A Fib Lecture Flashcards
A Fib is the loss of what
atrial contractility
Afib results in what?
irregular ventricular response
rapid heart rate
what is the HR with A fib
120-160
what can A fib lead to
clot formation and subsequent thromboembolic events (leading cause of stroke)
what is the most common sustained arrhythmia
A fib
what populations does A fib affect most
risk increases with age >65
men >women
whites > blacks, hispanics, asians
etiologies of atrial fibrillation
- acute hyperthyroidism
- acute vagotonic episode
- acute alcohol intoxication
- post operatively after major surgery
- atrial enlargement
- disruption of electrical conduction system (scarring or infiltration)
pathophys of afib
elevation in atrial pressure
majority of episodes of PAF are triggered by atrial premature beats
can be triggered by other supraventricular arrhythmia: atrial flutter or atrial tachycardia
what is A Fib
disorganized rapid and irregular atrial activation
ectopic foci in afib are most often located where
ostial portion of pulmonary veins (site of ablation)
risk factors for Afib
- age >64
- male
- HTN
- elevated BMI
- PR interval prolonged
- valvular dz
- CHF
classifications of Afib
- paroxysmal - intermittent
- persistent - fails to self terminate within 7 days and requires intervention in order to convert
- permanent - >12 months & no longer pursue rhythm control
- Lone AF - without structural heart dz, lowest risk of complications (term not used much anymore)
Dz associations with Afib
- valvular heart dz (significant stenosis or regurgitation; rheumatic heart dz)
- heart failure
- HTN heart dz
- acute myocardial infarction (probably due to atrial ischemia or stretch)
symptoms of afib
- asymptomatic
- heart palpitations
- light headedness, pre syncope, syncope
- SOB and exercise tolerance
- chest pain - rare unless concomittant CAD
- fatigue
common triggers of afib episodes
sleep deprivation physical illness post surgery stress hyperthyroidism physical exertion/exercise stimulant medications alcohol caffeine dehydration
initial presentation of new onset of a fib
heart palpitations fatigue or lightheadedness SOB angina incidental
what do you want to control in new onset of afib
- rate and rhythm control
2. prevention of systemic emboli
diagnostic studies for afib
EKG
echo
stress test
labs: CBC, BMP, TSH
history taking for afib
symptoms: onset, frequency, duration, quality, severity (tachy and fatigue)
precipitating causes (alcohol, exercise)
underlying dz:
CAD, CHF, CVA/TIA, DM, HTN, COPD, thyroid disorder
phyiscal exam in afib
complete cardiovascular exam
- BP and pulse
- murmurs
- evidence of heart failure (JVP etc)
- extremity pulses
EKG for Afib
needed to make the diagnosis -LVH -pathologic Q waves delta waves, short PR interval QT interval duration
echo for afib
size of atria size and functino of R/L ventricles valvular heart dz pericardial dz atrial thombus**low sensitivity
TEE for afib
transesophageal echocardiogram
far more sensitive for detecting atrial thrombus
-prior to cardio conversion
-could throw a clot
when to do exercise stress test with afib
assess for ischemic heart dz
differences of ST segments bw ischemia and MI
ischemia - ST segment depressed in ischemia (no death of tissue yet, just not being perfused)
MI - ST elevation
why give pt home heart monitors?
to determine if persistent or paroxysmal
lab testing for afib
TSH - all patients with first episode of afib or incr frequency
CBC
chemistries/electrolytes (incld kidney function tests)
4 goals for afib
- rhythm control (if not yet permanent)
- reduce the risk of stroke and other peripheral emboli (prevention of systemic embolization)
- prevent tachycardia mediated cardiomyopthy and ischemia (rate control)
- alleviate symptoms (usually d/t increased HR)
management decisions for new afib
is cardioversion indicated and should it be urgent?
does the pt need rate control
does the pt need to be anticoagulated for emobolization prevention
does the pt need to be hospitalized
are tehre correctable causes of afib (drugs)
possible indications for urgent direct current cardioversion
- active ischemia
- unstable hemodynamics
- evidence of organ hypoperfusion
- severe manifestations of heart failure (pulm edema)
- the presence of WPW
* *risks and benefits of cardioversion must be weighed carefully
indications for nonurgent DC cardioversion
new onset or newly recognized atrial fibrillation
pts with persistent AF who are limited by their symptoms
reasons not to cardioconvert in afib
- known afib and minimally symptomatic
- multiple comorbities
- unlikely to maintain NSR
- benefits of cardioversion decrease after 80yo
- paroxysmal AF (go in and out on their own)
what do you give a pt prior to cardioversion
IV heparin
control ventricular RATE
what happens in afib duration >48hrs
hold off bc its too risky to do cardioversion d/t clot, need full anticoags (3weeks) and do transesophageal echo to look for clot
afib with rapid ventricular response can reach what bpm
> 150
complications of rapid afib
symptoms - fatigue, chest pain
ischemia
pulm edema
tachycardia induced cardiomyopathy (LV dilation, cellular morphologic changes)
4 classes of pharm tx of afib
- beta blockers
- calcium channel blockers
- digoxin
- amiodarone
beta blockers for tx of rapid afib
- immediate control: IV metoprolol start at 5mg IVP can give 2nd dose of 5mg if first didnt work or if it wears off
- long term control: oral metoprolol (tartrate: short acting: every 6hrs OR succinate: long acting: 1/day)
what beta blockers would be used in afib with the following comorbidities?
