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Critical Care > Conduction Disturbances/Dysrhythmias > Flashcards

Conduction Disturbances/Dysrhythmias Flashcards

1
Q

Properties of Cardiac Cells

A

automaticity: ability to initiate an impulse spontaneously and continuously
excitability: ability to be electrically stimulated
conductivity: ability to transmit an impulse along a membrane in an orderly manner
contractility: ability to respond mechanically to an impulse

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2
Q

3 Main Components of Functions of the Heart

A
  1. Electrical
  2. Plumbing (cardiac vessels, whether they are occluded)
  3. Pump itself (heart failure, cardiac myopathy, dilated cardiac myopathy, hypertrophy, etc.)
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3
Q

Intrinsic Rates of the Conduction System

A

SA node: 60-100 times/min

AV node: 40-60 times/min

Bundle of His and Purkinje Fibers: 20-40 times/min

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4
Q

Phases of Action

A

0: rapid depolarization and corresponds with ventricular contraction
1, 2, and 3: repolarization
4: complete repolarization and corresponds to diastole

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5
Q

Telemetry Monitoring

A

the observation of a pt’s HR and rhythm to rapidly dx ischemia or infarction

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6
Q

Methods to calculate HR from ECG

A

when the rhythm is regular:

  • count the number of QRS complexes in 1 min
  • count number of R-R intervals in 6 seconds and x 10
  • count the number of small squares between one R-R interval, divide by 1500
  • count the number of large squares between one R-R interval, divide by 300
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7
Q

Waveforms

A

P wave: impulse through atrium causing atrial depolarization (when SA node fires and contracts atrium)

QRS complex: time taken for depolarization of both ventricles

ST segment: end of the QRS complex to the T wave, the time between ventricular depolarization and repolarization.

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8
Q

STEMI

A

ST elevation myocardial infarction

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9
Q

Depressions and T-wave inversion on ECG

A

usually caused by toxicity of drugs (usually digoxin toxicity) and electrolyte imbalance (high or low - K, Mg, Na, Ca)

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10
Q

Artifact on ECG

A

can occur if:

  • leads and electrodes are not firmly placed (hair, old conduction gel)
  • there is muscle activity (shivering, seizures, hiccups, brushing teeth, strong respiratory/muscle movement, etc.)
  • electrical interference from an outside source
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11
Q

Questions to Ask Self when Assessing Cardiac Rhythms

A
  1. Note the P wave. Is it upright or inverted? Is there one for every QRS complex?
  2. Evaluate the atrial rhythm. Is it regular or irregular?
  3. Calculate the atrial rate.
  4. Measure the duration of the PR interval. Is it normal duration or prolonged.?
  5. Evaluate the ventricular rhythm. Is it regular or irregular?
  6. Calculate the ventricular rate.
  7. Measure the duration of the QRS complex. Is it normal duration or prolonged?
  8. Assess the ST segment. Is it isoelectric, elevated, or depressed?
  9. Measure the duration of the QT interval Is it normal duration or prolonged?
  10. note the T wave. Is it upright or inverted?
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12
Q

Cardiac Stress Test (Things to Know as Nurse)

A
  • not NPO, need light and good breakfast (need calories and sugar for exercise)
  • ensure sugars are at a good level
  • hold beta blockers for the day so HR can elevate
  • hold all caffeine (b/c unnecessarily raises HR)
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13
Q

Things that stop Cardiac Stress Test

A
  1. chest pain
  2. EKG changes

*SOB does not stop test b/c you’re expected to have SOB when exercising

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14
Q

Normal Sinus Rhythm

A

Rate: 60-100 bpm

Rhythm: P-P interval regular, R-R interval regular

P waves: positive (upright), one precedes each QRS complex, P waves look alike.

PR interval: 0.12-0.20 second and consistent from beat to beat

QRS duration: 0.10 second or less an intraventricular conduction delay exists

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15
Q

Sinus Bradycardia

A

Rate: less than 60 bpm

Rhythm: P-P interval regular, R-R interval regular

P waves: positive (upright), one precedes each QRS complex, P waves look alike.

