Term
| what are the 3 mechanisms of arrythmia formation |
|
Definition
1) increased automaticity
2) re-entry
3) triggered |
|
|
Term
| Explain what happens in increased automaticity |
|
Definition
Increased automaticity can be due to
a) increased sympathetic stimulation of the SA node
b) cells outside the SA node are spontaneously depolarizing
c) increase in resting membrane potential that makes it easier to depolarize |
|
|
Term
| what could be the causes of triggered activity |
|
Definition
1) early afterdepolarization
2) delayed afterdepolarization |
|
|
Term
| explain what triggered activity is |
|
Definition
| abnormal depolarization triggered by a previous beat |
|
|
Term
| explain what happens in early afterdepolarization |
|
Definition
depolarization before repolarization is complete
-increased repolarization time due to
prolonged opening of calcium channels in phase 2
OR
opening of na channels in phase 3 |
|
|
Term
| what causes early afterdepolarization |
|
Definition
"chi"
cathecholamine excess
hypokalemia
ischemia |
|
|
Term
| what is delayed afterdepolarization |
|
Definition
depolarization after a repolarization but before a normal AP occurs
- this is due to excess calcium w/in SR which results in spontaneous depolarizations |
|
|
Term
| what are the common causes of delayed afterdepolarization |
|
Definition
1) cathecholamines
2) digoxin toxicity
3) hypercalcemia
4) hypokalemia |
|
|
Term
|
Definition
an accessory pathway exists where impulses can TRAVEL RETROGRADE and BACK to ORIGINAL pathway
-this requires a UNIDIRECTIONAL BLOCK and slow conduction so there is enough time for reentry |
|
|
Term
| what are the 2 types of re-entry |
|
Definition
1) microreentrant = occurs WITHIN the AV node = av nodal re-entrant tachycardia
2) macroreentrant = occurs outside the AV node = AV reentrant tachycardia |
|
|
Term
| what causes atrial fibrillation |
|
Definition
multiple foci in atria fire continuously in a chaotic pattern
results to quivering atria and rapid ventricle |
|
|
Term
| what would u see in an ecg of someone with atrial fib? |
|
Definition
no P waves
irregularly irregular QRS |
|
|
Term
| what are the complications of a fib |
|
Definition
1) maybe asymptomatic
2) dyspnea
3) syncope
4) STROKE
5) ANGINA
6) hypotension
7) embolic diseases |
|
|
Term
|
Definition
1) rate control = CCBs or beta blockers
2) anti-arrythmic = AMIODARONE
3) anticoag = aspirin for low risk
= warfarin for high risk
if not controlled:
1) cardioversion = convert pt back to sinus rhythm
= unless on warfarin therapy = do echo to make sure no thrombus
2) ablation = ablate around the pulmonary veins |
|
|
Term
| what causes atrial flutter |
|
Definition
single focus firing at the atria; firest at 250-350bpm
-atrial impulses transmitted to ventricles in a predictable pattern (2:1 or 3:1) |
|
|
Term
| what do u see in the ecg of someone with atrial flutters |
|
Definition
| sawtooth pattern (atrial contractions) |
|
|
Term
| what things can cause atrial flutters |
|
Definition
1) CAD
2) COPD
3) CHF
4) valvular disease |
|
|
Term
| how would someone with atrial flutters present |
|
Definition
1) fatigue
2) palpitations
3) embolic disease |
|
|
Term
| how would you treat someone with atrial flutters |
|
Definition
| same as a fib except ABLATION = more EFFECTIVE |
|
|
Term
| explain the pathophysiology of Wolf- Parkinson- White disease |
|
Definition
1) Bundle of Kent = ACCESSORY PATHWAY from atria to ventricles in the av valvular rings
= this allows early depolarization of part of the ventricles |
|
|
Term
| what do you see in the ecg of someone with wolf-parkinson-white syndrome |
|
Definition
1) DELTA WAVES!!!!
