Flipped Classroom - 3 and 5 lead EKG

Question 1

What does ECG measure?

Answer 1

Electrocardiography (ECG) measures electrical activity in the heart, producing waveforms that represent cardiac cycles. used to diagnose arrhythmias and detect ischemia.

Question 2

Why is ECG monitoring crucial in anesthesia?

Answer 2

allows real-time assessment of cardiac function, helps in identifying potential complications, and enhances patient safety.

Question 3

What types of ECG monitoring devices are available?

Answer 3

various ECG systems available, including portable devices, full-featured monitors, and telemetry systems, each serving unique roles in different clinical settings.

Question 4

When is ECG monitoring essential?

Answer 4

procedures involving general anesthesia, sedation, or patients with known cardiovascular conditions to enable early detection of cardiac events.

Question 5

What are the guidelines for ECG use according to the American Society of Anesthesiologists?

Answer 5

Continuous intraoperative ECG monitoring is mandatory, with no known contraindications.

Question 6

What is the role of lead II and lead V5?

Answer 6

Lead II is standard for rhythm analysis, while V5 can
enhance detection of anterior ischemia.

Question 7

What is a 3-lead ECG?

Answer 7

The most basic and commonly used system, utilizing three electrodes to capture heart activity.

Question 8

What is a 5-lead ECG?

Answer 8

Provides a more detailed picture of heart function by using five electrodes to capture electrical signals from different areas of the chest.

Question 9

What is a 12-lead ECG?

Answer 9

Offers the most comprehensive view of heart activity, typically employed in a diagnostic setting.

Question 10

What is the electrode placement in a 3-lead ECG system?

Answer 10

In a 3-lead ECG setup, electrodes are positioned at specific anatomical locations—right arm, left arm, and left leg.

Question 11

Which lead is often used as the primary lead for continuous monitoring in a 3-lead ECG?

Answer 11

Lead II is often used as the primary lead for continuous monitoring, as it provides optimal visualization of the PQRST complex.

Question 12

What is the purpose of adding a V5 lead in a modified 3-lead ECG configuration?

Answer 12

Adding a V5 lead enhances the detection of ischemic changes, especially useful in a perioperative setting.

Question 13

How are electrodes placed in a 5-lead ECG system?

Answer 13

In a 5-lead system, electrodes are placed at the same positions as in the 3-lead setup with added electrodes on the chest.

Question 14

Which leads are typically used as primary leads in a 5-lead ECG system?

Answer 14

Typically, leads I, II, and V5 are used as primary leads, providing comprehensive coverage of the heart’s electrical activity.

Question 15

What is the advantage of the 5-lead ECG system for high-risk patients?

Answer 15

The 5-lead ECG system offers earlier detection of cardiac issues and allows for rapid clinical intervention if needed.

Question 16

What does the P wave represent in ECG waveforms?

Answer 16

The P wave represents atrial depolarization, the electrical signal that initiates contraction of the atria.

Question 17

What does the QRS complex reflect in ECG waveforms?

Answer 17

The QRS complex reflects ventricular depolarization, the electrical impulse responsible for contracting the ventricles.

Question 18

What does the T wave indicate in ECG waveforms?

Answer 18

The T wave indicates ventricular repolarization, the process of the ventricles returning to a resting state before the next heartbeat.

Question 19

What issues can ECG help detect?

Answer 19

ECG helps detect arrhythmias, myocardial ischemia, conduction abnormalities, pacemaker malfunctions, and electrolyte imbalances.

Question 20

What does ST Depression (>1 mm, 80 msec after J-point) indicate?

Answer 20

High likelihood of myocardial ischemia.

Question 21

What does ST Elevation (>1 mm, 80 msec after J-point) suggest?

Answer 21

Suspicion of acute myocardial infarction (STEMI).

Question 22

What is the J-point?

Answer 22

The point where the QRS complex ends and the ST segment begins.

(Butterworth et al., 2022)

Question 23

What are common sources of artifacts in ECG monitoring?

Answer 23

Common sources include patient movement, lead-wire displacement, electrocautery use, and 60-Hz interference from nearby medical devices.

Question 24

What is 60-Hz interference?

Answer 24

It refers to electrical noise generated by nearby alternating current (AC) devices that operate at 60 Hz.

Question 25

What are common sources of 60-Hz interference?

Answer 25

Common sources include fluorescent lights, patient monitors, computer screens, and electrosurgical devices (e.g., cautery machines).

Question 26

What is a strategy for minimizing artifacts in ECG monitoring?

Answer 26

Proper lead placement: Clean skin, avoid bony areas, shave if needed. Stable electrode contact: Use fresh electrodes, press firmly, replace regularly.

Question 27

How can patient movement be minimized during ECG monitoring?

Answer 27

Minimize patient movement by stabilizing posture and using telemetry if necessary.

Question 28

How can 60-Hz interference be reduced in ECG monitoring?

Answer 28

Keep ECG away from interfering sources as much as possible.

Question 29

What is a best practice for organizing lead wires?

Answer 29

Securely place and avoid tangling.

