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
In a standard 12-lead ECG, lead aVR views the heart from which angle?
Answer: Right shoulder, looking toward the heart's base from above-right
Lead aVR is the augmented unipolar lead placed at the right arm, providing a view from the right shoulder looking down and toward the heart's base and right side. It is often inverted relative to other leads.
Which leads make up the inferior leads on a standard 12-lead ECG?
Answer: II, III, and aVF
Leads II, III, and aVF are the inferior leads because their positive electrodes are located near the left foot, providing a view of the inferior wall of the left ventricle, which is supplied by the right coronary artery in most patients.
A properly performed 12-lead ECG should be recorded at what standard paper speed?
Answer: 25 mm/second
The international standard paper speed for ECG recording is 25 mm/second, which makes each small square (1 mm) equal to 0.04 seconds and each large square (5 mm) equal to 0.20 seconds.
What does the standard calibration signal on an ECG represent, and what should its amplitude be?
Answer: 1 mV electrical signal that should deflect the stylus exactly 10 mm (2 large squares) upward
The standard calibration (1 mV) signal should produce a 10 mm deflection on standard gain. This allows the interpreter to verify that the gain setting is correct and that ECG amplitudes can be accurately measured.
In Einthoven's triangle, which statement correctly describes the relationship between leads I, II, and III?
Answer: Lead II = Lead I + Lead III (Einthoven's Law)
Einthoven's Law states that at any given moment, the voltage in Lead II equals the sum of Lead I and Lead III (II = I + III). This mathematical relationship is the basis of the bipolar limb lead system.
Which precordial lead is typically located at the 4th intercostal space, right sternal border?
Answer: V1
V1 is placed at the 4th intercostal space at the right sternal border. It provides a view of the right side of the heart, the interventricular septum, and is particularly useful for identifying right bundle branch block and P wave morphology.