Anesthesia for Coronary Artery Disease — MCQs
Which anesthetic agent is considered the least cardiotoxic?
In which clinical scenario would you find a patient requiring the vital signs assessment technique shown in the image?
Drug that does not cause cardiac depression:
Most sensitive method of monitoring cardiovascular ischemia in the perioperative period is -
Which local anesthetic is considered the most cardiotoxic?
45 year old woman is posted for elective incisional hernia repair. On reviewing her history, she is known hypertensive patient for the past 10 years on regular captopril. What is your concern for the patient
What is the primary cardiotoxic effect of bupivacaine?
Problems which may result from hypotensive anesthesia include:
An induction agent of choice for poor-risk patients with cardiorespiratory disease as well as in situations where preservation of a normal blood pressure is crucial:-
Which of the following is not used in controlling heart rate intraoperatively?
Anesthesia for Coronary Artery Disease Indian Medical PG Practice Questions and MCQs
Question 1: Which anesthetic agent is considered the least cardiotoxic?
- A. Isoflurane
- B. Enflurane
- C. Sevoflurane (Correct Answer)
- D. Halothane
Explanation: ***Sevoflurane*** - Sevoflurane is known for its **smooth induction** and rapid recovery, making it a common choice, especially in pediatric anesthesia [3]. - It has a relatively **low pungency** and minimal cardiovascular depressant effects compared to other volatile anesthetics, contributing to its favorable cardiotoxicity profile [1], [4]. *Enflurane* - Enflurane can cause **myocardial depression** and may induce **seizures** at higher concentrations, limiting its use [1]. - Its widespread use has decreased due to concerns about its **cardiovascular effects** and potential for **renal toxicity**. *Isoflurane* - While Isoflurane is a commonly used anesthetic, it can cause **coronary steal phenomenon** in patients with coronary artery disease due to its potent vasodilatory effects. - It also causes dose-dependent **myocardial depression** and can increase heart rate, which may be detrimental in some patients [4]. *Halothane* - Halothane is known for significant **myocardial depression**, causing a decrease in cardiac output and systemic vascular resistance [2]. - It also sensitizes the myocardium to **catecholamines**, increasing the risk of arrhythmias, and is associated with **halothane hepatitis**, a rare but severe liver injury [3].
Question 2: In which clinical scenario would you find a patient requiring the vital signs assessment technique shown in the image?
- A. Pulse absent, breath present
- B. Pulse and breath both not present
- C. Pulse and breath present
- D. Pulse present, breath absent (Correct Answer)
Explanation: ***Pulse present, breath absent*** - The image depicts a **mouth-to-mouth resuscitation** technique, specifically rescue breaths being administered by one person to another. - This technique is applied when a person has a **detectable pulse** but is **not breathing** or is only gasping, indicating respiratory arrest while the heart is still circulating blood. *Pulse absent, breath present* - This scenario would represent **cardiac arrest** where the heart has stopped, but the person is still attempting to breathe. This is a rare, transient state. - In such a case, the primary intervention would be **chest compressions**, not just rescue breathing, as circulation is the immediate priority. *Pulse and breath both not present* - This describes **cardiopulmonary arrest (CPA)**, where both the heart and lungs have ceased functioning. - The appropriate intervention is **cardiopulmonary resuscitation (CPR)**, which involves a combination of **chest compressions and rescue breaths (30:2 ratio)**, not just rescue breaths alone. *Pulse and breath present* - If both vital signs are present, the person is **conscious and breathing adequately**, or unconscious but breathing normally. - No advanced respiratory intervention like mouth-to-mouth resuscitation is needed; the priority would be maintaining their airway and monitoring their condition.
