Cardiovascular Anesthesia Practice Questions

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

Etomidate. **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.

Q: Which of the following produces the least damage to blood elements during cardiopulmonary bypass?

Membrane oxygenator. **Explanation:** The primary goal of an oxygenator in a cardiopulmonary bypass (CPB) circuit is to facilitate gas exchange (O₂ uptake and CO₂ removal) while minimizing trauma to blood components. **1. Why Membrane Oxygenator is the Correct Answer:** The **Membrane Oxygenator** is currently the gold standard because it utilizes a semi-permeable membrane (usually microporous polypropylene or silicone) to separate the blood phase from the gas phase. This prevents a **direct gas-blood interface**, which significantly reduces the denaturation of plasma proteins, hemolysis of red blood cells, and activation of platelets and complement systems. It mimics the natural alveolar-capillary barrier of the human lung, making it the least traumatic option for long-term bypass. **2. Why Other Options are Incorrect:** * **Bubble Oxygenator (C):** Here, oxygen is bubbled directly through the blood. The direct contact between gas and blood causes significant hemolysis and protein denaturation. It also carries a higher risk of gaseous microemboli. * **Disc (A) and Screen (D) Oxygenators:** These are older "film" oxygenators. They work by spreading blood over a large surface area (rotating discs or wire screens) exposed to an oxygen-rich atmosphere. Like bubble oxygenators, the direct gas-blood interface leads to high rates of cellular damage and is rarely used in modern practice. **Clinical Pearls for NEET-PG:** * **Ideal Oxygenator:** The membrane oxygenator is preferred for procedures lasting >2 hours to prevent "post-perfusion syndrome." * **Priming:** CPB circuits are typically primed with balanced salt solutions (like Ringer's Lactate) to maintain volume and reduce viscosity (hemodilution). * **Monitoring:** During CPB, the **Activated Clotting Time (ACT)** must be maintained >400–480 seconds to ensure adequate anticoagulation.

Q: What is the anesthetic of choice for cardiac anesthesia?

Isoflurane. **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.

Q: Most sensitive method of monitoring cardiovascular ischemia in the perioperative period is -

TEE. ***TEE*** - **Transesophageal echocardiography (TEE)** is the most sensitive method for detecting perioperative myocardial ischemia because it can visualize **regional wall motion abnormalities** and changes in **ventricular function** much earlier than ECG. - **Ischemia** directly impairs the contractility of the affected myocardium, leading to subtle changes in wall motion that TEE can identify. *NIBP* - **Non-invasive blood pressure (NIBP)** monitoring can detect **hemodynamic changes** (like hypotension or hypertension) that may precede or accompany ischemia. - However, these changes are **non-specific** and occur relatively late, making NIBP a less sensitive indicator of early ischemia. *ECG* - **Electrocardiography (ECG)** monitors the electrical activity of the heart and can detect **ST-segment changes** indicative of ischemia. - While useful, ECG changes may appear later than wall motion abnormalities, and **silent ischemia** can be missed if the leads are not optimally placed or if the ischemia does not produce significant electrical changes. *Pulse oximeter* - A **pulse oximeter** measures **oxygen saturation** in the peripheral blood. - It is primarily used to assess **respiratory function** and tissue oxygenation, and it does not directly monitor myocardial ischemia or cardiac function.

Q: Coronary steal syndrome is associated with

Isoflurane. ***Isoflurane*** - **Isoflurane** is a potent coronary vasodilator which can cause coronary steal syndrome in patients with existing **coronary artery disease**. - It preferentially dilates normal coronary arteries, diverting blood flow away from stenotic areas, potentially worsening **myocardial ischemia**. *Sevoflurane* - **Sevoflurane** is also a vasodilator but is generally considered to have a lower risk of coronary steal compared to isoflurane. - Its vasodilatory effects are less pronounced in diseased arteries, making it a safer option for patients with **ischemic heart disease**. *Halothane* - **Halothane** is known for myocardial depression and arrhythmias, but its coronary dilating properties are less pronounced and it is infrequently associated with coronary steal. - It is an older inhalational anesthetic that has largely been replaced due to its side effect profile, including potential **hepatotoxicity**. *Desflurane* - **Desflurane** is a potent vasodilator, similar to isoflurane, but it typically causes peripheral vasodilation rather than significant coronary steal. - Its rapid onset and offset are beneficial, but it can cause **tachycardia** and **hypertension** with rapid increases in concentration.

Q: Which of the following is not used in controlling heart rate intraoperatively?

