Atrial Standstill in Cats
If ECG (electrocardiogram) findings identify missing P-waves in the cat's atria, it is probably suffering from a rare heart rhythm disturbance called atrial standstill. A measure of the electrical activity of the atria (the top two chambers in the cat's heart), P-waves that are absent may be an indicator of a more serious underlying disease.
Atrial standstill can be temporary, persistent, or terminal due to complications such as heart failure. Along with absent P-waves, the ECG of the cat may demonstrate a slow heart rate with regular or irregular rhythm.
Symptoms and Types
- Muscle wasting
- Slow heart rate (bradycardia)
- A spontaneous loss of consciousness (syncope)
- Abnormally high concentrations of potassium in the bloodstream (hyperkalemia)
- Heart disease, especially those associated with the atria (e.g., atrial myopathy, cardiomyopathy)
Although routine laboratory tests, including complete blood count, biochemistry profile, and urinalysis, are conducted on the animal, often atrial standstill is confirmed through ECG (electrocardiogram) findings. Other common findings include abnormally high levels of potassium and sodium in the blood -- both of which are only found with a biochemistry profile. These results may also indicate abnormalities related to other concurrent diseases. Echocardiography, meanwhile, will help your veterinarian diagnose the type of heart disease and the severity of the issue.
In some cats, atrial standstill is not a life-threatening condition and no hospitalization is required. However, in others it may be serious enough to require immediate intensive care. Such animals typically have an abnormally high blood potassium level or are suffering from severe dehydration. In these cases, intravenous fluid therapy is used to stabilize the animal. If the cat's heart rhythm cannot be rectified by ordinary means, a pacemaker may be surgically implanted into the chest or abdomen. This small medical device helps control the abnormal heart atria activity.
Living and Management
The prognosis of the cat depends on the underlying disease causing the heart rhythym disturbance. If it is corrected quickly and (when present) hyperkalemia is reversed, the long-term prognosis is excellent.
Your cat will require rest in a stress-free environment, away from other pets and active children, to help control the symptoms of persistent atrial standstill. Even with a pacemaker, however, the symptoms of lethargy and weakness may persist. Cats with pacemakers also require regular follow-up exams and periodic ECGs to monitor the effectiveness of the device and the heart's rhythm.
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