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What is HCM?
primary yocardial disease of unknown origin characterized by concentric hypertrophy and diastolic dysfunction of the LV and rarely the RV (thought to be genetic)
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What is a sign that dogs with CHF usually have that cats usually DO NOT?
coughing
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____________ are very sensitive are relatively specific for cardiac abnormalities/ myocardial dz in cats.
gallops and murmurs
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Is heart rate a good indicator of cardiac dz in cats?
no- cats tend to have high sympathetic tone during PE
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What are primary idiopathic cardiomyopathies in cats? (4)
HCM**, restrictive cardiomyopathy, DCM, arrhythmogenic RV CM (more a dog thing)
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What are common causes of secondary cardiomyopathies in cats? (7)
hyperthyroidism, hypertension, chronic anemia, ischemia/infarction, taurine deficiency, myocarditis, acromegaly
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End-stage HCM has a(n) ___________ phenotype because...
mixed hypertrophy; the heart dilates to try and compensate (increase SV and CO).
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What breeds of cat commonly are associated with HCM?
Maine Coon (4-7 years old), Ragdolls (early onset- 6-12 months old)
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Males are _________ commonly affected with HCM than females.
more
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Describe the pathogenesis of HCM.
genetic abnormality--> mutation causing impaired structure and sarcomere assembly--> contractile dysfunction and compensatory peripheral repair--> pressure, modifier genes, lifestyle--> hypertrophy, myofiber disarray, fibrosis, and small vessel dz--> HCM--> burn out--> DCM
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What is the mutation associated with HCM?
impaired structure and assembly of sarcomeres (poison peptides), causing contractile dysfunction
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What pathological processes are associated with HCM? (5)
concentric hypertrophy, myofiber disarray, fibrosis, small vessel disease (narrow lumen--> ischemia); end stage/ burn out- DCM
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Abnormalities of LV diastolic function. (3)
abnormal filling (diastolic dysfunction), abnormal relaxation, increased stiffness/ decreased compliance
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What are potential presentations/ prognostic profiles of HCM? (5)
sudden death, CHF, end-stage (DCM), FATE, benign/stable/ normal longevity (majority)
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What are PE findings commonly associated w/ HCM? (7)
systolic murmur, gallop sounds (use bell to hear this), arrhythmia, systolic click, syncope, signs of ATE, CHF
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What clinical signs are always seen with HCM?
none- cats may have no outward signs of disease at all
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What are ECG findings common with HCM? (5)
[may be normal] increased R amplitude (LV enlargement), left axis deviation (LV hypertrophy or left fascicular block), wider P waves (LA enlargement), arrhythmias, ST segment depression (ischemia)
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What are signs of LV enlargement on ECG? (2)
increased amplitude R waves, left axis deviation
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What are signs of LA enlargement on ECG? (1)
wider P waves
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What are signs of ischemia on ECG? (1)
ST segment depression
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__________ on ECG is relatively specific for myocardial disease in cats.
Ventricular ectopy
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What might be radiographic findings with HCM? (3)
[may be normal!] LV elongation, LA enlargement, evidence of CHF
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What are echo findings that are common with ECG? (8)
- LV hypertrophy (diastolic wall thickness >6mm)
- LA enlargement, dynamic LVOT obstruction, secondary mitral regurg, LV diastolic dysfunction (Doppler),increased LV systolic dysfunction, rare LV dilation (end stage), +/- RV involvement
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What is hypertrophic obstructive cardiomyopathy?
dynamic obstruction of the LVOT, causing flow turbulence, flow acceleration, dagger shaped flow signal, mitral regurg; grave prognosis
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LV systolic function is ___________ in HCM.
normal or increased
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Describe the Doppler profile with HCM.
- LV relaxation delay- smaller E, large A wave
- Endstage--> restrictive filling- huge E wave and almost no A wave
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Is serum cTI useful in diagnosing HCM?
may help you identify patients that are fully compensated (no value in patients with heart failure or decompensated); indicates myocardial necrosis due to infarction, myocarditis, reperfusion; NOT A USEFUL SCREENING TEST
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__________ is a useful screening test for cats with murmurs.
NT-proBNP
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How is NT-proBNP used in the workup of HCM?
- Postive snap test--> move forward with echo
- Negative snap test--> rule out HCM
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What is the cutoff for NT-proBNP for ruling out HCM in cats?
normal < 100pmol/L
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NT-proBNP snap test has high ________.
NPV (negatives are very reliable; positive, need to go to echo to confirm)
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When is genetic testing used in the setting of HCM?
[this is not recommended ever] mouth swab in Maine Coon and Ragdoll cats; negative test does not tell you that the cat will never develop HCM; positive test does not predict how the cat will progress (some cats never develop clinical decompensation)
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What are differentials for concentric hypertrophy in a cat? (7)
- HCM, systemic hypertension, feline hyperthyroidism
- mitral valve dysplasia w/ dynamic LVOT obstruction
- aortic stenosis
- pseudohypertrophy (dehydration)
- infiltration
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Management of acute CHF in a cat with HCM. (6)
- Furosemide
- Oxygen
- Nitroglycerine paste (ear pinnae)
- Sedation
- Tap (if there is pleural effusion)
- reduce stress/ stabilize before more procedures (re-assess every 30 min)
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When managing acute CHF in a cat with HCM, HR should be around ________ within a few hours of initiating treatment.
40/min
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If __(2)__, the cat is in cardiogenic shock, and you must administer __________.
hypothermia and hypotension; Dobutamine +/- Pimobendan +/- Dopamine
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Describe the management of postclinical HCM (chronic management after stabilization). (3)
Furosemide, ACEi, Plavix (unless a contraindication exists for one of these)
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Do NOT give _________ to cats with CHF.
Atenolol
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How is preclinical HCM managed?
usually "watchful waiting" and annual re-checks, advise owner on what to expect with decompensation
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Preclinical HCM cat with moderate-severe LVOT obstruction; use ___________.
Atenolol
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Preclinical HCM cat with moderate-severe LA enlargement; use __________.
Aspirin or Plavix
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Preclinical HCM cat with atrial fibrillation; use ___________.
Diltiazem
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Preclinical HCM cat with DCM phenotype; use __________.
Taurine supplementation
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What are contraindications for Atenolol? (3)
CHF, very large LA, bradycardia
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What is prognosis for HCM?
- Good for most
- Asymptomatic- up to 10 years
- FATE- grave
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What are the morphological characteristics of "burn-out" HCM? (2)
restrictive AND dilated CM
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What is "SAM" and how is it treated?
- systolic anterior motion of the septal mitral valve leaflet, causing dynamic obstruction of the LVOT
- Atenolol (decreases dynamic obstruction)
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What are the 2 main reasons for dynamic outflow tract obstruction in HCM? What are the hemodynamic consequences of this?
- SAM of septal MV leaflet; LV hypertrophy or pseudohypertrophy
- pressure overload of LV--> concentric hypertrophy--> decreased CO--> exercise intolerance, syncope
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What are differentials for concentric hypertrophy in cats? (5)
HCM, systemic hypertension, pulmonic/ aortic stenosis, pulmonary hypertension, hyperthyroidism
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How can the definitive diagnosis of FATE be made? (3)
strong clinical suspicion and: cardiac and abdominal US (distal aorta), Doppler to confirm absence of flow in femoral arteries, elevation of skeletal muscle enzymes and K+
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