Cardiac arrhythmias are abnormal heart rhythms. These disorders are classified based on the area of the heart in which they originate. They originate either in the upper chambers of the heart, the lower chambers of the heart, the area of the heart responsible for creating each heart beat (the sinoatrial [SA] node), or the system within the heart responsible for conducting electrical impulses throughout the heart.

Each heartbeat originates as an electrical signal generated in the SA node, which is in the upper right chamber of the heart. The electrical impulse then travels through the upper chambers of the heart (atria) to an intermediate station (the atrioventricular node), and finally to the lower heart chambers (ventricles). Series of these electrical impulses are responsible for the typical waveform seen on an electrocardiogram (EKG or ECG) and bring about the rhythmic mechanical contractions of the heart. Disturbances of electrical signal generation or the conduction system anywhere along its course will cause irregular heart rhythms. Some cardiac arrhythmias are temporary and do not cause illness. Others are serious and, if not treated, potentially life-threatening.

Cardiac arrhythmias can affect cats of any age, breed or sex.

The prognosis for animals with cardiac arrhythmias depends on the type of arrhythmia present, and the underlying cause and extent of heart disease. Animals in congestive heart failure have a guarded-to-poor prognosis.

What to Watch For

Weakness

Collapse

Slow heart rate

Fast heart rate

Erratic heart rate

Difficulty breathing

Lack of appetite

Diagnosis

Blood work, including a complete blood count and biochemical profile, should be performed to detect any underlying abnormalities. Some animals may be anemic, have an elevated white blood cell count, or have organ dysfunction. Some diseases, such as hyperthyroidism, may underlie heart rhythm disturbances.

Cardiac arrhythmias are diagnosed with an electrocardiogram (EKG, ECG). The type of arrhythmia can be diagnosed from an ECG oscilloscope or by viewing abnormalities on a print out of the ECG trace.

Radiographs (X-rays) of the chest may help determine the extent and type of heart disease.

A cardiac ultrasound (echocardiogram) is sometimes performed to evaluate any underlying heart disease.

Treatment

Treatment depends on the type and severity of the cardiac arrhythmia and the underlying disease process. Each type of arrhythmia is managed differently. Some require medication whereas others are innocuous and do not require any treatment.

In addition to treating the arrhythmia, any underlying heart disease or other disease should be addressed.

Home Care and Prevention

There is no home care treatment for abnormal heart rhythms, except giving any medication prescribed by your veterinarian. If you suspect that your pet has an abnormal heart rate or rhythm, you should contact your veterinarian immediately.

Cardiac arrhythmias are difficult to prevent, but early diagnosis and treatment of predisposing causes can reduce the risk of arrhythmias developing.