PR interval: 0.12-0.20 second and consistent from beat to beat

QRS duration: 0.10 second or less an intraventricular conduction delay exists

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16
Q

Symptomatic v. Asymptomatic Bradycardia

A

symptomatic bradycardia: requires intervention
-may be experiencing SOB, dizziness, lightheadedness, decreased LOC d/t heart not keeping up with CO and demand

asymptomatic bradycardia: no intervention necessary, just monitor

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17
Q

Tx for Symptomatic Bradycardia

A
  • Atropine (first line drug)
  • Temporary Pacemaker (transcutaneous or transvenous)
  • Permanent Pacemaker
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18
Q

Transcutaneous v. Transveous Pacemaker

A

transcutaneous: patch goes right on skin
transvenous: used after open heart surgery when bypass is used. Heart is irritable d/t bypass and may need assistance for 2-3 days post surgery until it gets in groove again.

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19
Q

Sinus Tachycardia

A

Rate: 101-180 bpm

Rhythm: P-P interval regular, R-R interval regular

P waves: positive (upright), one precedes each QRS complex, P waves look alike. At fast rates it may be hard to tell the difference between a P wave and a T wave.

PR interval: 0.12-0.20 second (may shorten with faster rates) and consistent from beat to beat

QRS duration: 0.10 second or less an in traventricular conduction delay exists

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20
Q

Causes of Tachycardia

A 
pain
exercise
fever
anemia
dehydration
anxiety
sepsis
heart failure
MI
PE
stimulant use
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21
Q

Tx of Sinus Tachycardia

A

Tx underlying cause:

antipyretic (for fever)
analgesics (for pain)
fluids (for dehydration)
avoiding caffeine or nicotine
relaxation techniques (for anxiety)
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22
Q

PSVT

A

Rate: 100-300 bpm

Rhythm: regular or slightly irregular

P waves: often hidden in the preceding T wave, but if seen, it may have an abnormal shape

PR interval: may be shortened or normal

QRS complex: usually normal

  • need to tx b/c heart cannot sustain a rate that high for very long and will stop
  • Sx: SOB b.c CO is down d/t high HR
  • CO = HR x SV (ex. when HR is 200 bpm, SV decreases b/c it’s shortened, not enough time for ventricles to fill and move blood forward)
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23
Q

Tx of PSVT

A
  1. Vagal Maneuvers if pt is awake and able to follow commands (cough, hold breath, bear down like having a BM)
    * children: cold to face to stimulate vagus nerve b/c they can’t follow these commands
  2. Adenosine: slows rate of SA node, slows conduction time through the AV node to reset heart.
    - first dose = 6mg via large IV closest to heart, push as fast as possible, follow with immediate flush (adenosine has short half life, need to get med to heart ASAP).
    - in EKG you see heart beating quickly, then momentary pause.
    - ensure good IV access and pads in place in case heart does not start again so you can immediately defibrillate
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24
Q

Synchronized Cardioversion

A

shock delivered on the R wave of the electrical activity of heart using lower energy levels than with defibrillation

machine picks up pts rhythm and knows wen to shock

25
Q

Preparing Pt for Cardioversion

A
  • Informed consent required
  • NPO b/c they get sedating meds
  • Recent ECG
  • 18g IV w/ fluids (large bore)
  • O2 b/c they are getting sedation
  • Sedation
26
Q

Premature Atrial Contraction (PACs)

A

premature heartbeats originating in the atria

Rate: usually 60-100 bpm

Rhythm: irregular

P waves: abnormal shape

PR interval: normal

QRS complex: normal (usually)

  • PACs and PVC aka “line jumpers” b/c they are outlying electrical activity that originate outside the normal conduction system
  • called ectopic foci (electrical activity that occurs outside normal conduction system)
27
Q

PVC

A

premature heartbeats originating in the ventricles

28
Q

Atrial Fibrillation

A

Rate: atrial: 350-600bpm
ventricular: >or< 100bpm

Rhythm: irregular

P waves: fibrillatory

PR interval: not measurable

QRS complex: normal (usually)

  • no definable P waves b/c there is no contraction. SA node is out of commission, resulting in no P waves (atria are just quivering)
  • Pt is on anticoagulants to prevent PEs
29
Q

Atrial Fibrillation w/ Rapid Ventricular Respons (RVR)

A

atria chambers fibrillate resulting in rapid and irregular pumping of blood through the heart

in some cases of aFib, the fibrillation of the atria causes the ventricles to beat too fast which is called RVR.

