Cardiovascular Anesthesia Practice Questions

Q: Which of the following is NOT a treatment for supraventricular tachycardia with hypotension in a patient under general anesthesia?

Verapamil 5 mg IV. ### Explanation The management of intraoperative supraventricular tachycardia (SVT) depends primarily on the patient's **hemodynamic stability**. **1. Why Verapamil is the Correct Answer (The "NOT" treatment):** In a patient with SVT and **hypotension** (hemodynamic instability), calcium channel blockers like Verapamil are **contraindicated**. Verapamil has potent negative inotropic and vasodilator properties. Administering it to a hypotensive patient can cause a further drop in systemic vascular resistance and myocardial contractility, potentially leading to cardiovascular collapse or cardiac arrest. **2. Analysis of Other Options:** * **Direct Current (DC) Cardioversion (Option C):** This is the **treatment of choice** for any tachyarrhythmia causing hemodynamic instability (hypotension, altered mentation, or pulmonary edema) under general anesthesia. Synchronized cardioversion (starting at 50-100J) provides immediate rhythm correction. * **Adenosine (Option B):** If the patient is unstable but IV access is immediately available, Adenosine (6mg, then 12mg) can be attempted as it has an ultra-short half-life and may terminate the reentry circuit without prolonged hemodynamic depression. * **Carotid Sinus Massage (Option A):** This is a non-invasive vagal maneuver that can be attempted quickly to increase vagal tone and slow AV node conduction while preparing for cardioversion. **Clinical Pearls for NEET-PG:** * **Unstable Tachycardia:** Always choose **Synchronized DC Cardioversion**. * **Stable SVT:** First-line is Vagal maneuvers, followed by Adenosine (Drug of Choice). * **Verapamil Warning:** Never give Verapamil in wide-complex tachycardias of unknown origin or in patients with WPW syndrome + Atrial Fibrillation, as it can lead to ventricular fibrillation. * **Amiodarone:** Preferred for stable ventricular tachycardia or refractory SVT.

Q: A 62-year-old man is suffering from arrhythmias post triple coronary bypass surgery. Potassium has been administered, and his urine output is 20 to 30 mL/h. The serum potassium level is 6.2 mEq/L. Which of the following medications counteracts the cardiac effects of hyperkalemia without reducing the serum potassium level?

Calcium gluconate. ### Explanation The correct answer is **Calcium gluconate**. **Mechanism of Action (Why it is correct):** Hyperkalemia (K⁺ > 5.5 mEq/L) increases the resting membrane potential of cardiac myocytes, bringing it closer to the threshold potential. This leads to membrane hyperexcitability followed by inactivation of sodium channels, causing bradycardia, heart block, or ventricular fibrillation. **Calcium gluconate** (or Calcium chloride) acts as a **membrane stabilizer**. It antagonizes the cardiotoxic effects of potassium by increasing the threshold potential, thereby restoring the normal gradient between resting and threshold potentials. Crucially, calcium **does not lower** the serum potassium level; it only protects the heart. **Analysis of Incorrect Options:** * **Sodium polystyrene sulfonate (Kayexalate):** This is a cation-exchange resin that removes potassium from the body via the GI tract. It lowers the total body potassium level. * **Sodium bicarbonate:** This promotes an intracellular shift of potassium ions in exchange for hydrogen ions (alkalosis-induced shift), thereby reducing serum potassium levels. * **50% Dextrose with Insulin:** Insulin stimulates the Na⁺-K⁺ ATPase pump, shifting potassium from the extracellular to the intracellular compartment. This reduces serum potassium levels. **High-Yield Clinical Pearls for NEET-PG:** * **First-line treatment:** In hyperkalemia with ECG changes (e.g., peaked T waves, widened QRS), Calcium gluconate is the **immediate first step**. * **Duration:** The effect of Calcium gluconate is rapid (1–3 minutes) but short-lived (30–60 minutes). * **Caution:** Use calcium with extreme caution in patients taking **Digoxin**, as it can potentiate digoxin toxicity ("stone heart"). * **Calcium Gluconate vs. Chloride:** Calcium chloride contains 3x more elemental calcium than gluconate but is more irritating to peripheral veins.

Q: What is the anesthetic agent of choice in congenital heart disease with a right-to-left shunt?

Ketamine. **Explanation:** In congenital heart disease (CHD) with a **right-to-left (R-L) shunt** (e.g., Tetralogy of Fallot), the primary anesthetic goal is to maintain or increase **Systemic Vascular Resistance (SVR)** while avoiding increases in Pulmonary Vascular Resistance (PVR). A drop in SVR worsens the shunt, leading to increased cyanosis and "Tet spells." **Why Ketamine is the Correct Answer:** Ketamine is a sympathomimetic agent that increases SVR by stimulating the release of endogenous catecholamines. By increasing systemic pressure relative to pulmonary pressure, Ketamine effectively **decreases the R-L shunt fraction**, thereby improving arterial oxygenation. It also maintains heart rate and contractility, making it the safest induction agent for cyanotic heart disease. **Why the Other Options are Incorrect:** * **Propofol & Thiopentone:** Both agents are potent vasodilators that significantly **decrease SVR**. This drop in systemic pressure allows more blood to bypass the lungs via the shunt, leading to profound hypoxia and cardiovascular collapse in R-L shunt patients. * **Etomidate:** While cardiostable, Etomidate typically causes a mild decrease or no change in SVR. It does not provide the beneficial increase in SVR seen with Ketamine, making it a secondary choice. **High-Yield Clinical Pearls for NEET-PG:** * **Induction Speed:** In R-L shunts, **intravenous induction is faster** (bypass of lungs), while **inhalation induction is slower** (decreased pulmonary blood flow). * **The "Tet Spell" Management:** Treatment includes 100% $O_2$, knee-chest position (to increase SVR), and drugs like **Phenylephrine** (pure alpha-agonist to increase SVR) or **Morphine** (to calm the patient and reduce infundibular spasm). * **Avoid:** Dehydration, crying/struggling (increases PVR), and histamine-releasing drugs.

