WKU Med Surg 2 Exam 2 Dysrhythmias

what is automaticity

hearts ability to automatically start a beat (pacing function)

what is excitability

heart has the potential to respond to an impulse

what is conductivity

allows passage/sends electrical impulse

what is contractility

heart responds to impulse by contracting and pumping blood

what is the conduction pathway in the heart

1. SA node

2. AV node

3. bundle of his

4. right and left bundle branches

5. purkinje fibers

what is the SA node

hearts primary pacemaker that generates a HR between 60-100 bpm

what happens if the SA node fails

the AV node takes over and produces a HR of 40-60 bpm

what happens if both the SA and AV nodes fail

bundle of his takes over and produces a HR of 20-40 bpm

how many different types of leads are there

- 3 lead: white, black, red

- 5 lead: white, black, green, red, brown

- 12 lead: provides 12 views of cardiac electrical activity

how many electrodes are used in a 12 lead

10: 4 on limbs, 6 on chest

what is a 12 lead used for

diagnose dysrhythmias

what should you teach the pt about a 12 lead

lie still and breathe normally

what makes 12 leads different from other leads

not a continuous monitor: only looks at a 1 time still frame

what is a ECG

graphic representation of cardiac electrical activity

what things are included in a ECG

- requires placement of electrodes

- lead systems provide various views from different sides of the heart: determines if SA node is stimulating every part of the heart

what are the different patterns in a ECG

- isoelectric line

- positive deflection

- negative deflection

what is the isoelectric line

flat line part; see no electrical changes at that time (PR and ST segment)

what are positive deflections

waves that go above isoelectric line (P wave, part of QRS)

what are negative deflections

waves that go below isoelectric line (part of QRS)

what does the x axis of a ECG strip represent

duration/ time

what does the y axis of a ECG strip represent

amplitude/ voltage

how many sec are 5 boxes on a ECG

0.20 s

how many sec is 1 box on a ECG

0.04 s

what are the normal parts of an ECG

- p wave

- PR segment

- PRI

- QRS complex

- ST segment

- t wave

- QTI

what does a p wave represent

SA node fired and atrial depolarized (contracted)

what does a PR segment represent

atrial kick (last squeeze from atria)

what does a PRI represent

- contains P wave and PR segment

- full length of time for atrial depolarization

what is the normal time of a PRI

0.12-0.20 s

what does a QRS complex represent

• ventricular depolarization (contraction)

what is the normal time of a QRS complex

0.04-0.10 s

what time frame of a QRS complex starts to become concerning

>0.12 s

what does a ST segment represent

- early ventricular repolarization (relaxation) starts

- starts from J point and goes to the beginning of the T wave

which part of a ECG do most lethal dysrhythmias occur

t wave (esp electrolyte imbalances like K which causes a peaked t wave)

what does a t wave represent

completing ventricular repolarization (relaxation)

how tall is a t wave usually

<10 mm

what does a QTI represent

- full time for ventricular depolarize and repolarize

- starts at the beginning of QRS and ends at the end of the T wave

what is the normal time of a QTI

0.32-0.44 s

U wave

• never supposed to be part of ECG

• opposite of T wave

• indicates hypokalemia → bc slowing ventricular repolorization

• occurs after T wave

what is the 6 s strip method for determining HR on a ECG

count ventricular rate and times it by 10 (goes for both ventricular and atrial rate)

normal sinus

∙ Rate - 60-100

∙ Regularity of Rhythym - Regular

∙ P wave - round, upright, and symmetrical

∙ P:QRS - 1:1

∙ PRI: 0.12 - 0.20 seconds

∙ QRS: 0.04-0.10 seconds

sinus arrhythmia

• gradual change between the distance in the beats

• rate: 60-100 → not consistent (increase & decrease_

• rhythm - regularity varies w/ breathing (irregular)

• p wave - round, upright, symm

• P:QRS - 1:1

• PRI: 0.12-0.20

• QRS: 0.06-0.10

what rhythm is this

sinus arrhythmia

sinus tachycardia

∙ Rate: > 100 beats/min

∙ Regularity of rhythm: regular

∙ P wave: round, upright, and symmetrical

∙ P:QRS = 1:1

∙ PRI: 0.12 to 0.20 sec and constant

∙ QRS: 0.06 to 0.10 sec and constant

what can cause sinus tachycardia

- hypovolemia - losing all volume → HR increases to compensate

- enhanced automaticity

- increased sympathetic (fight or flight) activity

- hypoxia - if can’t breathe → HR increases to try to circulate O2

what are the s/s of sinus tachycardia

- palpitations

- chest pain

- restlessness, anxiety

- SOA

- hypotension

- HF: dyspnea, crackles, JVD, fatigue, weakness

how should you tx sinus tachycardia

• tx the cause

what rhythm is this

sinus tachycardia

sinus bradycardia

∙ Rate: < 60 beats/min

∙ Regularity of rhythm: regular

∙ P wave: round, upright, and symmetrical

∙ P:QRS = 1:1

∙ PRI: 0.12 to 0.20 sec and constant

∙ QRS: 0.06 to .10 sec and constant

what are the causes of sinus bradycardia

- decreased automaticity

- increased parasympathetic (rest and digest) activity: vagal response

when do you tx someone with sinus bradycardia

• if they are symptomatic and HR is <50 bpm

• need to know if acute/chronic → if it’s something that is baseline w/ no s/s → no tx

what are the s/s of sinus bradycardia

- syncope

- dizziness

- hypotension

- confusion

what is the first line tx for sinus bradycardia

atropine - 1mg q3-5 mins w/max of 3 mg → bolus

what are some other tx options for sinus bradycardia

• transcutaneous pacemaker - deliveers smaller stimulus to try and generate pace that is effective

