CCT - Certified Cardiographic Technician ECG Fundamentals and Leads Questions and Answers 1 — Questions and Answers
Question 1: A Certified Cardiographic Technician is preparing to perform a standard 12-lead ECG. At what speed should the technician set the electrocardiograph machine to ensure the tracing is recorded according to industry standards?
- 10 mm/sec
- 25 mm/sec (Correct answer)
- 50 mm/sec
- 100 mm/sec
Correct answer: 25 mm/sec
The standard paper speed for recording a 12-lead ECG is 25 mm/sec. This speed allows for accurate measurement and interpretation of wave forms, intervals, and segments. Running the machine at a different speed without a specific clinical indication would distort the ECG and could lead to misinterpretation.
Question 2: A patient's ECG tracing shows significant artifact in leads I and II, but lead III appears clear. Which of the following electrodes is the most likely source of the artifact?
- Left Arm (LA)
- Left Leg (LL)
- Right Arm (RA) (Correct answer)
- Right Leg (RL)
Correct answer: Right Arm (RA)
Lead I measures the potential difference between the Right Arm (RA) and Left Arm (LA). Lead II measures the potential difference between the Right Arm (RA) and Left Leg (LL). The common electrode in both leads I and II is the Right Arm (RA). Therefore, an issue with the RA electrode, such as poor contact or movement, is the most probable cause of artifact in both of these leads simultaneously.
Question 3: Which of the following lead groups provides the primary view of the inferior wall of the left ventricle?
- V1, V2
- I, aVL, V5, V6
- V3, V4
- II, III, aVF (Correct answer)
Correct answer: II, III, aVF
Leads II, III, and aVF are known as the inferior leads because they are oriented to view the electrical activity from the inferior surface (diaphragmatic surface) of the heart. V1-V2 view the septum, V3-V4 view the anterior wall, and I, aVL, V5-V6 view the lateral wall.
Question 4: During a 12-lead ECG, the technician ensures all electrodes are placed correctly. What is the primary function of the electrode placed on the patient's right leg?
- It serves as the positive electrode for lead aVR.
- It acts as a ground to reduce electrical interference. (Correct answer)
- It measures the electrical potential of the inferior wall.
- It is the negative electrode for leads II and III.
Correct answer: It acts as a ground to reduce electrical interference.
The right leg (RL) electrode serves as the ground electrode in a standard 12-lead ECG. Its purpose is not to record cardiac electrical activity but to minimize electrical interference (artifact) from other sources, resulting in a cleaner and more interpretable tracing.
Question 5: A CCT student incorrectly places the V1 and V2 electrodes two intercostal spaces higher than the standard location (i.e., in the 2nd intercostal space instead of the 4th). Which of the following ECG changes is a likely result of this misplacement?
- An exaggerated R wave in V1
- A pattern that may mimic an anterior ST-elevation MI or incomplete RBBB (Correct answer)
- Inversion of the QRS complex in all precordial leads
- A significant increase in the amplitude of the T wave in V6
Correct answer: A pattern that may mimic an anterior ST-elevation MI or incomplete RBBB
Placing the V1 and V2 electrodes too high is a common error that can create false positive findings. This placement can alter the P wave and QRS morphology, potentially creating a pattern that resembles an incomplete right bundle branch block (RBBB), septal infarction, or an anterior ST-elevation MI (STEMI).
Question 6: Which of the following are considered the standard bipolar limb leads, forming the basis of Einthoven's triangle?
- aVR, aVL, aVF
- V1, V2, V3
- I, II, III (Correct answer)
- V4, V5, V6
Correct answer: I, II, III
Leads I, II, and III are the standard bipolar limb leads. They are called 'bipolar' because they record the difference in electrical potential between two specific limb electrodes. These three leads form the sides of Einthoven's triangle, a foundational concept in electrocardiography.
CCT - Certified Cardiographic Technician ECG Fundamentals and Leads Questions and Answers 1
A Certified Cardiographic Technician is preparing to perform a standard 12-lead ECG.
At what speed should the technician set the electrocardiograph machine to ensure the tracing is recorded according to industry standards?