The Electrocardiogram

Question 1

Can give a vasoconstrictor to increase

Answer 1

afterload

Question 2

Fick Principle:

Answer 2

calculates the rate at which a substance is being added to or removed from the blood as it passes through an organ

Question 3

Fick equation

Answer 3

Xtc = Q × ([X]a – [X]v)
Q = Xtc / ([X]a – [X]v)

Question 4

Cardiac Index =

Answer 4

Cardiac Output / body surface area
Relates cardiac function to the size of the individual
Normal values range from 2.6 – 4.2 L/min per square meter

Question 5

PR interval

Answer 5

from start of P to the beginning of Q

Conduction time through atria & AV node (120 – 200 msec)

Question 6

P wave

Answer 6

atrial depolarization

Question 7

QRS complex

Answer 7

start of Q to the end of S

Ventricular depolarization

Question 8

QT interval

Answer 8

start of Q to the end of T
Total duration of ventricular systole
(

Question 9

ST segment

Answer 9

end of S to the beginning of T

the plateau phase of ventricular AP

Question 10

T wave

Answer 10

ventricular repolarization

Question 11

ECG paper: small box = ___seconds

Answer 11

.04 seconds or 40 ms

Question 12

ecg paper: 10 mm = ____mv

Answer 12

1 mv

Question 13

End of PR Interval: where nothing is seen on ecg, what is happening

Answer 13

• Depolarization wave reaches non-muscular (non-excitable) border between atria & ventricles
• Atrial muscle cells depolarized (Phase 2)
• Ventricular cells still resting
• Electrical field created during passage through AV node too small to see

Question 14

ST Segment: nothing is seen on ecg, what is happening

Answer 14

• No rapid changes in membrane potential occurring anywhere
• Atrial cells returned to resting
• Ventricular cells depolarized (Phase 2)–>can be elevated/depressed in myocardial injury or inadequate blood flow

Question 15

Left Axis Deviation:

Question 16

Right Axis Deviation:

Answer 16

> +90°
Physical displacement of heart to the right
Right ventricular hypertrophy
Loss of electrical activity to the left ventricle