• dopamine or epinephrine IV infusions

• transvenous pacing: continuous pacemaker used for symptomatic bradycardia

what is a permanent pacemaker

• battery powered device that delivers electrical stimulus to the right myocardium which causes a contraction

• always sending little stimulus 

• indicated for symptomatic bradycardia

what should you monitor for/ teach to someone who got a permanent pacemaker

• monitor for infection/ hematoma at insertion site: assess for bleeding, swelling, tenderness, redness

• monitor for complications

• dressing CDI (typically for 24 hrs) → shower day after removed

• follow activity restrictions: no lifting, no big arm movements for first 24 hrs → sling used

• teach self management → always carry info card

what are some complications of permanent pacemakers

• ectopic beat (PVCs)

• malfunction

• electromagnetic interference: pts cannot have MRIs unless you know the material is not magnetic

• stimulation of chest wall due to lead coming unattached from heart and sticks to chest: can cause perforation and cardiac tamponade (s/s: consistent hiccupping)

what is a temporary pacemaker

• emergency management of bradycardia

• two types

  • transcutaneous = external → use Lifepak

  • transvenous system = internal

ACLS: Bradycardia Algorithm Steps

1. Identify and treat underlying cause

2. Identify if persistent bradyarrythmia is occurring and causing different symptoms → no (mon and observe) or yes (move to step 3)

3. Move to administering atropine → is it effective? → yes (move to step 4) or no (administer other)

4. considering additional things

ACLS: Bradyarrhythmia Step 1. Identify and treat underlying cause

- maintain patent airway; assist breathing as necessary

- O2: if hypoxemic

- cardiac monitor to identify rhythm; monitor BP and oximetry

- IV access

- 12 lead ECG if available; dont delay therapy

- consider possible hypoxic and toxicologic causes

ACLS: Bradyarrhythmia Step 2. persistent bradyarrhythmia - what can this cause/what should you monitor for

- hypotension

- acutely altered mental status

- signs of shock

- ischemic chest discomfort

- acute HF

ACLS: Bradyarrythmia Step 3. Administering Atropine

If atropine ineffective:

• Transcutaneous pacing

and/or

• dopamine infusion or epinephrine infusion

ACLS: Bradyarryhtmia Step. 4 - after giving tx meds for persistent bradyarrhythmia, what should you consider

- expert consultation

- transvenous pacing

what are premature atrial contractions (PAC)

• this is an ectopic or "extra" beat occurring within a rhythm

• the atrial beat (p wave) comes early

• p wave: abnorm → don’t use to measure PRI

• P:QRS - 1:1

• QRS: norm

what should you consider/ use to tx for PACs

• treat the cause!

  • caffeine

  • alcohol

  • stress, stimulants, anxiety

  • inflammation/ irritability in heart tissue

  • electrolytes

• need to know if baseline or new

when should you start becoming concerned about PACs

when you have a lot or recurrent ones → frequeny can lead to atrial dysrhythmias

what rhythm is this

premature atrial contractions

Ex: Sinus tachycardia with PAC → how to describe it

what is supra ventricular tachycardia (SVT)

• atrial prob bc supra (on top) → above ventricles

• rapid stimulation of atrial tissue

• occurs rapidly and is consistent → in norm rhythm, then jump into SVT

ECG values for SVT

∙ Rate: 100-280 beats/min (usually > 150)

∙ Regularity of rhythm: regular

∙ P wave: may not be visible

∙ P:QRS = typically unmeasurable

∙ PRI: typically unmeasurable

∙ QRS: norm

what are the causes of SVT

- usually reentry mechanism over stimulation

- starts in atria

what are the s/s of SVT if it persists

- palpitations

- chest pain

- weakness

- fatigue

- SOA

- nervousness, anxiety

- hypotension

- syncope

when should you start becoming concerned when it comes to SVT

when there is cardiovascular deterioration → not enough time for ventricles to stretch and fill → can’t effectively pump

SVT tx for stable pt

• vagal maneuvers → can reset conduction pathway → if works, still need to find underlying cause

• adenosine IV (1st line) - chemical cardio version → temp send into asystole to send rhythm back into NS

  • given as stop-cock (med on one side and flush on other) → have to give med and then flush immediately after to push adenosine in all the way

