Chapter 1

Question 1

What are some of the clinical uses of EKG?

Answer 1

1. detection of arrhythmias and cardiac abnormalities
2. indication of myocardial damage
3. detection of electrolyte imbalance
4. screening tool for diagnosis of ischemia disease
5. can indicate anatomic and physiologic state of the heart (i.e. hypertrophy, stenosis, etc)
6. can diagnose some non-cardiac pathology (i.e. PE, hypothermia, etc)

Question 2

What does the dicrotic notch of aortic pressure corresponds to?

Answer 2

closing of the aortic valve

Question 3

What does the S1 sound correspond to?

Answer 3

closing of the AV valve; beginning of systole

Question 4

List the order of the electrical system through the heart.

Answer 4

SA in RA -> AV -> bundle of His -> R and LBB -> Purkinje fibers

Question 5

Name the three types of cardiac cell.

Answer 5

1. Pacemaker cells- automatically generate AP
2. Conducting cells- hardwiring of heart
3. myocardial cells- contractile machinery

Question 6

An AP propagating toward the positive electrode produces _________ deflection. An AP propagating away from the positive electrode produces ________ deflection.

Answer 6

positive; negative

Question 7

What are the six limb leads?

Answer 7

Bipolar limb leads: Lead I, II, III

Augmented voltage leads: aVR, aVL, aVF

Question 8

What are the precordial leads and where are they placed?

Answer 8

V1- 4th intercostal space (right of sternum)
V2- 4th intercostal space (left of sternum)
V3- between V2 and V4
V4- left midclavicular line in the 5th intercostal space (below nipple)
V5- left anterior axillary line in the 5th intercostal space
V6- left midaxillary line in the 5th intercostal space