Clinical and Diagnostic Findings of Heart Failure

Question 1

describe consequences of inadequate output/forward heart failure (5)

Answer 1

1. generalized weakness
2. decreased exercise tolerance (esp in performance animals like horses)
3. syncope (fainting)
4. hypotension, hypothermia
5. lactic acidosis, azotemia, oliguria due to inadequate tissue perfusion

body not getting perfused as it should!

Question 2

describe consequences of congestion/backward heart failure

Answer 2

1. abnormal fluid accumulation!!!
   -if left sided: interstitial (CT) pulmonary edema; in and around the alveoli
   -if right-sided: pleural (cavitary) and/or abdominal effusions, peripheral pitting tissue edema (more in horses and cows)
   -most patients have a comb o of both though
2. in cats, LEFT sided CHF may also lead to pleural effusion, pulmonary edema, or both (do whatever they want)
3. physical exam:
   -for both left and right sided: USUALLY abnormal cardiac exam (murmur, gallop, arrhythmia)
   -TACHYCARDIA (except hypothermic cats, become bradycardic); tachycardia is an attempt to increase CO

Question 3

describe outward signs of right sided backwards CHF

Answer 3

1. visual evidence of high right-sided filling pressures
   -jugular venous distension/pulsation
   -hepatojugular reflux (dogs)
2. signs of abnormal fluid accumulation
   -abdominal distension from liver enlargement and/or ascites
   -decreased/absent lung sounds from pleural effusion
   -dependent/pitting peripheral edema: rare in dogs and cats, common in horses and cattle)

Question 4

describe outward signs of left sided backward CHF

Answer 4

1. respiratory signs due to pulmonary edema
   -dyspnea, tachypnea, orthopnea
   -cough (not in cats)
   -expectoration of frothy fluid or frothy blood-tinged fluid in nostrils (horses)
   -fine inspiratory pulmonary crackles
2. cats only: may have decreased/absent lung sounds due to pleural effusion

Question 5

describe clinical diagnosis criteria of CHF

Answer 5

to confirm CHF diagnosis, must establish

1. patient has heart disease sufficiently severe to cause clinical signs noted (imaging)
2. clinical signs directly relate to patient’s heart disease (vs. other condition)

Question 6

describe clinical diagnosis process of CHF

Answer 6

physical exam first ofc

1. echocardiography (cardiac ultrasound)
   -assessment of heart size/function + sidedness of disease if present
   -assessment of pleural and pericardial spaces
   ***is edema or effusion likely cardiogenic? (is there atrial enlargement?)
   -most sensitive and specific test to say if heart disease and what type!
2. thoracic radiographs:
   -big picture of cardiac silhouette
   -assessment of heart, lungs, great vessels, pleural space
   ***is there evidence of fluid accumulation/congestion?
3. electrocardiography (ECG/EKG)
   -assessment of rhythm and rate
   ***supportive of heart failure if arrhythmia/tachycardia present
4. circulating biomarkers (NT-proBNP, released from heart in response to stretch)
   -ancillary: are respiratory signs likely cardiogenic?

Question 7

describe thoracic radiographs in diagnosis of CHF

Answer 7

1. most useful tool to establish whether respiratory signs are likely due to heart failure!
2. left-sided CHF:
   -left-sided heart enlargement pattern
   - +/- pulmonary vein enlargement
   -pulmonary infiltrates: unstructured interstitial/alveolar pattern, perihilar/caudodorsal distribution (exception: cats, can be anywhere!)
   - +/- pleural effusion
3. right-sided CHF
   -right-sided enlargement pattern (careful! super large left could push into right side!! really need to have rounded border/inverted D to say right side enlargement)
   -enlargement of caudal vena cava (should be same diameter as aorta at same level)
   -pleural and//or abdominal effusion (ascites)- increased ST opacity in pleural space with fissure lines

Question 8

what if a patient is too unstable for rads of has confusing radiographic signs?

Answer 8

B (brightness)-mode (2D) echocardiography; short axis view at heart base

-this view is used widely for assessment of left atrial size
-handy clinical parameter: left atrium:aortic annulus (La:Ao ratio), measured on a stopped image when aortic valve is closed (diastole)
–normal La:Ao <1.6 (dog, cat, horse)
–La:Ao >1.6 is left atrial enlargement

ALSO:
-dogs with marked sinus arrhythmia (high vagal tone) or slow heart rates are unlikely to be in CHF
–this is not true

Question 9

what if a patient is too unstable for rads of has confusing radiographic signs that is NOT ultrasound

Answer 9

1. dogs with marked sinus arrhythmia (high vagal tone) or slow heart rates are unlikely to be in CHF
   -this is not true for cats (esp hypothermic, bradycardic)
2. in cats with resp distress, CHF is more likely IF:
   -gallop sound
   -hypothermia: <99.5
   -HR <200bpm
3. furosemide trial:
   -in house if unstable: 2mg/kg BID for 7d, SRR + thoracic rads before/after if stable
4. role for NT-proBNP
   -released by ventricular myocytes in response to stretch/hypoxia
   -elevated = greater liklihood of detecting significant heart disease WITH an echocardiogram
   -not specific for any one disease (can also be due to renal insufficiency)
   -false positive are common

Question 10

describe use of NT-proBNP to distinguish cardiogenic vs. non-cardiogenic edema in cats versus dogs

Answer 10

cats:
-for CHF detection
-sensitivity/specificity: 90-95%
-when added to findings of CXR and PE, will increase accuracy of diagnosis
-clinical use/recommendations: NT-proBNP >270 (low threshold = best used to rule OUT heart failure)
-if echo is available by specialist, NT-proBNP is not necessary
-ancillary and complements other tests, good to rule OUT CHF

dogs:
-for CHF detection: no SNAP available like in cats
-ambiguous use