Electrocardiography

Question 1

Fascicles

Answer 1

three conducting fiber bundles (right branch of bundle of HIS + anterior and posterior hemibranches)

Question 2

unifascicular block of conduction through one of the three bundles

Answer 2

still allows impulse from atria into ventricles

Question 3

bifascicular block

Answer 3

still allows impulse from atria into ventricles

Question 4

trifascicular block

Answer 4

same effect as AV node blockade…prevents signals from atria to ventricles

Question 5

trifascicular block causes

Answer 5

myocardial scarring from infarction
amyloidosis
sarcoidosis in the heart, esp. in young AA

Question 6

A cardiac arrhythmia (esp. heart block) in young african american suggests…

Answer 6

possible cardiac sarcoidosis

Question 7

Each heartbeat is reflected on EKG by 3 major deflections

Answer 7

1. P wave
2. QRS complex
3. T wave

Question 8

PR interval

Answer 8

onset of P to end of QRS

represents length of time for signals to propagate from SA node through AV node and ventricles

Question 9

Normal PR interval

Answer 9

120-200ms

Question 10

first degree AV block (1st degree heart block)

Answer 10

PR>200ms but w/ all impulses from atria getting through

Question 11

QRS interval

Answer 11

less than or equal to 100ms

Question 12

longer QRS intervals

Answer 12

aberrantly conducted impulses or impulses from abnormal places

Question 13

If the QRS interval is not widened, QT interval represents…

Answer 13

ventricular repolarization

needs correction for heart rate to be helpful, since faster HRs mean faster repolarization

Question 14

QTc

Answer 14

QT interval corrected for heart rate

normally less than or equal to 440ms

Question 15

prolonged QT…most common cause

Answer 15

dangerous!

myocardial ischemia

Question 16

other causes of prolonged QT

Answer 16

blood electrolyte abnormalities (i.e. hypokalemia, hypocalcemia, hypomagnesemia)

channelopathy

Question 17

reflect anatomic site of heart disease w/in organ

Answer 17

abnormalities in 12-lead EKG

Question 18

Disease of the anterior LV served by LAD coronary artery

Answer 18

Abnormalities in leads V1-V4

Question 19

disease of lateral left ventricle served by left circumflex coronary artery

Answer 19

abnormalities in V5-V6

Question 20

disease in right coronary artery territory, the inferior left ventricle

Answer 20

Abnormalities in leads II, III, and aVF

Question 21

acute blockage of a major epicardial coronary artery

Answer 21

elevation of ST segment (end of QRS and beginning of T wave)

T wave commonly inverted

Question 22

large transmural myocardial infarction

Answer 22

permanently misshapen QRS complex w/ abnormally large, long, deep initial downward deflection (pathologic Q wave)

Question 23

innocent Q waves

Answer 23

some heart murmurs

some S3s and S4s

Question 24

abnormalities in 12-lead EKG

Answer 24

reflect anatomic site of heart disease w/in organ

Question 25

Abnormalities in leads V1-V4

Answer 25

Disease of the anterior LV served by LAD coronary artery

Question 26

abnormalities in V5-V6

Answer 26

disease of lateral left ventricle served by left circumflex coronary artery

Question 27

Abnormalities in leads II, III, and aVF

Answer 27

disease in right coronary artery territory, the inferior left ventricle

Question 28

elevation of ST segment (end of QRS and beginning of T wave)

T wave commonly inverted

Answer 28

acute blockage of a major epicardial coronary artery

Question 29

permanently misshapen QRS complex w/ abnormally large, long, deep initial downward deflection (pathologic Q wave)

Answer 29

large transmural myocardial infarction

Question 30

Differentiate b/w sinus tachycardia and tachyarrhythmia

Answer 30

sinus tachycardia knows its limits and will not go over rate of 220 minus pt’s age

Question 31

a 20 yr old w/ sinus tachycardia of 200 (who has not just sprinted) is…

Answer 31

critically ill, but not likely from intrinsic heart disease

look for:
anaphylaxis
PE
cocaine
occult bleeding
sepsis
SIRS
thyroid storm

Question 32

many tachyarrhythmias that orriginate from above ventricles (supraventricular) are…

Answer 32

sort of innocent

examples:
**atrial fibrillation
atrial flutter
supraventricular tachycardia

Question 33

atrial fibrillation

Answer 33

easy to spot
rhythm is irregular
rate is high or normal (60-220)
no P waves

Question 34

atrial flutter

Answer 34

results from reentrant circuit around tricuspid valve

two P waves for each QRS

HR around 150

Question 35

Supraventricular tachycardia

Answer 35

reentrant pathway in atria right near AV node

can respond to home remedy vagal maneuvers such as Valsalva maneuver, carotid sinus massage, immersion of face in a pan of ice water

Question 36

Ventricular tachyarrhythmias

Answer 36

dangerous

Question 37

2 major types of ventricular arrhythmias

Answer 37

ventricular tachycardia

ventricular fibrillation

Question 38

QRS complex wide (over 120ms) and HR usually less than 200

Answer 38

ventricular tachycardia

• -If all QRS look alike…monomorphic
• -if QRS complexs vary in morphology…polymorphic

Question 39

ventricular tachycardia

Answer 39

can degenerate into ventricular fibrillation

Question 40

ventricular fibrillation

Answer 40

immediately life-threatening

totally diordered rapid stimulation of ventricles

due to fragmentation of wave of depolarization into numerous tiny wavelets going every which way

Question 41

chaotic pattern w/out discrete QRS complexes

Answer 41

Ventricular fibrillation

Question 42

Treatment for v fib

Answer 42

elecrical defibrillation or punch to the sternum if not available

(RARE: punch to sternum in healthy individual can cause fatal arrhythmia…commotio cordis)