atrial fibrillation and mode switch

[mariete]

  Dear doctors!
  First o fall I would like to thank you that you take the time and effort to help everyone with all their question! Thanks!
  My question is as follows:
  I had 2 strokes recently (I am 30 years old), have a pacemaker and clotting trouble (8x DVT as well as PE). My most recent pacemaker check-up indicated several mode switches. The mode switch is operational as from 175 bpm, whereas an atrial high rate is indicated and reported as from 180 bpm. Now is my question:
  1) would it be possible that when the pacemaker (Medtronic Kappa) detects and reports a mode switch that it was a high atrial rate (and therefore caused the mode switch) due to a-fib?
  2) is it possible to have a-fib while having a lower rate? Or is a-fib always at a high rate?
  3) is is wise to have the pacemaker programmed with the feature mode switch "on"?
  and
  4) what are the symptoms of a-fib under a lower rate? Sometimes I can feel a "fluttering" sensation.
  I am on coumadin, aspirine and sotalol. Therefore:
  5? what in your opinion is the best drug to prevent the a-fib?
  The neurologist suspects that the strokes were caused by the a-fib.
  Any help would be very much appreciated! Thanks very much in advance!
  Mariette (NL)

[Cleveland Clinic, MD]

Dear Mariette,
Thank you for your detailed question.    
Q1) would it be possible that when the pacemaker (Medtronic Kappa) detects and reports a mode switch that it was a high atrial rate (and therefore caused the mode switch) due to a-fib?
A: This is usually the cause.
Q2) is it possible to have a-fib while having a lower rate? Or is a-fib always at a high rate?
A: It is possible to have "rate controlled" atrial fibrillation with rates as low as the 40’s or 50’s.
Q3) is is wise to have the pacemaker programmed with the feature mode switch "on"?
A: This depends upon the particular patient.  Your cardiologist can determine what the best is for you.
Q4) what are the symptoms of a-fib under a lower rate?
A:  The symptoms may be nothing or may be the sensation of an irregular rhythm.  Fluttering could certainly be one of the symptoms.
Q5) what in your opinion is the best drug to prevent the a-fib?
A: Once again this would depend upon the particular situation.  There are many drugs used to control afib.  You can find more information on afib below.

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
Information provided here is for general educational purposes only. Only your doctor can provide specific diagnoses and treatments. If you would like to be seen at the Cleveland Clinic, please Call 1 - 800 - CCF - CARE for an appointment at Desk F15 with a cardiologist.