Lecture 6 Arrhythmias Flashcards by Isabel Ostroski

SA node

heart’s natural pacemaker at the top of the right atrium
60-100 bpm

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AV node

between the atria and ventricle at the interatrial septum
slows electrical impulses to give time for the atria to contract and ventricles to fill
40-60 bpm

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Bundle of His

begins conduction to the ventricles
located in the ventricular septum

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purkinje fibers

moves impulses through the outside of the ventricle to cause contraction

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telemetry

continuous monitoring with 5 leads

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Reading rate on EKG

count number of full complexes in 6 seconds and multiply by 10
atrial rate = # of P waves
ventricular rate = # of QRS complexes

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Reading rhythm on EKG

regular = complexes are roughly same distance apart
irregular = complexes are not equal distance apart

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Reading intervals on EKG - P wave

atrial depolarization (contraction)
should be round and upright

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what does it mean if P wave is normal?

assume that electrical impulse originated in the SA node

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PR interval

tracks impulse from atria to AV node
beginning of P wave to Q
should be 0.12-0.2 seconds, delay indicates AV block

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QRS Complex

ventricular depolarization
creates pulse
should be 0.06-0.12 seconds

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T wave

ventricular repolarization = relaxation
follows the ST segment

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QT interval

represents ventricular depolarization and repolarization
measure from beginning of QRS complex to end of T wave
shorter QT = faster HR
longer QT = slower HR
should be 0.36-0.44 seconds

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dysrhythmia

irregular or erratic heart rate
can cause disturbances of HR AND/OR rhythm

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what to do if you see a dysrhythmia

always stop and check how patient is tolerating it

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risk factors for dysrhythmias

age
caffeine, smoking, drugs, alcohol
heart valve disease (mitral valve near AV node)
MI, HTN, cardiomyopathy, heart surgery

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sinus bradycardia

rate <60, regular rhythm
SA node is firing at slower rate
P waves are present and normal
QT interval may or may not be prolonged

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causes of sinus bradycardia

lower metabolic needs - athletes
vagal stimulation - vomiting, severe pain
medications - beta blockers
acute decompensated heart failure
sinus node dysfunction
RCA lesion in MI

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managine sinus bradycardia

assess hemodynamic effects
check reversible causes
if symptomatic and unstable, treat with atropine
0.5 mg atropine every 3-5 minutes, max dose of 3 mg

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sinus tachycardia

> 100 bpm
regular rhythm
SA node firing at faster rate

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s/sx of sinus tachycardia

low BP
change in LOC
N/V
doom and anxiety

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causes of sinus tachycardia

compensating for acute blood loss, hypovolemia, anemia to try and meet oxygen needs of body
infection
cardiac ischemia
pain
exercise
stimulants

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why is sinus tachycardia bad

it decreases ventricular filling time, which decreases cardiac output

sinus tachycardia management

assess hemodynamic effects
reverse possible causes
vagal maneuvers - gagging, bearing down, sustained coughing, blowing through a straw, cold stimulus to face

medical management of sinus tachycardia

adenosine IV - slam it and have flush ready beta blockers IV calcium channel blockers IV

assessing patients with arrhythmias

history of cardiac disease medications blood pressure s/sx of fluid retentions auscultation

atrial fibrillation

abnormally fast and chaotic HR atria quiver instead of beating abnormal electrical pathways in the atria ventricular rate stays relatively consistent

atrial fibrillation EKG

atrial rate 300-600 ventricular rate 100-120 irregular rhythm no consistent P wave, no PR interval

paroxysmal Afib

sudden onset and termination lasts less than 7 days, may reoccur

persistent Afib

lasts >7 days

long standing persistent Afib

continuous for >12 months

permanent Afib

long standing, but deciding to not restore or maintain normal sinus rhythm

s/sx of atrial fibrillation

fatigue palpitations lightheadedness SOB decreased BP

pharmacological management of Afib

beta blockers potassium channel blockers - amiodarone calcium channel blockers - verapamil, diltiazem

where do 90% of afib clots form?

left atrial appendage

anticoagulants for Afib

warfarin - must for mechanical valves - INR testing - vitamin K for reversal DOACs - Eliquis and Xarelto - less monitoring and fewer drug interactions

when must anticoagulants be initiated?

if Afib lasts for more than 48 hours

watchman device

Left Arterial Appendage Occlusion Device for patients who can't tolerate anticoagulants

atrial flutter

sawtooth waves atrial rate - 250-400 bpm ventricular rate - 75-100 bpm p waves are called F waves same cases, management, s/sx of afib easier to treat than Afib because irregular electrical impulses are coming from one location, not all over the atria

Ectopy

Extra or Early beats Premature atrial contraction premature ventricular contraction

ventricular tachycardia

ventricular rate >100 bpm irregular rhythm p-wave difficult to detect

QRS in ventricular tachycardia

wide: >0.12 seconds with abnormal shape

monomorphic vs polymorphic vtach

one shape vs many shapes

causes of vtach

cardiac ischemia hypoxia acidosis electrolyte imbalances heart failure heart surgery - scarring heart valve disorders

signs and symptoms of vtach

chest pain palpitations dizziness lightheadedness shortness of breath fainting

sustained vtach

> 30 seconds

non-sustained vtach

bursts with breaks

first steps of vtach management

assess pulse, symptoms, and VS immediately back to bed asap in case of cardiac arrest notify MD code cart and lifepak ready

vtach management if sustained or patient unstable

cardioversion if patient is awake and has a pulse defibrillate if patient is unconscious and does not have a pulse

cardioversion vs defibrilation

both use lifepak cardioversion synchronized defibrillation unsynchronized

ventricular fibrillation

no measurable rate, irregular, no pulse defibrillate immediately

asystole

CPR and intubation IV epinephrine no defibrillation because there's no electrical activity to correct

Hs and Ts

reversible causes of cardiac arrest hypovolemia hypoxemia hyper and hypokalemia H+ ion excess - acidosis hypothermia tension pneumothorax tamponade thrombosis - MI and PE toxins

ICD

Implantable Cardioverter Defibrillator detects and terminates arrhythmias

who is eligible for ICD?

Systolic heart failure Vtach or Vfib

Life vest

external defibrillator must be worn at all times, including sleeping can be removed for bathing but someone else should be home

pacemaker indications

slow impulse formation symptomatic AV or ventricular conduction issues