30
Q

Atrial Flutter (ECG)

A

Rate: atrial: 250-350 bpm, ventricular: >or< 100bpm

Rhythm: atrial: regular, ventricular: may be regular or irregular

P wave: flutter (F) waves (sawtooth pattern) more flutter waves than QRS complexes; may occur in a 2:1, 3:1, 4:1, etc. pattern

PR interval: not measurable

QRS complex: normal (usually)

31
Q

S/Sx of Atrial Fib/Flutter

A

palpitations
weakness
dizziness
SOB

d/t 20% loss of CO from atria not contracting properly and not squeezing the blood into the ventricles

32
Q

Tx for Atrial Fib/Flutter

A

medications:

  • calcium channel blockers (slow HR, specifically the ventricular rate)
  • beta blockers
  • antiarrhythmic
  • antiplatelet aggregators
  • anticoagulants

synchronized cardioversion
cardiac ablation

33
Q

Cardiac Ablation

A

procedure to scar or destroy tissue in your heart that’s allowing incorrect electrical signals to cause an abnormal heart rhythm

diagnostic catheters are threaded through blood vessels to the heart where they are used to map the heart’s electrical signals

34
Q

Heart Blocks

A

aka conduction delay

can be born with it or have “acquired heart block”

causes:
- surgeries that affect the heart’s electrical system
- changes in your genes
- MI
- heart issues like clogged arteries, inflammation of the heart muscle, and heart failure
- muscle disorders or other diseases
- some meds (can try to change doseage or Rx to fix)

35
Q

First Degree Heart Block (ECG)

A

Rate: 60-100 bpm

Rhythm: regular

P wave: normal

PR interval: >0.20 seconds

QRS complex: normal

*Pt in normal sinus rhythm but PR interval is greater than 0.2 seconds.

totally fine if pt is asymptomatic

36
Q

Heart Block Clinical Manifestations

A

usually w/ first degree and sometimes w/ second degree pts are asymptomatic

most common s/sx d/t decrease CO:

  • bradycardia
  • hypotension
  • syncope
  • chest pain
  • dizziness
  • dyspnea
37
Q

Tx of Heart Block

A

*same as for symptomatic bradycardia

  • atropine
  • transcutaneous pacemaker
  • permanent pacemaker
38
Q

Third-Degree Heart Block (ECG)

A

Rate: atrial: 60-100 bpm, ventricular: 20-40 bpm

Rhythm: atrial: regular but may appear irregular d/t P waves hidden in the QRS complex

P wave: normal, but no connection with the QRS complex

PR interval: variable

QRS complex: normal or widened, no relationship w/ P waves

39
Q

Third-Degree Heart Block

A

can lead to lethal rhythms

atrium and ventricles are doing their own thing, not working together anymore

no perfusion occurring to the body or heart

emergency situation requiring immediate medical attention

call 911 for any:

  • cardiac arrest
  • dizziness
  • fainting
  • new, severe tiredness
  • irregular heartbeat or new palpitations
40
Q

Tx of Third-Degree Heart Block

A

permanent pacemaker

need to get them to cath lab ASAP, do transcutaneous pacemaking in interim

41
Q

Pt Teaching for Pacemaker

A
  • know what kind of pacemaker you have
  • let all health care providers know about pacemaker
  • wear medical alert bracelet or necklace
  • stay away from electrical devices w/ strong magnetic fields (get pat down at airport, don’t go through x-ray machine)
  • it’s ok to be active w/ Dr.’s approval, but don’t do contact sports like football or ice hockey
  • get pacemaker checked regularly to ensure it’s working well
  • pacemaker batteries have shelf-life of 5 years, need to replace every 5-7 years
42
Q

Permanent Pacemaker

A

pacemaker’s power source is implanted subcutaneously over the pectoral muscle on the pt’s non-dominant side

