Atrial Fibrillation in age 100 beats/min at rest (or >110 beats/min on light activity). ![]() Atrial Fibrillation expected to resolve after treatment of secondary cause.Examples: MI, PE, Pericarditis, Myocarditis, Hyperthyroidism, Pneumonia.Results in cardiac remodeling (see above) and less likelihood overtime of restoring sinus rhythm.New onset or recurrent Atrial Fibrillation lasting 7 days and does not spontaneously resolve or self-terminate.However, with increased activity, the atrial contraction becomes more important to Cardiac Output.Ventricular diastolic filling is primarily driven by a suction effect rather than atrial contraction.Reduced Ventricular Filling (absent "Atrial Kick").Results in increased Thromboembolism and Cerebrovascular Accident risk.Coronary circulation compromised and Cardiomyopathy increase morbidity and mortality.Tachycardia and diminished diastolic filling decrease Cardiac Output.Functional Consequences: Atrial contractions are uncoordinated.Possibility of restoring to normal sinus rhythm becomes less likely over time.Longterm Atrial Fibrillation results in atrial enlargement (irreversible).Later Consequences: Chronic Atrial Remodeling.Initial Consequences: Acute Atrial Remodeling.Reentry via small aberrant circuits that spontaneously arise in atria.Arise near origin of pulmonary veins at the left atrium.May result from repeatedly firing Premature Atrial Contractions (PACs).Multiple small simultaneously wavelets arise and propagate.Enhanced automaticity at depolarizing foci.
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