Page 54 - Feline Cardiology

48 Section B: Diagnostic Testing

may be evident in the 2–3 o’clock position. A double examination. Echocardiography is more sensitive at
opacity of the atrial body over the heart base may also evaluating mild changes in heart structure; however, use
be evident. The “valentine-shaped heart” can occur due of the VHS is an objective way to evaluate heart size and
to left atrial enlargement or biatrial enlargement and is an excellent screening technique in clinically ill cats.
not specific to an underlying form of cardiomyopathy. Radiography may be an effective way to screen asymp-
Diagnostic Testing on a lateral projection, it is suggestive of left or biatrial or is prohibitively expensive for a client. However, cats
tomatic cats if echocardiography is unavailable locally
Rather, similar to the tilted ice cream cone appearance
with early disease (and normal heart size) can be mis-
enlargement. The VD or DV projection is the most sen-
takenly identified as unaffected with this approach, and
sitive for detecting left atrial enlargement in cats (Fox
1999).
the cost:benefit ratio of choosing radiographic evalua-
Left ventricular enlargement can be noted on the
cussed with the owner.
lateral projection as a straightened, more vertical than tion for screening must be carefully weighed and dis-
normal, caudal heart border. On the VD/DV projection
there may be rounding of the left ventricular border. REFERENCES
However, the specific pattern of cardiac enlargement Boldface font indicates key references.
(i.e., tilted ice cream cone) yields no information regard- Bahr RJ. Heart and pulmonary vessels. In: Textbook of Veterinary
ing the underlying heart disease which has led to the Diagnostic Radiology, 5th ed, Thrall DE, ed. St. Louis, Saunders
remodeling. An echocardiogram would be required to Elsevier, 2007, 568–590.
define the underlying disease process. Right atrial and Buchanan JW, Bucheler J. Vertebral scale system to measure
canine heart size in radiographs. J Am Vet Med Assoc 1995;206:
ventricular enlargement are much less commonly 194–199.
observed in cats because the diseases that could lead to Carlisle CH, Thrall DE. A comparison of normal feline thoracic
these changes are less common than left-sided heart dis- radiographs made in dorsal recumbency versus ventral recum-
eases in this species. However, when it occurs, marked bency. Vet Radiol 1982;23:3.
right ventricular hypertrophy tends to cause an increased Drost WT, Reese DJ, Hornoff WJ. Digital radiography artifacts. Vet
Radiol US 2008;49:S48–S56.
convexity to the cranial cardiac border and dorsal dis- Fox PR. Feline cardiomyopathies. In: Textbook of Canine and Feline
placement of the apex from the sternum. Right heart Cardiology, 2nd ed., Fox PR, Sisson DD, Moïse NS, eds.
disease, particularly if the right atrium is enlarged, will Philadelphia, WB Saunders Company, 1999, 621–678.
tend to cause vena caval enlargement as well. Despite the Fox PR, Moïse NS, Evans HE, Bishop SP. Cardiovascular anatomy.
potential increase in right ventricular afterload, In: Textbook of Canine and Feline Cardiology, 2nd ed, Fox PR,
Sisson DD, Moïse NS, eds. Philadelphia, WB Saunders Company,
necropsy-confirmed pulmonary thromboembolism 1999, 14.
(PTE) has been associated with normal thoracic radio- Ghadiri A, Avizeh R, Rasekh A, Yadegari A. Radiographic measure-
graphic findings in cats. Therefore, PTE should be a top ment of vertebral heart size in healthy stray cats. J Feline Med Surg
differential in a feline patient with severe respiratory 2008;10:61–65.
distress, no upper airway obstruction, and normal tho- Hayward NJ, Baines SJ, Baines EA, Herrtage ME. The radiographic
racic radiographs (Schermerhorn et al. 2004). See appearance of the pulmonary vasculature in the cat. Vet Radiol
Ultrasound 2004;45:501–504.
Chapter 25 for further discussion on feline PTE. Jimenez DA, Armbrust LJ, O’Brien RT, Biller DS. Artifacts in digital
Thoracic radiographs should also include the cranial radiography. Vet Radiol Ultrasound 2008;49:321–332.
abdomen and a thorough assessment includes interpre- Litster AL, Buchanan JW. Vertebral scale system to measure
tation of the visible abdomen. Hepatomegaly and ascites heart size in radiographs of cats. J Am Vet Med Assoc 2000a;216:
210–214.
are rare in the cat, but can occur secondary to right heart Litster AL, Buchanan JW. Radiographic and echocardiographic mea-
disease such as tricuspid valve dysplasia. Also, the diag- surement of the heart in obese cats. Vet Radiol Ultrasound
nosis of peritoneopericardial diaphragmatic hernia is 2000b;41:320–325.
supported by an enlarged, rounded cardiac silhouette Moon ML, Keene BW, Lessard P, et al. Age related changes in the feline
and missing or cranially displaced abdominal organs cardiac silhouette. Vet Radiol Ultrasound 1993;34:315–320.
(see Chapter 22 for a discussion of common feline peri- Nelson OL, Reidesel E, Ware WA, Christensen WF. Echocardiographic
and radiographic changes associated with systemic hypertension
cardial diseases). Important abdominal lesions may be in cats. J Vet Intern Med 2002;16:418–425.
recognized, unrelated to heart disease but associated Owens JM. The chest. In: Radiographic Interpretation for the Small
with clinical or thoracic radiographic abnormalities. Animal Clinician, Biery, ed. St. Louis, Ralston Purina Company,
Correct interpretation of feline radiographs requires 1982a, 89–115.
a complete, systematic approach to the entire radio- Rishniw M. Radiography of feline cardiac disease. Vet Clin No Am:
Small Anim Pract 2000;30:395–425.
graphic study as well as a good awareness of likely dif- Schermerhorn T, Pembleton-Corbett JR, Kornreich B. Pulmonary
ferentials based on a thorough history and physical thromboembolism in cats. J Vet Intern Med 2004;18:533.