EKG Basics

Question 1

On an EKG strip, what does the vertical axis represent?

Answer 1

Time

Question 2

On an EKG strip, what does the horizontal axis represent?

Answer 2

Voltage (mV)

Question 3

What does 1 small box represent?

Answer 3

0.04s and 0.1mV

Question 4

What do 5 small boxes represent?

Answer 4

1 big box = 0.2s, 0.5mV

Question 5

What is used to ensure the ECG machine is properly calibrated?

Answer 5

Calibration mark

(standard = 1.0mV = 2 large boxes = 10 vertical squares)

Question 6

What is defined as a flat line in which there is no electrical activity or impulses are too weak to be detected?

Answer 6

Isoelectric line

Question 7

What is used as a baseline to ID changes in electrical movement?

Answer 7

Isoelectric line

Question 8

What is defined as markings that are not products of heart’s electrical activity (ex. pt movement)?

Answer 8

Artifact

Question 9

What can artifacts mimic?

Answer 9

Life threatening dysrhythmias (therefore must r/o)

Question 10

The P wave represents depolarization of the RA and LA and is typically of what duration and what amplitude?

Answer 10

Duration- 0.06- 0.10s

Amplitude- 0.5- 2.5mm

Question 11

Where is the PR interval measured and what is the typicaly duration?

Answer 11

Start of P wave to beginning of QRS complex

Normal = 0.12- 0.20s

Question 12

The PR segment represents depolarization of the heart from the SA node through the atria, AV node, and His-purkinj system and is measured where?

Answer 12

Flat/ isoelectric line between end of P wave and start of QRS complex

Question 13

The QRS complex represents depolarization of the ventricles, is typically upright and narrow and is of what duration?

Answer 13

0.06- 0.12s

(will always be named QRS regardless if missing a wave)

Question 14

What is the Q wave on an EKG strip?

Answer 14

1st negative deflection

Question 15

What is the R wave on an EKG strip?

Answer 15

Any positive deflection following Q wave or PR segment

Question 16

What is the S wave on an EKG strip?

Answer 16

Any negative deflection below baseline following R wave

Question 17

Where is the ST segment measured on an EKG strip?

Answer 17

Flat line following QRS complex

Question 18

Where is the T wave on an EKG segment?

Answer 18

Larger, slightly, asymmetrical (vs P wave) waveform that follows ST segment (ventricular repolarization)

Question 19

What is the J point on an EKG strip?

Answer 19

Where QRS complex meets ST segment

Question 20

Where is the QT interval measured and what is a normal duration?

Answer 20

Beginning of QRS complex to end of T wave

Normal = 0.36- 0.44ms

Question 21

The QT segment will increase as what parameter slows?

Answer 21

HR

Question 22

With regular rhythm, how does the QT segment compare to R waves?

Answer 22

QT segment should be < 1/2 the distance between consecutive R waves

Question 23

What provide an electrical “view” of the heart to help distinguish a focal problem?

Answer 23

Leads

Question 24

What are the anterior leads?

Answer 24

V1-4

Question 25

What are the lateral leads?

Answer 25

I, aVL, V5-6

Question 26

What are the inferior leads?

Answer 26

II, III, aVF

Question 27

Bipolar leads record difference in electrical potential between what?

Answer 27

Positive and negative electrode with 3rd electrode as a ground

Question 28

What is postitive and negative with lead I?

Answer 28

RA neg, LA pos

Question 29

What is postitive and negative with lead II?

Answer 29

RA neg, LL pos

Question 30

What is postitive and negative with lead III?

Answer 30

LA neg, LL pos

Question 31

What is the reference point for unipolar leads?

Answer 31

Center of the heart (as calculated by ECG machine)

Question 32

What type of leads are enhanced by the ECG because waveforms produced by these leads are normally small?

Answer 32

Augmented limb leads

Question 33

Augmented limb leads use the same electrodes as limb leads but only 1 is positive and the other two...?

Answer 33

Have no charge and serve as common ground

Question 34

What electrode is positive with aVR and what view of the heart does it provide?

Answer 34

RA pos, views base of heart (atria and great vessels)

Question 35

What electrode is positive with aVL and what view of the heart does it provide?

Answer 35

LA pos, views lateral wall of LV

Question 36

What electrode is positive with aVF and what view of the heart does it provide?

Answer 36

LL pos, views inferior wall of LV

Question 37

What leads are all positive electrodes and provide anterior and lateral views of the heart in a horizontal plane?

