Off-Pump Cardiac Surgery — MCQs

10 questions

Which of the following signs of congestive cardiac failure constitute a major risk to the surgical patient undergoing anaesthesia ?

Drug that does not cause cardiac depression:

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

Which of the following is the LEAST significant risk factor for postoperative pulmonary complications?

The most sensitive and practical technique for detection of myocardial ischemia in the perioperative period is -

A 48-year-old male patient is scheduled to undergo coronary arterial bypass surgery due to chronic angina. Coronary arteriography reveals nearly total blockage of the posterior descending interventricular artery. When exposing this artery to perform the bypass procedure, which accompanying vessel is most at risk of injury?

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 is not an obvious advantage of high-flow nasal cannula (HFNC):

Patient shows ST depression, troponin rise 6h post-surgery. Next best step is:

Q10

Which of the following devices typically requires the most stringent safety protocols before MRI scanning?

Off-Pump Cardiac Surgery Indian Medical PG Practice Questions and MCQs

Question 1: Which of the following signs of congestive cardiac failure constitute a major risk to the surgical patient undergoing anaesthesia ?

A. Pedal oedema
B. Jugular venous distention and third heart sound (Correct Answer)
C. Basal crepitations on auscultation
D. Cardiomegaly

Explanation: ***Jugular venous distention and third heart sound*** - **Jugular venous distention (JVD)** indicates elevated right atrial pressure and **central venous pressure**, signifying significant volume overload and potential right ventricular dysfunction. - A **third heart sound (S3)** is a strong indicator of **ventricular dysfunction** and high filling pressures, suggesting severe heart failure and poor cardiac reserve, which poses a major risk during anesthesia. *Pedal oedema* - **Pedal edema** can be a sign of fluid overload, but it is a relatively mild and chronic symptom of heart failure compared to acute decompensation. - While it reflects increased hydrostatic pressure, it doesn't alone signify the immediate, critical hemodynamic instability that poses a major perioperative risk. *Basal crepitations on auscultation* - **Basal crepitations** (rales) suggest **pulmonary congestion** due to left ventricular failure, indicating fluid in the small airways. - Although concerning, this sign primarily reflects lung involvement and not necessarily the critical, global hemodynamic compromise indicated by JVD and S3. *Cardiomegaly* - **Cardiomegaly** (enlarged heart) is an imaging finding that reflects chronic cardiac remodeling due to long-standing heart disease. - It indicates a history of heart failure but does not directly reflect the **acute hemodynamic status** and immediate risk of decompensation during surgery.

Question 2: 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 3: 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 4: Which of the following is the LEAST significant risk factor for postoperative pulmonary complications?

A. Age >70
B. Patient with 7 pack years of smoking
C. Upper abdominal surgery
D. BMI>30 (Correct Answer)

Explanation: ***BMI>30*** - While **obesity (BMI >30)** is associated with some surgical risks, it is generally considered a less significant independent risk factor for postoperative pulmonary complications compared to other factors like age, smoking, and surgical site. - The impact of obesity on pulmonary function is complex and varies depending on the type of surgery and presence of comorbid conditions like **sleep apnea**. *Age >70* - **Advanced age (>70)** is a significant independent risk factor due to decreased physiological reserve, reduced pulmonary function (e.g., decreased lung elasticity, impaired cough reflex), and increased prevalence of comorbidities. - Older patients are more susceptible to **atelectasis**, **pneumonia**, and **respiratory failure** postoperatively. *Patient with 7 pack years of smoking* - Even a relatively low cumulative smoking history of **7 pack-years** can impair mucociliary clearance, increase bronchial secretions, and cause airway inflammation, significantly increasing the risk of pulmonary complications. - Smoking compromises lung function and increases the risk of **bronchospasm** and infection. *Upper abdominal surgery* - **Upper abdominal surgery** is a significant risk factor because incisions close to the diaphragm interfere with diaphragmatic movement, leading to reduced lung volumes, impaired cough, and increased risk of **atelectasis** and **pneumonia**. - Pain from the incision further restricts deep breaths and coughing, contributing to pulmonary complications.

Question 5: The most sensitive and practical technique for detection of myocardial ischemia in the perioperative period is -

A. Direct measurement of end diastolic pressure
B. Radio labeled lactate determination
C. Magnetic Resonance Spectroscopy
D. Regional wall motion abnormality detected with the help of 2D transoesophageal echocardiography (Correct Answer)

Explanation: ***Regional wall motion abnormality detected with the help of 2D transesophageal echocardiography*** - **Transesophageal echocardiography (TEE)** provides high-resolution images of the heart, allowing for the sensitive detection of **regional wall motion abnormalities (RWMA)**, an early and practical indicator of myocardial ischemia in the perioperative setting. - The development of new or worsening RWMA is often the **first sign of ischemia**, preceding ECG changes or hemodynamic alterations, making it a highly sensitive and clinically useful tool. *Direct measurement of end-diastolic pressure* - While an elevated **end-diastolic pressure** can indicate ventricular dysfunction, it is an **indirect sign** and not specific enough for early myocardial ischemia detection. - This measurement often requires invasive monitoring, which is less practical for routine detection compared to TEE. *Radio-labeled lactate determination* - **Lactate production** can increase in ischemic tissue, but its detection is a **biochemical marker** that typically lags behind the onset of ischemia. - This technique is generally **research-oriented** and not a practical, bedside method for rapid perioperative ischemia detection. *Magnetic Resonance Spectroscopy* - **Magnetic Resonance Spectroscopy (MRS)** can provide detailed metabolic information about tissue, including changes related to ischemia. - However, it is a **complex, time-consuming, and expensive imaging modality** that is not practical for routine, real-time perioperative monitoring of myocardial ischemia.

