamine
C. Methoxyflurane
D. Halothane

Explanation: **Explanation:** **Isoflurane (Option A)** is considered the anesthetic of choice for cardiac anesthesia among the given options due to its favorable hemodynamic profile. Its primary advantage is the **preservation of cardiac output** and its unique property of **"Ischemic Preconditioning,"** which protects the myocardium against ischemic injury. While it causes a decrease in systemic vascular resistance (SVR) leading to a drop in blood pressure, it does not significantly depress myocardial contractility compared to older agents. Furthermore, it is less likely to sensitize the myocardium to catecholamines. **Why other options are incorrect:** * **Ketamine (Option B):** While often used in hemodynamically unstable patients, it is generally avoided in patients with coronary artery disease (CAD) because it increases sympathetic outflow, leading to tachycardia and hypertension, which significantly increases myocardial oxygen demand. * **Methoxyflurane (Option C):** It is highly nephrotoxic due to the release of inorganic fluoride ions and has a very slow onset/offset, making it obsolete in modern cardiac anesthesia. * **Halothane (Option D):** It is a potent myocardial depressant and sensitizes the myocardium to endogenous and exogenous catecholamines, increasing the risk of fatal ventricular arrhythmias. It also lacks the protective preconditioning effects of isoflurane. **High-Yield Clinical Pearls for NEET-PG:** * **Coronary Steal Phenomenon:** Historically associated with Isoflurane (potent coronary vasodilator), but clinically insignificant at standard anesthetic doses (0.5–1.5 MAC). * **Sevoflurane vs. Isoflurane:** Sevoflurane is also widely used due to its rapid onset and lack of airway irritability, but Isoflurane remains a classic "textbook" answer for its stability and cost-effectiveness. * **Etomidate:** Often the induction agent of choice for cardiac surgery due to its superior hemodynamic stability.

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