Answer 37

Precordial leads (V1-6)

Question 38

Where is V1 placed?

Answer 38

4th ICS, right of sternum

Question 39

Where is V2 placed?

Answer 39

4th ICS, left of sternum

Question 40

Where is V3 placed?

Answer 40

Halfway between V2 and V4

Question 41

Where is V4 placed?

Answer 41

5th ICS in MCL

Question 42

Where is V5 placed?

Answer 42

Anterior axillary line, same horizontal plane as V4

Question 43

Where is V6 placed?

Answer 43

Midaxillary lines, same horizontal plane as V4

Question 44

Which leads are used for patient monitoring in the ED, telemetry, and ICU?

Answer 44

Modified chest leads

Question 45

What do MCL1 and MCL6 provide and where are they placed?

Answer 45

Provide continuous cardiac monitoring, positive electrode placed in same position as precordial leads V1 or V6

Question 46

What is normal sinus rhythm (NSR)?

Answer 46

Regular rhythm, rate 60-100 bpm

Question 47

How do you determine regularity?

Answer 47

* Distance between consecutive P waves and consecutive QRS complexes should be the same (up to 1 square difference) * R-R and P-P intervals are the same (if differ, then rhythm= irregular = abnormal)

Question 48

What are the 3 methods for calculating regularity?

Answer 48

Caliper method, pen and paper method, counting small squares method (irregular if # is different)

Question 49

How do you define "occasionally irregular"?

Answer 49

Mostly irregular but occasional areas of irregularity

Question 50

How do you define "very irregular"?

Answer 50

Has many areas of irregularity

Question 51

A wandering atrial pacemaker is defined how?

Answer 51

Slightly irregular (pacemaker changes location from site to site and produces a slightly irregular rhythm) (should look at appearance of P wave)

Question 52

Paroxysmal tachycardia is defined as what with respect to regularity?

Answer 52

Sudden HR acceleration (normal rate that suddenly accelerates to a rapid rate producing an irregular rhythm)

Question 53

How do you define patterened irregularity?

Answer 53

Irregularity repeats in a cyclical fashion

Question 54

Sinus dysrhythmia and 2nd degree AV block type 1 are examples of what?

Answer 54

Patterned irregularity (sinus dysrhythmia = with inspiration increases, decreases with expiration)

Question 55

Atrial fibrillation is an example of what type of regularity?

Answer 55

Totally irregular (no discernable pattern to irregularity)

Question 56

Irregularity can also be seen in dysrhythmias with a varying ratio of what?

Answer 56

Atrial to ventricular conduction ratio (P wave to QRS ratio)

Question 57

What HR is bradycardia?

Answer 57

\< 60

Question 58

What HR is tachycardia?

Answer 58

\> 100

Question 59

If rhythm is found to be irregular, you should look at what? OR describe the irregular rhythm with what?

Answer 59

Look at most regular portion of ECG to determine underlying rate OR Describe irregular rhythms with HR range

Question 60

How do you use the 6-second interval x 10 method to determine HR?

Answer 60

of QRS complexes in 6 seconds x 10 (not very accurate)

Question 61

How do you use the large box estimate (300, 150, 100, 75, 60) to determine HR?

Answer 61

Find R wave located on/near bold line and count down along each subsequent bold line until next R wave → closest bold line = rate

Question 62

When using the large-box method to determine HR, if 2nd R is not on a bold line, what should you do?

Answer 62

Determine what two #s it falls between and record HR as range

Question 63

The large-box method for determining HR is less accurate for what type of rhythms?

Answer 63

Irregular rhythms

Question 64

How can the large-box method for determining HR be made more precise?

Answer 64

Divide difference of 2 bold lines by 5 to determine how many “beats” each small box represents and subtract that from last bold line

Question 65

What is the most accurate method for estimating HR but cannot be used with irregular rhythms?

Answer 65

1500 method (count # of small squares b/w two consecutive R waves and divide 1500 by that #)

Question 66

What method for measuring HR do you position the "start mark" on an R wave, then find the next consecutive R wave and where it lines up is the approximate HR?

Answer 66

Rate calculator

Question 67

When evaluating P waves, an amplitude of \> 2.5 suggests what?

Answer 67

Right atrial enlargement (RAE) = P pulmonale

Question 68

When evaluating P waves, a width of \> 0.10s suggests what?

