atrial fibrillation (brigham and women's)
TRANSCRIPT
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/