Myocardial Protection Strategies — MCQs
BETA-blockers are contraindicated in which of the following conditions?
Which of the following inhalational agents sensitizes myocardium to catecholamines?
Which of the following agents is not used to provide induced hypotension during surgery ?
Which drug is used as an adjunct to epinephrine in refractory ventricular fibrillation/ventricular tachycardia during cardiac arrest?
A 67-year-old man presents to the emergency department for squeezing and substernal chest pain. He states that he was at home eating dinner when his symptoms began. The patient has a past medical history of diabetes, hypertension, and dyslipidemia. He is currently taking atorvastatin, lisinopril, insulin, metformin, metoprolol, and aspirin. Six days ago he underwent percutaneous coronary intervention. His temperature is 99.5°F (37.5°C), blood pressure is 197/118 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam reveals an uncomfortable elderly man who is sweating. An ECG is ordered. Which of the following is the best next step in management for this patient?
Which of the following is most cardio depressant
Which of the following is not true about cardiopulmonary resuscitation (CPR)?
What is the primary method of primordial prevention for Coronary Artery Disease (CAD)?
Most sensitive method of monitoring cardiovascular ischemia in the perioperative period is -
Drug that does not cause cardiac depression:
Myocardial Protection Strategies Indian Medical PG Practice Questions and MCQs
Question 1: BETA-blockers are contraindicated in which of the following conditions?
- A. Hypertension
- B. Thyrotoxicosis
- C. Variant angina (Correct Answer)
- D. None of the options
Explanation: ***Variant angina*** - Beta-blockers can paradoxically worsen **variant angina** by enhancing coronary vasospasm due to unopposed **alpha-receptor stimulation**, especially with non-selective agents. - This condition involves transient, focal coronary artery spasms reducing blood flow, which beta-blockers may exacerbate by inhibiting **beta-2 receptor-mediated vasodilation**. *Hypertension* - Beta-blockers are a **first-line treatment** for hypertension, particularly in patients with co-existing conditions like **angina** or **post-myocardial infarction** [2]. - They reduce blood pressure by decreasing **cardiac output** and inhibiting renin release [2]. *Thyrotoxicosis* - Beta-blockers are highly effective in managing the **symptomatic features** of thyrotoxicosis, such as **tachycardia**, palpitations, and tremor [1]. - They act by blocking the effects of **excess thyroid hormones** on beta-adrenergic receptors and can inhibit peripheral conversion of thyroxine to triiodothyronine [1]. *None of the options* - Since **variant angina** is a clear contraindication, this option is incorrect. - Beta-blockers have specific situations where their use is harmful or ineffective.
Question 2: Which of the following inhalational agents sensitizes myocardium to catecholamines?
- A. Ether
- B. Isoflurane
- C. Sevoflurane
- D. Halothane (Correct Answer)
Explanation: ***Halothane*** - **Halothane** significantly sensitizes the myocardium to the dysrhythmogenic effects of **exogenous and endogenous catecholamines**, leading to an increased risk of ventricular arrhythmias. - This effect is due to its interaction with myocardial ion channels and adrenergic receptors, making the heart more susceptible to the arrhythmogenic actions of **norepinephrine** and **epinephrine**. *Ether* - **Diethylether** does not significantly sensitize the myocardium to catecholamines; in fact, it tends to have a more stable cardiovascular profile in this regard. - While it can cause some sympathetic stimulation, its arrhythmogenic potential with catecholamines is much lower compared to halothane. *Isoflurane* - **Isoflurane** has a minimal effect on myocardial sensitization to catecholamines, making it a safer option for patients with pre-existing cardiac conditions or those requiring exogenous catecholamine administration. - It maintains cardiac rhythm stability much better than halothane in the presence of adrenergic stimulation. *Sevoflurane* - **Sevoflurane**, similar to isoflurane, causes very little myocardial sensitization to catecholamines and is considered to be a **cardiac-friendly** inhalational agent. - It maintains **hemodynamic stability** and has a low incidence of arrhythmias even with concurrent use of epinephrine.
Question 3: Which of the following agents is not used to provide induced hypotension during surgery ?
