ECG

Question 1

Who developed the ECG?

Answer 1

1) Augustus Waller

2) William Einthoven

Question 2

Where does Lead I go?

Answer 2

Right arm (-) –> Left arm (+)

Question 3

Where does Lead 2 go?

Answer 3

Right arm (-) –> Left leg (+)

Question 4

Where does Lead 3 go?

Answer 4

Left arm (-) –> Left leg (+)

Question 5

Where does aVR go?

Answer 5

Lead 3 –> Right arm (+)

Question 6

Where does aVL go?

Answer 6

Lead 2 –> Left arm (+)

Question 7

Where does aVF go?

Answer 7

Lead 1 –> Left leg (+)

Question 8

How many precordial leads may be used?

Answer 8

6

Question 9

What does the ECG measure?

Answer 9

extracellular electrical potential (affinity for electron to move away from - node toward + node)

Question 10

What is the plot output of the ECG?

Answer 10

voltage vs. time

Question 11

What is the scale for each axis of the ECG plot?

Answer 11

X: 1in = 1sec
Y: 1cm = 1mV

Question 12

Why is the T wave positive?

Answer 12

repolarization occurs from epicardium to endocardium

Question 13

How does depolarization occur in terms of heart layers?

Answer 13

endocardium to epicardium

Question 14

What represented by inconsistently-shown U wave?

Answer 14

papillary muscle repolarization

Question 15

With what part of the ECG does ventricular contraction correlate with?

Answer 15

ST segment (plateau phase of myocyte ap)

Question 16

How is activation of AV node & bundle of His shown on the ECG?

Answer 16

PR/PQ interval

Question 17

Define tachycardia?

Answer 17

HR > 100 bpm

Question 18

Define bradycardia.

Answer 18

HR < 60 bpm

Question 19

Define sinus arrhythmia.

Answer 19

HR variance during inhaling & exhaling (inhaling > exhaling)

Question 20

Define 1st degree heart block.

Answer 20

PR > 0.2 seconds

Question 21

Define 2nd degree heart block.

Answer 21

PR > 0.25 seconds

Question 22

Define 3rd degree heart block.

Answer 22

complete blockage, aka Stokes-Adams syndrome

Question 23

What are causes of heart block?

Answer 23

1) AV bundle ischemia
2) AV bundle compression (scar tissue)
3) AV bundle inflammation
4) extreme vagal stimulation (basovagal block)

Question 24

What are causes of ectopic pacemakers?

Answer 24

1) local ischemia
2) coronary calcification
3) AV Node- & Purkinje-altering drugs (Nicotine/caffeine)
4) Catheterization

Question 25

How does premature atrial contraction present on an ECG?

Answer 25

1) premature P wave
2) compensatory pause
- - depolarized SA node must repolarize

Question 26

What are the two pathophysiologies of pvc?

Answer 26

1) AV node becomes ectopic

2) irritable focus in the ventricle

Question 27

How does pvc via irritable ventricular focus manifest in an ECG?

Answer 27

1) prolonged QRS
2) amplified QRS
3) negative T-wave

Question 28

Why would a QRS be amplified?

Answer 28

signal propagates in 1 direction

Question 29

Why would the t-wave be negative?

Answer 29

when myocytes (instead of purkinje) are used to depolarize…slower depol & therefore first to depol are first to repol

Question 30

What are causes of irritable ventricular foci causing pvc?

Answer 30

1) nicotine/caffeine
2) sns
3) sleep deprivation
4) ischemia
5) ion channel disorders

Question 31

what is paroxysmal tachycardia?

Answer 31

spontaneous tachycardia in the atria or ventricles

Question 32

how does an atrial paroxysmal tachycardia manifest?

Answer 32

QRS with obscured P

Question 33

What causes V-fib?

Answer 33

abnormal lack of full refractory period in a depolarizing event caused by sudden electric shock, or ischemia

Question 34

What is treatment for V-fib?

Answer 34

defib-& hope SA node re-fires

1) 110 V for 0.1 seconds
2) 1000 V for 0.003 seconds

Question 35

What generally causes a-fib?

Answer 35

many ectopic foci

Question 36

what is atrial flutter?

Answer 36

coordinated contractions @ 200-350 bpm

Question 37

What generally causes atrial flutter?

Answer 37

1 ectopic focus