Question 30

What is dual lead monitoring?

Answer 30

Simultaneously monitoring both Lead II and V5 improves detection capability and ensures comprehensive analysis of the heart’s rhythm.

Question 31

Why is proper electrode placement important?

Answer 31

It's critical to ensure electrodes are placed correctly and securely adhere to the skin's surface to minimize movement artifacts.

Question 32

How can conductive gel enhance ECG monitoring?

Answer 32

Applying conductive gel can enhance electrode-skin conductivity, crucial for obtaining optimal signal quality in ECG monitoring.

Question 33

Which of the following statements about ECG lead selection are correct? (Select all that apply) A. Lead II is commonly used for arrhythmia detection. B. Lead V5 is optimal for detecting ischemia in the anterior and lateral walls. C. A modified V5 lead can be achieved using a 3-lead system. D. The standard 3-lead system provides the most comprehensive ischemia monitoring. E. The best ECG lead for ischemia detection is always Lead I.

Answer 33

Correct Answers: ● A,B,C Rationales: ● Lead II aligns with the heart’s electrical axis, providing the best P-wave visibility, making it ideal for detecting arrhythmias. ● Lead V5 is positioned over the 5th intercostal space at the anterior axillary line, making it highly sensitive for ischemia detection in the anterior and lateral walls of the heart. ● In a 3-lead system, the LA electrode can be repositioned to the V5 location to provide better ischemia monitoring (CS5 configuration). ● The 3-lead system is primarily used for basic arrhythmia detection, while 5-lead ECG provides better ischemia monitoring due to additional precordial lead placement. ● Lead I is not the most sensitive for ischemia. Instead, Lead V4 and V5 are more effective for detecting ischemic changes.

Question 34

How can ECG signal quality be improved? (Select all that apply) A. Ensuring proper electrode placement B. Using conductive gel to lower skin resistance C. Positioning lead wires parallel to power cords D. Selecting an appropriate filter setting for motion artifacts E. Avoiding the use of a precordial lead

Answer 34

Correct Answers: * A,B,D Rationales: ● Correct placement prevents signal distortion and improves lead accuracy. ● Conductive gel enhances electrical conduction between the skin and electrode, reducing impedance. ● Lead wires should be positioned perpendicularly to power cords to minimize 60-Hz interference. ● Using low-pass or notch filters can help reduce motion artifacts while preserving key ECG features. ● Precordial leads (e.g., V4, V5) enhance ischemia detection, so avoiding them would reduce diagnostic accuracy.

Question 34

What are common causes of ECG artifacts? (Select all that apply) A. Patient movement B. Electrocautery interference C. Faulty electrodes D. Low heart rate E. 60-Hz electrical interference

Answer 34

Correct Answers: * A,B,C,E Rationales: ● Patient movement can create motion artifacts, leading to false readings on the ECG. ● Electrical signals from surgical cautery can disrupt ECG signals, creating artifacts. ● Poor electrode contact, dried gel, or disconnected leads can cause erratic readings. ● Alternating current (AC) devices operating at 60 Hz (in the U.S.) or 50 Hz (in other regions) can cause interference in ECG readings.

Question 35

Which ECG lead combination provides the highest sensitivity for detecting myocardial ischemia? A. Lead I and Lead II B. Lead II and Lead III C. Lead II and Lead V5 D. Lead V1 and Lead V4

Answer 35

Correct Answer * C Rationales: ● Lead II is best for arrhythmia detection, while Lead V5 is most sensitive for anterior and lateral wall ischemia. * Studies show that monitoring Lead II + V5 can detect up to 85% of ischemic episodes.

Question 36

What is the primary function of the 3-lead ECG system in anesthesia? A. Continuous ischemia monitoring B. Basic arrhythmia detection C. Comprehensive cardiac assessment D. Diagnosing complex conduction abnormalities

Answer 36

Correct Answer: * B Rationales: * 3-lead ECG is mainly used for basic rhythm monitoring (arrhythmia detection). * 5-lead or 12-lead ECG is needed for more detailed ischemia or conduction abnormality analysis. * Comprehensive cardiac assessment requires a full 12-lead ECG.

Question 37

A 62-year-old male with a history of hypertension and diabetes is scheduled for an elective laparoscopic cholecystectomy. During preoperative evaluation, he reports experiencing exertional chest discomfort over the past few weeks. A preoperative ECG shows 1.5 mm ST-segment depression in leads V4 and V5, recorded 80 msec after the J-point. What is the most likely cause of this ECG finding, and what should be the next step in management? A. Normal variant, proceed with surgery without further testing B. Myocardial ischemia, consider further cardiac evaluation C. Electrolyte imbalance, check potassium and calcium levels D. Pericarditis, look for PR segment depression

Answer 37

Correct Answer: * B Rationales: ● ST-segment depression (>1 mm, 80 msec after J-point) is a strong indicator of myocardial ischemia, especially when seen in leads V4-V5 (which reflect the anterior/lateral walls). ● Patients with exertional chest discomfort and risk factors (HTN, DM) should be further evaluated before proceeding with elective surgery.