- A. Mephenteramine (Correct Answer)
- B. Sodium nitroprusside
- C. Hydralazine
- D. Esmolol
Explanation: ***Mephenteramine*** - **Mephentermine** is a **vasopressor** used to **increase blood pressure**, acting primarily through the release of **norepinephrine**. - Its effects are opposite to what is desired for **induced hypotension** during surgery, as the goal is to lower systemic blood pressure to reduce blood loss and improve surgical field visibility. *Sodium nitroprusside* - **Sodium nitroprusside** is a potent **vasodilator** that directly relaxes both **arterial** and **venous smooth muscle**, leading to a rapid and significant decrease in blood pressure. - Its rapid onset and offset of action make it a valuable agent for **controlled induced hypotension** during surgery. *Hydralazine* - **Hydralazine** is a **direct-acting arterial vasodilator** that primarily relaxes arterial smooth muscle, leading to a decrease in **peripheral vascular resistance** and blood pressure. - It can be used to induce or maintain **hypotension** during surgery, although its onset of action is slower compared to nitroprusside. *Esmolol* - **Esmolol** is a **short-acting beta-1 selective adrenergic blocker** that reduces heart rate and myocardial contractility, thereby decreasing cardiac output. - By reducing cardiac output, esmolol can contribute to **induced hypotension**, often used in conjunction with vasodilators or in situations where controlling heart rate is also desired.
Question 4: Which drug is used as an adjunct to epinephrine in refractory ventricular fibrillation/ventricular tachycardia during cardiac arrest?
- A. Atropine
- B. Adenosine
- C. High dose vasopressin
- D. Amiodarone infusion (Correct Answer)
Explanation: ***Amiodarone infusion*** - **Amiodarone** is a **Class III antiarrhythmic** drug commonly used in advanced cardiac life support (ACLS) protocols for refractory **ventricular fibrillation (VF)** or **pulseless ventricular tachycardia (VT)** that persists despite defibrillation and epinephrine [1]. - It works by blocking potassium channels, prolonging repolarization and the refractory period, which helps to stabilize the electrical activity of the heart. *Atropine* - **Atropine** is an anticholinergic drug primarily used to treat **symptomatic bradycardia** by increasing heart rate. - It is not indicated for the treatment of **ventricular fibrillation** or **ventricular tachycardia** during cardiac arrest. *High dose vasopressin* - **Vasopressin** was previously included in some ACLS algorithms as an alternative to epinephrine for **vasoconstrictive effects**, but recent guidelines do not support its routine use in cardiac arrest. - While it can cause **vasoconstriction**, there is no evidence that high-dose vasopressin improves outcomes in refractory VF/VT over epinephrine. *Adenosine* - **Adenosine** is an antiarrhythmic drug used to treat **supraventricular tachycardias (SVTs)** by transiently blocking the AV node. - It is not effective for **ventricular fibrillation** or **ventricular tachycardia** and can even be harmful in these rhythms.
Question 5: A 67-year-old man presents to the emergency department for squeezing and substernal chest pain. He states that he was at home eating dinner when his symptoms began. The patient has a past medical history of diabetes, hypertension, and dyslipidemia. He is currently taking atorvastatin, lisinopril, insulin, metformin, metoprolol, and aspirin. Six days ago he underwent percutaneous coronary intervention. His temperature is 99.5°F (37.5°C), blood pressure is 197/118 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam reveals an uncomfortable elderly man who is sweating. An ECG is ordered. Which of the following is the best next step in management for this patient?
- A. Stress testing
- B. Angiography (Correct Answer)
- C. Cardiac troponins
- D. Creatine kinase-MB
- E. Myoglobin
Explanation: ***Correct: Angiography*** - This patient presenting with **acute chest pain 6 days post-PCI** is at high risk for **stent thrombosis or acute in-stent restenosis**, which represents a life-threatening emergency. - Given the **clinical instability** (severe hypertension 197/118, tachycardia 120/min, diaphoresis) and classic ACS symptoms in the immediate post-PCI period, **urgent coronary angiography** is the best next step in management. - While ECG and troponins are important diagnostic tools, this patient requires **immediate intervention** to evaluate the recent PCI site and potentially perform emergent revascularization. - In the setting of suspected **acute stent thrombosis**, time to reperfusion is critical, and angiography allows both diagnosis and treatment. *Incorrect: Cardiac troponins* - While troponins are essential biomarkers for myocardial injury and should be obtained, they are a **diagnostic test** rather than definitive management. - Waiting for troponin results would delay definitive management in a patient with clear clinical evidence of ACS. - In this high-risk post-PCI patient with active symptoms, management should not wait for biomarker confirmation. *Incorrect: Stress testing* - Stress testing is **absolutely contraindicated** in patients with active chest pain and suspected acute MI. - It could precipitate further myocardial ischemia, arrhythmias, or cardiac arrest. - Stress testing is reserved for risk stratification in stable patients or after ACS has been ruled out. *Incorrect: Creatine kinase-MB* - CK-MB is less sensitive and specific than troponins for myocardial injury, as it can be elevated in skeletal muscle conditions. - It has a shorter elevation window and has largely been replaced by troponins in modern practice. - Like troponins, it would not change the immediate management need in this clinically unstable patient. *Incorrect: Myoglobin* - Myoglobin lacks cardiac specificity (present in both cardiac and skeletal muscle) and has poor diagnostic accuracy for MI. - Its rapid rise and fall make it unreliable, and it generates many false positives. - It has no role in guiding management decisions in suspected ACS.
