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Background
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Irregular heartbeat that is caused by
rapid, disorganized electrical signals
§ These
signals cause the atria to contract very fast and irregularly (fibrillate)
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Currently 33.5 million people worldwide
have AFib
§ 3
million Americans (expected to rise to 8 million)
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70% of those with AFib are between the ages
of 65 and 85 years old
o
Caucasians are more likely to develop AFib
than other ethnicities
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Risk factors for development are:
hypertension, coronary heart disease, heart defects, heart failure, rheumatic
heart disease, pericarditis, hyperthyroidism, obesity, diabetes, lung/kidney
disease, sleep apnea, and a family history
o
Other behavioral factors include: caffeine
abuse, alcohol abuse, and stress
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Pathophysiology
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In a normal heart the SA node (right
atrium) begins the electrical signaling. It sends signals to begin a new
heartbeat 60-100 times a minute. From the SA node, the electrical signal moves
to the right and left atria. This causes a contraction and blood is pumped to
the ventricles. Once in the ventricles, the electrical signal moves to the AV
node which slows the signal down so the ventricles can fill with blood. Once
leaving the AV node the ventricles contract and blood is pumped to the rest of
the body.
o
In AFib, electrical signals begin in a
different part of the atria or pulmonary veins, not the SA node. Those
electrical signals all stimulate the atria causing the fibrillation and they
flood the AV node causing the ventricles to beat faster (just not as fast as
atria). This causes the atria and ventricles to not beat in a coordinated way
causing a fast and irregular heart rhythm. The blood is not pumped out of the
ventricles in a regular fashion so the body gets inconsistent amounts of blood
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There are 3 common types of AFib
§
Paroxysmal or temporary: faulty electrical
signals begin suddenly but stop on their own Usually stop within 24 hours
§
Persistent: Abnormal heart rhythm lasts for
more than a week and either stops on own or with treatment
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Permanent: Normal heart rhythm cannot
revert to normal with treatment
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Symptoms/Diagnosis/Complications
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Not everyone has symptoms of AFib
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Commonly patients present with general
weakness and fatigue
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Other symptoms include:
§
Rapid, irregular heartbeat
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Fluttering or thumping in the chest
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Shortness of breath and anxiety
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Chest pain or pressure
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Diagnostic tests include: EKG or Holter
monitor which can show images of the heart
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Two major complications of AFib: stroke and
heart failure
§
Stroke: Some blood is not pumped out of the
atria causing pooling and a clot is formed which can travel to the brain
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Heart Failure: Heart does not pump enough
blood to meet the needs of the body. In AFib the ventricles are beating quickly
to keep up with the atria and are unable to completely fill with blood
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Treatment
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Multiple goals of therapy which use
different medications
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Goal 1: Prevent blood clots from forming
§
Risk assessed via CHADS2-VASc score (heart
failure, hypertension, age, diabetes, previous stroke, women, PVD, and age
>65)
§
One of the most common treatments of AFib
§
Most common medications are warfarin and
aspirin
·
Aspirin is preferred with lower stroke risk
(score of 0 or 1)
·
>2 is high risk and oral anticoagulation
should be considered
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Other medications include: dabigatrin,
rivaroxiban, apixaban, and endoxaban
·
Recently approved in non-valvular AFib
·
Advantages: no routine monitoring required,
not affected by diet or supplements, and less likely to cause hemorrhagic
stroke versus warfarin
·
Disadvantages: effects disappear shortly
after a skipped dose and no antidote if bleeding occurs
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Goal 2: Rate control
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Slow down the rate of ventricle beats
therefore decreasing the heart rate
§
Recommended treatment for those with AFib
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Medications that control rate include:
·
Beta blockers
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Cardio selective: metoprolol, atenolol,
bisoprolol
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Non-cardio selective: carvedilol,
propranolol, nadolol
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Calcium channel blockers
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Slow heart rate and decrease strength of
contraction
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Diltiazem and verapamil
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Digoxin- slows conduction of electrical
currents
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Goal range: 1-2ng/mL
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Goal 3: Rhythm control
§
Attempt to restore abnormal rhythm back to
normal
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Medications that control rhythm include:
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Sodium channel blockers- slow ability to
conduct electricity
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Flecanide, propafenone, and quinidine
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Potassium channel blockers- slow down
electrical signals that cause AFib
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Amiodarone, sotalol, and dofetilide
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Surgical intervention
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Electrical cardioversion- use electrical
shocks to convert to normal rhythm
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Catheter ablation- restores normal rhythm
through radio waves
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Prevention
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Lifestyle changes
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Healthy diet
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Low sodium diet
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Smoking cessation
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Stress reduction
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Monitor other chronic conditions
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Hyperlipidemia, hypertension, and
hyperthyroidism
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