ECG Fundamentals and Leads Flashcards
6 cards from real CCT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 ECG Fundamentals and Leads flashcards as text
What is the significance of a delta wave on the ECG?
Answer: It indicates ventricular pre-excitation via an accessory pathway, as seen in Wolff-Parkinson-White syndrome
A delta wave is a slurred, slowly rising initial deflection of the QRS complex caused by early ventricular activation (pre-excitation) through an accessory pathway that bypasses the AV node, as in Wolff-Parkinson-White (WPW) syndrome.
Which leads are considered the 'lateral' leads in a 12-lead ECG?
Answer: I, aVL, V5, and V6
The lateral leads — I, aVL, V5, and V6 — view the lateral wall of the left ventricle, which is typically supplied by the left circumflex artery.
What is the normal R-wave progression across the precordial leads (V1 through V6)?
Answer: R wave amplitude progressively increases from V1 to V5/V6, with transition (equal R and S) typically at V3 or V4
Normal R-wave progression shows a small r in V1 that gradually grows in amplitude through V2, V3, V4, and peaks at V5 or V6, with the R/S ratio transitioning from negative (S>R) to positive (R>S) typically at V3 or V4.
What does 'right axis deviation' (RAD) mean on an ECG, and what is its typical axis range?
Answer: The mean QRS axis is greater than +90 degrees, indicating the electrical axis points toward the right ventricle
Right axis deviation is defined as a mean QRS axis greater than +90 degrees (some criteria use +100 degrees). It indicates that the net electrical force of ventricular depolarization is directed toward the right side.
When an ECG shows a completely negative P wave in lead I with a positive P wave in aVR, what electrode error has most likely occurred?
Answer: Left arm and right arm electrodes have been reversed
Left arm/right arm reversal is the most common electrode placement error. It causes the P wave and QRS to invert in lead I (appearing as if lead I is read backwards) and makes aVR appear positive (looking like aVL).
What is meant by 'poor R-wave progression' (PRWP) in the precordial leads?
Answer: The R wave fails to increase in amplitude across V1-V4, or the transition zone (R=S) occurs later than V4
Poor R-wave progression describes the ECG finding where R waves do not progressively increase in amplitude from V1 through V4 as expected, or where the transition from predominantly negative to predominantly positive QRS occurs later than normal (after V4).