Question 6: Which of the following is most cardio depressant
- A. Sevoflurane
- B. Halothane (Correct Answer)
- C. Isoflurane
- D. Desflurane
Explanation: ***Halothane*** - **Halothane** is known for causing significant **myocardial depression** by directly reducing myocardial contractility and stroke volume. - It also **sensitizes the myocardium to catecholamines**, increasing the risk of arrhythmias. *Sevoflurane* - **Sevoflurane** causes less **myocardial depression** and is often preferred in patients with compromised cardiac function. - Its effects on heart rate and blood pressure are generally moderate compared to halothane. *Isoflurane* - **Isoflurane** can cause **systemic vasodilation** and a dose-dependent decrease in blood pressure but is generally less cardio-depressant than halothane. - It maintains **cardiac output** better than halothane, sometimes increasing heart rate to compensate for vasodilation. *Desflurane* - **Desflurane** typically causes a **lesser degree of myocardial depression** and tends to preserve cardiac output. - It can, however, lead to transient increases in heart rate and blood pressure upon rapid increases in concentration due to **sympathetic stimulation**.
Question 7: Which of the following is not true about cardiopulmonary resuscitation (CPR)?
- A. The most common cause of sudden death is ischemic heart disease
- B. Closed chest massage is as effective as open chest massage (Correct Answer)
- C. Standard chest massage generally provides less than 15% of normal coronary and cerebral blood flow
- D. Early defibrillation improves survival rates in ventricular fibrillation
Explanation: ***Closed chest massage is as effective as open chest massage*** - This statement is **not true** because **open-chest cardiac massage**, while more invasive, can provide significantly higher blood flow (coronary and cerebral) compared to closed-chest compressions. - Open-chest massage allows for direct compression of the heart, leading to better hemodynamics, especially in specific situations like **cardiac tamponade** or trauma. *The most common cause of sudden death is ischemic heart disease* - **Ischemic heart disease**, particularly conditions like myocardial infarction and severe coronary artery disease, is indeed the **leading cause of sudden cardiac death** in adults. - This is due to the high prevalence of atherosclerosis and its propensity to cause life-threatening arrhythmias such as **ventricular fibrillation**. *Standard chest massage generally provides less than 15% of normal coronary and cerebral blood flow* - Standard **closed-chest compressions** are known to generate only a fraction of normal cardiac output, typically **10-30% of normal cerebral blood flow** and **5-15% of normal coronary blood flow**. - This limited blood flow underscores the importance of high-quality, continuous compressions and prompt definitive treatment to improve outcomes. *Early defibrillation improves survival rates in ventricular fibrillation* - **Ventricular fibrillation (VF)** is a common cause of cardiac arrest, and **early defibrillation** (delivery of an electrical shock) is the most effective treatment to terminate VF and restore a perfusing rhythm. - The probability of successful defibrillation and survival **decreases significantly** with every minute that passes without defibrillation.
Question 8: What is the primary method of primordial prevention for Coronary Artery Disease (CAD)?
- A. Lifestyle change (Correct Answer)
- B. Coronary bypass
- C. Treatment of CAD
- D. Screening for hypertension
Explanation: ***Lifestyle change*** - **Primordial prevention** aims to prevent the development of risk factors themselves, which is best achieved through promoting healthy behaviors like diet, exercise, and avoiding tobacco at the population level. - This approach acts *before* the onset of risk factors, addressing societal and environmental determinants of health. - Examples include promoting healthy eating habits in schools, creating walkable communities, and tobacco-free environments. *Coronary bypass* - **Coronary bypass surgery** is a treatment for established CAD with significant blockages, not a preventive measure. - It falls under the category of **tertiary prevention**, aiming to reduce complications and improve quality of life in existing disease. *Treatment of CAD* - **Treating CAD** (e.g., medications like statins or antiplatelets, procedures like angioplasty) is a form of **secondary** or **tertiary prevention**. - It focuses on managing existing disease or preventing its progression, rather than preventing the initial development of risk factors. *Screening for hypertension* - **Screening** is a form of **secondary prevention** aimed at early detection of risk factors or disease. - While important, it occurs *after* risk factors have already developed, unlike primordial prevention which prevents risk factors from emerging.
Question 9: 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 10: 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.
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