Question 6: A 48-year-old male patient is scheduled to undergo coronary arterial bypass surgery due to chronic angina. Coronary arteriography reveals nearly total blockage of the posterior descending interventricular artery. When exposing this artery to perform the bypass procedure, which accompanying vessel is most at risk of injury?

A. Middle cardiac vein (Correct Answer)
B. Great cardiac vein
C. Anterior cardiac vein
D. Small cardiac vein

Explanation: ***Middle cardiac vein*** - The **posterior descending interventricular artery** runs in the **posterior interventricular groove** along with the **middle cardiac vein**. - During surgical exposure or manipulation of the posterior descending interventricular artery, the closely associated middle cardiac vein is at high risk of injury. *Great cardiac vein* - The **great cardiac vein** runs in the **anterior interventricular groove** with the anterior interventricular artery (left anterior descending artery). - It is located on the anterior surface of the heart, anatomically distant from the posterior descending interventricular artery. *Anterior cardiac vein* - The **anterior cardiac veins** typically drain directly into the right atrium and are found on the anterior surface of the right ventricle. - They do not accompany the posterior descending interventricular artery. *Small cardiac vein* - The **small cardiac vein** runs in the right atrioventricular (coronary) groove, often alongside the right marginal artery and sometimes the right coronary artery. - While it drains parts of the right ventricle, it is not found in the posterior interventricular groove with the posterior descending interventricular artery.

Question 7: 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 8: Which is not an obvious advantage of high-flow nasal cannula (HFNC):

A. Bypassing nasopharyngeal dead space
B. Hot and Humidification of air (Correct Answer)
C. PEEP
D. Decreases need for intubation

Explanation: *Hot and Humidification of air* - This is an **obvious advantage** of HFNC, as it delivers warmed and humidified oxygen directly, improving patient comfort and mucociliary clearance. - The constant flow ensures the upper airway mucosa remains hydrated, preventing dryness and irritation that can occur with conventional oxygen therapy. ***Bypassing nasopharyngeal dead space*** - While HFNC does replace the gas in the **nasopharynx** with fresh gas, reducing dead space, this benefit is related to the high flow rate and is considered an **obvious advantage** in improving ventilatory efficiency. - The continuous washout of CO2 from the upper airway directly contributes to improved gas exchange. *PEEP* - HFNC can generate a modest level of **positive end-expiratory pressure (PEEP)**, which is an intentional and recognized effect due to the high flow rates. - This PEEP helps to recruit collapsed alveoli and improve oxygenation, making it an **obvious advantage** in respiratory support. *Decreases need for intubation* - The ability of HFNC to improve oxygenation, reduce work of breathing, and minimize airways inflammation is a well-established and **obvious advantage** that often prevents the need for invasive mechanical ventilation. - Clinical studies consistently demonstrate that HFNC can reduce intubation rates in patients with acute respiratory failure.

Question 9: Patient shows ST depression, troponin rise 6h post-surgery. Next best step is:

A. 12-lead ECG
B. Echocardiogram
C. Cardiology consult (Correct Answer)
D. Start heparin

Explanation: ***Cardiology consult*** - A cardiology consult is the most appropriate next step given the presence of **ST depression** and a **troponin rise** post-surgery, indicating a likely myocardial infarction (MI). - This allows for prompt comprehensive evaluation, risk stratification, and initiation of specialized cardiac management by an expert. *12-lead ECG* - While a 12-lead ECG is an important diagnostic tool, the patient's existing **ST depression** suggests it has already been performed or noted. - A repeat ECG might be useful for tracking changes, but it doesn't replace the need for expert cardiac evaluation and management. *Echocardiogram* - An echocardiogram can assess **cardiac function**, wall motion abnormalities, and valvular issues, which are relevant in MI. - However, it's a diagnostic test that should be ordered and interpreted in the context of a broader cardiac workup, which a cardiologist can best coordinate. *Start heparin* - **Heparin** is an anticoagulant that may be part of the management for an MI, especially in certain types or for prevention of clot extension. - However, initiating anticoagulation should be done after a thorough assessment of the patient's cardiac status, bleeding risk post-surgery, and in consultation with cardiology, rather than as the immediate next best step.

Question 10: Which of the following devices typically requires the most stringent safety protocols before MRI scanning?

A. Prosthetic cardiac valves
B. Insulin pump
C. Cochlear implants
D. Automatic Cardioverter-defibrillators (Correct Answer)

Explanation: ***Automatic Cardioverter-defibrillators*** - **Implantable cardioverter-defibrillators (ICDs)**, while increasingly MRI-conditional, require stringent protocols due to potential for **heating, lead damage, and inappropriate pacing/shocks**. - Detailed device interrogation, programming to asynchronous modes or MRI mode, and continuous monitoring are often required to mitigate risks and ensure patient safety. *Prosthetic cardiac valves* - Most modern **prosthetic cardiac valves** (both mechanical and bioprosthetic) are **MRI-conditional** or **MRI-safe** and generally do not pose significant risks. - They are typically made of non-ferromagnetic materials, reducing concerns about displacement or heating. *Insulin pump* - External insulin pumps are generally considered **MR-unsafe** and must be **removed from the patient** before entering the MRI scan room. - While removal is a safety protocol, they don't involve complex internal electronic interactions in the same way an implanted ICD does, making their protocol simpler (remove and resume). *Cochlear implants* - Many **cochlear implants** are now **MRI-conditional**, but they often require specific protocols such as removing the external processor and sometimes applying a head bandage to secure the implant. - Older models or certain configurations may still be considered MR-unsafe due to potential for magnet displacement or device damage.

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