Understanding ECG Tracing

Question 1

P Wave

Answer 1

1st wave
Upright wave
Denotes depolarization & contraction of atria
Represents impulse generated by SA node at moment it reaches R atrium

Question 2

PR Interval

Answer 2

Represents delay occurring in AV node
Lack of interval = atria & ventricle simultaneous contraction
Measures lag btwn P wave & QRS complex
Indicates time taken for impulse to travel from atria to ventricles

Question 3

QRS Complex

Answer 3

Indication of ventricular depolarization and contraction
Q wave = 1st negative deflection
R wave = positive deflection
S wave = negative deflection
Represents impulse moving through ventricular myocardium via R/L bundle fibers
Includes rapid action of Purkinje fibers

Question 4

ST segment

Answer 4

Measures distance btwn end of S wave & start of T wave

Time gap btwn ventricular depolarization & start of repolarization

Question 5

T wave

Answer 5

Small, rounded upright wave following QRS complex
Indication of ventricular depolarization
Ventricles ready for start of new cardiac cycle

Question 6

QT Interval

Answer 6

Measures time btwn start of QRS complex to end of T wave

Indicates complete duration of ventricular activity

Question 7

U Wave

Answer 7

Small wave following T wave
Repolarization of Purkinje fibers
Indicates 1 cycle of cardiac system complete
More visible in slow heart rate

Question 8

Regularity

Answer 8

Measures R-R intervals and P-P intervals

Question 9

Dropped Beats

Answer 9

Indicates presence of sinus arrest or AV block

Question 10

Bigeminy

Answer 10

QRS complex normal but followed by premature complex

Question 11

Trigeminy

Answer 11

Repeating pattern of 2 normal QRS complexes followed by premature complex

Question 12

Quadrigeminy

Answer 12

Repeating pattern of 3 normal QRS complexes followed by premature complex

Question 13

Triplets

Answer 13

3 consecutive premature complexes

Question 14

Couplets

Answer 14

2 consecutive premature complexes