Atrial Fibrillation (Brigham and Women's)

Atrial FibrillationAmeer Ahmed

Objectives Identify patients with A-Fib in two casesDefine Atrial FibrillationCompare and contrast A-Fib and Atrial FlutterSee what A-Fib looks like on an EKGLearn about the different types of A-FibUnderstand the causes of A-FibAnalyze graphs

Examining a Patient 65 year-old male Patient History:

Heart Attack Stented Sleep Apnea

All of these, including the abnormal EKG, showed that the patient had atrial fibrillation

What is Atrial Fibrillation? The 2 top chambers of the heart receive quick

irregular electrical signals, causing fast and irregular contraction

It is the most common type of arrhythmia Approx. 33% of arrhythmia-related

hospitalizations are A-Fib A-Fib increases the risk of stroke 5x and the risk

of death 2x

Atrial Fibrillation vs. Atrial Flutter Atrial Fibrillation

Variable in amplitude, shape, and timing Not a reentrant circuit-comes from

different activation points Atrial Flutter

The electrical signals travel in a reentrant circuit, causing the upper two chambers to beat faster than the lower two chambers A loop that keeps reactivating

Electrocardiographic Features

Without negative dromotropic agents, ventricular rate is between 100 and 160 bpm

On an EKG, the “f waves” are variable in amplitude, shape, and timing

Electrocardiographic Features However, when the ventricular rate is very fast

(rate> 170 bpm), then the f waves can seem weaker and look like they fall into a rhythm, giving the impression that atrial fibrillation is NOT present

Normal EKG

Abnormal EKG with Atrial Fibrillation

Classification of Atrial Fibrillation First Episode

First occurrence of AF Recurrent

More than 2 episodes of AF Paroxysmal

Ends within 7 days Persistent

Present continuously for 7+ days

Classification of Atrial Fibrillation Longstanding (Persistent)

Present for longer than 1 year *Permanent (Accepted)

Longstanding A-Fib refractory to cardioversion

Note: “Permanent AF” does not have to be permanent as it can be cured by surgical or catheter ablation

Mechanisms of Atrial Fibrillation Drivers

Send rapid electrical signals Circuits

Terminate and change wavelets, continuing the irregular electrical activity

In many studies, the left atrium has the dominant frequency discharge (left-to-right gradient)

Genetic Factors of Atrial Fibrillation Many mutations responsible for AF have been

identified Gain of function of repolarization of

Potassium currents that cause shortening of atrial response and facilitation of atrial reentry

Atrial responsefaster top chambers vs. bottom chambers

Genetic Factors of Atrial Fibrillation Many polymorphisms, connected to structural

heart disease, have been identified to affect Sodium and Potassium channels to predispose to AF

Causes of Atrial Fibrillation Hypertension (usually left ventricular) Risk increased by heart diseases:

Ischemic heart disease Mitral valve disease Hypertrophic cardiomyopathy Dilated cardiomyopathy

Induced by tachycardia

Causes of Atrial Fibrillation Obesity and Sleep Apnea increase risk of AF Temporary:

Alcohol Surgery

Examining a Patient with Arrhythmias

45 year-old female Stress test given

Heart rate increase Heart rate increased while sleeping.

Subtle enough not to wake her, but noticeable when awake

Diagnosis is that she has atrial fibrillation Echocardiogram shows irregular beats, but

nothing continuous As it turns out, she had atrial flutter, not atrial

fibrillation

Personal Impact/Conclusion

Observing for the past 2 weeks has given me a great amount of insight into the world of cardiology

My passion for cardiology has increased even more

I have learned more presentational skills by participating in this project

I met some wonderful people who taught me a great deal of life lessons

References List Heart Disease: A Textbook of Cardiovascular Medicine ;

Braunwald's Heart Disease. Review and Assessment. Philadelphia: Saunders, 1998. Print.

http://meds.queensu.ca/central/assets/modules/ECG/normal_ecg.html

http://lifeinthefastlane.com/ecg-library/hyperthyroidism/

http://lifeinthefastlane.com/ecg-library/atrial-fibrillation/ http://www.learntheheart.com/cardiology-review/atrial-

fibrillation/