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atrial fibrillation

Terms in this set (21)

atrial fibrillation definition
a supraventricular tachyarrhythmia defined by rapid, irregular atrial activation
-->loss of coordinated atrial contraction
-->irregular electrical input to the AV node typically leads to sporadic ventricular contraction rate
EKG hallmarks of afib
no coordinated P waves (absent or very coarse/fine) & irregularly irregular ventricular contraction rhythm
cause of afib
anything that stretches the atrium
-reversible causes: thyrotoxicosis, alcohol intoxication, stimulant drugs, supraventricular tachycardia, sleep apnea
classification of afib
-new diagnosis (1st dx, regardless of duration or sx)
-paroxysmal (recurrent)
-persistent
-long-standing persistent
-permanent
-silent or asymptomatic
sequelae/morbidity of afib
-thromboembolism-->stroke; dementia
-CHF
-cardiomyopathy
-angina
-hospitalization
-mortality
risk of stroke in untreated a-fib
*Very high= previous ischemic stroke
*High= > 65 y/o and 1 other risk factor from: HTN, DM, HF, left ventricular dysfunction
*Moderate= > 65 y/o with no other risk factors; < 65 y/o with other risk factors
*Low= < 65 y/o with no other risk factors
epidemiology of afib
**most common sustained cardiac arrhythmia
-increasing risk w/ age
-
prognosis of afib
-mortality in people with Afib is twice that of the general population
- linked w/ the severity of underlying disease
risk factors for new onset afib
-HTN
-diabetes
-CHF
-valvular heart disease
-older age
-hypertrophic cardiomyopathy (HCM)
-extreme athleticism
diagnosing Afib
-identify risks
-EKG
-exercise testing: identify CAD
-ambulatory monitoring (with paroxysmal Afib)
-echo
-electrophysiology
-chemistry: TSH, BUN/creatinine
benefits of rhythm control
-controls symptoms
-better exercise tolerance, lower risk of stroke, reduced risk of thromboembolism, better quality of life, and better survival if sinus rhythm is maintained
cons of rhythm control
-those on drugs for rhythm control experienced more ADRs than those taking rate-control drugs
-increased risk of thromboembolism in patients who have been in AF for more than 2 days (they need warfarin before & after)
-relapse rate following electrical cardioversion is high (it helps to give anti-arrhythmic drugs afterward)
method of rhythm control in those w/ persistent Afib
Cardioversion: electrical (preferred method) and pharmacological (less initial success, but doesn't require sedation or anesthesia)
drugs used in pharmacological cardioversion
**flecainide best supported by evidence
-quinidine, disopyramide, propafenone, and amiodarone
-NOT digoxin, beta blockers, and verapamil
indications for attempted cardioversion
-recent onset A-fib
-no structural heart disease
-young age is best
-IMMEDIATELY in people w/ acute A-fib and severe hypotension, acute HF, acute MI, or unstable angina who don't respond promptly to medical management
Anticoagulation for cardioversion
-to INR > 2.5 for 3-4 weeks before cardioversion(can skip if no atrial thrombus)
-to INR > 2.5 at time of cardioversion and 3-4 weeks after, even with restoration of sinus rhythm
rate control
-goal is to keep the ventricular rate less than 90/min at rest and less than 180/min at exercise
-use drugs that slow down conduction through AV node
-for those who don't respond to or tolerate meds: radio-frequency ablation of AV node & pacemaker implantation
drugs used for rate control
*beta blockers: control resting HR and HR during exercise, but decreased exercise tolerance
*rate-limiting CCBs: control HR at rest and during exercise, w/o a decrease in exercise tolerance
*Dixogin: contols resting HR, not exercise
(first line therapy is beta blocker or CCB)
what to do if one drug doesn't control rate?
-combine digoxin w/ a beta blocker OR verapamil, or consider referral
*combining beta blocker with verapamil gives risk of bradycardia
*use lower doses in elderly and renal impairment
Anticoagulation with rate control
Warfarin > aspirin if risk factors for stroke are present
*decision based on balance of overall risk of stroke and the risk of ADRs
overall management of A-fib
-in unresponsive, persistent A-fib: can do ablation of AV node & lifelong pacemaker
-anticoagulation is paramount to survival
-many people still experience symptoms despite attempts to control the ventricular rate-->rhythm control is often needed in these people (anti-repeated cardioversion w/ arrhythmic drugs)
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