What is Heart Valve Narrowing?
The narrowing of heart valves is a serious condition that requires prompt veterinary attention. There are many possible complications and without treatment the cat may develop congestive heart failure and will likely not survive.
Narrowing of heart valves, also called stenosis, is a serious condition that affects the flow of blood from the heart to various parts of the body. Cats with this condition often experience fatigue, cough, and may have difficulty breathing. A heart murmur is sometimes present, and the condition may be secondary to bacterial endocarditis or cancer of the heart.
Symptoms of Heart Valve Narrowing in Cats
Heart valve narrowing is most commonly an inherited condition that is present at birth and develops early in life. It may be much later in the affected cat’s life before symptoms begin to show. Depending on the location of the narrowing and the extent of the obstruction, cats may show one or more of the following symptoms:
- Difficulty breathing
- Rapid breathing
- Heart murmur
- Exercise Intolerance
- Abnormal lung sounds
- Pale or blue-tinted skin
- Stunted growth
- Spitting up blood
- Sudden loss of consciousness
- Illness with fever
Aortic stenosis and atrioventricular valvular stenosis are two variations of the disorder.
Aortic stenosis occurs under the aortic valve of the left heart ventricle. It is categorized into three types based on the location of the obstruction:
- Valvular stenosis (occurs at the valve)
- Subvalvular stenosis (below the valve)
- Supervalvular stenosis (above the valve)
Atrioventricular valvular stenosis is further subcategorized depending on the valve that is impacted:
- Mitral valve stenosis (affects blood flow to lungs)
- Tricuspid valve stenosis (affects blood flow to the rest of the body)
In addition to the symptoms above, mitral valve stenosis is likely to cause high blood pressure and coughing. Tricuspid valve stenosis may cause leg or paw swelling and abdominal swelling. X-rays may reveal an enlarged liver.
Causes of Heart Valve Narrowing in Cats
Both aortic stenosis and atrioventricular valvular stenosis are most commonly caused by an inherited birth defect. More rarely, either condition may be secondary to bacterial endocarditis. Atrioventricular valvular stenosis may also be caused by cancer of the heart or hypertrophic cardiomyopathy which is often secondary to a thyroid tumor. There is no prevalence in any particular breed, with the exception of mitral valve stenosis which is often found in Siamese cats.
Diagnosis of Heart Valve Narrowing in Cats
Prior to examination, the vet will review the cat’s complete medical history and gather details regarding the onset and severity of symptoms. Since the condition is often hereditary, any information regarding the cat’s bloodline will be helpful. A physical exam will be completed, with special attention paid to the condition of the heart. The vet will check for a heart murmurs or other irregular sounds. A murmur on its own could be caused by stress, but in the presence of other symptoms it may help lead to a positive diagnosis.
Standard lab tests will likely be ordered to review the overall health of the cat. These include a complete blood count (CBC), biochemistry profile, and urinalysis. Chest X-rays may show an enlarged heart, and lung X-rays will help to diagnose the presence of congestive heart failure. The vet may order an echocardiogram and a biopsy may be recommended to rule out the possibility of cancer.
Treatment of Heart Valve Narrowing in Cats
There is some difference in opinion among veterinary professionals regarding best practices for treatment of narrowed heart valves in cats. Regardless of the specific treatment methods chosen, the overall goal is to address symptoms, avoid complications, and improve the cat’s overall quality of life.
A narrowed heart valve is rarely actually cured, as this would require open-heart surgery to replace or repair the heart valve. The procedure is very expensive is the survival rates for cats is so low that it is very rarely recommended.
A second surgical option is to expand the heart valve using cardiac catheterization. Again, the surgery is expensive and has not been shown to improve cats’ survival rate enough to make it a recommended form of treatment.
Managing symptoms through the use of prescription medication is the most common treatment option. In most cases, broad spectrum antibiotics will be prescribed to avoid the potential development of bacterial infections in the heart. Diuretics may be used to reduce fluid retention and other medications prescribed to manage additional symptoms.
A non-surgical procedure called balloon valvuloplasty may be used to widen the obstructed valve. This is a complicated procedure that should only be performed by an experienced specialist. The treating veterinarian will help to determine if this is a viable option and will need to provide a referral.
Recovery of Heart Valve Narrowing in Cats
Activity must immediately be limited as overexertion can be fatal to cats suffering from a narrowed heart valve. Low sodium diets are recommended, particularly if the cat is already experiencing congestive heart failure. The cat will need check-ups approximately every three months following diagnosis. It is likely that an EKG, echocardiogram, and X-rays will be performed during each follow-up visit. Between appointments, owners should carefully monitor their cats and seek veterinary attention if concerning symptoms arise.
If a cat has been diagnosed with a mild case of aortic stenosis, it is possible that it can live a fairly normal lifespan. Unfortunately, most cases of stenosis are more severe and the prognosis is poor even with proactive treatment. Since the condition is usually hereditary, affected animals should be spayed or neutered once they are healthy enough to undergo surgery.