43
Q

Single-chambered Pacemaker v. Dual-chambered Pacemaker

A

single-chambered: either working on atrium OR ventricles

dual-chambered: working in both atrium AND ventricles
*atrial spike before P wave and then ventricular spike then QRS complex

44
Q

Atrial Pacemaker

A

atrial pacing:
pacing system with lead attached to right atrium designed to correct abnormalities in SA node

on ECG: can see pacer spike just before P wave, which is how you know they’re being atrial paced

45
Q

Ventricular Pacemaker

A

ventricular pacing: pacing system w/ a lead attached in the right ventricle

on ECG: can see pacer spike then QRS complex

QRS complex is inverted in pt’s w/ pacemakers.

In normal sinus rhythm, conduction system is working from SA node and is moving downward, so when it moves down you have normal QRS complex.

B/c conduction is being stimulated and started at the bottom of the ventricle (tip of pacemaker is sitting at bottom of ventricle), so energy is moving up through the heart instead of down and as a result of that you will see a reciprocal deflection of the QRS complex (it’s moving in the opposite direction), which is why pacemaker QRS complexes look this way.

46
Q

Failure to Capture

A

ventricles did not contract after pacemaker spike meaning something is wrong with pacemaker and it needs to be tweaked/fine-tuned

47
Q

Failure to Sense

A

pacemaker should sense when heart is going to fire on its own and sit back and not fire

failure to sense = pacemaker doesn’t sense this and fires regardless

a malfunction of the pacemaker that needs to be addressed

48
Q

Types of PVCs

A

unifocal: PVCs look alike meaning they’re coming from same foci
multifocal: PVCs look differently meaning they’re coming from different foci

ventricular bigeminy: every other beat/complex is a PVC

ventricular trigeminy: every third complex is a PVC

couplet: two PVCs together

49
Q

Ventricular Tachycardia (ECG)

A

Rate: 150-250 bpm

Rhythm: regular or irregular

P waves: occurring independently of the QRS complex, and usually buried in the QRS complex

PR interval: not measurable

QRS complex: distorted

50
Q

Tx of Ventricular Tachycardia

A

depends on if pt has pulse or not

if they have a pulse, try meds and synchronized cardioversion

if they don’t have a pulse, defibrillation

51
Q

Causes of Ventricular Tachycardia

A

CAD, cardio myopathy, congenital disorder

52
Q

Types of Ventricular Fibrillation

A
  • course
  • fine

*no pulse with either

need to do CPR and defibrillate right away

53
Q

Asystole

A

aka ventricular standstill

non-shockable rhythm

need to do CPR and give meds until pulse returns

54
Q

PEA

A

pulseless electrical activity

electrical activity on ECG but there is no mechanical activity of the ventricles and pt has no pulse

poor prognosis unless the underlying cause can be identified and quickly corrected.

55
Q

Causes of PEA

A

6 H’s:

  • hypovolemia
  • hypoxia
  • hydrogen ion (acidosis)
  • hypo/hyperkalemia
  • hypoglycemia
  • hypothermia

5 T’s:

  • toxins (poisons/ODs)
  • tamponade (cardiac)
  • tension pneumothorax
  • thrombosis (coronary. or pulmonary)
  • trauma
56
Q

SCD

A

sudden cardiac death

death from cardiac causes

most often from ventricular dysrhythmias, specifically ventricular tachycardia or fibrillation

57
Q

Implantable Cardioverter-Defibrillator (ICD)

A

device that senses when pt is going into lethal rhythm and defibrillates the pt

58
Q

Ischemia v. Injury v. Infarction

A

Ischemia: reduction of myocardial oxygen for less than 20 min. Damage is reversible. In ECG, you see changes in T wave.

Injury: persistence of oxygen deficiency for more than 20 min. Damage is reversible. Injury is characterized by ST segment abnormalities.

Infarction: Persistence of oxygen deficiency for more than two hours. Damage is irreversible. Infarction is characterized by pathological Q waves on the ECG. Scarring occurs which leads to conduction delay.

Critical Care (14 decks)

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