Electrocardiogram (ECG)

Question 1

Where are the 4 limb leads located?

Which is the ground electrode?

Answer 1

Right Arm(RA): infraclavicular fossa
Left Arm (LA): infraclavicular fossa
Leg LEG (LL): left side of abdomen below rib cage
Right Leg (RL): right side of abdomen
RL IS GROUND ELECTRODE

Question 2

How many leads vs. how many electrodes are used with ECG?

Answer 2

12 lead
10 electrodes (4 limb leads and 6 precordial leads)

Question 3

What is the location for the precordial leads?

Answer 3

V1: 4th intercostal space at right sternal border (start on other side of heart)
V2: 4th intercostal space on left sternal border
V3: midway between V2 and V4
V4: 5th intercostal space at left midclavicular line
V5: left anterior axillary line at V4 level
V6: left midaxillary line at V4/V5 level

Question 4

What occurs during

1. P wave
2. PR interval
3. QRS Complex
4. QT Interval
5. ST Segment
6. T Wave

Answer 4

1. P wave - atrial depolarization
2. PR interval - time for atrial depolarization and conduction from SA node to AV node
3. QRS Complex - ventricular depolarization and atrial repolarization
4. QT Interval - time for both ventricular depolarization and repolarization (INCLUDES ENTIRE T WAVE)
5. ST Segment - isoelectric period following QRS
6. T Wave - ventricular repolarizations

Question 5

1. How long is the PR interval?
2. How long is QRS complex?
3. How long is QT interval?

Answer 5

1. 0.12 - 0.20 seconds OR 12 to 20 ms (includes entire P wave)
2. 0.06-0.10 seconds or 6 to 10 ms
3. 0.20 - 0.40 or 20 to 40 ms (includes entire Q and T waves)

Question 6

what is normal sinus rhythm?

Answer 6

60-100 bpm

Question 7

Sinus brachy vs. tachycardia?

Answer 7

Brachy <60 bpm

Tachy > 100 bpm

Question 8

What is a sinus rhythm but with intermittent failure of either SA nod impulse formation or AV node conduction that results in the occasional complete absence of P or QRS waves?

Answer 8

Sinus Arrest

Question 9

What occurs when an ectopic foci in the atrium initiates an impulse before the SA node and the P wave is premature with ABNORMAL CONFIGURATION?

Answer 9

Premature Atrial Contractions (PACS)

Question 10

What is the clinical significance of Premature Atrial Contractions?

Answer 10

very common and generally benign (stress, affeine, smoking, alcohol)
However may progress to atrial flutter, tachycardia, or fibrillation

Question 11

what is ectopic very rapid atrial tachycardial with a rate of 250-350 bpm?

Answer 11

Atrial Flutter

Question 12

What is the shape of the P waves with Atrial Flutter?

Answer 12

Saw-tooth P waves

Question 13

What are 2 main conditions that Atrial Flutter occurs with?

Answer 13

Valvular Disease (especially mitral) and ischemic heart disease

Question 14

Common arrhythmia where atria depolarized 350-600 times per minute?

Answer 14

Atrial Fibrilation

Question 15

What does the ECG look like with Atrial Fibrilation?

Answer 15

irregular undulations of ECG without discrete P waves

Question 16

What 3 conditions does A-Fib appear in?

Answer 16

Coronary artery disease, hypertension, and valvular disease

Question 17

What does a 1st degree AV block look like on ECG and what are symptoms?

Answer 17

PR interval longer than 0.2 seconds but constant beat to beat
No symptoms or significant change in cardiac function

Question 18

what causes first degree AV block?

Answer 18

many reasons including medication to suppress AV conduction

Question 19

How does a second degree AV block appear on ECG?

Answer 19

AV conduction disturbance in which impulses between atria and ventricles fail intermittently

Question 20

What are the two types of Second Degree AV blocks and whats the differenc?

Answer 20

Mobitz I: progressive prolongation of PR interval until 1 impulse is not conducted (GENRALLY BENIGN)
Mobitz II: consecutive PR intervals are same and normal followed by non-conduction of one or more impulses (more serious)

Question 21

What occurs with 3rd degree heart block?

