Week 3 EKG

Question 1

A physician has documented an irregularly irregular cardiac rhythm with a heart rate of 150 bpm in a chart of a patient. The BEST interpretation of this rhythm is:

Answer 1

Uncontrolled atrial fibrillation

Question 2

The presence of a significant Q wave (one-third the size of the QRS complex) on an ECG indicates which of the following?

Answer 2

Previous infarction

Question 3

Which of the following reasons are considered indications for a Holter monitor?

Answer 3

All of the above
(Evaluating antiarrhythmic therapy or pacemaker functioning, Identifying symptoms caused by arrhythmias, Describing the arrhythmias noted with activity)

Question 4

Which of the following changes on an EKG BEST indicates the presence of an acute infarction?

Answer 4

ST-segment elevation

Question 5

What is the significance of the “big boxes” on the EKG tracing?

Answer 5

Each big box represents 0.2 seconds

Question 6

an EKG detects ___ issues and may indirectly relate to __ problems?

Answer 6

electrical conduction; mechanical

Question 7

how much time does one small box = on an EKG?

Answer 7

0.04 sec
1mm

Question 8

one an EKG you use time to determine:

Answer 8

HR and duration of certain features of the EKG

Question 9

how many small boxes are in a large box on an EKG?

Answer 9

5

Question 10

on the Y axis of the EKG was does each mm equal?

Answer 10

0.1mV

Question 11

on the y axis of an EKG how many boxes = 1mV?

Answer 11

10 small boxes (10 mm) or 2 big boxes

Question 12

what can the voltage measure on an EKG be used as criteria for?

Answer 12

ventricular hypertrophy

Question 13

What does the PR interval represent?

Answer 13

the pause at the AV node
(time between atrial depolarization and ventricular depolarization)
after the atria depolarize and before the ventricles depolarize

Question 14

what does a long PR interval indicate?

Answer 14

a delay or heart block

Question 15

What does the QT interval represent?

Answer 15

The time to depolarize and repolarize the ventricles

Question 16

what does the P wave represent?

Answer 16

atrial depolarization

Question 17

what does the distance from the t-wave to the next p-wave represent?

Answer 17

after the ventricles have completed repolarization and before the atra depolarize

Question 18

what does the ST segment represent?

Answer 18

after the ventricles depolarize and before the ventricles repolarize

Question 19

what are the 3 times in the cardiac cycle where isoelectric condition should occur?

Answer 19

t-wave to p-wave
PR segment
ST segment

Question 20

what is happening if all three of the areas where isoelectric condition are supposed to occur are not the same?

Answer 20

-an area of the heart has a different potential than another
-an area of the heart is not depolarizing normally
-an area is not repolarizing normally

Question 21

what are some causes for a wandering baseline?

Answer 21

-poor preparation of the electrode and skin
-loose wires
-moving clothing

Question 22

what is the 60 cycle interference?

Answer 22

devices such as elevators and overhead lights using 60 Hz wall current superimposed on the trace

Question 23

what is the path of depolarization of the heart?

Answer 23

-impulse spread from SA node throughout both atria
-reaches the AV node; delays the spread of impulse and allows time for efficient blood flow
-travels into left and right bundle branches
-then into perkinje fibers

Question 24

what is the sequence of depolarization?

Answer 24

-SA node
-atria
-AV node (brief pause)
-bundle of His and bundle branches
-apex of the heart
-base of the heart

Question 25

normally the wave of depolarization moves ___.

Answer 25

down and to the left

Question 26

what is upward (+) deflection?

Answer 26

current moving almost directly toward positive electrode

Question 27

what is downward (-) deflection?

Answer 27

current moving away from positive electrode

Question 28

what happens if movement is perfectly perpendicular to the positive electrode?

Answer 28

a flat line will show

Question 29

what happens if movement is close to perpendicular to the positive electrode?

Answer 29

a small upward deflection followed by a nearly equally-sized downward deflection

Question 30

what does Q represent?

Answer 30

1st part of ventricular depolarization

Question 31

what does the PR interval represent?

Answer 31

pause, atrial depolarization in complete and AV impulse has not yet started

Question 32

what does the ST segment represent?

Answer 32

ventricular depolarization is complete

Question 33

what does the t-wave represent?

Answer 33

ventricular repolarizatoin

Question 34

Which direction should the axis of depolarization be pointing and why?

Answer 34

down and to the left towards the muscular left ventricle which is the workhorse of the heart

Question 35

what should the p-wave look like?

Answer 35

upright and symmetric

Question 36

what does a large Q wave indicate?

Answer 36

disease

Question 37

what on an EKG is indicative of an old MI?

Answer 37

a q-wave with a magnitude of greater than 1/3 of the magnitude of the QRS complex

Question 38

what does the size of the R wave relative to the S wave indicate?

Answer 38

whether the vector is more towards the positive electrode or away from the positive electrode

Question 39

what shape should the t-wave be?

Answer 39

upright and symmetric

Question 40

what does an inverted, flat or biphasic t-wave indicate?

Answer 40

abnormal repolarization usually due to ischemic disease

Question 41

what is an R' wave?

Answer 41

a 2nd upward deflection following the r-wave

Question 42

what does an R' wave indicate?

Answer 42

abnormal conduction through one bundle branch (blocked)

Question 43

what is a segment?

Answer 43

between two wave

Question 44

what is an interval?

Answer 44

between two waves but includes a wave

Question 45

the PR interval represents the time elapsed between the:

Answer 45

onset of atrial depolarization and the onset of ventricular depolarization

Question 46

what is ST segment depression?

Answer 46

ST segment drawn below isoelectric line T-wave starts below the isoelectric line and finishes on the isoelectric line

Question 47

what does ST depression indicate?

Answer 47

ischemia

Question 48

what is ST segment elevation?

Answer 48

ST segment drawn above the isoelectric line the r wave begins on the isoelectric line and finishes above it the t wave begins at an elevated position on the tracing and finishes on isoelectric liine

Question 49

what does ST segment elevation indicate?

Answer 49

acute myocardial infarction in the area of the heart "best seen" by this lead

Question 50

what is the conduction rate of the SA node?

Answer 50

60-100 bpm

Question 51

what is the conduction rate of the AV node?

Answer 51

40-60 bpm

Question 52

what is the conduction rate of the bundle of his?

Answer 52

40-60bpm

Question 53

what is a pacemaker cell?

Answer 53

the cell that has the fastest rate of spontaneous depolarization normally the SA node but can be AV node or ventricular cells

Question 54

the AV node and some ventricular cells can become pacemaker due to:

Answer 54

increased automaticity of these cells failure of faster pacemaker

Question 55

how does the ANS influence the rate of spontaneous depolarization?

Answer 55

slowed by the release of ACh by parasympathetic nerves accelerated by release of NE by sympathetic nerves or circulating epinephrine

Question 56

what is bradycardia?

Answer 56

<60bpm

Question 57

what is tachycardia?

Answer 57

>100bpm