Question 3: Drug that does not cause cardiac depression:
- A. Thiopentone
- B. Ketamine
- C. Propofol
- D. Etomidate (Correct Answer)
Explanation: ***Etomidate*** - Etomidate is known for its **cardiovascular stability**, making it a preferred induction agent in patients with **compromised cardiac function**. - It maintains **myocardial contractility** and does not typically cause a significant drop in blood pressure. *Thiopentone* - Thiopentone causes **dose-dependent myocardial depression** and peripheral vasodilation. - This can lead to a significant **decrease in blood pressure** and cardiac output, especially in hypovolemic patients. *Propofol* - Propofol is a potent **vasodilator** and can cause significant **myocardial depression**, leading to hypotension. - Its cardiovascular effects are often more pronounced than those of other induction agents, necessitating careful titration. *Ketamine* - Ketamine causes indirect cardiovascular stimulation (due to **sympathetic nervous system activation**), but direct myocardial depression. - While it often increases heart rate and blood pressure, this is a compensatory mechanism and its direct effect on the myocardium is depressant.
Question 4: Most sensitive method of monitoring cardiovascular ischemia in the perioperative period is -
- A. NIBP
- B. ECG
- C. Pulse oximeter
- D. TEE (Correct Answer)
Explanation: ***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.
Question 5: Which local anesthetic is considered the most cardiotoxic?
- A. Procaine
- B. Prilocaine
- C. Ropivacaine
- D. Bupivacaine (Correct Answer)
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.
Question 6: 45 year old woman is posted for elective incisional hernia repair. On reviewing her history, she is known hypertensive patient for the past 10 years on regular captopril. What is your concern for the patient
- A. Stop captopril a week before surgery and switch to a calcium channel blocker like amlodipine.
- B. Stop captopril a week before surgery and restart only if needed.
- C. Stop captopril one day before surgery to prevent intraoperative hypotension.
- D. Continue captopril until the day of surgery to maintain blood pressure control. (Correct Answer)
Explanation: ***Continue captopril until the day of surgery to maintain blood pressure control.*** - Maintaining **blood pressure control** is crucial in hypertensive patients undergoing surgery to prevent perioperative cardiovascular events. - **Captopril**, an ACE inhibitor, helps manage chronic hypertension, and discontinuing it without a strong indication could lead to a **rebound hypertensive crisis**. *Stop captopril one day before surgery to prevent intraoperative hypotension.* - While ACE inhibitors can cause **hypotension** under anesthesia, the risk of **uncontrolled hypertension** from stopping it acutely may outweigh this concern for elective surgery. - Recent guidelines often recommend **continuing ACE inhibitors** until the day of surgery, especially for patients with well-controlled hypertension. *Stop captopril a week before surgery and switch to a calcium channel blocker like amlodipine.* - Switching medications a week before surgery introduces a new variable that might not be fully monitored, potentially leading to **unpredictable blood pressure responses**. - There is no strong evidence to suggest that switching to a **calcium channel blocker** offers a significant advantage over continuing a stable ACE inhibitor immediately before elective surgery. *Stop captopril a week before surgery and restart only if needed.* - Discontinuing captopril a week in advance without substituting it would leave the patient's **hypertension untreated** for an extended period, increasing the risk of adverse cardiovascular events. - **Abrupt cessation** of antihypertensive medication can lead to poorer outcomes, including **hypertensive crisis**, particularly with short-acting medications like captopril.
Question 7: What is the primary cardiotoxic effect of bupivacaine?
- A. Depressed pacemaker activity (Correct Answer)
- B. Toxic compound damaging myocardial cells
- C. Depressed neural control on heart
- D. Vascular thrombosis and Myocardial ischemia
Explanation: ***Depressed pacemaker activity*** - **Bupivacaine** is a potent **local anesthetic** that blocks voltage-gated **sodium channels** in myocardial cells with **high affinity** and **slow dissociation kinetics**. - This prolonged channel blockade leads to decreased cardiac excitability and **depressed automaticity** of pacemaker cells, particularly affecting the **SA node** and **His-Purkinje system**. - Results in slowing of the **heart rate**, **bradyarrhythmias**, **conduction blocks**, and potentially **ventricular arrhythmias** or **asystole**. - Bupivacaine is **more cardiotoxic** than other local anesthetics due to its **lipophilicity** and prolonged binding to cardiac sodium channels. *Toxic compound damaging myocardial cells* - While **bupivacaine** is cardiotoxic, its primary mechanism is not direct **cellular damage** through cytotoxic effects, oxidative stress, or cell membrane lysis. - The toxicity is predominantly due to **electrophysiological effects** on ion channels, interfering with normal cardiac conduction and contractility. *Depressed neural control on heart* - **Bupivacaine's** cardiotoxicity primarily affects the **myocardium directly** through sodium channel blockade, rather than indirectly through the **autonomic nervous system**. - Although high systemic concentrations can affect the **central nervous system** (causing seizures and CNS depression), the direct cardiac effects occur independently of neural influence. *Vascular thrombosis and Myocardial ischemia* - **Bupivacaine** cardiotoxicity does not typically involve formation of **thrombi** or mechanisms leading to **myocardial ischemia** through coronary artery occlusion. - Its effects are predominantly on the **electrical conduction system**, **myocardial contractility**, and **cardiac ion channels**, not the vascular supply to the heart.
