Page 210 - Small Animal Internal Medicine, 6th Edition

182 PART I Cardiovascular System Disorders

although this should be unnecessary if sterile technique was choose conservative therapy (repeated pericardiocentesis)
used and the effusion shows no signs of infection. Periodic until episodes of cardiac tamponade become unmanageable.
VetBooks.ir reevaluation of these dogs by radiography or echocardiogra- Therapy with epsilon aminocaproic acid, an antifibrolytic
agent that prevents activation of plasminogen to plasmin,
phy is recommended to detect recurrence. Apparent recov-
ery occurs after one to three pericardial taps in about half of
cardial effusion associated with RA HSA. Conversely, a small
affected dogs. Cardiac tamponade can recur after a variable anecdotally has been helpful in reducing hemorrhagic peri-
time span (days to years). Nevertheless, extended survival retrospective study of dogs with a RA mass and pericardial
times are possible in dogs with idiopathic pericardial effu- effusion found no difference in time to recurrence of clinical
sion, even in those requiring more than three pericardio- signs from cardiac tamponade between dogs that had been
centeses. However, recurrent effusions that were thought treated with Yunnan Baiyao, a Chinese herbal remedy that
to be idiopathic can be caused by mesothelioma or other can decrease clotting time and bleeding, either given alone
neoplasia. Sometimes this becomes evident on repeated or with epsilon aminocaproic acid compared with untreated
echocardiographic examination. Recurrent effusion that dogs.
does not respond to repeated pericardiocenteses and antiin- The prognosis in dogs with RA HSA with or without
flammatory therapy (e.g., after two or three pericardial taps) surgery alone is poor (median survival of 2-3 weeks). Multi-
usually is treated by pericardiotomy (pericardial window) or agent chemotherapy reportedly has allowed survival times of
subtotal pericardiectomy (removing the pericardium ventral 4 to 8 months in some dogs with atrial HSA. Survival time
to the phrenic nerves), which allows drainage to the larger in dogs with mesothelioma might be slightly longer than in
absorptive surface of the pleural space. those with HSA, but the overall prognosis is poor. Therapy
with IV doxorubicin and intracavitary cisplatin might extend
Neoplastic Pericardial Effusion survival time in some dogs. Heart base tumors (chemodec-
These also are drained to relieve cardiac tamponade. Recur- toma) tend to be slow-growing and locally invasive, although
rence of effusion is expected. Depending on tumor size, loca- some do metastasize; pericardiotomy or partial pericardiec-
tion, and histologic diagnosis, management might involve tomy may prolong survival for years. More information
surgical biopsy or perhaps even resection, pericardiotomy or about cardiac tumors is found later in this chapter (p. 185).
partial pericardiectomy, chemotherapy, or repeated pericar-
diocenteses. Surgical resection of most HSA and heart base Infectious Pericarditis
tumors is not possible because of the tumor’s invasiveness, Infection involving the pericardium should be treated
although small tumors involving only the tip of the right aggressively with appropriate antimicrobial drugs (ideally
auricle have been successfully removed. Surgery can be asso- determined by microbial culture and sensitivity testing) and
ciated with significant morbidity and mortality, and is only pericardiocentesis as needed. Infusion of appropriate antimi-
palliative in most cases. Thoracoscopic pericardiotomy pro- crobial agent directly into the pericardium after pericardio-
vides a less invasive option compared with partial pericardi- centesis can be helpful. Continuous drainage with an
ectomy by open thoracotomy but might not be as effective indwelling pericardial catheter or surgical debridement
as pericardiectomy. Biopsy samples for histopathologic eval- should be pursued if a foreign body is suspected or intermit-
uation can be obtained by both techniques. The thoraco- tent pericardiocentesis is ineffective. Surgery can remove a
scopic pericardial window procedure generally requires penetrating foreign body, provide more complete flushing of
shorter procedure and hospitalization times than open tho- exudates, and manage pericardial constrictive disease. The
racotomy and has low morbidity. Partial pericardiectomy prognosis with infective pericarditis is guarded. Even with
also is possible using thoracoscopy in some animals. Percu- successful elimination of infection, epicardial and pericar-
taneous balloon pericardiotomy (see Suggested Readings for dial fibrin deposition may lead to constrictive pericardial
more information) is another minimally invasive means of disease.
providing long-term continuous pericardial drainage that
might be useful if thoracoscopy is unavailable and thora- Intrapericardial Hemorrhage
cotomy is declined. These procedures can be effective for Pure hemorrhage into the pericardial space, whether from
preventing recurrence of tamponade in idiopathic as well as trauma, LA rupture associated with advanced mitral valve
some cases of neoplastic pericardial effusion, especially from disease, or a systemic coagulopathy, warrants pericardiocen-
a heart base tumor. The increased potential for tumor dis- tesis if signs of cardiac tamponade exist. Only enough volume
semination throughout the thoracic cavity does not appear to control signs of tamponade should be removed, because
to affect survival time, compared with pericardiocentesis continued pericardial drainage could predispose to further
alone, in dogs with HSA or mesothelioma. Chemotherapy, bleeding. The remaining blood usually is resorbed through
based on biopsy or clinicopathologic findings, may slow neo- the pericardium (autotransfusion). Surgery might be neces-
plastic progression, although most cardiac tumors are fairly sary to stop continued bleeding or remove large clots. Dogs
resistant. Radiation therapy might provide some palliation that survive an initial episode of intrapericardial bleeding
for selected cases, as well. Consultation with a veterinary from LA rupture still have a guarded to poor prognosis
oncologist is recommended for dogs whose owner wishes to because risk of recurrent LA tearing is high. Animals with
try chemo- or radiation therapy. Alternatively, many owners intrapericardial hemorrhage of unclear cause should be