A-fib Flashcards
Most common clinically significant arrhythmia?
A-fib (about 2% of the population)
What is the epidemiology of a-fib
- Prevalence increases with age
- Men > Women
- More prevalent in north america
- White > Black
Most common predisposing diseases for A-fib?
- HTN
- CAD
- CHF
- Valvular disease
Basic pathophys of A-Fib
Many reentrant circuts in the atria -> not all beats make it through -> irregularly irregular ventricular rythm
Some triggers for A-Fib
- Spontaneous ectopy in atrialized musculature of pulmonary veins often triggers AF
- Surgery (esp. CT surgery)
- Infection
- Acute MI
- Acute alcohol consumption (holiday heart)
- Thyrotoxicosis
- Acute pericarditis
- PE or acute lung condition
- Heart Failure
Classifications of A-fib
- Paroxysmal
- Self-terminates within 7 days
- Most within <24-48 Hrs
- Self-terminates within 7 days
- Persistent
- Lasts > 7 days
- Longstanding Persistent
- Continuous AF >/= 12 months
- Permanent
- Efforts to restore or maintain NSR have either failed or been abandoned
Important to note there is no “Chronic AF” classification
What is Paroxysmal AF?
Self terminates within 7 days most within < 24-48 Hrs
What is persistent AF
Lasts > 7 days
What is longstanding persistent AF?
Continuous AF >/= 12 months
What is permanent AF
When efforts to restore or maintain NSR have either failed or been abandoned
What are the most common symptoms of AF?
- May be asymptomatic
- Palpitations
- Fatigue, dyspnea, dizziness, diaphoresis
- Symptoms of heart failure or other underlying disease
- S/S of hemodynamic compromise
- CP, pulmonary edema, syncope
- Irregularly irregular pulse palpated/auscultated
- CVA/TIA (often Pts will be asymptomatic until they have a CVA/TIA)
Key features of a EKG showing A-fib
- Absence of P waves
- Irregularly irregular QRS intervals
- Irregular or fluctuating baseline
- Rate often uncontrolled
- Usually 110-150 BPM
- Termed AF with RVR one rate > 100
- Usually narrow complex
- Many see fine or coarse fibrillatory waves
- Can trick you into thinking P waves are there
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Ways to test for A-fib
- Ambulatory monitoring
- Holter monitor, implantable loop monitor
- Good for finding a-fib if it is intermittent
- Holter monitor, implantable loop monitor
- TSH
- CBC
- BMP, Mg
- Others based on likely triggers/underlying factors
- You have an unstable patient with A-fib, what is the first line treatment?
- Examples of unstable Pateint
- Active ischemia
- Evidence of organ hypoperfusion
- Severe manifestations of heart failure
- Examples of unstable Pateint
Cardiovert them!!!
Why do we want to control the heart rate in patients with A-fib?
- Avoid hemodynamic instability and symptoms
- Avoid tachycardia-mediated cardiomyopathy
- Rate tends to increase the longer someone has A-fib
What are the two HR goals for a Pt with AF?
- Strict: <80
- Lenient: <110
RACE II trial compared strict vs lenient HR goals in pateints with permanent AF and found that Lenient HR control was noninferior to strict rate control
Rate control is generally preferred over rhythm control
Generally Rate control for Pts with Af is preferred over rhythm control, this is especially true in Pts > 80 years old. Why?
Pts over 80 are usually more sensitive to antiarrhythmics having worse S/E, and their AF is often permanent so rhythm control would do nothing for them.
If emergent or urgent rate control is needed what are the two classes of drugs used?
- IV beta blockers: Slow sinus rate, decrease AV nodal conduction
- Esmolol
- Very rapid acting (duration 10-20 minutes)
- Metoprolol
- Propranolol
- Esmolol
- IV Calcium channel blockers
- Diltiazem (Cardizem) preffered
- Can usually control the rate within several minutes with bolus -> drip
- Diltiazem (Cardizem) preffered
Name the IV beta blockers for emergent/urgent rate control
- Esmolol
- Metoprolol
- Propranolol
What is the preferred IV calcium channel blocker for emergent/urgent rate control?
Diltazem (Cardizem)
Chronic use of Beta Blockers can be used for long term rate control in patients with AF, what do they do?
- Decrease resting HR and blunt HR response to exercise
- M&M benefit to Pts with HFrEF
- Most Beta blockers are equally effective
Name some of the Beta Blockers used for long term rate control in Pts with AF and their side effects
- Atenolol
- Metoprolol
- Nadolol
- Bisoprolol
- Carvedilol
S/E: Wrosening CHF, bradycardia, hypotension, bronchospasm, reduced exercise tolerance, AV block
Calcium channel blockers can also be used for long term rate control in AF. What are the two most commonly used ones?
- Diltiazem (Cardizem)
- 30 mg QID
- Sustained release pill available
- Verapamil (Calan)
- 40 mg TID-QID
- Sustained release pill avalible
- Cautions when using CCBs: Pts with CHF (can exacerbate CHF and worsen edema associated with it), combination with beta blockers, significant hypotension, verapamil increases serum digoxin, heart block.
Digoxin can also be used to control rate in Pts with Af. What are the two circumstances when it would be used?
- Patients with HFrEF and AF
- Improves contractility and reduces ventricular rate
- Patients whose rate isn’t adequately controlled with BB and/or CCB
- Digoxin can be added on as a medication as well as BB and/or CCB
What are some disadvantages to using Digoxin?
- Not as effective as BB/CCB
- May be associated with higher mortality
- Narrow therapeutic window and levels can be increased by many medications
- Renally cleared but cannot be removed by dialysis
- Can cause: Caridac arrhythmias, visual distrubances (blurred or yellow vision), n/v, anorexia
What methonds may be used to attempt to restore sinus rhythm in Pts with AF
- Antiarrhythmic drugs
- Radiofrequency catheter ablation
- Surgical procedures
What is the goal of rhythm control for Pts with AF?
Reduce symptoms
Pts with A-fib who have their rhythm controled and maintained in sinus rhythm still need to be on anticoagulants, why?
- Maintaining sinus rhythm does NOT reduce the frequency of thromboembolism
- AFIRM and RACE trials found that embolic events happened at equal frequency regardless of whether a Pt was rate or rhythm controlled
When is the best time to attempt rhythm control for Pts with AF?
Early in the course of AF