A Family Doctor's Tale - ATRIAL FIBRILLATION

DOC I HAVE ATRIAL FIBRILLATION

Atrial fibrillation usually happens in an older patient with hypertension, heart  or lung problems.

The main symptoms is a fast heart beat with irregularities and breathing difficulties.

It is important to thin the blood to prevent blood clots to be thrown out from the heart causing possible strokes or heart attacks.

The best treatment is cardioversion of the irregular heart beats to normal.

In the meantime the heart can be controlled with medications to reduce the heart beats.


Atrial Fibrillation is a heart condition where the disordered electrical impulses of the atrial muscle leads to irregular electrical impulses to the ventricular heart muscles resulting in irregular heart beats.

Atrial Fibrillation can occur in the following:


1.Age: 8% of people over 80 has AF

2.family history of AF increases risk by 30%.



Atrial Fibrillation is caused by underlying heart conditions such as:

1.Primary heart diseases:
a.coronary artery disease
b.mitral stenosis
c.mitral regurgitation
d.hypertrophic cardiomyopathy
e.pericarditis
f.congenital heart disease
g.previous heart surgery

2.Hypertension (High blood pressure)

3.Lung diseases such as
a.pneumonia,
b.lung cancer,
c.pulmonary embolism,
d.sarcoidosis

4.Excessive alcohol consumption

5.Hyperthyroidism



Atrial fibrillation often do not present with symptoms.

When they do the symptoms are generally non -life threatening:

Symptoms:

1.fast heartbeat or palpitations

2.Breathlessness

3.fainting

4.chest pain

Signs:


1.Pulse is fast and irregular in rhythm and strength

2.Angina pectoris (pain over heart area)

3.Congestive cardiac failure with ankle swelling and breathlessness

4.exercise intolerance

5.Abnormal ECG reading with absent P waves and irregular rhythm

6.Underlying heart disease such as hypertension, pericarditis, valvular disease of heart,

7.Underlying systemic disease such as hyperthyroidism, diabetes, stroke

Diagnosis of Atrial Fibrillation is made by:


1. History and physical examination
Palpitations, atrial fibrillation episodes

2. Blood tests:
renal function and electrolytes,
thyroid hormones, thyroid-stimulating hormone,
blood count.

Where there is chest pain,
blood cardiac enzymes and
coagulation tests are also done

3.Electrocardiogram

a.absence of P waves,
b.irregularity of R-R interval due to irregular conduction of impulses

4.Echocardiography
transthoracic echocardiogram is done in newly diagnosed AF to detect
valvular heart disease ,
left and right atrial size,
left ventricular size and function,
peak right ventricular pressure ,
presence of left ventricular hypertrophy
pericardial disease

5. Chest X-ray
chest X-ray is generally only performed if a pulmonary cause of atrial fibrillation is suggested,

6.Transesophageal echocardiogram
transesophageal echocardiogram (TEE) is done to detect thrombus formation

7.Ambulatory holter monitoring
A holter monitor is a heart monitor which can be worn by the patient to check the heart rate and heart rhythm for 24 hours.
It can detect presence of AF.

8.Exercise stress testing
A threadmill test can gauge the heart rate in response to exertion.

Complications of Atrial Fibrillation are:


1.fibrosis of the atria

2.Enlarged atria and heart

3.Thrombosis to the brain(stroke),
intestines(ischemia),
fingers and toe(ischemia or gangrene)



The treatment of atrial fibrillation is aimed at

1.regulating the heart beat and rhythm- digoxin, dilatrend,  betablockers


2.preventing blood clots to be thrown out in the blood stream  -anticoagulants such as warfarin and aspirin
3.In cases of uncontrolled tachycardia, immediate cardioversion may be done.

Regulating the heart beat:
a.rate control
Rate control is by drugs to reduce the heart rate to 60 to 100 bpm without changing to a regular rhythm.
The medications work by blocking the AV node reducing the electrical impulses to the ventricles.

1.Beta blockers  such as metoprolol, atenolol, bisoprolol
2.Cardiac glycosides ( digoxin)
3.Calcium channel blockers (i.e. diltiazem or verapamil)
4.amiodarone has AV node blocking effects which can be used when other agents are contraindicated (eg.hypotension).

b.rhythm control
Rhythm control work to restore the regular heart rhythm and maintain it with drugs.
The anti-arrhythmic medications makes the heart tissue less excitable.
These medications are often used in concert with electrical cardioversion.

Prevention of blood clots in blood stream:

Anticoagulation with drugs as below reduce the risk of blood clots being thrown out from the heart and blocking the passage of blood in the arteries of the heart or brain

1.aspirin
2.clopidogrel in those who are allergic to aspirin
3.warfarin or similar drugs.
4.heparin intravenously prevents blood clotting in urgent cases.

Cardioversion


Cardioversion is the conversion of an abnormal heartbeat to a normal heartbeat using electrical or chemical means
1.Electrical cardioversion restores the heart rhythm by applying a DC electrical shock to the heart.


2.Chemical cardioversion uses medicine such as amiodarone, dronedarone, procainamide, ibutilide, propafenone or flecainide.
Cardioversion should not be done unless adequate anticoagulation has been given to patients for 48 hours.
There is a relapse rate of 1% following cardioversion.


3.Catheter ablation
It is possible to destroy the bundle of cells connecting the upper and lower chambers of the heart - the atrioventricular node - which regulates heart rate, and to implant a pacemaker Another method involves ablating groups of cells near the pulmonary veins where atrial fibrillation is thought to originate.This method do not need a pacemaker.


4. Radiofrequency ablation  uses radiofrequency energy to remove abnormal electrical pathways in heart tissue.


5. laser, cryothermy and high intensity ultrasound has been use to eliminate the responsible heart tissue causing the irregular heart beats.

Surgical Maze procedure
A series of incisions is made in the atria in a maze-like pattern.
This block abnormal electrical circuits that AF requires.

Minimaze surgery is a minimally invasive cardiac surgery that do not require a median sternotomy or cardiopulmonary bypass.
Laser, cryothermy, radiofrequency, or acoustic energy are used to destroy atrial tissue near the pulmonary veins and and other ablations to mimic the maze.



Most cases of patients treated with rate control and cardioversion with ablation has excellent prognosis, usually better than those with rhthym control.

Recurrence may recur especially if there is an underlying condition which cannot be cured.

Prevention measures for Atrial Fibrillation are:


1.Rest and a healthy lifestyle may help to prevent an onset or recurrence of atrial fibrillation.

2.Avoid stress and anxiety.