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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.

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  1. Which precordial lead is placed at the 4th intercostal space, right sternal border?

    Answer: V1

    V1 is the first precordial lead, positioned at the 4th intercostal space immediately to the right of the sternum, and it provides an important view of right ventricular activity and bundle branch blocks.

  2. What is the correct electrode color code for the LEFT LEG in a standard US ECG system?

    Answer: Green

    In the American/AHA color coding system for ECG electrodes, the left leg (LL) electrode is green. The mnemonic 'traffic light' helps: Red=RA, Yellow=LA, Green=LL, Black=RL (ground).

  3. If the right arm (RA) and left arm (LA) electrodes are accidentally reversed during a 12-lead ECG, which lead will appear abnormal FIRST?

    Answer: Lead I (P wave and QRS will appear inverted/negative)

    Accidental right-left arm reversal causes Lead I to show an inverted P wave, negative QRS complex, and inverted T wave (mirror image) because Lead I measures the potential difference from RA to LA — reversing the electrodes reverses the polarity.

  4. What does a normal PR interval duration indicate on an ECG?

    Answer: Normal conduction through the AV node (0.12–0.20 seconds)

    The PR interval (measured from the beginning of the P wave to the start of the QRS complex) represents conduction time through the atria and AV node; a normal duration of 0.12–0.20 seconds (3–5 small boxes) indicates intact AV nodal conduction.

  5. When placing ECG electrodes on a female patient, where should the V3–V6 chest electrodes be positioned?

    Answer: Under the breast tissue, directly on the chest wall at the correct anatomical landmark

    In female patients, chest electrodes V3–V6 should be placed beneath the breast tissue against the chest wall at the correct anatomical positions; placing them on top of breast tissue shifts the electrode away from the heart and alters the tracing.

  6. Which of the following best describes the T wave on a normal ECG?

    Answer: A rounded, positive deflection after the QRS complex representing ventricular repolarization

    The T wave follows the QRS complex and represents ventricular repolarization (the heart muscle cells resetting their electrical charge); it is normally rounded, upright (positive) in most leads, and precedes the next P-QRS-T cycle.