ECG Laboratory

Question 1

EKG Reading Format

Answer 1

1. Rate
2. Rhythm
3. Axis
4. Intervals (PR, QRS, QT)
5. ST segments (Ischemia, injury, infarction)

Question 2

Sinus bradycardia

Answer 2

Under 60 BPM

Question 3

Sinus tachycardia

Answer 3

Over 100 BPM

Question 4

Rate interpretation on EKG

Answer 4

1 box = 300 BPM
2 boxes = 150 BPM
3 boxes = 100 BPM
4 boxes = 75 BPM
5 boxes = 60 BPM
6 boxes = 50 BPM

Question 5

Rhythm is assess by comparing which intervals on the EKG?

Answer 5

R-R intervals

Question 6

Lead and axis pairs (3)

Answer 6

1. Lead I and AVF
2. Lead II and AVL
3. Lead III and AVR

Question 7

Positive Lead I and Positive AVF would put the heart in which axis?

Answer 7

Normal axis

Question 8

Positive Lead I and Negative AVF would put the heart in which axis?

Answer 8

Left axis

Question 9

Negative Lead I and Positive AVF would put the heart in which axis?

Answer 9

Right axis

Question 10

Negative Lead I and Negative AVF would put the heart in which axis?

Answer 10

Indeterminate/Extreme axis

Question 11

The PR interval represents what part of the cardiac cycle?

Answer 11

Atrial depolarization
Conduction velocity between the SA node and AV node.
This is the best marker to asses AV node conduction velocity as it takes up the majority of the PR interval.

Question 12

Normal PR interval range

Answer 12

120-200ms

Question 13

Why is the P wave followed by a pause?

Answer 13

The pause represents the slowing of depolarization through the AV node, which allows for filling of the ventricles from the atria.

Question 14

The AV node should be the only conducting pathway between the atria and ventricles. Other pathways are ________.

Answer 14

Pathologic.

Question 15

Short PR intervals (below 120ms) may be indicative of what?

Answer 15

The presence of a bypass tract, accessory pathway, bundle of Kent, and pre-excitation.

Question 16

Short PR intervals often characteristically show what on EKGs?

Answer 16

Delta waves.

No pause between the P wave and the QRS complex.

Question 17

A prolonged PR interval greater than 200ms is indicative of what?

Answer 17

First degree AV block: prolonged AV node conduction.

Question 18

The QRS complex represents which part of the cardiac cycle?

Answer 18

Ventricular depolarization

Question 20

QRS complex labeling conventions

Answer 20

The first negative wave is Q
The first positive wave is R
The second negative wave is S

It is possible to have more than one R and S wave.

Question 21

Normal QRS interval

Answer 21

Below 120ms

Question 22

A wide QRS (greater than 120ms) may be indicative of what?

Answer 22

Bundle branch block, impaired conduction in the right/left bundle, or possibly a beat of ventricular origin.

Question 24

The QT interval represents which part of the cardiac cycle?

Answer 24

Ventricular depolarization to ventricular repolarization.

Question 25

Normal QT interval

Answer 25

Generally under 440ms

Question 26

ST elevations are commonly seen in patients with a history of ________

Answer 26

MI

Question 27

Prolonged QT intervals can lead to ________ and ________ ________.

Answer 27

Arrhythmias; sudden death

Question 28

Factors that can affect the QT interval include ________ and ________ ________.

Answer 28

Medications; electrolyte abnormalities