ECG

Question 1

Myocytes have 3 properties

Answer 1

automaticity
rhythmicity
conductivity

Question 2

Automaticity

Answer 2

-able to discharge/depolarize w/o stimulation from a nerve
automatically discharge

Question 3

Rhythmicity

Answer 3

-depolarization occurs at regular intervals
-cardiac muscle cells can depolarize at regular intervals

SA node- rhythmicity creates sinus rhythm (60-100)

Question 4

AV
His-purkinje fibers

Answer 4

AV: 40-60 times per min

His: 30-40 times per min

faster/higher discharge rate predominates
autonomic influence >SA>AV>Purk

Question 5

conductivity

Answer 5

-ability to spread impulses quickly w/o nerve involvement

Question 6

ECG tracings are…

Answer 6

superficial recordings of electrical events/ ionic events occuring within the myocytes

Question 7

P wave

Answer 7

atrial depolarization is depicted on ECG as p wave.
impulse spread to L atrium via bachmann bundle

Question 8

PR interval

Answer 8

when spread of depolarization reaches AV node, slight delay occurs
reads as PR interval

Question 9

Purkinjes/ bundle branches

Answer 9

-L and R division, L has an A and P division
ventricular depolarization occurs when impulse reaches PFs, carries signal to myocytes .

QRS complex reflects this
greater amp bc of greater muscle mass

Question 10

T wave

Answer 10

-represents repolarization of ventricles
interval from beginning of QRS complex to apex of t wave = absolute refractory period

most leads- T wave is positive (upward deflection) and reflects repolarization of myocytes

Question 11

Limb leads

Answer 11

I,II,III (standard limb leads)
aVR,aVL,aVF (augmented)

each leads records from different angle, providing a diff view of same cardiac activity

Question 12

Chest leads

Answer 12

6, show gradual changes
record in horizontal plane

Question 13

Single lead assessment
look for:

Answer 13

-heart rhythm or rate
-normal waveforms
-abnormal wavefroms

use lead II!!!

Question 14

ECG recording

Answer 14

vertical deflections: voltage
horizontal axis- time
1 large square=0.20sec, 5=1 sec
30=6secs
horizontal distance becomes a stopwatch!

Question 15

determine HR from ECG

Answer 15

count large boxes between two R waves
300/count
lower number R waves= higher BPM and vise versa
can only do this with normal

Question 16

Assessing cardiac cycle

Answer 16

1. eval P wave
2. eval PR interval (norm is 0.12-0.20 or 3-5 small boxes)
3. eval QRS (look alike?)
4. Eval QRS interval (0.06-0.10 or 1.5-2.5 small boxes)
5. eval t wave
6. eval RR wave interval
7. eval HR (6 sec strip, norm 60-100)
8. observe pt and eval sxs

Question 17

First degree AV block

Answer 17

-occurs when impulse initiated in SA node but is delayed on way to AV node
-AV conduction time is prolonged

if R is far from P, you have first degree

Question 18

2nd degree, Wenckeback

Answer 18

-progressive lengthening of PR interval

longer longer longer drop, that MF in Wenckeback!!

Question 19

2nd degree AV block Mobitz II

Answer 19

-intermittent non-conducted p waves W/O progressive prolongation of PR interval
P waves constant
RR is exact multiple of preceding RR interval

If some p’s don’t get thru you have Mobitz II!

Question 20

3rd degree AV block

Answer 20

–NO impulses initiated above the ventricles are conducted to the ventricle
atria fire at own rate
ventricles fire at own rate

If p’s and q’s dont agree, then you have 3rd degree

Question 21

Tx 1st degree

Answer 21

benign and not treated

Question 22

2nd degree tx

Answer 22

depends on type
no tx necessary or pacemaker
result of an MI

Question 23

3rd degree tx

Answer 23

LIFE threatening
MI, degen of conducting system
permanent pacemaker
medical emergency

Question 24

PAT/PSVT

Answer 24

a sudden recurrence of atrial tachycardia

p waves present but may be merged with t wave
PR less than 0.20
QRS identical but between 0.06-0.10
RR regular and may show start/stop of PAT

Question 25

PAT/PSVT arryhtmia

Answer 25

-emotional, overexertion, caffeine, nicotine, aspirin, RHD, mitral valve dysfunc, PE dizziness, weakness, SOB determine cause and treat accordlingly

Question 26

atrial flutter

Answer 26

P waves are sawtooth pattern (uniform due to only one ectopic focus) rapid succession of atrial depolarization, rate of 250-350

Question 27

A fib

Answer 27

-quiver/twitch of atrial muscle p waves absent RR is irregular QRS between 0.06-0.10 old age, CHF, drugs, stress/pain, RHD, renal failure not threatening unless HR elevated at rest lose atrial kick potential to develop mural thrombi

Question 28

WPW syndrome

Answer 28

-common -HB abnorm fast -preexcitation syndrome sxs: pounding HB, chest pain, difficult breathing, fainting, SOB, anxiety cause: congential, or heart defects tx: cardioversion, propranolol (b blocker)

Question 29

PVCs

Answer 29

-ectopic focus originates an impulse from somewhere in the ventricles QRS wide and bizzaew without P wave followed by compensatory pause heart skips beat tx depends on cause, frequency, severity, sxs serious when: paired together, mutlifocal, >6 per min, land on t wave, triplets or more

Question 30

Vtach

Answer 30

3+ PVCs in a row twisting of points' bc rapid firing by a single ventricular focus with increased automaticity P waves absent prolonged QT interval QRS wide and bizzare 100-250 ventricular tachy can be precursor to vent fibrillation

Question 31

Vtach causes and tx

Answer 31

causes: ischemia, acute infarc, CAD, hypertensive HD, med reaction tx: cardioversion, defib, meds MED emergency- mostly unconscious

Question 32

Vfib

Answer 32

quivering of ventricular muscle = no CO creates asynchrony ECG shows irregular up/down in zigzag MED emergency causes same as vtach tx: defib followed by resuscitation, O2, and meds

Question 33

Hypertrophy

Answer 33

longer QRS

Question 34

Ischemia

Answer 34

inverted T wave ST seg depression

Question 35

ST deg depression at rest in presence of chest pain

Answer 35

-subendocardial infarc may indicate a pending transmural infarc

Question 36

ST seg depression in absence of ischemia or angina

Answer 36

may be due to digitalis toxicity

Question 37

ST seg elevation/depression is diagnostic for

Answer 37

-acute infarc -also presence of sig Q wave

Question 38

Leads that demonstrate presence of t wave inversion, ST seg changes, or Q waves identify...

Answer 38

location of ischemia, injury or infarc