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Heart Base Tumor 407

Heart Base Tumor Client Education
Sheet
VetBooks.ir Diseases and Disorders

BASIC INFORMATION
occasionally locally invasive and uncom-
monly metastatic • CT and/or MRI may provide additional
anatomic information for surgical or radia-
Definition • Ectopic thyroid carcinoma tion therapy planning.
Heart base tumor is a general term describing ○ 5%-10% of heart base tumors in dogs;
a cardiac neoplasm of any type located at the usually nonfunctional TREATMENT
base of the heart, often in association with ○ Risk of metastasis increases with tumor
the ascending aorta but without right atrial size Treatment Overview
involvement. • Mesothelioma may rarely form a mass lesion Treatment is generally aimed at removal of
at the heart base (dogs). pericardial fluid when cardiac tamponade occurs
Synonyms • Regardless of type, heart base tumors typically and eliminating recurrent effusion. When a
Chemoreceptor cell tumor, chemodec- result in pericardial effusion, causing cardiac heart base tumor is an incidental finding, no
toma, aortic body tumor, nonchromaffin tamponade and right-sided CHF. treatment may be necessary initially.
paraganglioma • Large masses may cause clinically significant
compression of cardiac structures and great Acute General Treatment
Epidemiology vessels, inhibiting inflow or outflow. • Pericardiocentesis (p. 1150) is essential for
SPECIES, AGE, SEX cardiac tamponade but may not be neces-
• Dogs: second most common cardiac tumor DIAGNOSIS sary if only mild effusion is present and not
(after hemangiosarcoma), mean age of 10 causing hemodynamic effects.
years (range, 5-15 years), males may be Diagnostic Overview • Diuretics are contraindicated in acute treat-
overrepresented The diagnosis is most often made with echo- ment of cardiac tamponade.
• Cats: reported but rare cardiographic identification of a mass at the
heart base. Although a presumptive diagnosis Chronic Treatment
GENETICS, BREED PREDISPOSITION of chemodectoma is often based on echocardio- • Repeated pericardiocentesis as needed for
Brachycephalic breeds (English bulldogs, boxers, graphic appearance, definitive diagnosis of the recurrent pericardial effusion
Boston terriers) are predisposed. tumor type requires histopathologic evaluation. • Diuretics to delay effusion recurrence are
controversial.
RISK FACTORS Differential Diagnosis • Pericardiectomy alone is an effective pal-
Chronic hypoxemia may be a contributing • Other intrapericardial tumors (hemangio- liative treatment for recurrent pericardial
factor. sarcoma, mesothelioma, lymphoma, rare effusion. Less-invasive alternatives to surgi-
primary cardiac tumors, metastatic tumors) cal pericardiectomy include thoracoscopic
ASSOCIATED DISORDERS • Other causes of pericardial effusion (p. 773) pericardiectomy and percutaneous balloon
Pericardial effusion, right-sided congestive heart pericardiotomy.
failure (CHF), cardiac tamponade Initial Database • Complete surgical resection is rarely possible
• Echocardiography (p. 1094): diagnostic due to high vascularity of the tumor and
Clinical Presentation test of choice. Heart base tumors typically close association with great vessels.
DISEASE FORMS/SUBTYPES originate from the ascending aorta, most • Radiation therapy has been reported to reduce
• Most commonly causes clinical signs due to commonly the left cranial aspect, and lie tumor size, but long-term benefit is unknown.
pericardial effusion and cardiac tamponade between the aorta and the main pulmonary • Chemotherapy with toceranib phosphate
• May be an incidental finding artery. They are usually homogeneous with (Palladia, Zoetis) may provide clinical benefit
smooth margins. Presence and severity of in some cases, but controlled efficacy data
HISTORY, CHIEF COMPLAINT pericardial effusion is also assessed. are lacking.
• Acute collapse/syncope • Thoracic radiographs: enlarged or globoid
• Lethargy/exercise intolerance cardiac silhouette in most, but not all, cases Possible Complications
• Abdominal distention of cardiac tamponade (80%). A soft-tissue • Pericardiocentesis-related (p. 1150)
• Anorexia/inappetence mass effect at the heart base may cause dorsal • Surgical complications related to pericardi-
• Cough or tachypnea/dyspnea and lateral deviation of the trachea. ectomy; surgical resection carries substantial
• Electrocardiogram (p. 1096): sinus tachycar- risks.
PHYSICAL EXAM FINDINGS dia, low-amplitude QRS complexes, and/or • Because most heart base tumors are benign,
• Findings associated with pericardial effusion electrical alternans with pericardial effusion. metastasis is uncommon.
(tachycardia, weak peripheral pulses, and • CBC, serum biochemistry profile, and
muffled heart sounds) urinalysis: often unremarkable Recommended Monitoring
• Findings consistent with right-sided CHF • Follow-up exams and echocardiography to
(ascites, hepatomegaly, jugular distention/ Advanced or Confirmatory Testing assess for recurrent pericardial effusion and
pulsation) • Cytologic evaluation and pH of the pericardial tumor progression
• ± Tachypnea/dyspnea effusion are not generally useful. Heart base • Thoracic radiographs and abdominal ultra-
tumors typically do not exfoliate cells, reac- sound for tumor staging
Etiology and Pathophysiology tive mesothelial cells mimic malignant cells,
• Chemodectoma and there is much overlap in pH between PROGNOSIS & OUTCOME
○ Tumor of specialized neuroepithelial pericardial effusions from various causes.
cells in the adventitia of the aortic arch; • Histopathologic evaluation of the tumor • Guarded to fair without pericardiectomy
majority of heart base tumors in dogs allows a definitive diagnosis of tumor type. • Pericardiectomy alone improves survival time
○ Typically benign and slow growing but Requires surgical biopsy and often does not considerably (median survival, 730 vs. 42
may be very large at the time of diagnosis; alter treatment plan days).

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