Page 275 - Feline Cardiology

282 Section G: Congestive Heart Failure

these patients require a reduction or termination of unless it becomes readily available in commercial veteri-
antihypertensive medications if they are receiving them; nary laboratories for clinical samples.
intravenous therapy with fluid replacement if hypovole-
mic, or vasopressors if persistently hypotensive when Specific Blood Tests
euvolemic; and careful monitoring. Specific blood tests include the following:

Central venous pressure • Plasma and whole blood taurine levels should be mea-
sured in cats with dilated cardiomyopathy to evaluate
Measurement of elevated central venous pressure for taurine deficiency induced myocardial failure.
(>10 mm Hg) may help confirm the diagnosis of right- • Neurohormonal biomarkers for heart disease and
sided congestive heart failure. A jugular venous catheter heart failure include atrial natriuretic peptide, brain
may be placed; the tip of the catheter is advanced natriuretic peptide, troponin I, and endothelin 1.
to the junction of the cranial vena cava and right • The inactive fragment amino terminal proBNP (NT-
atrium, and a radiograph is obtained to confirm appro- proBNP) is a useful screening test to evaluate whether
priate placement (Petrollini 2007; de Madron 2011). dyspnea is due to heart failure or primary respiratory
Multiple invasive pressure measurements are obtained disease in cats.
with the manometer placed at the level of the heart. Whole blood and plasma taurine
Congestive Heart Failure and a better candidate for the jugular catheterization Plasma and whole blood taurine concentrations should
Thoracocentesis should be done prior to measurement
of CVP for two reasons: 1) the cat will be more stable

be measured in any cat with echocardiographic evidence
procedure, and 2) pleural effusion independently ele-
of significant myocardial failure regardless of diet history
vates CVP and may obscure one’s ability to discrimi-
(see Chapter 13). It is important to recognize taurine
nate right heart failure from other causes of pleural
deficiency when it exists since it confers a much better
effusion. In an experimental study of cats with conges-
tive heart failure and cats with iatrogenic pleural effu-
cardiomyopathy. Although taurine deficiency is defined
sion, there was a positive linear relationship between prognosis than the grave prognosis of idiopathic dilated
central venous pressure and pleural fluid volume as plasma taurine <60 nmol/ml and whole blood taurine
(Gookin and Atkins 1999). The mean difference in CVP <250 nmol/ml, most cats with taurine deficiency induced
before and after thoracocentesis was 4.5 mm Hg. myocardial failure have markedly lower plasma taurine
However, only cats with pleural effusion secondary to concentrations, typically less than 20 nmol/ml and whole
right-sided CHF had a CVP >10 before and after blood concentration typically less than 100 nmol/ml.
thoracocentesis.
Circulating biomarker tests
Pleural effusion analysis and cytology Natriuretic peptides
Pleural effusion fluid analysis with cytology is a neces- Natriuretic peptides, including atrial natriuretic peptide
sary diagnostic test to help refine the differential diag- (ANP) and brain natriuretic peptide (BNP), are a family
noses for cats with pleural effusion. Heart failure can be of neurohormones that have emerged as useful bio-
ruled out if the fluid is classified as a septic exudate, markers for heart disease, heart failure, and early cardio-
nonseptic exudate, or hemorrhagic effusion. Fluid char- vascular mortality in people (Bettencourt et al. 2002).
acteristics of cardiogenic pleural effusion are highly BNP is upregulated in various cardiac diseases that
variable, and may be classified as a transudate, modified result in systolic or diastolic dysfunction and are further
transudate, chylous, or pseudochylous (see Chapter 3). elevated in proportion to the severity of heart failure.
Measurement of fibronectin concentration of pleural Veterinary medicine is now exploring the use of these
effusion was useful to discriminate heart failure from neurohormones as screening tests for heart disease and
neoplastic etiologies in cats (Hirschberger and Pusch heart failure in dogs and cats, and early experience is
1996). Using pooled plasma samples, a discrimination very encouraging.
line of 31.5% yielded a sensitivity of 100% for diagnosis Natriuretic peptides share common biologic effects of
of neoplastic pleural effusion (which all had higher increased renal excretion of sodium and water, vasodila-
fibronectin levels) (Hirschberger and Pusch 1996). tion by inhibiting endothelin I and renin (thereby
Although there is no feline or canine specific test to decreasing angiotensin II), and modulation of the sym-
measure fibronectin concentration, a nephelometric test pathetic nervous system. Atrial natriuretic peptide is
kit for human fibronectin has been validated for use in synthesized in the atria and stored in granules, which are
cats and dogs. The clinical utility of this test is likely low released when the atria are volume overloaded and walls