Question Title: Electric Defibrillation Effect on Mitral Valve Replacement

I am a 61 year-old women who had a mitral valve replacement (Bjork-Shiley) 17 years ago. During a recent examination by my doctor it was discovered that I have atrial fibrillation. My heart rate was 135 and irregular. Toprol-XL, 50 mg per day, was prescribed but it has only slowed the pace of my heartbeat, not returned it to sinus rhythm. My cardiologist has scheduled an appointment for me to have cardioversion the first of next month. It is my understanding that I will be sedated and an electric charge used to convert my irregular heart beat. My questions are: What is the prognois for this procedure returning my heart to a normal rhythm? Is there any danger that this procedure would in any way effect the functioning of my artificial valve? Thank you for your response.

---------------------------------------------------------------------------------------------------------------------
Dear Cecilia,

Thank you for your question. There is no risk to the valve from the cardioversion procedure. The success will depend upon several factors including atrium size, duration of the fibrillation, and current medical therapy. Remember that afib is a chronic condition and the goal is never to "cure" the rhythm but to maintain sinus rhythm for as much of the time as possible. I have attached additional information on afib for you. Good luck.

Atrial fibrillation
Definition:
A disorder of heart rate and rhythm in which the upper heart chambers (atria) are stimulated to contract in a very rapid and/or disorganized manner; this usually also affects contraction of the ventricles.

Causes, incidence, and risk factors:
Arrhythmias are caused by a disruption of the normal functioning of the electrical conduction system of the heart. Normally, the atria and ventricles contract in a coordinated manner. In atrial fibrillation and flutter, the atria are stimulated to contract very quickly. This results in ineffective and uncoordinated contraction of the atria.

The impulses may be transmitted to the ventricles in an irregular fashion, or only some of the impulses may be transmitted. This causes the ventricles to beat more rapidly than normal, resulting in a rapid or irregular pulse. The ventricles may fail to pump enough blood to meet the needs of the body.

Causes of atrial fibrillation and flutter include dysfunction of the sinus node (the "natural pacemaker" of the heart) and a number of heart and lung disorders including coronary artery disease, rheumatic heart disease, mitral valve disorders, pericarditis, and others. Hyperthyroidism, hypertension, and other diseases can cause arrhythmias, as can recent heavy alcohol use (binge drinking). Some cases have no identifiable cause. Atrial flutter is most often associated with a heart attack (myocardial infarction) or surgery on the heart.

Atrial fibrillation or flutter affects about 5 out of 1000 people. It can affect either sex. Atrial fibrillation is very common in the elderly, but it can occur in persons of any age.

Prevention:
Follow the health care provider's recommendations for the treatment of underlying disorders. Avoid binge drinking.

Symptoms:

sensation of feeling heart beat (palpitations)
pulse may feel rapid, racing, pounding, fluttering,
pulse may feel regular or irregular
dizziness, lightheadedness
fainting
confusion
fatigue
shortness of breath
breathing difficulty, lying down
sensation of tightness in the chest

Note: Symptoms may begin and/or stop suddenly.

Signs and tests:
Listening with a stethoscope (auscultation) of the heart shows a rapid or irregular rhythm. The pulse may feel rapid or irregular. The normal heart rate is 60 to 100, but in atrial fibrillation/flutter
the heart rate may be 100 to 175. Blood pressure may be normal or low.

An ECG shows atrial fibrillation or atrial flutter. Continuous ambulatory cardiac monitoring--Holter monitor (24 hour test)-- may be necessary because the condition is often sporadic (sudden beginning and ending of episodes of the arrhythmia).

Tests to determine the cause may include:

an echocardiogram
a coronary angiography (rarely)
an exercise treadmill ECG

Treatment:
Treatment varies depending on the cause of the atrial fibrillation or flutter. Medication may include digitalis or other medications that slow the heart beat or that slow conduction of the impulse
to the ventricles.

Electrical cardioversion may be required to convert the arrhythmia to normal (sinus) rhythm.

Expectations (prognosis):
The disorder is usually controllable with treatment. Atrial fibrillation may become a chronic condition. Atrial flutter is usually a short-term problem.

Complications:

incomplete emptying of the atria which can reduce the amount of blood the heart can pump
emboli to the brain (stroke) or elsewhere--rare

Calling your health care provider:
Call your health care provider if symptoms indicate atrial
fibrillation or flutter may be present.

The links below are good sources of information about atrial fibrillation.

http://www.med-edu.com/patient/arrhythmia/atrial-fib.html
http://www.americanheart.org/Heart_and_Stroke_A_Z_Guide/afib.html
http://www.merck.com/!!vDXoe16kTvDXpz08Of/pubs/mmanual_home/chapt16.htm

I hope you find this information useful. Information provided in the heart forum is for general purposes only. Only your physician can provide specific diagnoses and therapies. Please feel free to write back with additional questions.

If you would like to make an appointment at the Cleveland Clinic Heart Center, please call 1-800-CCF-CARE or inquire online by using the Heart Center website at www.ccf.org/heartcenter. The Heart Center website contains a directory of the cardiology staff that can be used to select the physician best suited to address your cardiac problem.

---