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28 Pericardial Disease 279

(a) (b)
VetBooks.ir

Figure 28.2 Transthoracic echocardiographic images of the left ventricle (LV) from a right parasternal short‐axis view. (a) A large‐volume
pericardial effusion in a dog. (b) A small‐volume pericardial effusion in a cat with hypertrophic cardiomyopathy and congestive heart
failure. PE, pericardial effusion.

visualize cardiac tumors, but therapeutic pericardiocen- mechanism to improve cardiac output. Low‐voltage
tesis should not be delayed for an echocardiographic QRS complexes can be indicative of pericardial effu-
examination in an unstable patient. Tumors are most sion in dogs (Figure 28.5b). It is important to recognize
often located in the right atrial or auricular wall in the that QRS complexes are typically small in cats, making
case of hemangiosarcoma or at the heart base associated this an insensitive indicator of effusion. Electrical
with the aorta or main pulmonary artery (Figure 28.3). alternans, identified as a beat‐to‐beat variation in the
They can also be found, more rarely, within the right QRS complexes, is highly suggestive of pericardial
ventricular myocardium and right ventricular outflow effusion, although it is only identified in a small num-
tract. Hemangiosarcomas frequently appear cavitary. ber of dogs (Figure 28.5c). Lastly, a change (depression
Both the right and left imaging windows are recom- or elevation) in the ST segment associated with myo-
mended for identification and localization. In addition to cardial hypoxia (Figure 28.5d) may be documented.
identifying pericardial effusion, echocardiography can Ventricular arrhythmias are not uncommon and
provide evidence of cardiac tamponade by documenting supraventricular arrhythmias can also occur. Most
diastolic collapse of the right atrium and ventricle when ECG abnormalities will resolve shortly after the
intrapericardial pressures exceed right atrial or ventricu- removal of pericardial effusion.
lar end‐diastolic pressures (Figure 28.4). Left ventricular
internal dimensions will measure small when pericardial Laboratory Work
effusion inhibits preload of the heart. Comprehensive laboratory evaluation including com-
plete blood count, biochemical analysis, coagulation
Pericardial Fluid Analysis panel, and urinalysis can provide information regard-
Pericardial fluid is typically hemorrhagic in appearance, ing underlying etiology and the patient’s clinical sta-
although opaque fluid can be seen with chylous effu- tus. Abnormalities are not uncommon but are often
sions and exudates. Most cardiac tumors do not exfoli- nonspecific. Cardiac troponin I concentrations can be
ate well, and for this reason pericardial fluid analysis increased in dogs with hemangiosarcoma (>0.25 ng/
and cytology often are unrewarding for the identifica- mL) when compared to other causes of pericardial
tion of cardiac tumors. Careful cytologic evaluation is effusion.
required so that reactive mesothelial cells are not
mistaken for neoplastic cells. Occasionally, lymphoma Neoplastic Evaluation
or an infectious cause can be documented. Culture and Cardiac tumors are located adjacent to important vascu-
sensitivity are indicated for the identification of effu- lar structures, making the diagnosis challenging.
sions secondary to infectious etiologies. Definitive diagnosis is often made during surgery or at
necropsy. Surgical excisional biopsy has been described
Electrocardiography for the diagnosis of hemangiosarcoma of the right auricle
The most common finding is sinus tachycardia and for chemodectoma but is often not performed as a
(Figure 28.5a), which is a physiologic compensatory consequence of the overall risk to benefit ratio.