Page 260 - Feline Cardiology

Chapter 19: Congestive Heart Failure 267

has occurred, often there is pinkish fluid secondary to
capillary hemorrhage. Microscopically, edema fluid
appears acidophilic or faintly granular, and fills the
alveoli, interstitium, and lymphatics (Liu and Fox 1999).
Lymphatics and pulmonary capillaries appear engorged
and tortuous. Alveolar macrophages containing eryth-
rocytes or hemosiderin (i.e., heart failure cells) are
present throughout the lungs and increase in number
with chronicity of heart failure (Liu and Fox 1999).
There are often regions of red, well-demarcated, firm
tissue in the lung periphery, consisting of pulmonary
hemorrhage and infarction (SK Liu 1970). Muscular
hypertrophy of small pulmonary arteries and fibrous
thickening of pulmonary capillary walls is seen in cats
with pulmonary hypertension (uncommon).
Pleural effusion occurs secondary to left or right heart A
failure. Grossly, it may appear clear to tan, or chylous.
The mechanism of true chylous effusion occurring sec-
ondary to isolated left-sided cardiac disease is unknown.
True chylous effusion occurring secondary to right-
sided heart disease may occur due to increased hydro- Congestive Heart Failure
static pressures in the thoracic duct, since the thoracic
duct empties into the cranial vena cava which has ele-
vated hydrostatic pressure. The pleura typically appear
thickened in cases of chronic pleural effusion, and lung
lobe edges may be fibrotic. Lung lobe collapse is also
often seen (Figure 19.7).

B
Pathology of right-sided congestive
heart failure Figure 19.7. Gross pathology and radiograph of a cat with
severe HCM and pleural effusion. Gross pathology (A) of a
Ascites may develop in cats with isolated right heart
failure and is most often seen in conjunction with pleural cat euthanized due to refractory congestive heart failure depicts
serosanguineous pleural effusion (arrows) which was classified
effusion. In passive hepatic congestion (i.e., right heart as a modified transudate, atelectic ventral portions of the left
failure), the liver is heavy (∼115–133 grams), firm, and lung lobe (arrow head), and cardiomegaly. The heart weighs 30
swollen with rounded edges of the central lobes. Acute grams, which is massively increased due to the severe left ven-
passive hepatic congestion results in a swollen, dark liver tricular concentric hypertrophy and severe left atrial dilation. An
that oozes blood when sectioned. The capsule appears antemortem lateral thoracic radiograph (B) of this cat provides a
opaque and is often covered with a sheet of yellowish- clinical correlate, and shows severe pleural effusion that obscures
gray fibrin accumulating from extruded hepatic the cardiac silhouette and pulmonary vasculature.
lymph. Initial histopathologic abnormalities include
hepatic sinusoidal engorgement, and with chronicity,
the capsule develops a fine nodular appearance, and a
reticulated acinar pattern is seen on sliced sections Other pathologic abnormalities
(i.e., nutmeg liver). This nutmeg appearance is caused The kidneys of cats diagnosed with CHF often appear
by red congested centers of the liver lobes and periacinar irregular, with regions of firm, pale depressed scars
necrosis, surrounded by pale, slightly raised periportal or dark red, elevated, well-demarcated, wedge- or
regions containing fatty hepatocytes. Chronic passive cone-shaped areas, consistent with previous or recent
congestion also causes the spleen to be congested and renal infarctions, respectively (SK Liu 1970).
heavy, as well as congestion of other abdominal organs Antemortem arterial thromboemboli are commonly
including the stomach, intestines, and pancreas. seen in cats dying of heart failure. In a case series of 112
Microscopically, there is usually marked sinusoidal dila- cats with CHF due to acquired heart disease, “red”
tion of the spleen. thromboemboli were found in the abdominal aorta