Question 8: Problems which may result from hypotensive anesthesia include:
- A. Deep vein thrombosis
- B. Reactionary hemorrhage
- C. Retraction anemia
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - Hypotensive anesthesia is a technique used to reduce **blood pressure** during surgery, aiming to decrease **blood loss** and improve the **surgical field visibility**. - While beneficial, it carries inherent risks including **deep vein thrombosis (DVT), reactionary hemorrhage**, and complications like **retraction anemia** if not managed properly. *Deep vein thrombosis (DVT)* - While hypotension might seem to reduce the risk by lowering **blood flow velocity**, prolonged immobility and potential for **venous stasis** during any surgery, especially under hypotension, can increase DVT risk. - The combination of **endothelial dysfunction** and **hypercoagulability** often seen in surgical patients, coupled with reduced peripheral blood flow due to hypotension, can contribute to DVT formation. *Reactionary hemorrhage* - This is a common post-operative complication where bleeding restarts hours after surgery. With hypotensive anesthesia, **blood vessels** are constricted and may not be actively bleeding during the surgery. - As the patient's **blood pressure** returns to normal post-operatively, these previously undetected bleeds can manifest as significant **hemorrhage** due to the increased pressure. *Retraction anemia* - This term is less commonly used in medical literature. However, it likely refers to the complications arising from prolonged tissue retraction during surgery, which, when combined with reduced **perfusion** from hypotensive anesthesia, can lead to **tissue ischemia** or damage akin to anemia in the affected area. - The reduced **oxygen delivery** to tissues during hypotensive states, especially when further compromised by retraction, may result in localized tissue injury or contribute to systemic complications if severe or prolonged.
Question 9: An induction agent of choice for poor-risk patients with cardiorespiratory disease as well as in situations where preservation of a normal blood pressure is crucial:-
- A. Ketamine
- B. Etomidate (Correct Answer)
- C. Propofol
- D. Thiopentone
Explanation: ***Etomidate*** - Etomidate is preferred in patients with **cardiac disease** or **hemodynamic instability** due to its minimal effects on cardiovascular function. - It maintains **cardiovascular stability**, including myocardial contractility and blood pressure, making it ideal for procedures where maintaining a normal blood pressure is crucial. *Ketamine* - Ketamine often causes a **sympathetic stimulating effect**, leading to increases in heart rate and blood pressure, which may be detrimental in such patients. - It is associated with **tachycardia** and **hypertension**, undesirable in a poor-risk patient with cardiorespiratory disease. *Propofol* - Propofol is a potent **vasodilator** and myocardial depressant, which can lead to significant **hypotension**, especially in volume-depleted or critically ill patients. - Its use can result in a dose-dependent decrease in **arterial blood pressure** and **cardiac output**. *Thiopentone* - Thiopentone can cause **myocardial depression** and significant **hypotension**, especially in patients with compromised cardiovascular function. - It leads to a notable decrease in **vascular tone** and venous return, thus lowering blood pressure.
Question 10: Which of the following is not used in controlling heart rate intraoperatively?
- A. Verapamil
- B. Esmolol
- C. Propanolol/Metoprolol
- D. Procainamide (Correct Answer)
Explanation: ***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.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free