Heart Failure Due to Valve Defect in Cats

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Atrioventricular Valve Endocardiosis in Cats

There are four chambers of the heart: the upper two are called the atria (singular: atrium), and the bottom two chambers are called the ventricles. A valve is present between each atrial and ventricular pair. These valves are referred to as the atrioventricular valves. The valve between the left atrium and ventricle is called the mitral valve, and the valve between the right atrium and ventricle is the tricuspid valve.

Endocardiosis is a condition in which excessive fibrous tissue develops in the atrioventricular valves, affecting both the structure and function of the valves. This defect ultimately leads to congestive heart failure (CHF) in such patients. In a failing state, the heart is not able to pump adequate blood and must work harder in order to meet the body's requirements. This increased effort leads to structural damage to the heart, eventually leading to functional incapacitation. This disease is uncommon in cats, but when it does occur it is more likely to affect older cats.

Symptoms and Types

Following are some of the symptoms related to atrioventricular valve endocardiosis. Please note that the severity and frequency of these symptoms may vary depending upon the severity of the disease itself.

  • Murmurs (abnormal heart sounds which can be heard by your veterinarian)
  • Cough
  • Lethargy and weakness
  • Exercise intolerance
  • Difficult breathing
  • Abdominal distention
  • Orthopnea (breathing becomes more difficulty when lying down)
  • Cyanosis (blue discoloration of the skin and mucous membranes)
  • Fainting
  • Syncope/Loss of consciousness
  • Death

As the disease advances, cough, exercise intolerance, breathing problems and other symptoms become more severe and may occur more frequently.


Idiopathic – obscure or unknown cause.


You will need to give a thorough history of your cat’s health and onset of symptoms. The history you provide may give your veterinarian clues as to which organs are being affected secondarily, especially since heart failure affects all other organs of the body, notably the kidney and liver. After taking a detailed background history from you, your veterinarian will perform a complete physical examination on your cat. Laboratory testing is of high value in overall diagnostic workup, and will include complete blood tests, biochemical profiling, and urinalysis. These tests will provide important information to your veterinarian for a preliminary diagnosis, as well as information about the current status of the problem.

Further confirmation of the diagnosis may be assured by using X-ray and ultrasound imaging, along with electrocardiography (ECG), echocardiography to measure the heart's electrical impulses, and color Doppler to evaluate the blood's ability to flow freely. Together, these diagnostic tools provide vital information about the structure and function of the heart and the extent of the problem your cat is experiencing. Your veterinarian will evaluate the AV valves, as well as the other heart structures, in detail using these techniques. Modern advancements have made it possible to diagnose this condition with relative speed and ease so that treatment can begin in a timely fashion.


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