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Atrial Fibrillation (Risk Factors (Older than 60 years of age
With age,…
Atrial Fibrillation
Risk Factors
Older than 60 years of age
With age, the heart becomes more susceptible to developing arrhythmias such as atrial fibrillation due to ‘wear and tear’.
Diabetes
It is common for people with diabetes to have left ventricular hypertrophy and vascular, these two components increase the chances of developing atrial fibrillation.
Diabetes increases the risk of atrial fibrillation by 3% for each subsequent year in which a person is treated for diabetes.
High Blood Pressure
Blood pressure is the force of blood against the walls of the arteries so over time high blood pressure can cause damage to the hearts electrical system. I.e can increase the risk of developing atrial fibrillation.
Coronary artery disease
Coronary artery disease is defined as the narrowing of the coronary arteries due to buildup called atherosclerosis. These arteries are responsible for supplying blood to the heart muscle. Due to this narrowing the heart is no longer receiving blood as efficiently as it should and can be a leading risk factor of atrial fibrillation.
Prior heart attacks
During a heart attack, sudden and complete blockage of an artery occurs, stopping the arteries ability to supply blood to the heart. This narrowing of the artery is due to build up of atherosclerosis which is commonly associated with Coronary Artery Disease.
Thyroid disease
The thyroid gland which is located in the neck, regulates metabolism through the production of thyroid hormones. These hormones are responsible for regulating heart rate and when when the thyroid overproduces the hormone thyroxin, hyper and hypothyroidism is the result which can lead to heart failure which is a risk of atrial fibrilation.
Valvular Heart Disease
The valves of the heart control the direction of blood flow. Damage to these valves can impede the hearts ability to pump oxygen rich blood efficiently. Because of this the heart must work harder in order to compensate for the damaged valve which can weaken the heart and in turn, can lead to atrial fibrillation.
Cardiomyopathy
Cardiomyopathy covers many diseases whereby the heart becomes enlarged, thick and tough meaning the heart is unable to beat as efficiently and pump blood which in turn increases the risk of atrial fibrillation occurring.
Sleep apnea
Sleep apnea is described as breathing pauses caused by a temporary blockage of the airway. These pauses strain the cardiovascular system and can contribute to rapid and erratic electrical impulses which can increase the risk of atrial fibrillation.
Excessive alcohol or stimulant use
Stimulants cause the heart to beat at a much higher rate and at an excessive level this can increase the risk of atrial fibrillation and arrhythmia. This can be anything from caffeine, alcohol, certain medications and illegal drugs.
Epidemiology
Atrial fibrillation is a common arrhythmia of the heart. A small amount (10%) of A-fib cases, occur in people who suffer from rheumatic mitral valve disease, have a prosthetic heart valve or mitral valve repair. This is referred to as valvular AF. The remaining 90% of A-fib sufferers are termed nonvalvular AF.
Nonvalvular AF affects 1 – 2% of the Australian population which is about 240 000 to 400 000 people.
An average of 1 in 20 people over the age of 65 suffer from nonvalvular AF. This statistic increases to 1 in 10 for people over the age of 75.
Based on statistics from the United States, it is thought that 750 000 Australian people will have A-fib by the year 2030.
Men have been found to have a higher incidence of A-fib than women in all age groups.
Women on average, have been found to develop symptoms 5 years later than men. The median age for men to develop atrial fibrillation is 66.8 years, whilst for women it is 74.6.
Of those who have atrial fibrillation, it is estimated about 2 percent are 40 to 60 years of age, around 6% are between the ages of 60 and 65, and on average 70% are 65 to 85 years old
Of those who have atrial fibrillation, it is estimated about 2 percent are 40 to 60 years of age, around 6% are between the ages of 60 and 65, and on average 70% are 65 to 85 years old.
Presentation
Signs and symptoms of Atrial Fibrillation are as follows:
Palpitations
• Patient may become aware of the heart ‘fluttering’ which is due to the abnormal electrical signals in the right and left atrium reaching the ventricles resulting in the heart contracting at a much higher and irregular rate.
Rapid and irregular heartbeat
• Caused by contractions of the upper and lower chambers being uncoordinated.
Dizziness, fatigue and fainting and weakness.
• During A-fib, the atrioventricular node is unable to process the amount of irregular electrical impulses, resulting in the heartbeat becoming rapid and irregular. This irregularity prevents the heart from efficiently pumping the blood out to the circulatory system. Because of this, the brain is not receiving as much oxygen – rich blood, which is vital for the body to function. This results in dizziness, fainting, fatigue and weakness.
Shortness of breath
• Because the heart is beating at an irregular rate, it can’t pump blood into the body efficiently. Resulting in blood build up in the pulmonary veins. This causes fluid build up in the lungs, which, in turn, means the lungs cannot receive and relay oxygen as efficiently causing shortness of breath.
Fatigue when exercising
• Caused by the heart rate increasing beyond normal limits resulting in a drop in blood pressure which can lead to the feeling of fatigue and general tiredness.
Chest pain
• People who suffer from atrial fibrillation, have a resting heart rate of 100 to 175 beats per minute. Because of this, atrial fibrillation can cause chest pain or as it is commonly called – angina. This is due to the reduced blood flow to the heart muscle.