Answer 21

ALL impulses are blocked at AV node and none are transmitted to ventricles

atria and ventricles paced independently with atria>ventricles

Question 22

What degree of AV block is a medical emergency requiring a pacemaker?

Answer 22

3rd degree AV block

Question 23

what are 4 causes of third degree AV block?

Answer 23

degenerative changes of conduction systems, digitalis, heart surgery, and acute MI

Question 24

How does a Premature Ventricular Contraction (PVC) generally appear on the ECG?

Answer 24

P wave is usually absent and QRS complex has a wide and abberant shape

GOOGLE

Question 25

What is a Bigeminy vs Trigeminy?

Answer 25

Bigeminy: normal sinus impulse followed by a PVC Tigeminy: PVC occurs after every two normal sinus impulses GOOGLE

Question 26

What is 3 or more consecutive PVCs at a ventricular rate >150 bpm?

Answer 26

Ventricular Tachycardia (V-Tach)

Question 27

How does ventricular tachycardia appear on ECG?

Answer 27

P waves are absent and QRS complexes are wide adn abberant in appearance GOOGLE

Question 28

When does V-tach become life threatening?

Answer 28

When it lasts longer than 30 seconds or if it degenerates into ventricular fibrillation

Question 29

what is it called when ventricles do not beat in a coordinated fashion but fibrillate or quiver asynchronously and ineffectively?

Answer 29

Ventricular Fibrillation

Question 30

How does Ventricular Fibrillation appear on ECG?

Answer 30

fibrallatory waves with irregular pattern that is either fine or course GOOGLE

Question 31

What is the immediate intervention required for Ventricular Fibrillation?

Answer 31

Defibrilation

Question 32

What shows a stright line pattern on ECG and requires immediate CPR and medications to stimulate cardiac activity?

Answer 32

Ventricular Asystole

Question 33

what are 4 possible areas to find signs of Myocardial Ischemia and Infarction on an ECG?

Answer 33

1. ST Segment depression 2. ST Segment Elevation 3. Q Wave 4. T Wave Inversion

Question 34

Where is ST elevation seen on ECG?

Answer 34

0.08 seconds AFTER (2 small boxes) the J point (junction between end of QRS complex and beginning of ST segment)

Question 35

What are 3 causes of ST segment depression?

Answer 35

1. Subendocardial Ischemia 2. Digitalis Toxicity 3. Hypokalemia

Question 36

What is the earliest sign of acute transmural infarction on ECG? TRANSMURAL: MI is characterized by ischemic necrosis of the full thickness of the affected muscle segment(s), extending from the endocardium through the myocardium to the epicardium

Answer 36

ST Segment Elevation

Question 37

What is a characteristic marker of infarction?

Answer 37

Q wave longer than 0.04 sec and larger than 1/3 the amplitude of the R wave Small box is 0.04 seconds and 1 mm

Question 38

When does T wave inversion occur?

Answer 38

hours or days after MI as the result of delay in repolarization produced by injury

Question 39

Other than infarction, what is another reason a T-Wave inversion may occur? (2)

Answer 39

with right and left bundle branch blocks and after a CVA

Question 40

How many seconds are typically on an ECG strip?

Answer 40

10 seconds

Question 41

how many millimeters is each large and small box on ECG? what is the time interval per box???? *********KNOW BOTH OF THESE*************

Answer 41

Small box: 1 mm LArge box: 5 mm Small box: 40 ms Large box: 200 ms

Question 42

How to caculate HR?

Answer 42

Multiple QRS complexes by 6 in 10 second strip OR count the number of large squares between two consecutive P waves and divide by 300

Question 43

Measuring the PR interval will determine what?

Answer 43

Determine if a conduction block is present Normal time is 0.12 to 0.20 seconds

Question 44

Where is ST segment evaluated?

Answer 44

0.08 seconds after the J point

Question 45

What is the difference between ST segment depression and ST segment elevation on ECG?

Answer 45

ST Segment Depression inidicates subendocardial (non-full thickness) ischemia ST Segment Elevation indicates acute transmural (full thickness) infarction