DEFINTION:
Irregular beating of the heart is also called an arrthymia.
Atrial fibrillation (AF) is the most common
arrthymia.
The
heart is a muscular organ divided into 4 chambers (2 at the top
called the Atria and 2 at the bottom called the Ventricles). The
heart contracts (beats) and pumps blood with a regular rhythm. The
heart may beat faster or slower along with shorter or longer
intervals, but the intervals (or rhytm) between the beats remains
constant. The rhythm results from the electrical impulses which
travel through the heart and makes the heart muscle contract. In
some individuals the coordination of the electrical impulses in the
atria "malfunction" such that a normal rhythm cannot be maintained
and this can lead to quivering/shaking of the atria which is
AF.

CAUSES:
- Advancing age: Affects less than 1% of those under 50 years old
and ~10% of those greater than 80 years old
- Physical or emotional stress
- High blood pressure (also called hypertension)
- Heart diseases: Heart surgery, previous heart attack, angina,
or those with heart valve problems
- Lung disease: Such as blood clot in the lungs (also called
pulmonary embolism)
- Medications/drugs such as caffeine, alcohol, tobacco
- Overactive thyroid gland (hyperthyroidism )
- Family history of AF
Many
patients have no symptoms (referred to as asymptomatic) and AF may
be discovered during a routine medical examination.
The
most common complaint of AF is palpitations, an uncomfortable,
rapid and irregular heartbeat, which usually makes patients
anxious.
Symptoms may vary from person to person and may include:
- Exercise intolerance/ weakness
- Fatigue
- Dizziness
- Lightheadedness
- Fainting
- Shortness of breath
- Chest pain
- Stroke
AF can lead to stroke:
One of the most
important symptoms of AF is Stroke. Normally, blood enters the
heart through the atria and is then pumped into the lower chambers
(or ventricles), before being pumped again to the brain and the
rest of the body. However in AF, because of the shaking of the
atria, the blood flow slows down and can lead to formation of blood
clots within the atria. These clots then flow into the ventricle
and can be pumped out of the heart to any part of the body, and the
brain in particular. When a blood clot blocks a blood vessel in the
brain a stroke occurs. Consequently, the presence of AF increases
the risk of stroke.

