Ch. 35: cardiac monitoring, rhythm recognition

Question 1

What does a polarized state mean?

Answer 1

-cell is at rest
-negative charge

Question 2

What does depolarization mean?

Answer 2

-inside of cell is positive
-contraction

Question 3

What does repolarization mean?

Answer 3

slow movement of ions across the membrane restores the cell to the polarized states

Question 4

What does the P wave represent?

Answer 4

time for passage of electrical impulse thru the atrium causing ATRIAL DEPOLARIZATION (contraction)

Question 5

What does the PR interval represent?

Answer 5

time for impulse to spread thru atria, AV node, and bundle of His and Purkinje fibers to a point immediately preceding ventricular contraction

Question 6

What does the QRS complex represent?

Answer 6

It represents the time taken for depolarization (contraction) of both ventricles (systole)

Question 7

How many large boxes represents 1 second on an EKG strip?

Answer 7

5

Question 8

What does one small square represent vertically?

Answer 8

0.1 millivolt

Question 9

How do you calculate the atrial rate with the 10-times method?

Answer 9

1) get a 6 second strip
2) count # of p waves
3) multiply by 10

Question 10

How do you calculate the atrial rate with the 10-times method?

Answer 10

1) get a 6-second strip
2) count # of p waves
3) multiply by 10

Question 11

How do you calculate the ventricular rate with the 10-times method?

Answer 11

1) get a 6-second strip
2) count # of r waves
3) multiply by 10

Question 12

How long should a P wave last?

Answer 12

0.06-0.12 sec

Question 13

How long should a PR interval last?

Answer 13

0.12-0.20 sec

Question 14

How long should a QRS complex last?

Answer 14

0.06-0.12 sec

Question 15

How long should a ST segment last?

Answer 15

0.12 sec

Question 16

How long should a QT interval last?

Answer 16

0.34-0.43 sec

Question 17

How long should a T wave last?

Answer 17

0.16 sec

Question 18

What is a normal sinus rhythm?

Answer 18

-starts in sinus node and progresses to ventricles through a normal conduction pathway
-sinus node > atria > AV node> bundle of His > bundle branches > Purkinje fibers

Question 19

What are the characteristics of a normal sinus rhythm?

Answer 19

1) atrial and ventricular rhythms REGULAR
2) atrial and ventricular rates are 60-100
3) P waves: round, smooth, upright in lead II, precedes each QRS complex
4) PR interval is normal (0.12-0.20 sec)
5) QRS complex is normal (<0.12 sec)
6) T wave is upright in lead II
7) QT interval os 0.36-0.44 sec
8) NO ectopic or aberrant beats

Question 20

What does stimulation of the vagus nerve cause?

Answer 20

decreases SA node’s firing rate

Question 21

What does stimulation of the SNS cause?

Answer 21

increase SA node’s firing rate

Question 22

What is sinus bradycardia?

Answer 22

-SA node fires at < 60bpm
-regular rhythm
-normal P waves
-normal PR interval
-normal QRS complex

Question 23

When is sinus bradycardia considered normal?

Answer 23

-aerobically trained athletes
-in some ppl during sleep

Question 24

When can sinus bradycardia occur?

Answer 24

-in response to PNS stimulation
-certain drugs: BB, CCB

Question 25

What diseases states is sinus bradycardia associated with?

Answer 25

-hypothyroidism -↑ ICP -inferior MI

Question 26

What is the clinical significance of sinus bradycardia?

Answer 26

depends on how low the rate is and if the pt is symptomatic

Question 27

Is treatment necessary for sinus bradycardia?

Answer 27

there is usually no symptoms and its insignificant = no treatment UNLESS pt shows symptoms of decreased CO

Question 28

What is symptomatic bradycardia?

Answer 28

HR < 60 bpm and is inadequate for pts condition -PROMPT ATTENTION IS CRITICAL

Question 29

What are the symptoms of sinus bradycardia?

