Heart Waveforms/ECG

Question 1

P wave

Answer 1

atrial depolarization

Question 2

PR interval

Answer 2

time for atrial depolarization and conduction from SA node to AV node
duration 0.12-0.20 seconds

Question 3

QRS complex

Answer 3

ventricular depolarization and atrial repolarization
duration 0.06-0.10 seconds

Question 4

QT interval

Answer 4

time for both ventricular depolarization and repolarization
duration 0.20-0.40 seconds

Question 5

ST segment

Answer 5

isoelectric period following QRS when ventricles are depolarized

Question 6

T wave

Answer 6

ventricular repolarization

Question 7

Premature atrial contractions (PAC)

Answer 7

P wave is premature with abnormal configuration
very common
benign
atrial flutter, tachy, fibrillation

Question 8

Atrial flutter

Answer 8

sawtooth P waves
occurs with valvular disease, ischemic heart disease, HTN, MI

Question 9

A-fib

Answer 9

not discrete P waves

Question 10

1st degree AV block

Answer 10

PR interval is longer than 0.2 seconds but relatively constant from beat to beat
no symptoms
can be caused from medications

Question 11

2nd degree AV block

Answer 11

disturbance which impulses between atria and ventricles fail intermittently
two types

Question 12

Mobitz I (2nd degree AV block)
Mobitz II

Answer 12

progressive prolongation of PR interval until one impulse is not conducted
consecutive drop in PR interval

Question 13

3rd degree AV block

Answer 13

all impulses are blocked
considered medical emergency

Question 14

PVC

Answer 14

P wave is usually absent and QRS has wide aberrant shape
Bigeminy- normal sinus impulse followed by PVC
Trigeminy- PVC occurs after every two normal sinus impulses
common
asymptomatic

Question 15

V-tach

Answer 15

P waves are absent and QRS are wide and aberrant
longer than 30 seconds is life threatening

Question 16

V-fib

Answer 16

no cardiac output
pt becomes unconscious

Question 17

Ventricular asystole

Answer 17

death
CPR

Question 18

MI ECG signs:
ST segment depression
ST segment elevation
Q wave
T wave inversion

Answer 18

subendocardial ischemia
earliest sign of acute transmural infarction
marker of infarction due to necrosis
occurs hours or days after MI

Question 19

Absolute indication for ending a stress test

Answer 19

drop in SBP>10 mmHg with other evidence of ischemia
moderately severe angina (3/4)
increasing nervous system symptoms (ataxia, dizziness)
cyanosis, pallor
sustained v-tach
>1.0 mm ST elevation

Question 20

Relative indications for ending a stress test

Answer 20

drop in SBP> 10 mmHg without other evidence of ischemia
>2 mm ST displacement (horizontal or downsloping)
arrhythmias other than sustained v-tach
fatigue, SOB, wheezing, leg cramps and claudication
development of BBB
increasing chest pain
hypertensive response (>250 and/or >115)

Question 21

How to analyze a ECG?

Answer 21

scan the rhythm
determine HR
evaluate R-R interval
Evaluate P waves
measure PR interval
examine QRS
assess ST segment 0.08 seconds after J point

Question 22

How to determine HR on ECG

Answer 22

count number of QRS complexes in 6 second strip and multiply by 10

Question 23

R-R intervals time

Answer 23

0.04

Question 24

P waves in ECG

Answer 24

present vs absent
identical in shape
upright in leads I, II, III
each P wave followed by a QRS

Question 25

P waves present measure PR interval and what should the length be

Answer 25

0.12-0.20

Question 26

QRS width

Answer 26

0.04-0.10

Question 27

Negative stress test=
Positive stress test=

Answer 27

low probability of coronary artery disease
high probability of coronary artery disease

Question 28

Percussion interpretation:
flat or dull
resonance
hyperresonance
tympany

Answer 28

like on a thigh (suggest neoplasm in lung, atelectasis or consolidation)
normal air filled lung
emphysematous lung; pneumothorax
drumbeat-large pneumothorax