EKG/ECG Lead Placement and Artifacts Flashcards
6 cards from real NCMA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 EKG/ECG Lead Placement and Artifacts flashcards as text
Where is the V4 precordial lead electrode placed?
Answer: 5th intercostal space at the midclavicular line
V4 is placed at the 5th intercostal space in the midclavicular line (directly below the midpoint of the clavicle on the left side), which overlies the apex of the heart.
What type of artifact on an ECG tracing is caused by patient movement or shivering?
Answer: Somatic muscle artifact (wandering or irregular baseline spikes)
Somatic (skeletal muscle) artifact appears as irregular, high-frequency spikes or a fuzzy, irregular baseline caused by involuntary or voluntary patient movement, shivering, or tremors.
In a standard 12-lead ECG, how many limb leads are there?
Answer: 6 (I, II, III, aVR, aVL, aVF)
There are 6 limb leads in the standard 12-lead ECG: three bipolar limb leads (I, II, III) and three augmented unipolar limb leads (aVR, aVL, aVF), with the remaining 6 being precordial (chest) leads.
A medical assistant notes that the ECG baseline drifts slowly up and down in a wave-like pattern. What is the MOST likely cause?
Answer: Wandering baseline caused by poor electrode contact or patient breathing
Wandering baseline (also called baseline drift) appears as a slow, undulating movement of the isoelectric line, most commonly caused by inadequate skin preparation, poor electrode contact, or respiratory movement of chest electrodes.
Which lead records electrical activity from a viewpoint directly at the bottom (inferior) surface of the heart?
Answer: aVF
aVF (augmented vector foot) has its positive electrode at the left leg, recording electrical activity as seen from directly below the heart, making it the primary inferior lead along with II and III.
To minimize 60-cycle AC interference on an ECG, which of the following actions should a medical assistant take?
Answer: Ensure all electrode cables are properly connected and move electrical devices away from the patient
AC (alternating current) interference creates a regular 60 Hz thickening of the baseline; it is minimized by securing all lead connections, keeping electrical equipment (phones, infusion pumps, electric blankets) away from the patient, and using properly functioning cables.