Atrial fibrillation (AF) is a common electrical disturbance or arrhythmia of the heart, marked by rapid randomized contractions of the atrial heart muscle causing a totally irregular, often rapid , ventricular rate. In this arrhythmia the normally coordinated electrical activity in the upper heart chambers, the right atrium and left atrium, is lost. The muscle of these chambers begins to wiggle like a "bag full of worms." Atrial flutter is similar to AF, but the atrial contractions are rapid but regular. Both rhythms are very abnormal and reduce heart function.
AF can occur as a single problem (lone AF) or more often as a complication of heart muscle disease (cardiomyopathy) or chronic heart valve disease. It occurs in both dogs and cats but is much more common in dogs. Many cats with AF are also in congestive heart failure (CHF).
Once established, these heart arrhythmias are often permanent. What to Watch For
The symptoms of atrial fibrillation are not very specific. Congestive heart failure with fluid accumulation in the chest or abdomen
Reduced exercise tolerance
Chaotic heart rhythm
Diagnostic tests are needed to recognize AF, and exclude other diseases. The evaluation of a cat with AF is similar to that needed to evaluate any cardiac patient. These tests may include:
Complete medical history and physical examination, including auscultation with a stethoscope
An electrocardiogram (EKG) to diagnose the rhythm with certainty
Chest radiographs to assess heart size and detect evidence of congestive heart failure
An echocardiogram for definitive diagnosis of underlying heart disease
Serum biochemical tests with special interest on kidney function and electrolytes
Thyroid function in cats receiving supplementation with thyroxine
Heartworm (HW) antigen test if appropriate for your geographic area
Treatments for AF depend on the underlying heart condition. In most cases, heart failure is also evident and must be managed medically.
Hospital control of congestive heart failure includes:
Furosemide – a diuretic drug.
Possible use of a nitrate to dilated blood vessels
Oxygen if needed
Digoxin to improve heart function and decrease the heart rate
Thoracocentesis, which is a procedure to remove chest fluid by inserting a needle into the chest and removing excess fluid by syringe
Home therapy includes:
Oral digoxin (Lanoxin, Cardoxin).
Addition of either a beta blocker drug or a calcium channel antagonist (diltiazem) to control heart rate
Treatment for CHF such as oral furosemide, enalapril or benazepril and dietary sodium restriction
Home Care and Prevention
Administer all medications as prescribed by your physician. Learn the side effects of each medication; for example, digoxin can lead to loss of appetite or vomiting. Alert your veterinarian if there are signs of difficult breathing, loss of appetite, exercise intolerance, coughing or other symptoms.
There is no specific preventative measure for atrial fibrillation. It is important to give all medication for any existing heart condition. See your veterinarian for routine examinations to monitor the progress of the disease.