Procainamide. ***Procainamide*** - While an antiarrhythmic, **procainamide** is primarily used for the treatment of various *atrial* and *ventricular arrhythmias* and *Wolff-Parkinson-White syndrome*, not for heart rate control alone. - Its mechanism involves blocking sodium channels and some potassium channels, affecting myocardial excitability and conduction. *Verapamil* - **Verapamil** is a **non-dihydropyridine calcium channel blocker** frequently used intraoperatively to **slow heart rate** by acting on the sinoatrial and atrioventricular nodes. - It is effective in treating *supraventricular tachycardias* (SVT) and controlling ventricular rate in *atrial fibrillation* or *flutter*. *Esmolol* - **Esmolol** is a **short-acting, cardioselective beta-1 adrenergic blocker** that is often administered intraoperatively due to its rapid onset and offset of action. - It is used to quickly **decrease heart rate** and blood pressure, particularly in response to surgical stress or in cases of *supraventricular tachycardia*. *Propranolol/Metoprolol* - **Propranolol** (non-selective) and **Metoprolol** (cardioselective) are **beta-adrenergic blockers** commonly used to **reduce heart rate** and myocardial oxygen demand. - They are effective in managing *tachycardia*, *hypertension*, and preventing *myocardial ischemia* during surgery.

Q: A patient with history of coronary artery disease presents with pulse rate of 48/min and low BP. Patient has decreased myocardial contractility on Echo. Which of these anesthetic agents is contraindicated?

Dexmedetomidine. ***Dexmedetomidine*** - Dexmedetomidine is a **highly selective alpha-2 adrenergic agonist** that causes a dose-dependent decrease in heart rate and blood pressure, which would exacerbate the patient's existing **bradycardia** and **hypotension**. - Its negative chronotropic and inotropic effects make it contraindicated in patients with compromised cardiac function and already low heart rate and blood pressure, as it could worsen **myocardial contractility** and perfusion. *Fentanyl* - Fentanyl is an **opioid analgesic** that primarily causes respiratory depression and can lead to bradycardia, but its direct myocardial depressant effects are generally minimal compared to other agents and it can maintain hemodynamics. - While it can cause bradycardia, it does not typically cause the profound hypotensive and myocardial depression seen with dexmedetomidine, especially when used appropriately. *Etomidate* - Etomidate is a **hemodynamically stable induction agent** that has minimal effects on heart rate, blood pressure, and myocardial contractility, making it a good choice for patients with cardiovascular compromise. - Its main side effect is **adrenocortical suppression**, but it does not cause significant cardiac depression. *Ketamine* - Ketamine generally causes **sympathetic stimulation**, leading to an increase in heart rate and blood pressure by releasing **catecholamines**, which would be beneficial in a hypotensive patient with low cardiac output. - While it can have direct myocardial depressant effects in very high doses, its overall effect is often **cardiovascular stimulation**, making it a relatively good choice in this scenario.

Question 1

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

Accepted Answer

Etomidate

Answer

Ketamine

Answer

Propofol

Answer

Midazolam

Question 2

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?

Accepted Answer

DC cardioversion

Answer

Adenosine 6 mg/12 mg

Answer

Amiodarone

Answer

Esmolol

Question 3

Which of the following produces the least damage to blood elements during cardiopulmonary bypass?

Accepted Answer

Membrane oxygenator

Answer

Disc oxygenator

Answer

Bubble oxygenator

Answer

Screen oxygenator

Question 4

Which of the following is NOT desirable for a patient with a pacemaker?

Accepted Answer

Unipolar diathermy

Answer

Thiopentone sodium

Answer

ECG monitoring

Answer

Suxamethonium

Question 5

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

Accepted Answer

Phenylephrine

Answer

Ephedrine

Answer

Dopamine

Answer

Dobutamine

Question 6

What is the anesthetic of choice for cardiac anesthesia?

Accepted Answer

Isoflurane

Answer

Ketamine

Answer

Methoxyflurane

Answer

Halothane

Question 7

Most sensitive method of monitoring cardiovascular ischemia in the perioperative period is -

Accepted Answer

TEE

Answer

NIBP

Answer

ECG

Answer

Pulse oximeter

Question 8

Coronary steal syndrome is associated with

Accepted Answer

Isoflurane

Answer

Sevoflurane

Answer

Halothane

Answer

Desflurane

Question 9

Which of the following is not used in controlling heart rate intraoperatively?

Accepted Answer

Procainamide

Answer

Verapamil

Answer

Esmolol

Answer

Propanolol/Metoprolol

Question 10

A patient with history of coronary artery disease presents with pulse rate of 48/min and low BP. Patient has decreased myocardial contractility on Echo. Which of these anesthetic agents is contraindicated?

Accepted Answer

Dexmedetomidine

Answer

Fentanyl

Answer

Etomidate

Answer

Ketamine

Cardiovascular Anesthesia — MCQs

Cardiovascular Anesthesia — MCQs

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