Answer 29

-hypotension -pale, cool, clammy skin -weakness -angina, chest pain -dizziness or syncope -confusion or disorientation -SOB

Question 30

What are nursing interventions for sinus bradycardia?

Answer 30

1) Give O2 if appropriate 2) obtain IV access 3) monitor ECG, BP, SpO2, record 12-lead ECG 4) ID and TREAT reversible causes 5) Atropine 1 mg dose by RAPID INJECTION (may repeat every 3 to 5 mins up to a max of 3 mg) 6) epi infusion at 2-10mcg/min if Atropine not effective 7) Dopamine infusion at 5-20 mcg/kg/min if low bp

Question 31

What do you do if the pt has symptomatic bradycardia and is NOT responding to meds?

Answer 31

1) temp pacemaker can support pt until condition resolved OR 2) temp pacemaker can serve as a bridge until a permanent pacemaker is inserted

Question 32

What is transcutaneous pacing?

Answer 32

-for EMERGENCIES -noninvasive -bridge until TRANSVENOUS pacer can be inserted -use LOWEST current that will "capture" -pt may need analgesia/sedation

Question 33

What is sinus tachycardia?

Answer 33

HR >100 -p wave normal -PR interval normal -normal QRS complex

Question 34

What is sinus tachycardia caused by?

Answer 34

vagal inhibition or sympathetic stimulation

Question 35

What kind of stressors is sinus tachycardia associated w/?

Answer 35

exercise, fever, pain, hypotension, hypovolemia, anemia, hypoxia, hypoglycemia, myocardial ischemia, HF, hyperthyroidism, anxiety, fear

Question 36

What drugs can cause sinus tachycardia?

Answer 36

Epinephrine, norepinephrine, atropine, caffeine, theophylline, hydralazine, OTC (sudafed), energy drinks, street drugs

Question 37

What is the clinical significance of sinus tachycardia?

Answer 37

-depends on underlying cause 1) may be body's response to exercise, pain, stress, emotion (NO CLINICAL SIG) 2) compensatory response w/ hypovolemia, hemorrhage, shock, PE, sepsis, HF, cardiogenic shock, pericarditis

Question 38

What does the clinical significance of sinus tachycardia also depend on?

Answer 38

the pts tolerance of increased HR -can be a sig arrhythmia w/ dire consequences bc ↑ myocardial O2 consumption associated w/ ↑ HR

Question 39

What are some symptoms of sinus tachycardia?

Answer 39

-dizziness, dyspnea, hypotension: bc of ↓ CO -pt may report chest pain, palpitations, anxiety -angina may accompany sinus tachy pts w. CAD or MI

Question 40

What is the pathophysiology of sinus tachy?

Answer 40

-↓ ventricular volume leads to hypotension and decreased peripheral perfusion -worsens myocardial ischemia by

Question 40

What is the pathophysiology of sinus tachy?

Answer 40

-↓ ventricular volume leads to hypotension and decreased peripheral perfusion -worsens myocardial ischemia by ↑ hearts demand for O2 and ↓ duration of diastole (period of greatest coronary flow)

Question 41

What is the treatment for sinus tachy?

Answer 41

1) ID and treat cause (ASSESS PT HX) 2) vagal maneuver (in pts clinically stable) 3) BB 4) CCB

Question 42

What is the vagal maneuver?

Answer 42

-massaging carotid sinus stimulated vagus nerve (inhibits firing of SA node) -this can sometimes return rhythm back to normal

Question 43

What are the risks of the vagal maneuver?

Answer 43

- ↓ HR - vasodilation - ventricular arrhythmias - stroke - cardiac standstill * if used, have resuscitative equipment available*

Question 44

Who should you avoid performing cardiac sinus massage on?

Answer 44

ELDER PTS

Question 45

What is respiratory sinus arrhythmia?

Answer 45

-HB is tied to respirations -inspiration: HR ↑ -expiration: HR ↓

Question 46

Respiratory sinus arrhythmia typically occurs in_____

Answer 46

-younger ppl and athletes -often imperceptible and not cause for concern