3. Matching:
ECG wave information Action potential
QRS complex a) depolarization of ventricles
P wave d) depolarization of the atria
4. a) True
5. a) True
6. 40 Hz
PROBLEMS ANSWERS:
CHAPTER 7
QUIZ ANSWERS:
1. a) True
2. SA node
1. Beats/minute = 132; rhythm = regular; QRS duration = 0.08 sec; PR interval = 0.16
sec; ST segment = 1.5 mm depression. Interpretation = Sinus Tachycardia.
5. First determine the resultant between 0.5 mV lead I 0° and 1.2 mV lead II 60°. Then,
determine the final result with the lead III vector.
1.2 * cos(–60°) + j1.2 * sin(–60°) + 0.5 * cos0° + jsin0° = 0.6 – j1.04 + 0.5 = 1.1 – j1.04 =
1.51 , angle = –43.4°.
0.6 * cos(–120°) + j0.6 * sin(–120°) + 1.51 * cos(–43.4°) + j1.51 * sin(–43.4°) –0.3 –
j0.52 + 1.1 – j1.04 = 0.8 – j1.56 = 1.75 mV , angle = –62.85°