SVT tx unstable pt

- CARDIOVERSION → more likely to resolve condition

- adenosine IV - 6mg for 1st dose, 12 mg 2nd dose as needed

what rhythm is this

supraventricular tachycardia

what is cardioversion indicated for

- symptomatic/ unstable SVT

- afib with RVR

- monomorphic Vtach (with a pulse)

- tachydysrhythmias unresponsive to other txs

what should you consider before cardioversion

- sedation

- turn off O2

- clear from shock

what is important to do during cardioversion

- start slow, charge per order

- sync the rate so that the pt is receiving the same rate the whole time

what should you do after cardioversion

- maintain airway, oxygenation

- assess VS, LOC, and skin

- monitor for dysrhythmias

- administer prescribed antidysrhythmic

- document results

- watch ABGs

what is atrial fibrillation

• rapid and irregular electrical impulses in atria → they fibrillate (quiver) instead of contracting → can’t fill ventricles effectively → decreased CO

• heart weak in general

ECG values for A-FIB

∙ Rate: Atrial = 350-600; Ventricular = variable (up to 200s)

∙ Regularity of rhythm: irregularly irregular 

∙ P wave: unmeasurable; quivering

∙ P:QRS = no P waves; variable

∙ PRI: unmeasurable

∙ QRS: 0.04 to 0.10 sec 

∙ T wave is often hidden

what is A-FIB with RVR

A-FIB w/ tachycardia

what are the causes of afib

- HTN, CHF, CAD, hyperthyroidism

- associated with DM, sleep apnea, mitral valve disease

concerns w/ A-FIB

∙ Loss of atrial kick - no PR segment

∙ Loss of ventricular filling time r/t rapid ventricular rate (RVR)

∙ Loss of muscle mass in atria - bc not contracting effectively (so they become weak)

∙ Risk of clotting - blood isn’t effectively moving out, so it is just sitting (stasis)

how do you tx A-FIB

• consider underlying cause

  • ex: if potassium and magnesium imbalanced → correct mag and then k → will see improvement

• acute vs. chronic 

tx of acute A-FIB

• control the rate and convert the rhythm

• if stable → meds

  • IV antidysrhythmics- diltiazem, amiodarone, ibutilide

  • Beta Blockers (metoprolol, esmolol)

  • Digoxin (often used in cases with HF)

• if unstable → cardioversion

• if persistent → anticoagulant (heparin) IV

tx of chronic A-FIB

• control the rate and anticoagulate

• Same medications for stable, but PO

• Anticoagulant

• Left atrial appendage closure

• Radiofrequency catheter ablation

• Biventricular pacing

• MAZE procedure

what rhythm is this

atrial fibrillation

what is atrial flutter

• routine fluttering of atria → atria going much faster than ventricle

• * in most cases, tx same as a-fib

atrial flutter ECG values

∙ Rate: Atrial = 250-400; Ventricular = variable

∙ Regularity of rhythm: usually regular

∙ P wave: saw tooth

∙ P:QRS = variable (Ex: 4:1)

∙ PRI: unmeasurable

∙ QRS: 0.04 to 0.10 sec

∙ T wave is not visible

what rhythm is this

atrial flutter

what is the first step in the tachyarrhythmia algorithm according to ACLS

identify a HR of >150/ min

ACLS: Tachycardia Algorithm Steps

1. Assess appropriateness - HR > 150

2. Identify and treat underlying cause

3. Identify is persistent tachyarrythmia is occurring and causing s/s - no or yes (step 4)

4. Synchronized cardio version

5. If refractory, consider

ACLS: Tachycardia Algorithm Step 1. - how do you identify and tx underlying causes

- maintain patent airway, assist breathing as necessary

- O2 if hypoxemic

- cardiac monitor to identify rhythm; monitor BP and O2

- IV access

- 12 lead ECG

ACLS: Tachycardia Algorithm Step 2. - Is persistent tachyarrythmia occurring and is it causing these

• HOTN

• acutely altered mental status

• signs of shock

• ischemic chest discomfort

• acute HF

ACLS: Tachycardia Algorithm Step. 2 - if tachyarrhythmia is not causing s/s, what should you assess for next

wide QRS

ACLS: Tachycardia Algorithm Step 2. - if the pt does not have a wide QRS, what should you do next

- vagal maneuvers (if regular)

- adenosine

- beta blocker or calcium channel blocker

- consider expert consultation

ACLS: Tachycardia Algorithm Step 2. - if someone does have a wide QRS with tachyarrhythmia, what should you consider

- adenosine only if regular and monomorphic

- antiarrhythmic infusion

- expert consultation

ACLS: Tachycardia Algorithm Step 3. - if tachyarrhythmia is causing s/s, what should you do

- prepare for synchronized cardioversion

- consider sedation

- if regular narrow complex, consider adenosine

ACLS: Tachycardia Algorithm Step 4 - if someone has refractory with tachyarrhythmia after cardioversion or med tx what should you consider

- underlying causes

- need to increase energy level for next cardioversion

- addition of antiarrhythmic drug

- expert consultation

what is the dosage for adenosine

6 mg rapid IV push with NS flush for first dose and 12 mg for second dose