ECG

Question 1

P-R Interval

Answer 1

The time from the beginning of atrial activation to the beginning of ventricular activation
Measured from the point where the P wave leaves the baseline to the beginning of the QRS complex.

Question 2

P Wave

Answer 2

Atrial depolarization and the spread of electrical impulses throughout the L and R atria

Question 3

This precedes each QRS complex

Answer 3

P wave

Question 4

Why is a waveform representing atrial repolatization not seen on the ECG

Answer 4

It is buried in the QRS complex

Question 5

QRS Complex

Answer 5

Spread of the electrical impulse through the ventricles= ventricular depolarization, triggering contraction of the ventricles

Question 6

Why is the QRS complex bigger then the P wave?

Answer 6

QRS is significantly larger than the P wave b/c depolarization of the vents involves a considerably greater muscle mass

Question 7

T wave

Answer 7

Ventricular Repolarization, the absolute refractory period is still present during the beginning of the T wave, the normal T wave is slightly asymmetric, return of K inward and Na outward (change in polarization of the cell)

Question 8

What is an interval

Answer 8

It includes the waveform and the segment

Question 9

Time in between small squares (1mm) on the ECG paper

Answer 9

.04 sec

Question 10

Time in between each large square (5mm) on the ECG paper

Answer 10

.2 sec

Question 11

15 boxes = how many seconds

Answer 11

3 seconds

Question 12

Normal time and box count for PR interval

Answer 12

.12-.2 seconds or 3-5 little boxes

Question 13

Normal time and box count for QRS Complex

Answer 13

.06-.10 seconds or 1.5-2.5 little boxes

Question 14

ST segment

Answer 14

Slight pause after QRS complex, between QRS and T wave, normally flat segment of isoelectic line

Question 15

What is abnormal deviation of the ST segment

Answer 15

.5mm from baseline

Question 16

QT interval

Answer 16

Measure from the begining of the Q wave to the end of the T wave
Normally about .32-.40 seconds or 8-10 little boxes

Question 17

Longer the QT interval the increased risk for what?

Answer 17

arrhythmia

Question 18

What is the one abnormal factor about sinus bradycardia?

Answer 18

HR is less than 60 beats/min

Question 19

Pain, fear, exercise, artificial stimulants (caffeine, nicotine, amphetamines), CHF, infection, anemia, hemorrhage, MI and hyperthyroidism are all causes for what?

Answer 19

Sinus Tachycardia

Question 20

What is the difference between sinus arrhythmia and sinus block/pause?

Answer 20

• Sinus arrhythmia has a HR of 40-100, there is an irregular rhythm due to the R-R interval varying throughout
• Sinus pause/block has a HR 60-100 but the R-R is regular except for occasional pauses (usually see 1 pause in a 6 second segment)

Question 21

Delay or interruption in impulse conduction occurs within the AV node, bundle of His or Purkinje system the resulting dysrhythmia is called…

Answer 21

AV block

Question 22

PR interval reflects what?

Answer 22

depolarization of the R and L atria (p wave) and the spread of the impulse through the AV node, bundle of his, R and L bundle branches and the Prukinje fibers

Question 23

What is key when determining the type of AV block?

Answer 23

PR interval

Question 24

Impulses from the SA node to the ventricle are delayed (not blocked), usually occurs at the AV node…what degree of block is this?

Answer 24

First Degree

PR Interval > .20 seconds (>3-5 little boxes)

Question 25

The site of block in 2nd degree AV block type 1 is typically where?

Answer 25

At the AV node (above the bundle of his)

Question 26

The site of block in the 2nd degree AV type 2 is typically where?

Answer 26

The bundle of His or the bundle branches (below the AV node)

Question 27

3rd degree block there is what type of block?

Answer 27

Complete block in conduction of impulses between the atria and ventricles. The site may be at the AV node, but more commonly at the bundle of His or bundle branches

Question 28

All components of the ECG tracing are usually w/in normal limits with the exception of the PR interval..what degree block is this?

Answer 28

1st Degree AV Block, because all electrical impulses travel normally from the SA node though the atria but there is a delay in impulse conduction, usually at the level of the AV node

Question 29

What should you do if a 1st degree block is found?

Answer 29

Usually nothing, more than likely the block is asymptomatic. However, if sx can lead to higher degrees of AV block.

Question 30

When some but not all atrial impulses are blocked from reaching the ventricles because the SA node is generating impulses in a normal manner each P wave will occur at a regular interval across the strip but not every P wave will be followed by QRS--atria a depol normally but not every impulse is conducted to vents

Answer 30

Second Degree AC Block

Question 31

What blocks are the RR interval irregular

Answer 31

Second Degree AV block type 1 and 2

Question 32

In what block do the PR interval get longer and longer until you see a P wave with lack of a QRS complex?

Answer 32

Second Degree AV block Type 2 (Wenckebach)

Question 33

In this AV block the QRS complexes are wider then normal, not every P wave is followed by a QRS complex (see multiple P waves w/o QRS) and PR interval is usually within normal limits. May also see ST segment elevation.

Answer 33

2nd degree Type 2 (Mobitz II) *Remember, in Type 1 the QRS complexes are more narrow than usual b/c block is occurs at the level of the AV node and the PR intervals increase in length

Question 34

Second degree blocks are types of incomplete blocks because the AV junction conducts at least some impulses to the ventricles. In third degree AV blocks what happens to the impulses?

Answer 34

Impulses generated by the SA node are blocked before reaching the ventricles so no P waves are conducted. The atria and ventricles beat independently of each other. This is a COMPLETE block. A secondary pacemaker (either junction or ventricular) stimulates the ventricles; therefore, the QRS may be narrow or wide, depending on location of the escape pacemaker and the condition of the intraventriular conduction system.

Question 35

Where can a complete block occur? (3rd degree)

Answer 35

AV node, bundle of His, bundle branches

Question 36

What is the heart's least efficient pacemaker?

Answer 36

Ventricles--if they function as the heart's pacemaker the rate is usually 20-40 beats/min. This happens if SA node fails to discharge, SA node impulses are blocked, rate of discharge from SA is slower then vents, irritable site in either vent produces an early beat or rapid rhythm

Question 37

If an area of either ventricle becomes ischemic or injured, it can become irritable. This affects the manner in which impulses are conducted. When an ectopic site within vent assumes responsibility for pacing the heart, electrical impulse bypasses the normal intraventricualr conduction pathway. This results in stimulation of the ventricles at slightly different times. As a result, ventricular beats and rhythms usually have QRS complexes that are abnormally shaped and longer than normal.

Answer 37

Sorry....just a note.

Question 38

On a strip you see wide QRS w/o P wave, and T wave in the opposite direction of the QRS complex. What is this?

Answer 38

Premature Ventricular Complexes

Question 39

What do you call a PVC every other beat?

Answer 39

Bigeminy

Question 40

What do you call a PVC every third beat?

Answer 40

Trigeminy

Question 41

What do you call PVCs that are all identical?

Answer 41

Unifocal

Question 42

What if no two PVC appear similar in configuration?

Answer 42

Multifocal

Question 43

3 PVC's is what?

Answer 43

Ventricular Tachycardia | *When 3 PVC's occur in a row at a rate greater than 100 beats/min (No P waves, QRS is wide and bizarre)

Question 44

When you have a strip where the QRS complex varies in shape/amplitude beat to beat, looks as if the QRS is twisting around the isoelectric line

Answer 44

Tordade De Pointes