L11: The Electrocardiogram

Question 1

Draw a labelled diagram of a typical lead II ECG trace of the heart (label all waves, intervals and segments)

Answer 1

pl

Question 2

What do each of the peaks of the QRS complex represent?

Answer 2

Q = Ventricular septum
R = Ventricular apex
S = Ventricular base

Question 3

Draw a labelled diagram of Einthoven’s triangle

Answer 3

o

Question 4

Draw a diagram of unipolar lead on Einthoven’s triangle

Answer 4

Wilson’s central terminal 0V. -> Exploring electrode

Question 5

How is the mean QRS axis calculated?

Answer 5

Maximum deflection - Maximum deflection in opposite direction

Question 6

What are the angles for the normal QRS axis?

Answer 6

-30 to +110

Question 7

What is Wolff Parkinson White syndrome?

Answer 7

Caused by extra electrical connection from atria to ventricles other than the his bundle.

Question 8

Draw a ECG graph for a patient with Wolff-Parkinson-White syndrome

Answer 8

no Q dip (septum depolarization override by alternate connection)

Question 9

Draw a ECG graph for a patient with Wolff-Parkinson-White syndrome -
Re-entrant SVT NARROW COMPLEX

Answer 9

no P wave. increased T wave. no S-T segment. clockwise

Question 10

Draw a ECG graph for a patient with Wolff-Parkinson-White syndrome -
Re-entrant SVT
WIDE COMPLEX

Answer 10

upside down R peak. anti-clockwise

Question 11

Describe the ECG abnormalities

Answer 11

• Widened QRS = Slow depolarization of ventricles
• Prolonged PR segment = Delayed conduction from atria to ventricles
• ST segment elevation/depression (ischemia)
• Inversion of T wave (Ischemia)