INVESTIGATIONS:
In
general, people are not usually screened for atrial fibrillation,
unless they have symptoms that might suggest this condition, or a
healthcare professional (or patient) detects an abnormal pulse that
might raise the suspicion for AF. Also, since the incidence of AF
increases with age, doctors may obtain ECG
(Electro-Cardio-Gram)
during office visits to complement their physical examination. If
AF is detected, this may help doctors to select an appropriate
treatment plan which might include drugs to help
- Control heart rate (speed at which the heart beats)
- Control heart rhytm (in some case drugs can be used to switch
the heart from AF back into a normal rhythm)
- Use "blood thinning drugs" to help prevent formation of blood
clots and reduce risk of stroke
For
those patients suspected of having AF, the following tests may be
requested:
- ECG
(Electro-Cardio-Gram):
During an ECG, small patches with wire connections are attached to
the skin across the chest, arms and legs. These detect the small
electrical signals from the beating heart muscle which can be
displayed on a screen, or printed, allowing the
physician/healthcare professional to examine the patient's heart
rhythms
- Holter Monitor: This test might be considered
a "continuous ECG". Patients wear a device that records heart
rhythms during daily activities for 24, 48 or 72 hours
- Telemetry: Similar to a Holter monitoring, but
with the heart rhythms continually displayed on a monitor. Usually
used for in-patients most often within an emergency department,
cardiac care unit or intensive care unit
- ECHO (Echocardiogram): An ultrasound of the
heart which can show the heart valves and chambers (atria and
ventricles) as well as blood flow
- Transthoracic ECHO (TTE): Is conducted across
the chest wall. With the patient lying on an examining table a
small amount of gel is placed on the left chest and a probe is used
to generate sound waves which are then used to create an image of
the heart structures
- Transesophageal ECHO (TEE): Conducted through
the mouth. Patients may be mildly sedated and throat numbed
(anesthetized). A narrow tube with a small probe is passed down the
throat into the esophagus and an ultrasound image of the heart
obtained
- Chest X-Ray: Used to look for an enlarged
heart, or accumulation of fluid in the lungs
- Laboratory tests: There is no blood test that
can confirm atrial fibrillation. However some blood test might help
show if there has been recent heart injury, check the level of some
drugs used to control heart rhythm or check on the levels of
certain types of "blood thinning" drugs e.g. warfarin. Patients on
warfarin will have their international normalized ratio "INR"
checked on a regular basis, and the warfarin dose will be adjusted
depending on the INR level in the blood
Following type of blood tests may be ordered, for specific
reason
- Thyroid function tests for hyperthyroidism:
This condition can sometimes trigger AF
- Complete blood cell count: Used to check for
hemoglobin, and platelets. This is particularly important since
patients with very low hemoglobin (anemia) or platelets may not be
able to receive "blood thinning" drugs until these conditions are
corrected
- International normalized ratio (INR) or Prothrombin
time (PT): The latter is less commonly used. For patients
using warfarin (coumadin) to prevent blood clotting, these tests
show how well the drug is working. Also allows a healthcare
professional to adjust the warfarin levels
- Digoxin drug level (in patients taking this
medication)
- AF can sometimes occur in conjunction with heart injury/attack.
Some proteins are elevated in the blood during or just after a
heart attack (e.g. troponins and creatinine kinase [CK])
- Sodium and potassium levels: Sometimes changes
in the normal electrolytes within the blood can also lead to
irregular heart beating
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Title
TREATMENT
Treatment may involve
- Resetting of the heart rhythm (known as cardioversion)
- Controlling heart rate
- "Blood thinning" medications to avoid blood clots
(1) Resetting of Heart Rhythm:
Cardioversion:
- Cardioversion using drugs (pharmacological
cardioversion):
Doctors may prescribe a class of drugs known as anti-arrhythmic
that is designed to induce and maintain normal heart rhythm. Drugs
will generally be administered at the hospital either orally or
intravenously (IV). Patients may be required to continue taking
medication at home to prevent reoccurrence of AF.
- Electrical cardioversion:
The patient is given anesthetics to numb pain and a brief
electrical shock is applied to the chest, which resets the beating
from irregular to regular (normal) rhythm.
- Ablation therapy:
Within the heart muscle there is a small collection of nerves
(called the AV node) that controls the heart rhythm. Small tubes
called catheters are inserted into the blood vessels in the upper
leg/groin area, neck or below the collar bone. The catheters are
navigated into the heart, and can be used to locate and destroy (or
ablate) the region responsible for causing the irregular
heartbeat.
- Surgical maze procedure:
In this open heart surgery procedure, small incisions are made
into the walls of the atrium in order to create scar tissue. This
is intended to block the conduction of electrical signals
responsible for the irregularities in the heartbeat. Some patients
may require a pacemaker after this procedure.
- Maintenance of rhythm with medication:
After electrical cardioversion a number of drugs may be prescribed
to maintain a normal rhythm.
(2) Heart Rate Control:
- AF can cause the heart rate to rise above normal range of
between 60 to 100 beats/min, and may require medications or other
techniques and interventions (ablation/pacemaker) to help control
heart rate
- Medications: These may include drugs such as
digoxin, beta-blockers (e.g. metoprolol) and calcium channel
blockers (e.g. diltiazem)
(3) Clot Prevention:
- "Blood thinning" drugs known as anti-coagulants (e.g. apixaban,
dabigatran, rivaroxaban, warfarin) may be prescribed to selected
patients with AF to help prevent the formation of blood clots and
lower chances of suffering a stroke
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Title
Some
commonly used oral medications in AF are as follows:
**NB: Other trade names may exist for these
agents.
1a. **Rhythm controlling
agents (antiarrhythmics):

2a. **Rate controlling
agents:

3a. **Clot Preventing
Agents:

NOTE: While there are potential side effects from
using these medications, there are also the effects of untreated
AF-which includes palpitation, fainting and stroke. The latter is
associated with death, disability and poor quality of life.
Consequently, the treating physician will assess the side effect
risks versus the benefits of the medications to help control
symptoms and reduce the risk of blood clot formation and stroke. If
the patient has other medical conditions or using other
medications, these are taken into account when prescribing
medications. Patient is advised to take note of and report
potential side effects to the treating physician.
Non-modifiable risk factors:
- Ageing
- Family history of AF
- History of heart disease (previous heart attack, enlarged
heart, abnormal heart valve)
Modifiable risk factors:
- High blood pressure
- Reduce salt intake
- Exercise
- Weight loss
- Comply with prescribed medications
- Elevated thyroid (hyperthyroidism)
- Comply with medical/surgical management to reduce thyroid
levels
- Binge drinking-excess consumption of alcohol
- Avoid or eliminate, excessive alcohol consumption
- Excess caffeine intake