Diagnosis of Atrial Fibrillation
The evaluation of patients who develop atrial fibrillation includes a medical history and physical examination, an electrocardiogram (ECG), and an echocardiogram (cardiac echo). The doctor usually asks if there is a history of heart problems (such as heart attack) or chest pains (which might suggest coronary artery disease); if they suddenly develop a sensation of shortness of breath and chest pains (which can suggest that a blood clot has broken off from a blood vessel in the legs and traveled to the lungs); if they are losing weight or feel hot all the time (symptoms of an overactive thyroid gland); or if they regularly consume alcohol.
During the physical examination, the doctor usually feels the chest to see if the heart feels enlarged, listens with a stethoscope for sounds suggestive of leaky or sticky (stenotic) heart valves (heart murmurs), listens to the lungs for fluid congestion, feels the thyroid gland (located at the base of the neck) to determine if it is enlarged, and may test the reflexes (e.g., tapping the knee with a small rubber hammer) for signs of an overactive thyroid gland.
The diagnosis of atrial fibrillation is made by obtaining an electrocardiogram (ECG). The ECG creates a graph that represents the normal phases of activation of the heart. When patients' hearts beat normally in sinus rhythm, separate little bumps and lines indicate when the atria contract and when the ventricles contract. In patients with atrial fibrillation, the bumps showing organized contraction of the atria are no longer present. Instead, there are irregular, squiggly lines. The ECG can also suggest recent or past heart attack, inflammation of the pericardium, or a blood clot that has traveled to the lungs.
Almost all patients who develop atrial fibrillation undergo an echocardiogram (cardiac echo), during which a microphone-like device transmits and receives special sound waves that travel through the chest wall, to the heart, and then are reflected back. The reflected sound waves are translated into images of the heart, including the chambers and valves. Enlarged atria or impaired pumping function of the left ventricle can be shown. The echocardiogram can also be used to assess the valves of the heart for leakiness or stenosis ("sticky" valves).
More tests are sometimes needed to evaluate patients with atrial fibrillation. If an overactive thyroid is suspected, a TSH (thyroid-stimulating hormone) stimulation test is performed to make this diagnosis. If it is suspected that a blood clot has traveled from the legs to the lungs (a pulmonary embolus), scans of the legs or the lungs may be taken. If coronary artery disease or heart attack is suspected, a cardiac catheterization will be performed.