Lecture 6 Arrhythmias Flashcards
SA node
heart’s natural pacemaker at the top of the right atrium
60-100 bpm
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
Bundle of His
begins conduction to the ventricles
located in the ventricular septum
purkinje fibers
moves impulses through the outside of the ventricle to cause contraction
telemetry
continuous monitoring with 5 leads
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
Reading rhythm on EKG
regular = complexes are roughly same distance apart
irregular = complexes are not equal distance apart
Reading intervals on EKG - P wave
atrial depolarization (contraction)
should be round and upright
what does it mean if P wave is normal?
assume that electrical impulse originated in the SA node
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
QRS Complex
ventricular depolarization
creates pulse
should be 0.06-0.12 seconds
T wave
ventricular repolarization = relaxation
follows the ST segment
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
dysrhythmia
irregular or erratic heart rate
can cause disturbances of HR AND/OR rhythm
what to do if you see a dysrhythmia
always stop and check how patient is tolerating it
risk factors for dysrhythmias
age
caffeine, smoking, drugs, alcohol
heart valve disease (mitral valve near AV node)
MI, HTN, cardiomyopathy, heart surgery
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
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
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
sinus tachycardia
> 100 bpm
regular rhythm
SA node firing at faster rate
s/sx of sinus tachycardia
low BP
change in LOC
N/V
doom and anxiety
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
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
