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What is Atrial Fibrillation (AF or AFib)? 

 

Atrial fibrillation is the most common irregular heart rhythm that starts in the atria. The normal route of heart beating would start with an the SA node (sinus node sending out singular pulses of electrical stimulus at a time which flows through a predetermined route towards AV node next and dispersing to the ventricles. 

With Afib, SA node does not predominate as the singular starting point of the impulse. The atria has many different impulses rapidly fire simultaneously, causing a very fast, chaotic rhythm in the atria.

Normal Sinus Rhythm

Normal Sinus Rhythm

Atrial Fibrillation

Atrial Fibrillation

With such disorganized electrical impulse, atria cannot contract and/or squeeze blood effectively into the ventricle.

The many erratic atrial impulses converge on the AV node which a few of them pass of through and the ventricles contract irregularly, leading to a rapid and irregular heartbeat. The rate of impulses in the atria can range from 300 to 600 beats per minute.

 

Risk Factors

In developed countries hypertensive heart disease and coronary heart disease (CHD) are the most common underlying disorders. Rheumatic heart disease, although now uncommon in developed countries, is associated with a much higher incidence of AF. 

 

Diagnostic Tests 

Electrocardiogram (ECG)

afibrhythm

The modality of choice is EKG. A typical EKG for atrial fibrillation would exhibit “irregularly irregular rhythm.” There are no identifiable P waves, irregular RR intervals are irregular and the baseline EKG is a collection of numerous tiny and erratic spikes.

TREATMENT

Physicians must decide on optimal treatments for anticoagulation, rate control, and rhythm control.

(1) Prevention of systemic embolization

Every patient with AF should be evaluated for the need of antithrombotic therapy to prevent systemic embolization. This has traditionally been accomplished by the application of the CHADS2 risk score.

Modifications of this scoring system have resulted in the CHA2DS2-VASc score, which is now the recommended strategy for stroke risk assessment.

anticoagulation

Score Risk Anticoagulation Therapy Considerations
0 Low None or Aspirin Aspirin daily
1 Moderate Aspirin, Warfarin, or other oral anti-coagulant Aspirin daily or raise INR to 2.0-3.0, depending on patient preference
2 or greater Moderate or High Warfarin or other oral anti-coagulant Raise INR to 2.0-3.0, unless contraindicated

(Recommendations based on CHADS2 score)

Patients who may require antithrombotic therapy include those in whom cardioversion to sinus rhythm is being considered (regardless of the CHA2DS2-VASc score or method of cardioversion [electrical or pharmacologic]) and those who meet criteria for chronic anticoagulation. All patients whose risk of embolization exceeds the risk of bleeding are candidates for long-term antithrombotic therapy.

(2) Rate versus rhythm control

Majority of the AF patients quire the ventricular rate to be slowed down to a sinus rhythm. A rhythm control strategy uses either antiarrhythmic drug therapy, percutaneous catheter ablation, and/or a surgical procedure. Electrical cardioversion may be necessary prior to an attempt to maintain sinus rhythm.

Rate slowing drugs are generally started before rhythm control and continued in many patients who remain in sinus rhythm (in the event of return to AF).A rate control strategy generally uses drugs that slow conduction across the atrioventricular (AV) node, such as beta blockers, non-dihydropyridine calcium channel blockers, or digoxin.  

If you want to know more about your heart health, schedule an appointment with Dr. Uri Ben-Zur today and your friends at the Cardiac Institute of Greater Los Angeles where our patients ARE our family.

References 

Overview of atrial fibrillation (Overview of atrial fibrillation) http://www.uptodate.com/contents/overview-of-atrial-fibrillation?source=search_result&search=atrial+fibrillation&selectedTitle=1%7E150#H5
Atrial fibrillation (Wikipedia) http://en.wikipedia.org/wiki/Atrial_fibrillation
Cleveland Clinic – What is Atrial Fibrillation? (Cleveland Clinic) http://my.clevelandclinic.org/heart/atrial_fibrillation/afib.aspx#treated

Dr. Ben-Zur is a cardiologist and electrophysiologist who treats various heart conditions, including atrial fibrillation, a-fib, AF, arrhythmias, valvular disease, congestive heart failure, and many more. He services patients from Burbank, Sherman Oaks, Encino, Hollywood and beyond.

 

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