What is congestive heart failure?

Congestive heart failure is the clinical syndrome where a diseased heart’s inability to effectively pump blood in the correct direction results in a build up of fluid in different parts of the body. Different parts of the body are affected by retained fluids, depending on what side of the heart is most affected by heart disease.

• If the left side of the heart is affected fluid will build up in the lungs.
  Examples of conditions that affect the left heart include mitral valve disease, dilated cardiomyopathies (dilated or thin heart muscle), hypertrophic  cardiomyopathies (thickened heart muscle) and most congenital heart problems.
• If the right side of the heart is affected fluid will build up in abdominal cavity and less commonly in the legs or under the skin.

Why does congestive heart failure occur?

The heart is the body’s pump. The arteries, capillaries and veins are the network of tubes through which blood is flowing as it is pumped. The heart pushes blood to the lungs for oxygenation and receives the oxygenated blood back, which is in turn pushed to the rest of the body where the oxygen is needed and then receives the deoxygenated blood back to start the cycle again. Congestive heart failure occurs because the heart is not pumping blood properly causing the pressure in the veins and capillaries to increase to a point where fluid starts to leak out of the capillaries and veins into the surrounding tissues or organs. The capillaries and veins that drain into the left side of the heart come from the lungs so left side heart failure causes fluid to leak into the lungs. The capillaries and veins that drain into the right side of the heart come from the body, so right side heart failure causes fluid retention in the abdomen and less commonly in the legs or under the skin.

What causes congestive heart failure?

Congestive heart failure needs severe heart disease to occur, this then increases the heart’s resting pressure.

• Disease of the heart valves: If the heart valves no longer form a seal there is flow of blood in the wrong direction as the heart beats. This causes the blood volume in the heart to increase and increases the pressure in capillaries and veins.
• Cardiomyopathies: Where the heart muscle is too thin and weak or too thick. Either condition prevents the heart from pumping blood adequately which leads to increased pressure within the heart which in turn leads to increased pressure in capillaries and veins.
• Congenital heart disease: Heart disease that is present at birth including problems like a hole in the septum or patent connections between certain blood vessels that don’t close off properly soon after birth.

What are the clinical signs or symptoms of congestive heart failure?

This depends on which side of the heart is affected.

With left side heart failure fluid starts to collect in the lungs and there is then less chance for oxygen to be absorbed across this fluid barrier into the blood, so dogs and cats with left side heart failure might show exercise intolerance – they will not be able to walk as far as they used to and seem to get out of breath quicker. Often an increase in resting or sleeping respiratory rate can be noted and this is a great way an owner can pick up on early heart failure and even monitor progression of heart failure and response to medication. The resting respiratory rate is the number of breaths taken in one minute while at rest (normal is between 15-25 per minute). Some patients may show a cough although coughing is more often related to an enlarged heart pushing on bronchi or the trachea within the chest.

With right side heart failure the most common symptom is a distended abdomen due to fluid build-up. This distension may often be mistaken for being fat (overweight) or even being pregnant! Dogs and cats may also show an increase in respiratory rate because of fluid pushing on the diaphragm. They may also show a decrease in appetite because the fluid pushes on the abdominal organs causing discomfort.

How will your vet diagnose heart failure?

The diagnosis of congestive heart failure can be made by observation of an increased heart rate and/or increased respiratory rate with a newly audible heart murmur when listening with a stethoscope. The vet may also perform a chest radiograph to evaluate the size and position of the heart as well as
if any fluid is observed in certain parts of the lungs or abdomen. A specialist may also perform a heart ultrasound (echocardiography) which provides information on heart wall thickness, chamber size, valve disease or some congenital heart conditions.

How do we treat or manage congestive heart failure?

Ideally treatment of congestive heart failure would be focused on alleviating the cause of heart disease. Such as surgery to close a hole in the heart; close a patent ductus arteriosus or replace leaky valves. This is often done in humans but may not be possible in most cases with our dog and cat patients due to the highly invasive nature of procedures, the intensive aftercare required and of course the very high costs of such procedures.

In our pets, the mainstay of managing congestive heart failure is to make use of medications. Often these medications are prescribed on a chronic basis and would be life long because heart failure cannot be cured with medication, only managed. Medications used include the following:

• Medications which stimulate the heart muscle to contract more effectively thereby getting blood flowing around the body.
• Blood pressure medication to decrease pressures in the veins and capillaries.
• Diuretics to help get rid of fluid accumulated in the lungs or abdomen.

Each pet with congestive heart failure might need a different combination of medications depending on what stage of heart failure they are in and what symptoms they are presenting with. If there is fluid in the abdomen causing discomfort or trouble breathing – this fluid can be drained via a large catheter  by your vet and is done as often as necessary sometime even on a weekly basis. It is very important to monitor these patients continuously. This is done by recording the resting or sleeping respiratory rate. We can be fairly confident that if the respiratory rate at rest is normal we have adequate control of the heart failure. Any increase in resting respiratory must be brought to the vet’s attention so that adjustments to the medications can be made. A vet may also
want to perform blood tests every 6-12 months to make sure that other organs (such as kidneys or liver) are not deteriorating due to the primary heart failure or in response to chronic medications.

What is the prognosis ?

Prognosis depends very much on the cause of the heart failure. Most patients if diagnosed early and placed on the correct medications when indicated can live for many months to years with a good quality of life. Prognosis also improves if there is good monitoring of respiratory rate and regular check-ins with the vet to make sure any adjustments or additions to medications are done timeously.