Flashcards in dysrhythmias Deck (74)
What is Afib? EKG presentation?
- most common encountered arrhythmia in practice
- mult reentrant loops generate chaotic atrial depolarization (micro reentrant circuit)
- AV node is bombarded with rates greater than 400 bpm from atrial foci
- AV works hard to block impulses, ventricular rate is IRREGULAR IRREGULAR - bounding pulse
- b/t 110-170 bpm
- can be a slow rate as well: sign of sig underlying conduction disorder
- No distinguishable P waves on EKG
What conditions are Afib commonly found with?
- underlying cardiac disease:
ischemic heart disease
Afib can be precipitated by what conditions?
- acute alcohol ingestion
- post op cardiac surgery
- post op thoracotomy
- sleep apnea
Afib's impact on the body? heart? EF?
- EF may decrease 10% due to loss of atrial kick
- HF if rapid rate isn't controlled
- emobolic stroke due to pooling of blood in atria
- poor exercise tolerance
- worsening CHF or ischemic sxs
Risk of stroke? Prevention of thromboembolic complications in Afib?
- 5-6% risk of embolic stroke/year (cumulative)
- stasis of blood in atria:
pradexa, xalreto - new AC no INRs or dietary interactions
- healthy pts: aspirin
CHADS2 criteria? Who does it apply to?
- CHF = 1 pt
- HTN = 1
- older than 75 = 1
- DM = 1
- stroke or TIA = 2 pts
- if 2 pts or greater = anticoag unless CI
- under 2 pts: 325 mg of aspirin
- only applies to pts without valve disease
How do we control rate in afib? What is a good rate to have?
- ventricular rate b/t 60-110 had the same outcomes as pts who were converted to NSR
- Diltiazem (cardizem)
- digoxin (not first line)
How do we restore sinus rhythm if necessary? antiarrhythmics?
- class 1A antiarrythmics (only used with ACLS protocol):
- class III antiarrhythmics:
ibutilide (corvet) IV only
amiodarone (titrated up to 400 mg po qday)
** worry about long term toxicity issues, lungs, thyroid, liver and eyes need monitoring
- class IC: used only in pts with structurally normal hearts (absence of CAD or cardiomyopathy) - propafenone (rythmol), and flecainide (tambocor)
- cardioversion: less than 48-72 hrs of a-fib: safe to cardiovert (still might have to rule out thrombus)
- if duration unknown: rate control, anticoag for 4-6 weeks than cardiovert, or anticoag for 6 weeks after successful cardioversion or indefinitely if pt was unaware of afib
*** TEE to see if atrial thrombus present to prior cardioversion
What is next line of tx if cardioversion and medical therapy fail?
- afib ablation
- av node ablation in extreme cases which would require permanent pacemaker placement
Most feared complication of a fib? other complications?
- stroke (especially in pts older tha 75) - clots occur more in LA
- severe bradycardia
- rate related MI (tachy or brady rhythm)
Eval process of new onset afib pts?
- eval for presence of valvular heart disease (echo)
- eval for presence of ischemic heart disease (nuclear stress test)
- rule out sleep apnea even in pts with normal BMI (sleep study)
- thyroid function tests
What is a flutter?
- macro reentrant circuit
- atrial rate: 250-350
- ventricular rate: 150
- AV node blocks at 2:1, 3:1, 4:1
- can also have slow ventricular rate
- regularly irregular
- classic sawtooth pattern on EKG
- almost always occurs in diseased hearts
- it precipitates CHF
- and may be a precursor to fib
- may be precipitated by:
alcohol ingenstion (causes afib)
- rate is harder to control than afib
- tx depends on hemodynamic compromise
they should be at least getting 325 mg ASA daily
- Why is thrombolic event risk somewhat lower than afib?
- because there is atrial contraction that is occuring in a flutter as opposed to afib
Tx for aflutter?
- ablation if failed cardioversion and medical therapy
- class 1A antiarrythmics are used to convert to sinus rhythm: procainmide
- ventricular rate controlled with: BBs, CCbs, and digoxin
workup for aflutter?
- thyroid studies
- rule out structural and functional heart disease with echo
- rule out ischemic heart disease with nuclear stress test
- rule out sleep apnea
AV node disturbances?
- junctional escape rhythm: 40-60 bpm
-accelerated junctional rhythm: 60-100 bpm
* these 2 are common in pts with inferior MI, digoxin toxicity
EKG presentation of Junctional escape, accel junctional rhythm
- narrow complex QRS
- retrograde P wave:
inverted P with very short PR interval, P wave right after QRS, or sometimes no P wave
- specific tx is usually not required
What is junctional tachycardia?
- 150-250 bpm
- occurs more commonly in women
- may occur in absence of heart disease
- usually initiated by a PAC
tx for junctional tachycardia rhythms?
- acute: vagal maneuvers, adenosine (DOC, terminates 95% of cases)
- long term: BBs, CCBs, Class 1A, 1C, and III antiarrythmics for resistant cases
- 1st degree
- 2nd degree, mobitz type 1 (wenkebach)
- 2nd degree, mobitz type 2
- 3rd degree heart block (AV dissociation)
When does 1st degree AV block occur?
- occurs in both healthy and diseased hearts
- can be due to:
increased vagal tone
acute rheumatic fever
EKG: PR greater than 0.20
Tx of 1st degree AV block?
- interventions include tx the underlying cause
- usually don't need any other tx
- observe for progression to a more advanced AV block
When does 2nd degree AV block-mobitz type 1 (wenckebach) occur? EKG presentation?
- occurs in AV node above bundle of his
- often transient and may be due to acute inferior MI or digitalis toxicity
- tx usually not indicated as rhythm usually produces no sxs
- EKG: rate may be variable, PR interval gets progressively longer until a QRS is dropped (or blocked)
- observe for progression to more advanced AV block
2nd degree AV block mobitz type 2?
- usually occurs below bundle of his and may progress into higher degree AV block (more severe)
- can occur after an acute anterior MI due to damage in the bifurcation or bundle branches
- more serious than type 1
- tx is usually artificial pacing, via external pacer or temporary pacer wire insertion
tx: permanent pacemaker
EKG findings of AV block - mobitz type II?
- rate: variable
- P wave: normal
- QRS: usually widened because this is usually assoc with bundle branch block
- PR: may be normal until dropped QRS
What is a 3rd degree heart block (complete)?
- block of atrial impulses occurs at AV junction, common bundle or bilateral bundle branches (no comm b/t atria and ventricles)
- another pacemaker distal to block takes over in order to activate the ventricles or ventricular standstill occurs
- atrial and ventricular activities are unrelated due to complete blocking of atrial impulses to the ventricles
3r degree heart block findings on EKG?
- atrial rate is usually normal
- ventricular rate is usually less than 70 bpm
- atrial rate is always faster than ventricular rate
- P waves: normal with constant P-P intervals but not married to QRS complexes
- QRS: may be normal or widened depending on where the escape pacemaker is located in conduction system
Tx for 3rd degree heart block?
- external pacing and atropine for acute, sx episodes
- perm pacing for chronic complete heart block
- V fib
- idioventricular rhythm