- liver failure
- heart failure
- nadolol
2. carvediolol
what beta blocker is better for BP but can also be used to try and treat rapid afib
atenolol
calcium channel blockers for rapid afib
- immediate control: IV diltiazem (5-10mg IVP); can also do a Dilt drip: continuous infusion that is titrated up until target HR reached
- oral diltiazem - 3/day for short acting or 1/day for long acting
digoxin for rapid afib
can be IV or oral
-less effective for rate control particularly during exercise
can be added to beta blockers if insufficient or intolerant
-initial dose is loading dose (higher) then daily maintenance dose
-plasma digoxin levels should be monitored periodically d/t risk of dig toxicity
amiodarone for afib
- maintains sinus rhythm in AF pts (antiarrhythmic)
- can also slow rate for refractory afib with RBR after maximizing BB and CCB
- immediate use: IV
- long term maintenance: oral
- less likely to cause hypotension
- SEs: abnormal LFTs, pulm toxicity (months to years after initiation so dont use long term), chronic interstitial pneumonitis (scarring thruout lungs = restrictive dz)
arterial embolization from atrial fibrillation
risk 0.5% per year to 6.9% per year
- stasis of atrial blood leads to clot formation
- especially in left atrial appendage (LAA)
- ischemic stroke is the most frequent
- can occur at any point in time
- valvular heart dz increased risk
what scoring system is used to assess pts need to be on anticoagulants with afib
CHADS2 score
0: no anticoags
1-2: consider next scoring system
>=3: high risk, def need anticoags
what scoring system do you use if CHADS2 score is 1-2 (intermediate)
CHA2DS2 VASc model
pts with a score >=2 are recommended to have long term anticoagulation
what factors does the CHADS2 system use
HTN = 1pt
Age >75 = 1pt
DM = 1pt
prior stroke/TIA = 2pts**
what factors does CHADS2-VASc model use
age 65-74 = 1 age >=75 = 2 female = 1 CHF = 1 HTN = 1 Stroke/TIA = 2 vascular dz = 1 DM = 1
warfarin for anticoag for afib
- how often is it used?
- how effective?
- cost?
- downside
most commonly used effective inexpensive significant risk of bleeding frequent blood draws
how does warfarin work?
competively depletes functional vit K reserves and hence reduces synthesis of many active clotting factors
how to reverse warfarin
administer vitK
how long does warfarin take to start working
24-72hrs
full therapeutic effect starts when on warfarin
5-7 days
how is warfarin monitored
INR - 2.5 goal
how is warfarin metabolized
hepatically via CYP2C9 = lots of DI’s
what options can you use for anticoag for immediate use
IV heparin or lovanox
when to bridge warfarin with heparin or LMWH in pts with afib
not usually necessary
recent or ongoing stroke or other embolus
known arterial thrombus
currently hospitalized (bc its easy)
warfarin compared to newer agents
-newer anticoags: direct thrombin and factor Xa inhibitors similar or lower rates of ischemic stroke similar or lower rates of major bleeding do not require frequent lab draw EXPENSIVE**
indications for hospitalization for afib
immediate anticoagulation (bridge)
ablation of accessory pathway (WPW)
tx of associated medical problem that may trigger afib (infection, COPD, CHF)
management of rate or sick sinus syndrome
is afib common?
yes
what does afib put the pt at risk for
stroke and other embolic events
goals of afib
management of symptoms, rate vs rhythm control, and stroke prevention
occurence of aflutter vs afib
less common than afib
aflutter sometimes leads to
afib
aflutter commonly occurs after
initiation of an antiarrhythmic drug for afib
aflutter is associated with what
Left atrial enlargement
what are the rates like in aflutter
rapid ventricular rate (150bpm) atrial rate (250-350bpm) - f waves
associated disorders with aflutter
- hyperthyroidism
- heart failure
- obesity
- obstructive sleep apnea
- sick sinus syndrome
- pericarditis
- pulm dz
- pulm embolism
clinical manifestations of aflutter
palpitations lightheaded SOB tachycardia evidence of CHF
diagnostic studies for aflutter
EKG
echo
TEE
exercise stress test
complications of aflutter
cardiac ischemia
pulmonary edema
tachycardia induced cardiomyopathy
thromboembolism
treatment considerations in aflutter
control ventricular rate
convert to NSR
maintain NSR
prevent systemic embolization
rate control in aflutter
more difficult than afib
use BB or CCB (digoxin can be added)
amiodarone is rarely used
radiofrequency catheter ablation
what is radiofrequency catheter ablation
type 1 aflutter
large macroreentrant pathway in right atrium involving obligatory pathway bw inferior vena cava and the tricuspid annulus
ablation of IVC-TA area
maintains sinus rhythm after procedure
65-100% success rate
7-44% have recurrent atrial arrhythmia, usually afib
pharm therapy for conversion to NSR
only 20-30% effective at maintaing NSR
- dronedarone
- flecainide
- sotalol
- dofetilide
- amiodarone
anticoagulation for aflutter
- prior to RF catheter ablation - 4 weeks or consider TEE
- after RF catheter ablation - anticoagulation x 1month
- recurrent aflutter or afib after ablation plan indefinite anticoagulation if CHADS2 score >=1
aflutter pts at risk for
strok and other embolism