Diagnosis
In order to diagnose atrial fibrillation, signs and symptoms, medical history and physical examination must be taken into account. Following this, the following test can determine the condition:
An electrocardiogram or (ECG) assessed the electrical signals as they travel through the heart. On an ECG atrial fibrillation will have no discernible P wave present and an undetectable PR interval. The QRS complex will look normal and the Q wave must be checked for irregularities. The rate will vary and rhythm will be irregularly irregular. This is a primary too for diagnosing atrial fibrillation.
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A Holter monitor which much like the ECG, uses small electrodes to record the hearts activity over a period of 24 hours or longer. It is essentially a portable ECG machine that is carried in a pocket or on a belt.
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An event recorder is much like a holter monitor however it is used to monitor over a few weeks to a few months. It is to be activated when the patient is feeling symptoms of a fast heart rate. This allows the doctor to determine rhythm at the time of event
An echocardiogram is a test that uses sound waves to produce an image of the heart. This will detect any structural issues.
A blood test will allow the doctor to assess whether there is a thyroid issue or any other sustances/stimulants in the blood that could lead to atrial fibrillation.
Pathophysiology
Atrial Fibrillation (AF or A-fib) often occurs when the Arrhythmogenic Foci, located in the muscular sleeves of the pulmonary veins cause erratic action potentials. These erratic action potentials cause certain parts of the atrium to depolarise and polarise at uncoordinated times resulting in a loss of atrial contraction which, in turn, causes an ineffective quiver of the heart. During A-fib, signals move around the atria in a disorganised manner overriding the Sinoatrial Node, causing minute contractions of the left and right atrium. These overriding signals overwhelm the AV node with electrical impulses causing an irregularity in the way the heart would usually coordinate its contractions between the atrium and ventricles.
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Rapid and uncoordinated contractions in a person suffering from atrial fibrillation, results in a fast and irregular heart rhythm. The average heart rate for an adult at rest is 60 to 100 beats per minute. An adult with atrial fibrillation may have a resting heart rate anywhere from 100 to 175 beats per minute.
During atrial fibrillation, the atria do not contract regularly and blood does not empty efficiently into the ventricles, which causes pooling of blood in the atria (especially in the atrial appendages).
Pooling of blood in the atria can cause clots to form, which, if dislodged can travel in the bloodstream towards the brain. The clot or embolus can potentially obstruct narrow blood vessels, often the middle cerebral artery or its branches. This blockage can prevent the normal flow of blood and oxygen to a particular part of the brain, which can cause tissue death leading to ischaemic stroke.
Emergency Treatment
The Queensland Ambulance Service emergency treatment is as follows:
• Under the Cardiac/Tachycardia – narrow complex Clinical Practice Guidelines, it states that narrow complex tachycardia is defined as a heart rate above 100 bpm with a QRS width of less than 0.12 seconds and can be classified as either cardiac or non – cardiac.
• Atrial fibrillation is classified as cardiac and the clinical features are as follows:
• Palpitations
• Chest pain and/or discomfort. This is often rate related
• Dyspnoea
• ALOC
• Haemodynamic instability
• If there is a suspected cardiac origin with haemodynamic compromise, synchronised cardioversion should be performed as per the CPG. The following should also be considered :
• Oxygen
• Aspirin (if myocardial ischaemia is suspected)
• IV fluid
The Queensland Ambulance Service Cardiac/Synchronised Cardioversion Clinical Practice Guidelines are as follows: Note Cardioversion of atrial fibrillation is rarely required
• Synchronised cardioversion is a method utilised to restore a normal rhythm to the heart of patients presenting with signs of rapid ventricular rate associated with compromised cardiac output.
o ALOC
o Systolic blood pressure <90mmHg
o Chest pain
o Heart failure
• Synchronised cardioversion is achieved via a modified defibrillator, which delivers a direct countershock, synchronised with the R-wave of the ECG.
o On the LIFEPAK 12 the joule setting for the synchronised cardioversion of adults is as follows:
• Shock 1 100J
• Shock 2 150J
• Shock 3 200J
o A consult must be made with the QAS Clinical Consultation and Advice Line for paediatric synchronised cardioversion.
• Shocks to be performed at rate of 0.5 – 1J/kg increasing to 2J if deemed necessary.
How it is classified
Atrial fibrillation is classified in three ways:
Paroxysmal
o Brief episode of A-fib lasting less than 7 days AND
o Spontaneously resumes normal sinus rhythmPersistent
o Conditions lasts longer than 7 day OR
o Requires some form (electrical/chemical) attention or cardioversion.Permanent
o Patient has atrial fibrillation present at all times
o No signs of reverting to sinus rhythm
Pharmacology
Anticoagulants (blood thinners) are regularly prescribed especially if the patient has high blood pressure, diabetes or heart failure. The most common anticoagulant is warfarin (Coumadin).
For rate control, beta – blockers or calcium channel blockers may be prescribed to lower the heart (<100). These may be verapamil or diliazem.
Antiarrhythmic drugs may be used to maintain sinus rhythm. Some examples of antiarrhthmic medication prescribed by doctors may be amiodarone, disopyramide, flecainide and many more. These medications can have side effects and because of this, a person with atrial fibrillation must find the medication that is appropriate for them.
