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Tricuspid Valve Dysplasia
Tricuspid Valve Dysplasia (TVD) is an uncommon congenital heart defect. It accounts for approximately 7% of
all heart defects in dogs, and far less in cats. It is known
to be an inherited genetic defect in Labrador retrievers,
but is also seen in Golden retrievers, Irish Setters, Great
Danes, and German Shepherds. It is important to note
that any breed can be affected.
Tricuspid valve dysplasia is a malformation of the tricuspid valve and associated supporting structures that assist in proper valve closure. The tricuspid valve, or right
atrioventricular valve, separates the right atrium from the
right ventricle, allowing normally for unidirectional blood
flow through the right side of the heart. TVD results in
a lack of complete valve closure leading to a back flow
of blood (regurgitation) back into the right atrium. If the
regurgitation is severe enough, right atrial and right ventricular dilation occur secondary to the increased volume
and workload. The resulting increased pressures within
the right heart affect its ability to accept deoxygenated
blood back from the body. Pressures within the venous
system rise and free fluid may start to accumulate within
the abdomen (ascites) and the chest cavity (pleural effusion). This is known as right sided congestive heart
failure. Rarely, the tricuspid valve orifice may also be
narrowed (stenosis), leading to a more rapid development of congestive heart failure.
A preliminary diagnosis of TVD may be made by your
family veterinarian based on breed, physical exam and
x-ray findings. Often a heart murmur noted during a
puppy’s first routine veterinary visit is the first indication of
a problem, however some animals may go unrecognized
until they develop an arrhythmia (irregular heart rhythm)
or clinical signs of heart failure. A definitive diagnosis
is made with an echocardiogram, an ultrasound of the
heart, preferably performed by a veterinary cardiologist.
An echocardiogram provides important information on
the severity of the defect, the degree of heart chamber
enlargement, the presence of concurrent defects, and
helps to guide treatment.
Chesapeake Veterinary Cardiology Associates
Cardiac Care for Pets
www.cvcavets.com
Once a diagnosis is made, therapy is often not instituted
until signs of right sided volume overload are present.
This is a medically treated disease, as surgical correction
has been attempted with rather poor results. Medical
therapy is palliative and aimed at improving quality of
life, prolonging the time to congestive heart failure, and
controlling fluid accumulation once heart failure has
developed. Occasionally, a simple in-office procedure
is required to remove excess abdominal fluid. This provides immediate relief to any uncomfortable abdominal
distention.
Prognosis depends on the severity of the malformation
and the degree of the resultant valve regurgitation. Pets
with mild TVD live normal lives, often without medical
intervention. Sadly, pets with severe TVD often develop
congestive heart failure within the first several years
of life; however, recent advances in medications can
provide good quality of life for many months beyond the
onset of clinical signs.
RV
LV
TV
RA
LA
Echocardiogram images taken simultaneously. The left image
shows the severely dysplastic tricuspid valve (TV). The mosaic
of color shown on the right is Doppler technology revealing the
turbulent regurgitant blood flow.