Q: What is the drug of choice for intraoperative right heart failure due to pulmonary hypertension?

Milrinone. **Explanation:** The management of intraoperative right heart failure (RHF) secondary to pulmonary hypertension focuses on two goals: **reducing pulmonary vascular resistance (PVR)** to unload the right ventricle and **increasing myocardial contractility** (inotropy). **Why Milrinone is the Correct Answer:** Milrinone is a **Phosphodiesterase-3 (PDE3) inhibitor**. It increases intracellular cAMP in both cardiac muscle and vascular smooth muscle. This results in a dual action known as **"Inodilatation"**: 1. **Inotropy:** It increases right ventricular (RV) contractility without significantly increasing myocardial oxygen demand. 2. **Vasodilation:** It causes potent pulmonary vasodilation, thereby decreasing RV afterload. Unlike catecholamines, its effects are independent of beta-receptors, making it effective even in patients with receptor down-regulation or those on beta-blockers. **Analysis of Incorrect Options:** * **A. Dopamine:** At higher doses, dopamine causes alpha-1 mediated vasoconstriction, which can increase pulmonary artery pressure and worsen RV afterload. * **B. Isoprenaline:** While it is a potent inotrope and pulmonary vasodilator, it causes significant tachycardia and systemic hypotension, which can compromise RV coronary perfusion. * **D. Halothane:** This is a potent myocardial depressant and can worsen heart failure; it also lacks specific pulmonary vasodilatory properties. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard:** Inhaled Nitric Oxide (iNO) is the most specific pulmonary vasodilator as it does not cause systemic hypotension, but among systemic drugs, **Milrinone** is the drug of choice. * **The "Vicious Cycle":** In RHF, systemic hypotension must be avoided because the RV depends heavily on the pressure gradient between the aorta and the right ventricle for its coronary perfusion. * **Inodilator Concept:** Milrinone and Levosimendan are the two primary inodilators tested in exams.

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

Fentanyl. **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.

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.

Question 1

A 70-year-old patient with ejection fraction of 25% requires cardioversion for atrial fibrillation in the cardiology suite. During propofol induction (1.5 mg/kg), BP drops from 110/70 to 70/40 mmHg. What is the primary pathophysiological mechanism?

Accepted Answer

Propofol-induced myocardial depression in compromised ventricle

Answer

Coronary steal phenomenon

Answer

Loss of atrial kick after cardioversion

Answer

Excessive preload reduction from venodilation

Question 2

Which of the following is NOT a treatment for supraventricular tachycardia with hypotension in a patient under general anesthesia?

Accepted Answer

Verapamil 5 mg IV

Answer

Carotid sinus massage

Answer

Adenosine 3-12 mg IV

Answer

Direct current cardioversion

Question 3

A 62-year-old man is suffering from arrhythmias post triple coronary bypass surgery. Potassium has been administered, and his urine output is 20 to 30 mL/h. The serum potassium level is 6.2 mEq/L. Which of the following medications counteracts the cardiac effects of hyperkalemia without reducing the serum potassium level?

Accepted Answer

Calcium gluconate

Answer

Sodium polystyrene sulfonate

Answer

Sodium bicarbonate

Answer

50% dextrose with insulin

Question 4

What is the anesthetic agent of choice in congenital heart disease with a right-to-left shunt?

Accepted Answer

Ketamine

Answer

Thiopentone

Answer

Propofol

Answer

Etomidate

Question 5

A 71-year-old man returns from the operating room after undergoing a triple coronary bypass. His initial cardiac index is 2.8 L/(min*m2). His heart rate is then noted to be 55 beats per minute, BP is 110/80 mm Hg, wedge pressure is 15, and his cardiac index has dropped to 1.6 L/(min*m2). He has a normal left ventricle. Which of the following maneuvers will increase his cardiac output?

Accepted Answer

Increase his heart rate to 90 by electrical pacing.

Answer

Increase his peripheral vascular resistance.

Answer

Increase his central venous pressure.

Answer

Increase his blood viscosity.

Question 6

What is the drug of choice for intraoperative right heart failure due to pulmonary hypertension?

Accepted Answer

Milrinone

Answer

Dopamine

Answer

Isoprenaline

Answer

Halothane

Question 7

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

Accepted Answer

Fentanyl

Answer

Morphine

Answer

Meperidine

Answer

Pentazocine

Question 8

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

Accepted Answer

Heparin

Answer

Intravenous nitroglycerine

Answer

Calcium channel blocker

Answer

Atropine

Question 9

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

Accepted Answer

Spinal anesthesia with 15 mg bupivacaine

Answer

Propofol induction

Answer

Etomidate induction

Answer

Epidural anesthesia with 2% lidocaine

Question 10

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

Accepted Answer

Etomidate

Answer

Ketamine

Answer

Propofol

Answer

Midazolam

Cardiovascular Anesthesia — MCQs

Cardiovascular Anesthesia — MCQs

On this page

Practice by Chapter

Want unlimited practice?