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Atrial Fibrillation (DIAGNOSIS (5 Categories of A.F. (Paroxysmal-…
Atrial Fibrillation
DIAGNOSIS
P waves not identifiable, fibrillatory waves instead. Due to a quivering atrial muscle and no uniform wave of atrial depolarisation. from chaotic atrial signals
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Ventricular rate variable. This is due to very irregular atrial depolarization leading to irregularly irregular ventricular rhythm.
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Atrial rate usually 400-600. This is because of signals being generated from all over the atria, resulting in a quivering or fibrillating uncoordinated atrial activity
5 Categories of A.F.
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Permanent- Paroxysmal or Persistent A.F in which pharmacological or electrical cardioversion can't restore normal heart rhythm
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RISK FACTORS
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Age is a risk factor. U.S studies indicate 1% of the population are diagnosed up to 50 years old, with incidence rate increasing every decade ,with 23% of people being diagnosed over the age of 80.
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No definitive cause of A.F although it is believed to be a result of degenerative heart disease and atherosclerosis.
Genetic factors may be associated with A.F especially those with hereditary dispositions of long and short Q.T syndromes, Brugada syndrome and some cardiomyopathies
PATHOPHYSIOLOGY
Although A.V node does its best to block many of these signals in a bid to restore coordination between atria and ventricles, in the end its unable to process these rapid, disorganised electrical impulses, which then affects coordination between atrial and ventricular rate and rhythm leading to inadequate emptying of atria as well as decreased ventricular performance.
Due to atria not emptying their contents properly, pooling of blood can occur in atrial appendage leading to clot formation which can lead to stroke
Atrial Fibrillation is an abnormality of electrical signalling pathway in heart. Electrical signals that coordinate pumping of heart are not originating from SA node but instead one or multiple sites in the left atrium. These sites can fire at a rate of 300-600 times per minute. The A.V node normally receives 50 - 200 pulses from the S.A node in an orderly fashion depending whether a person is at rest or in state of high physical exertion.
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PRESENTATION
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Symptomatic
Patients may present with a variety of early warning signs and symptoms which include dyspnoea, tiredness, fatigue, palpitations, weakness , exercise intolerance, dizziness and light headedness.
Some of these symptoms can be normal with the aging process . Although if they are due to A.F, they are all symptomatic of lowered perfusion caused by inadequate emptying of the atria and ventricles.
More serious presentations include hypotension, chest pain, and those of decompensated heart failure. These are indications of various serious cardiac issues and must be addressed immediately.
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EPIDEMIOLOGY
Prevalence of A.F is similar in the U.S and Europe, but lower in Asia.
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