2) shortened PR interval
3) widened QRS
= antidromic ekg! |
|
|
Term
| what causes wolf parkinson white syndrome? |
|
Definition
|
|
Term
| what are the complications of wolf parkinson white syndrome? |
|
Definition
1) Ventricular fibrillations
2) death |
|
|
Term
| how would someone with WPW syndrome present? |
|
Definition
1) asymptomatic
2) syncope
3) palpitations |
|
|
Term
| explain what happens in orthodromic WPW syndrome |
|
Definition
accessory pathway functions in the retrograde direction
atria-> av node-> ventricles-> bundle of kent-> atria
QRS is normal!!! |
|
|
Term
| explain what happens in antidromic WPW syndrome |
|
Definition
accessory pathway functions in the anterograde direction
atria-> bundle of kent-> ventricles-> av node-> atria |
|
|
Term
| how would you treat someone with wolf parkinson white syndrome |
|
Definition
1) assess risk for atrial tachyarrythmias = b/c this predisposes to SUDDEN DEATH
2) ABLATION
3) avoid drugs that slow AV conduction b/c this increases conduction through the accessory pathway |
|
|
Term
| describe what happens in atrioventricular re-entrant tachycardia |
|
Definition
1) sinus beat conducted down both fast and slow pathways
2) premature atrial contraction shoots out but fast pathway still refractory = creates a UNIDIRECTIONAL BLOCK
3) conduction through the slow pathway results in retrograde conduction through the fast pathway
the pathways are located AROUND the VALVES |
|
|
Term
| what happens in AV nodal re-entrant tachycardia |
|
Definition
| same thing that happens in atrioventricular re-entrant tachy except that the pathway is in the AV NODE |
|
|
Term
| what would u see in the ecg of someone with av nodal or atrioventricular re-entrant tachycardia |
|
Definition
1) inverted P waves
2) narrow or widened QRS depending on w/c pathway is depolarizing the ventricles |
|
|
Term
| what are the presentations of someone with av nodal or atrioventricular re-entrant tachycardia |
|
Definition
not dangerous
may feel PALPITATIONS |
|
|
Term
| what may cause av nodal or atrioventricular re-entrant tachycardia |
|
Definition
1) ischemic heart disease
2) digoxin toxicity
3) caffeine/alcohol may exacerbate |
|
|
Term
| how would you treat someone with av nodal or atrioventricular re-entrant tachycardia |
|
Definition
1) MANEUVERS = valsalve, carotid massage, head immersion in cold water
2) adenosine
3) electric cardioversion
4) ablation= if episodes are recurrent and symptomatic |
|
|
Term
|
Definition
1) send ectopic electrical signals to the heart
2) used for certain bradyarrythmias |
|
|
Term
| what are indications for pacemakers |
|
Definition
1) mobitz type II av block
2) 3rd degree av block
3) symptomatic bradycardias |
|
|
Term
| describe a scar mediated re-entry |
|
Definition
1) scar= due to ischemia, cardiac injury
2)scar made of fibrous tissue (can't conduct impulse) and normal tissue
3) can lead to anterograde block or re-entry |
|
|
Term
| what role does structural heart disease play in arrythmia |
|
Definition
| there's conducting tissue where there should not be any (ex: in the av node or outside the valves of the wall of the myocardium |
|
|
Term
| what are the familial causes conduction abnormalities |
|
Definition
1) Long qt syndrome
2) brugada syndrome
3) Hypertrophic cardiomyopathy
4) right ventricular outflow track tachycardia |
|
|
Term
| what happens in LOng qt syndrome |
|
Definition
| a heritable condition that gives prolonged ventricular repolarization = long QT syndrome= increased incidence of torsades = sudden cardiac death |
|
|
Term
| explain what happens in brugada syndrome |
|
Definition
1) persistent ST elevation in leads S1-S3
2) right bundle branch block in ecg pattern
3) causes sudden cardiac death |
|
|
Term
| who is more at risk for brugada syndrome |
|
Definition
|
|
Term
| what happens in hypertrophic cardiomyopathy |
|
Definition
1) HYPERTROPHY = results in stretching of conduction fibers and disorganization
2) leads to LETHAL arrythmias |
|
|
Term
| explain what happens in right outflow track tachycardia |
|
Definition
left bundle branch block
wide complex QRS tachycardia
- ASYMPTOMATIC and NOT dangerous |
|
|
Term
| what are the different abnormalities of impulse formation |
|
Definition
1) sick sinus syndrome
2) tachy-brady syndrome
3) ischemia
4) iatrogenic
5) vasovagal reaction |
|
|
Term
| what happens in sick sinus syndrome |
|
Definition
1) sa node dysfunction
2) sinus brady
3) pause
4) arrest |
|
|
Term
| what happens in tachy brady syndrome? |
|
Definition
1) alternating sinus brady and tachy
- subset of sick sinus syndrome |
|
|
Term
| what happens in vasovagal reactions |
|
Definition
1) pain, anxiety,stress = causes sympathetic/parasympathetic response
SNS = vasodilation=hypotension
increase in PNS activity = bradycardia |
|
|
Term
| how do iatrogenic factors cause Bradycardia? |
|
Definition
1) beta blockers, CCBs, parasympathomimetics, digoxin, antiarrythmics
2) procedures: catheters, ep studies, surgery
ALL of these cause SCARRING = which doesn't conduct impulses |
|
|
Term
| how does ischemia cause bradyarrythmias |
|
Definition
infarction of coronary arteries may cause ISCHEMIA of sa and av nodes
RCA = supplies SA and AV node
LAD = supplies SA node |
|
|
Term
| what are the abnormalities in impulse conduction |
|
Definition
1) first degree av block
2) second degree av block = mobitz type I and II
3) 3rd degree av block |
|
|
Term
| What happens in a first degree av block |
|
Definition
1) delay across the AV node = PR interval >0.2 seconds
-every atrial impulse still results to a ventricular beat |
|
|
Term
| what happens in second degree av block /Mobitz Type I/ Wenkebach |
|
Definition
1) block at the AV node
2) PR interval PROGRESSIVELY PROLONGS and QRS drops out eventually |
|
|
Term
| what happens in second degree AV block , mobitz type II |
|
Definition
qrs drops out without graduation in PR interval
- block is in the HIS BUNDLE! |
|
|
Term
| what happens in 3rd degree av block |
|
Definition
no association between atrial impulses and ventricular beats
- block is in the av node or his bundle |
|
|
