exam 2 Flashcards
arrhythmia
- any electrical disturbance that changes rate, regulatity, site of origin or conduction pathway in pathologic way
- single beat or sustained
- benign to life threatening
causes of arrhythmias
- hypoxia
- ischemia and irritability
- sympathetic stimulation
- drugs
- electrolyte disturbances
- enlargement and hypertrophy
types of arrhythmias
- form SA node
- ectopic rhythm
- recurrent arrhythmia
ectopic rhythms
- originate form focus other than SA node
recurrent arrhythmias
electrical activity trapped in a continuous circuit
sinus tachycardia
- rhythm > 100 bpm
- normal or pathologic
- pathologic due to hyperthyroidism or PE**
sinus bradycardia
- rhythm < 60 bpm
- normal or pathologic
- normal happens in well conditioned athletes
- pathologic- vasovagal syncope
sinus arrest
- sinus node stops firing
- causes flat line
- length of line depends on if and when rescue beat occurs
asystole
prolonged sinus arrest
rescue beat
- aka escape beat
- originate from atria, AV node, or ventricles
sick sinus syndrome
- dysfunction of SA node
- inability to generate heart rate that meets physiological needs
possible results of sick sinus syndrome
- bradycardia
- sinus pauses
- sinus arrest
- paroxysmal supraventricular tachycardia
supraventricular arrhythmias
- originate in atria or AV node
- single beat or sustained rhythm
ectopic rhythms
- arises elsewhere not sinus node
- sustained rhythms
- enhanced automaticity of non-sinus site
- abnormal acceleration of depolarization
what is a common cause of ectopic rhythms
medication
what does AVNRT stand for
- AV node reciprocating tachycardia
- type of reentry loop
characteristics of AVNRT
- sudden onset and offset*
- can vary in size
- if no P wave then it originated below atria
what reentry loop involves entire heart
AV reentry tachycardia- AVRT
characteristics of AVRT
- accessory pathway between atrium and ventricle bypasses AV node
- connects directly to his bundle, ventricular myocardium or one of fascicles
4 questions to ask about rhyhm
- is it regular or irregular
- P waves present?
- do P waves precede each QRS?
- are QRS narrow or wide?
premature atrial contractinon
- usually due to ectopic focus
- isolated beat that comes early
- P wave morphology sometimes looks different
types of supraventricular arrhythmias
- paroxysmal supraventriclar tachy
- a flutter
- a fib
- multifocal atrial tachycardia
- paroxysmal atrial tachycardia
supraventricular tachycardia (SVT)
- usually initiated by premature supraventricular beat
- driven by recurrent loop in AV node
- regular rhythm, very rapid
causes of SVT
- very common
- can occur in normal heart
- alcohol
- coffee
- excitement
mechanisms to break SVT
- valsalva maneuver first
- if valsalva doesnt work give adenosine
- carotid massage
atrial flutter
- common
- regular but very rapid rate
- rapid fire atrium
- have “flutter” p waves
- saw tooth appearance
common conditions associated with a flutter
- HTN
- electrolyte abnormalities
- alcohol
- drug abuse (Stimulants)
- thryotoxicosis
- cardiac conditions
atrial fibrillation
- atria activity is completely chaotic
- AV node can be bombarded with > 500 impluses/ min
- multiple reentrant circuits
- no true P waves
- irregularly irregular ventricular rate
conditions associated with a fib
- HTN
- mitral valve disease
- PE
- thyrotoxicosis
- pericarditis
multifocal atrial tachycardia
- irregular rhythm at 100-200 bpm
- random firing of several different ectopic atrial foci
- common in lung disease
- p waves vary in morphology
what is multifocal atrial tachycardia called if its less than 100 bpm
wandering atrial pacemakers
premature ventricular contraction
- most common ventricular arrhythmia
- QRS wide and bizarre
- happens before next beat should occur
- isolated PVC is normal
ventricular bigeminy
- for every sinus beat you get a ventricular ectopic beat/ PVC
ventricular trigeminy
two normal beats to one PVC
when are PVCs dangrous?
- when frequent
- when runs of more than 3 in a row (called v tach)
- when variable in morphology
- when pt is having MI
ventricular tachycardia classifications
- non-sustained v tach (NSVT)
- sustained v tach (SVT)
non-sustained v tach
- common
- usually asymptomatic
- potential marker for sustained v tach but usually benign if no heart disease
- usually < 30 sec
sustained v tach
- pulse present vs. pulseless
- conscious vs unconcious
- leads to v fib -> death
- lasts greater than 30 sec
ventricular fibrilation
- v tach degenerates into v fib
- no discernible QRS complexes
- no cardiac output
- immediate CPR and defibrillation required
causes of v fib
- MI (most common)
- myocardial ischemia
- HF
- hypoxemia or hypercapnia
- hypotension/ shock
- electrolyte imbalances
- stimulants
- often preceded by v tach
torsades de pointe
- unique form of v tach
- usually seen with prolonged QT intervals
- QRS complexes spiral around baseline, change amplitude and axis
conduction block
- obstruction or delay of flow of electricity along normal electrical pathway
types of conduction blocks
- sinus node block
- AV block
- BBB
sinus node block
- sinus node fires but wave of depol is immediately blocked
- atria doesnt contract
- causes sinus pause/arrest
AV block
- any conduction block between sinuse node and purkinje fibers
types of AV block
- first degree AVB
- second degree- mobitz I or II
- third degree ABV
bundle branch block
- conduction block in one or both ventricular BB
- can occur in main BB or within one of fascicles
- wide QRS
what is LBB associated with
- coronary artery disease
- very concerning in setting of MI
first degree AV block
- prolonged delay in AV node conduction
- normal depol of atria
- prolonged PR
- every atrial impulse makes it through
second degree AV block
- not every atrial impulse makes it through
- P to QRS >1:1
- either mobitz I or mobitz II
mobitz type I
- aka wenchebach
- each atrial impulse gets has longer delay
- usually 3rd of 4th impulse fails to make it through
- not indication for pacemaker
mobitz type II
- block below AV node in his
- some but not at atrial impulses transmitted
- two or more beats with normal PR then dropped beat
- cycle is repeated
- indication for pacemaker
third degree heart block
- aka complete heart block
- no atrial impulses make it to ventricles
- site can be at AV node or lower
- escape rhythm generated below block
- atria and ventricles become dissociated
- pacemaker indicated
RBBB
- R ventricular depolarization is delayed
- wide QRS
- r-R’ bunny ear pattern
- wide S in V6
- can be in normal or sick hearts
LBBB
- delayed ventricular depolarization
- prolongation in rise of R waves in leads over left ventricle
- broad and notched QRS
- leads over R ventricle will show broad S wave
what does LBBB usually suggest
coronary artery disease
