Feline Cardiomyopathy Flashcards
describe feline cardiomyopathies
- primary disease of the cardiac muscle:
-hypertrophic cardiomyopathy!!
-restrictive cardiomyopathy
-dilated cardiomyopathy
-arrhythmogenic RV cardiomyopathy
-nonspecific - secondary disease of the cardiac muscle
-hyperthyroidism
-systemic hypertension
-dietary
-tachycardia-related
-acromegaly
describe hypertrophic cardiomyopathy (HCM)
- the most common feline cardiomyopathy!!
- pathology:
-ventricular thickening
-typically LV wall and IVS
-papillary hypertrophy
-may be asymmetric hypertrophy
-LA enlargement
describe HCM pathophysiology
- thickened, noncompliant ventricular walls cause DIASTOLIC dysfunction
- decreased cardiac output from reduced diastolic filling
- geometric changes in the ventricle and papillary muscles cause mitral regurgitation
- increased LA pressure leads to congestion (pulmonary edema, pleural effusion, pericardial effusion)
- increased myocardial O2 consumption and decreased perfusion leads to myocardial ischemia
- LV outflow obstruction may occur
-systolic anterior motion (SAM) of the mitral valve (MV pulled into LV outflow tract)
diastolic dysfunction caused increased LA pressure and leads to CHF
describe clinical findings of HCM
- compensated:
-cats may have clinically silent disease
-murmur, typically sternal or parasternal
-gallop!! very sensitive for occult cardiomyopathy in cats!!
-arrhythmias, femoral pulse deficits - decompensated:
-panting, tachypnea, dyspnea
-cyanosis (MM color variable: normal, pale, cyanotic)
-jugular vein distension
-crackles if pulmonary edema
-decreased/muffled lung sounds if pleural effusion
-ascites is rare
-evidence of arterial thromboembolism
what are different characteristics of feline cardiac disease/heart failure from dogs?
dogs:
-primary valvular most common
-CM: systolic dysfunction
-cough: frequent presenting sign
-signs gradually worsen
-frequently ascites
-echo may not be needed for dx
cats:
-cardiomyopathies most common
-CM: diastolic dysfunction
-very rare to cough with cardiac disease
-signs appear acutely (hide signs until super severe)
-frequently pleural effusion, less often ascites
-echo typically is necessary for definitive diagnosis
describe radiographic findings of HCM in cats
- generalized cardiomegaly
-VHS >7.75-8.0
-heart > 2.5-3.5 ICS - left atrial enlargement
- left ventricular enlargement
- CHF:
-distended pulmonary veins
-interstitial to alveolar infiltrates
-pleural effusion
-rare ascites
describe ECG of HCM in cats (3)
look for
- conduction abnormalities
- axis shifts
- signs of chamber enlargement
describe genetics of HCM in cats
- maine coon and ragdoll cats:
-mutations: MYBPC3
-can do genetic testing to see if patients have mutations that predispose to HCM!
describe echocardiography of HCM
- LV wall and septal thickening
-may be asymmetric or regional
-LV concentric hypertrophy differentials: systemic hypertension, hyperthyroid heart disease, so measure blood pressure and obtain T4
- +/- LVOT obstruction:
-fixed or dynamic (systolic anterior motion) - +/- LA enlargement: if massive LA enlargement, may add plavix?
- +/- smoke or intracardiac thrombus
describe acute therapy for CHF due to HCM
- oxygen
- IV furosemide: decrease preload
- +/- pimobendan (PO) or dobutamine (IV) to increase contractility
- +/- sedation: butorphenol
- thoracocentesis if pleural effusion
describe chronic therapy for CHF due to HCM
- furosemide: loop durietic
- ACE-inhibitor: enalapril or benazepril
-NEVER GIVE IN ACUTE: could cause AKI - +/- pimobendan: indodilator
- +/- spironolactone: aldosterone antagonist; also not for acute setting!
describe follow up from acute presentation of CHF due to HCM
- recheck in 5-7 days
- thoracic rads
- renal panel
- blood pressure
describe NT-proBNP for HCM patients
100% specific for distinguishing healthy from cardiomyopathy
-use in combo with history, PE, and echo!
-good for the cat that comes in with gallop and arrhythmia, plus some enlargement on rads, if NT-proBNP is high = very likely underlying HCM
contrast restrictive cardiomyopathy to end stage HCM on echo
RCM:
-normal wall thickness
-atrial enlargement
-diastolic dysfunction
end stage HCM:
-walls may be normal
-dilated chambers
- +/- myocardial infarction
describe DCM on echo in cats
- left ventricular dilation and systolic dysfunction
- primary DCM is rare
-secondary can be from taurine deficiency
describe sequelae of CM in cats
feline arterial thromboembolism! (ATE)
describe pathophysiology of ATE
- commonly associated with feline CM
- damaged cardiac endothelium
- hypercoagulable state
- intracardiac blood stasis
- thrombus leave the heart and embolizes to peripheral vasculature
-distal blood supply is disrupted
-thrombi cause release of vasoactive substances - acute event causes pain, then ischemia leads to necrosis of muscles or organs
- reperfusion injury can occur
describe ATE in the heart
- impaired relaxation (diastolic dysfunction)
- left atrial enlargement and left auricular enlargement cause blood stasis
-smoke: spontaneous echogenic contract - thrombus formation: endothelial injury, platelet activation
- superficial portions of an intracavitary thrombus can break off
-most common site: terminal abdominal aorta/saddle thrombus - alternate sites:
-brachial infarction
-cerebral infarction
-renal infarction
-splanchnic infarction
what are the 5 P’s of ATE saddle thrombus in cats?
- pain
- pulselessness
- pallor
- paresis
- polar (cold extremities)
describe clinical signs of ATE
- cats may regain some to all motor function within 4-6 weeks
-reestablishment of a collateral vascular network
-intrinsic dissolution of the embolus
-recanalization of the obstructed aorta - chronic complications from aortic infarction
-self mutilation of necrotic limb
-limb necrosis requiring amputation - renal: acute renal failure, renal pain
- central neurologic:
-stupor, seizures, sudden death - mesenteric: severe abdominal pain, vomiting
- additional:
-hypothermia
-murmur
-gallop
-arrhythmia
-CHF: in up to 60%
describe diagnostic tests for ATE
- chemistry:
-hyperglycemia: due to stress
-hypoglycemia in affected limb
-azotemia: hypoperfusion, embolism
-increased CK
-increased AST/ALT
-hyperkalemia - chest rads: rule CHF in or out
- echocardiogram: LA size and content
describe prevention of ATE
- if see left atrial enlargement or spontaneous echo contrast in LA
-start clopidogrel or aspirin!
describe management strategies of HCM in cats when ATE is suspected
- analgesia!!
- maintain hydration/perfusion
-judicious use of fluids, however caution if patient has CHF - manage CHF
- thrombolytic therapy (tPA): for hemorrhage, to avoid reperfusion injury
- anticoagulant therapy: heparin, low molecular weight heparin
-heparin: unfractionated: inhibits Xa and IIa
-low molecular weight heparin: pricier
describe prognosis of HCM in cats with ATE
- guarded
-survival rates 33-39% - single limb affected: improved survival compared to bilateral pelvic limb infarction
- acute prognosis is more clear after 24-72 hours