Answer 68

Left atrial enlargement (LAE) = P mitrale

Question 69

When might wide, notched or biphasic P waves be seen?

Answer 69

Increased left atrial pressure and left atrial dilation

Question 70

In what lead are biphasic P waves normal?

Answer 70

V1

Question 71

Variations in P waves are typically due to impulses arising from the atria but NOT where?

Answer 71

SA node

Question 72

What is a premature atrial complex (PAC)?

Answer 72

Early beat

Question 73

What will continually change in appearance in a wandering atrial pacemaker?

Answer 73

P wave

Question 74

If the P wave appears "buried" in the T wave of the preceding beat (short P-P interval) and the T wave is peaked, noted or larger than normal, what pathology should you suspect?

Answer 74

Atrial tachycardia

Question 75

When evaluating P waves, a "saw tooth pattern" is indicative of what?

Answer 75

Flutter waves (when atria fire @ rate 250-250 bpm)

Question 76

When evaluating an EKG strip you note absence of discernable P waves and instead note a chaotic looking baseline that preceeds the QRS complex. What are you suspicious for?

Answer 76

Fibrillatory waves (when atria fired from many sites @ rate \> 350 bpm)

Question 77

Inverted P waves produced by retrograde depolarization of atria (lower RA near AV node, LA, AV junction), can precede, occur during or follow a QRS complex. What is this pattern associated with?

Answer 77

Dysrhythmias that originate from AV junction

Question 78

If the P wave \> QRS complex, what does this indicate?

Answer 78

Impulse was initiated in SA node/atria but was blocked and didn’t reach the ventricles (P wave to QRS ratio should be 1:1)

Question 79

When evaluating the QRS complex, there can only be 1 what? But more than 1 what?

Answer 79

Only 1 Q wave but more than 1 R or S wave (R’ or S’ = R-prime or S-prime)

Question 80

When should a lowercase r or s be used when evaluating the QRS complex?

Answer 80

If R or S wave is small

Question 81

How is the QRS complex measured?

Answer 81

* Starting point = where 1st wave moves away from baseline * Ending point where last wave flattens (joint point) * Should include entire S but shouldn’t overlap into ST segment/T wave

Question 82

Abnormal QRS complexes are typically produced by what?

Answer 82

Abnormal depolarization of ventricles (SA node, atopic pacemakers in atria, AV junction, BB, purkinje network, ventricular myocardium)

Question 83

What are the possible causes of a tall QRS?

Answer 83

Hypertrophy of one or both ventricles, ABN pacemaker, aberrantly conducted beat

Question 84

What will the appearance of the QRS complex be with obesity, pericardial effusion, or hypothyroidism?

Answer 84

Low voltage QRS

Question 85

What is often the result of an intraventricular conduction defect (typically a result of LBBB)?

Answer 85

Wide-bizarre QRS (of supraventricular origin)

Question 86

What is defined as the following? Electrical impulses reach the BB while it is still refractory after conducting a previous electrical impulse (impulse travels down the unaffected BB first, follow by the other = wider QRS complex)

Answer 86

Aberrant conduction

Question 87

When is a PR interval considered abnormal?

Answer 87

Shorter, longer, absent or varied

Question 88

How will the PR interval appear when the impulse originates in atria close to or in AV junction or when impulses arise from SV site but travel through ABN accessory pathway to ventricles (faster pathway)?

Answer 88

Shorter (\<0.12 s)

Question 89

The following leads to what? Impulses arise from SV site but travel through ABN accessory pathway to ventricles (faster pathway)

Answer 89

Pre-excitation (premature ventricular depolarization)

Question 90

Travel of an impulse through an what abnormal accessory pathway may lead to a shorter PR interval?

Answer 90

Bundle of Kent (Delta wave)

Question 91

Delay in impulse conduction through AV node (ex. 1st degree AV block) will result in what change in the PR interval?

Answer 91

Longer

Question 92

The following will produce what PR interval? Wandering atrial pacemaker (pacemaker site moves from beat to beat)

Answer 92

Varying

Question 93

The following will produce what PR interval? 2nd degree AV block, type 1

Answer 93

Varying (PR intervals are progressively longer until QRS complex is dropped and then cycle repeats)

Question 94

The following will produce what PR interval? 3rd degree AV heart block (atria and ventricles are beating independently of eachother)

Answer 94

Varying

Question 95

The following will produce what PR interval? Atrial flutter, atrial fibrillation and ventricular dysrhythmias

Answer 95

Absent