Endocardial fibroelastosis is a congenital heart disease. The disease is inherited and many kittens die shortly after birth.

The heart has three layers of protective covering; the endocardium or outer most covering, myocardium or middle covering, and the pericardium or inner most (deepest) layer of the heart. The endocardium is a smooth layer which allows blood to flow effortlessly and is comprised of epithelial cells. This layer is a protective sac for the heart chambers and valves. The function of this protective layering also includes releasing an endocrine hormone (endocardin) to assist in other heart functions particular to the myocardium.

Endocardial fibroelastosis refers to the presence of a fibrous elastic type of abnormal thickening of the endocardium layer of the heart. Endocardial fibroelastosis a common heart disease in cats and is particularly prominent in Burmese and Siamese cats. It is also a disease that is under diagnosed.

Causes and Possible Causes

It is important to note that the exact cause of Endocardial fibroelastosis is still in its infancy stage. There are medical possibilities and links, or correlations that have not yet been proven to be the causation of this disease. The word possible will precede any of the causes listed below should it be the case.

Edema (abnormal amounts of fluids in the heart cavities or ventricles caused by collagen and elastic fibers in the endocardium

Trauma

Hypoxemia - which is pertains to insufficient amounts of oxygen in the body

Dilation (expansion) of the ventricle chamber

Jet Lesions, which are abnormal bursts of blood shooting into the heart valves because of valvular anomalies, or a congenital disorder; jet lesions cause a condition called subendocardial fibrosis

Limited motion in the myocardium

A form of cardiomyopathy

Possible congestive heart failure

Possible housing or incarceration of Purkinje fibers that promote blockage in the left ventricle chambers

The above list of causes and possible causes pertain to primary endocardial fibroelastosis, but there is also secondary endocardial fibroelastosis which essentially means the disease was aggravated by an external cause. This cause could be a virus invading the body or other feline medical conditions such as feline panleukemia. Research is still needed to determine if there is any evidence for hypothesis.

Symptoms

Tachycardia - (rapid heart beat)

Heart murmur (whooshing or swishing sound heard through an examination using a stethoscope)

Cardiomegaly (enlarged heart)

Heart Lesions - come in two forms, gross legions are smooth nodular thickenings that appear within the lining or on the valves, and micro legions which are fibroblasts filled with material, such as collagen

Congestive heart failure

Dyspnea (difficult or labored breathing)

Cyanosis - a bluish colour to skin, foot pads under the nails etc caused by poor circulation in the heart vessels.

The kitten will have a respiratory infection of some sort as early as three weeks of age and as late as four months of age. Within no time the endocardial fibroelastosis is so bad that it has reached the terminal stage; death occurs swiftly.

However if only a mild case is present these kittens do not show any symptoms. They can actually reach adulthood, albeit just long enough to pass the condition onto their progeny.

Diagnosis

For early detection veterinarians will use Doppler studies which are a visual image of the heart structures. Doctors will use ultrasounds, echocardiograms, and other instruments that detect both sound and visual images of lesions, blood flow etc. These instruments are useful for detecting changes in sensitive tissues.

Treatment

IV's intervenous fluids

Surgery is sometimes attempted to enlarge the ventricles and remove the fibroblasts.

However many veterinarians still maintain that the disease is fatal therefore no treatment is effective.


We have still much to learn about this disease, we do know that the disease resembles the human version, but the exact causes are still being researched. Obviously get your cat to the veterinarian the moment you suspect any of the symptoms. As new research unfolds, better diagnosis and treatments should develop as a result of the new information that we can obtain.