1.5 Cardiac electrophysiology 59-68

Question 1

an arrhythmia due to blockage in electrical conduction system of the heart (not a flow problem)

Answer 1

A-V heart block

Question 2

first degree A-V heart block is what degree of interruption to the heart?

Answer 2

mild interruption (slowdown)

Question 3

second degree A-V heart block is what degree of interruption to the heart?

Answer 3

moderate interruption

Question 4

third degree A-V heart block is what degree of interruption to the heart?

Answer 4

severe interruption/disruption

Question 5

what is a relatively common and essentially symptom-free AV heart block?

Answer 5

first degree

Question 6

what AV heart block is a complete disruption and results in CO problems such as syncope (lightheadedness)?

Answer 6

3rd degree

Question 7

lab findings for A-V heart block

Answer 7

abnormal ECG: lengthened P-R interval

Question 8

wiring system of the heart is called

Answer 8

conduction system

Question 9

the SA node is the fastest to recycle, it leads the pack and its therefore called the:

Answer 9

pacemaker

Question 10

the SA node produces what kind of rhythm

Answer 10

sinus

Question 11

when the SA node is stretched, it fires faster/slower/stays the same

Answer 11

faster. so increased venous return, increased atrial pressure, increased heart rate

Question 12

impulse propagation is held up at the AV node for how long

Answer 12

1/10th second

Question 13

knowledge of the electrical behavior of the heart lept forward with advances in cardiology sub-field of:

Answer 13

electrocardiography

Question 14

a display from a super sensitive voltmeter called an electrocardiograph is called

Answer 14

electrocardiogram

Question 15

the ECG represents electrical activity of the heart during its cycle. voltage recordings produce “___” on a graphical printout

Answer 15

waves

Question 16

atrial depolarization is what on the ECG

Answer 16

P wave

Question 17

ventricular depolarization is what on the ECG

Answer 17

QRS complex

Question 18

ventricular repolarization is what on the ECG

Answer 18

T wave

Question 19

Where are all the waves on the ECG/EKG? sketch it out

Answer 19

check yo’self

… before you wreck yo’self …

Question 20

corresponds to rapid reversal of the impulse direction at the apex and now toward the base (atria)

Answer 20

S wave

Question 21

rapid depolarization of the rest of the ventricles (initially toward apex)

Answer 21

R wave

Question 22

described as septal activation

Answer 22

Q wave

Question 23

the ___ wave corresponds to atrial muscle cells.

the ___ corresponds to steep phase of ventricular action potentials

the ___ corresponds roughly to the relative refractory periods

Answer 23

P wave; QRS complex; T wave

Question 24

a flat spot or baseline on the ECG is termed

Answer 24

segment

Question 25

combination of waves or waves/segments on the ECG is termed

Answer 25

interval

Question 26

Note: ST segment during the \_\_\_\_

Answer 26

absolute refractory period

Question 27

Note: PR segment due to \_\_\_

Answer 27

AV nodal slowdown

Question 28

an important stretch often examined in ventricles that are in trouble. Serious problem in the muscle cells of the pumping chambers when this segment is "elevated" (injury, infarct) or "depressed" (non-specific)

Answer 28

ST segment

Question 29

represents the delay at the AV node. long segments here indicate some sort of electrical system blockage between atria and ventricles

Answer 29

PR segment

Question 30

What could cause a shift in the mean QRS vector (AKA electrical axis of the ventricles)?

Answer 30

inhalation/exhalation or tall/thin or short/stocky body type

Question 31

How would inhalation or tall/thin body type shift the mean QRS vector (AKA electrical axis of the ventricles)?

Answer 31

right shift

Question 32

How would exhalation or short/stocky body type shift the mean QRS vector (AKA electrical axis of the ventricles)?

Answer 32

left shift

Question 33

what causes heart to shift right on axis?

Answer 33

inhalation or tall/thin body type

Question 34

what causes heart to shift left on axis?

Answer 34

exhalation or short/stocky body type

Question 35

a (heart) shift out of normal range

Answer 35

axis deviation

Question 36

asynchronous contractions

Answer 36

arrhythmia

Question 37

tachycardia can happen because:

Answer 37

high body temp, sympathetic stimulation to the heart

Question 38

bradycardia can happen because

Answer 38

athletic conditioning (normal), and abnormal when parasympathetic stimulation is excessive ie when baroreceptors in the neck become compressed by arteriosclerosis

Question 39

sinus arrhythmia usually due to

Answer 39

ventilation ... causes changes in sympathetic and parasympathetic signals. ie. inhalation = increased heart rate and exhalation = decreased heart rate

Question 40

ischemia of the AV node or bundle or bundle branches

Answer 40

atrioventricular block

Question 41

a heart block that results in minor lengthening of the PR interval or segment

Answer 41

1st degree AV block

Question 42

heart block that is serious lengthening of the PR interval with occasional missing, "dropped" beats in ventricles though atria still regular

Answer 42

2nd degree AV block

Question 43

heart block that is ventricular "escape" as atria beat at ~ 75bpm and ventricles at ~30 bpm

Answer 43

3rd degree AV block (complete)

Question 44

the "AV block" in the Purkinje system is called

Answer 44

intraventricular block

Question 45

usually produces a very abnormal QRS interval

Answer 45

intraventricular block

Question 46

an electrical event out of proper location (from the normal sequence)

Answer 46

Ectopi Foci

Question 47

atria prematurely beats

Answer 47

premature contration (usually harmless)

Question 48

premature ventricular contractions ("PVS"s)

Answer 48

premature contraction, can be deadly

Question 49

why premature contraction?

Answer 49

hyper-excitability of myocardial tissue such that it depolarizes at the wrong time

Question 50

what can cause hyper-excitability of myocardial tissue

Answer 50

over use of stimulants (caffeine, nicotine) lack of sleep local ischemia (atherosclerosis and low O2 availability)

Question 51

most common cause of fibrillation

Answer 51

myocardial ischemia due to atherosclerosis

Question 52

impulse re-entry (AKA circus movement)

Answer 52

positive feedback * Start at “12 o’clock” and proceed clockwise around a loop of cardiac muscle * Normally, impulse ends when it reaches absolutely refracted tissue (at the starting point) * However, imagine that the starting tissue is ready to go again! Due to: slow impulse conduction, long impulse paths * Impulse “reentry” occurs (and continues) with no coordinated contractions * Nearly zero ejection fraction so no cardiac output = no coronary blood flow = weakening heart

Question 53

technique to interrupt ventricular fibrillation by the application of a large electrical shock

Answer 53

defibrillation

Question 54

a technique used to get the SA node back on rhythm by timing a mild shock during an R-S wave

Answer 54

cardioversion

Question 55

a disease/condition of slowing or blockage of normal electrical impulse propagation through cardiac conducting system

Answer 55

A-V heart block