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Pericardial Effusion
The heart is normally encased by a protective thin fibrous sheet
of tissue called the pericardium. The pericardium functions
to keep the heart in place within the chest cavity and provide
lubrication and thus prevents friction between the moving
heart and surrounding tissues. Pericardial effusion is defined
by the abnormal accumulation of excessive/abnormal fluid
within the pericardial sac. This results in increased pressures
within the pericardial sac that can cause compression of the
chambers of the heart, known as cardiac tamponade. The right
side of the heart has much lower internal pressures than the
left side. Therefore, pericardial effusion usually results in the
development of fluid accumulation in the abdomen as the return
of blood from the body back to the right side of the heart is
impeded and the vessels leak into the abdomen. However, when
a sudden accumulation of fluid occurs from the spontaneous
hemorrhage of a tumor; clinical signs of weakness, respiratory
difficulties, and collapse can predominate due to acute changes
in hemodynamic balance.
Heart
Pericardium
Pericardial
fluid
Diagram depicting the relationship between the pericardium
and heart.
Initial management of clinically significant pericardial effusion
requires removal of the fluid from the pericardial sac. This is
done by inserting a catheter through the chest wall and into
the pericardial sac and then aspirating the fluid that is present. There is some risk in performing this procedure, but this
is minimized by utilizing ultrasound guidance and monitoring
the patient’s ECG. The fluid removed is frequently submitted
for cytology and fluid analysis and even cultured for underlying
organisms if indicated in an attempt to determine the underlying
cause.
Pericardial effusion in the canine patient is most commonly the
result of spontaneous hemorrhage from a cardiac tumor. However, it can develop from infections, secondary to heart failure, or
Chesapeake Veterinary Cardiology Associates
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for no known cause which is termed idiopathic pericardial effusion. The prognosis for pericardial effusion is dependent on the
underlying cause and can be highly variable. The optimal noninvasive evaluation of pericardial effusion is the performance of
an echocardiogram by a board-certified veterinary cardiologist
which allows real time evaluation for mass lesions, the hemodynamic consequences of the effusion, and therapeutic and
diagnostic recommendations based on the study’s findings.
Unfortunately, as many as two thirds of patients do not have an
identifiable cause on initial evaluation and follow-up rechecks
are required. Currently, we are actively researching the utility of
certain biomarkers as an aid in the determination of the underlying cause of pericardial effusion in these situations. However, if
a lesion is noted during the echocardiogram, then based on its
location and appearance a strong working diagnosis can generally be made.
In cases of recurrent pericardial effusion due to an idiopathic
cause or secondary to an identified heart base tumor; surgical
pericardiectomy (removal of the pericardium) is recommended.
By removing a portion of the pericardium it allows the fluid to
accumulate within the chest cavity and prevents excessive
compression of the heart, thus alleviating clinical signs. Pericardiectomy can be performed via a thoracotomy (surgical opening
of chest) or via thoracoscopic guidance, and decision of which
to pursue is based on individual clinical factors and is decided
upon with the attending surgeon. This procedure results in a
significant improvement in quality of life and long-term survival
in these types of patients. Ultimately, our goal is to provide diagnostic and therapeutic plans tailored to the individual patient
and carried out through open collaboration with you and your
primary care veterinarian in order to optimize your pet’s quality
and quantity of life at home.
Pericardial
effusion
RV
RA
LV
LA
Echocardiogram image of heart with pericardial fluid
surrounding the heart with all four chambers shown. (RV– right
ventricle, RA- right atrium, LV– left ventricle, LA– left atrium)