Cat Heart Disease

Q : My 15 year old Siamese cat has been diagnosed with a heart condition. The veterinarian called it cardiomyopathy. Could you explain what this is and if my cat can live with this kind of problem?

A: First let me explain the anatomy of the heart. The heart is a four chambered organ consisting of a right and left side and upper and lower chambers. The top chambers are called the atria and the lower chambers are called the ventricles. There are valves between the atria and ventricles to ensure that the blood flows in the correct direction. There is also a separation between the right and the left side of the heart called the septum. Blood from the body is received by the atria and blood from the left ventricle sends oxygen rich blood to the body.

     Cats can suffer from heart disease just as dogs can. The difference is that cats tend to get a disease of the heart muscle called cardiomyopathy. There are many types of heart muscle disease. The most common type of cardiomyopathy in the cat is called hypertrophic cardiomyopathy. This is a situation in which the walls of the heart muscle are thicker than normal which leads to an insufficiency in the pumping of the blood in a normal fashion. This can lead to an enlargement of the heart and possible arrthymias, in which the heart beats are irregular and conduction is disturbed.  Cats with this type of disease tend to have a rapid heart rate, are weak, have difficulty breathing, may have irregular heart rhythms, can accumulate fluid in the lungs, may collapse and go into a coma.
     Another type of heart muscle disease is called dilated cardiomyopathy. In this condition the chambers of the heart enlarge, often times causing the walls to be thinner than normal. Once again, the heart pumps blood inefficiently. Dilated cardiomyopathy is most commonly due to a deficiency of the amino acid taurine. This was discovered in the 1980’s by a cardiologist in California (someone I personally know). After that the better quality cat foods added taurine to their ingredient list. Cats with this type of disease are generally weak, lose weight and have difficulty breathing.
     The last type of cardiomyopathy is called restrictive cardiomyopathy. This is the rarest form. This is a situation in which scarring of the heart muscle prevents, once again, the proper flow and pumping of the heart. Sometimes this kind of disease occurs because there is an underlying inflammatory process going on. Cats with this type of disease are generally weak, have poor appetites, lose weight and have difficulty breathing.
     Diagnosis of heart disease in cats is determined by physical examination, radiographs (x-rays), EKG (electrocardiogram) and cardiac and/or abdominal ultrasound. Radiographs will give a two-dimensional view of the heart , lungs and surrounding vessels. The electrocardiogram will reveal any conduction disturbances or irregularities of the electrical system of the heart. Ultrasounds give a three-dimensional view of the heart, its chambers, the valves, the septum, blood flow to and from the heart and the vessels coming to and from the heart and lungs. Cardiac ultrasounds are an excellent and non-invasive way to evaluate the heart. Cardiac ultrasounds should only be performed by a qualified veterinary specialist with additional training and certification in veterinary cardiology.
     Once an assessment is made and the severity of the disease is determined, a treatment regimen can be decided. This can involve the administration of various types of cardiac drugs to improve the pumping strength of the heart, reduce the accumulation of fluid in the lungs or control any abnormal conduction disturbances that may be going on. The outcome or prognosis will depend on the type and severity of the heart disease and your ability to administer the appropriate medications. It is very important to follow the instructions given to you by your veterinary cardiologist. These are not medications that should be changed or stopped without consultation with your cardiologist. These are conditions that change over time and will need to be re-evaluated periodically.
     Additionally, it is important to realize that cats can hide their disease very well. Cats can develop cardiomyopathy over a number of weeks to months. It is therefore, very important to observe your cats on a daily basis so that any abnormality in their behavior, their breathing, their weight or their appetite can be addressed immediately. Any questions should be answered by your veterinarian so that an assessment can be made promptly.