Hypertrophic Cardiomyopathy and RCM Flashcards
T/F: feline hypertrophic myopathy is secondary to increased ventricular pressures
False
Primary concentric hypertrophy
Usually LV but RV can be affected
What breeds of cats are most predisposed to HCM?
Maine coon
Rag dolls
American shorthair
Cardiomyocyte hypertrophy occurs in reponse to _________
Sarcomeric dysfunction
What do you see on histopathology in HCM?
Myofiber disarray
Arteriosclerosis (hardening of the arteries)
Fibrosis
Hypertrophic cardiomyopathy results in _______ dysfunction due to increased ventricular wall stiffness
Diastolic
—> impaired relaxation
How does hypertrophic cardiomyopathy impact blood flow?
Diastolic dysfunction leads to increased ventricular filling pressures
—> increase LV pressures increase atrial and pulmonary venous pressures —> develop pulmonary edema +/- pleural effusion
What is the obstructive form of HCM?
Systolic anterior motion of the mitral valve (SAM)
—> papillary muscle hypertrophy leads to displacement of chordae tendineae to the LV outflow tract during systole
—> impaired flow to aorta and some regurgitation through mitral valve
T/F: cats with HCM do not have murmurs
True
Except in obstructive form
Why do you see left atrial dilation in HCM>
Dilation due to chronically elevated filling pressures of the ventricles
-can be exacerbated by mitral regurgitation from SAM
If the LA becomes moderately/severely dilated, what would you be concerned about in you cats?
Thrombus formation
What is the usual signalment of cats with HCM?
Av age 6years
Younger presentation in pure breeds
Male>female
DSH is the most common breed diagnosed
What is the most common presenting complaint in HCM cats?
Dyspnea (due to CHF)
Although 50% of cats are asymptomatic at time of diagnosis
What co-morbidities are common with HCM?
Hyperthyroidism and renal disease
Where is a murmur heard in a cat with HCM with SAM?
Systolic murmur, often left sided
What can be present in auscultation of a cat with HCM?
Normal auscultation normal in cats with HCM
Gallop
Heart rate normal, low, or high
Premature beats
Femoral pulses are usually normal (unless ATE, arrhythmia, low output HF)
Abnormal lung sounds with CHF
Hypothermic if ATE or low output
What are the DDX for murmurs in cats?
Structural heart disease
- HCM
- RCM
- degenerative valve disease
- congenital heart disease (young)
Physiological
- dynamic right ventricular outflow tract obstruction
- anemia
- hyperthyroid
- fever
Innocent
How can we get a definitive diagnosis for HCM?
Echo
What are DDX for LV concentric hypertrophy that you must rule out before you can contribute the hypertrophy to HCM?
Aortic stenosis
Systemic hypertension
Acromegaly
Infiltrative debase (lymphoma)
What are the most common arrhythmias in cats with HCM?
VPC VT APC SVT A fib
Test of choice if arrhythmia is auscultated is ECG
What is the test of choice if there are intermittent signs suspected to be due to arrhythmia ?
24hr holter monitor
What is the most commonly used biomarker in clinical feline cardiology?
N proBNP
-IDEXX snap test
What are drugs with potential benefits in treating asymptomatic cats with HCM
Diltiazem ACE inhibitor s Aldosterone antagonist B blocker Antiplatelet drug (clopidogrel)
—> consider severity, risk factors, disease progression, drug side effects
Left atrial enlargement is a risk factor for what diseases?
CHF
ATE
Sudden death
—cardiologists recommend 1>drugs when LAE is present
What drug has been show to significantly reduce dynamic LVOTO?
Beta blocker (atenolol) -negative inotropic
What is the inpatient procedure for CHF due to HCM?
Thoracocentesis for pleural effusion
Furosemide
Supplemental O2
Clopidogrel
Diltiazem /Pimobendan ?
Dobutamine for low output HF (uncommon in HCM)
What is the outpatient procedure for patients with CHF due to HCM?
Thoracocentesis
Oral furosemide
Clopidogrel
ACE inhibitor
Pimobdenan/Diltiazem
Refractory CHF: spironolactone, higher doses of furosemide, HCTZ, or pimobdenan
What is the treatment for arterial thromboembolism ?
Analgesia (fentanyl or buprenorphine)
Antithrombic therapy
- heparin
- clopidogrel
Supportive care
- bladder and prevention of urine/fecal scald
- musculoskeletal support
- nutritional
- monitor for reperfusion injury (hyperkalemia/acidosis), azotemia, arrhythmia, CHF, necrosis, infection
What is the criteria for treating arrhythmias?
Ventricular or supraventricular tachycardia
Frequent singles, couplets, and/or triplets
R on T
How can you treat acute SVT?
Diltiazem or esmolol
How do you treat chronic SVT?
Diltiazem Atenolol Digoxin Ivabradine Amiodarone
How do you treat acute ventricular tachycardia ?
Lidocaine
Esmolol
How do you treat chronic ventricular tachycardia?
Atenolol
Sotalol
Amiodarone
How can clients monitor for progression of heart failure?
Sleeping/resting respiratory rate (>30br/min indicates HF)
New/increased cough (dog)
Lethargy, syncope, weakness, decreased appetite, abdominal distention
How can progression of HR be monitored in the clinic?
HR and rhythm RR and effort Mentation BP Weight Renal values and electrolytes Radiographs ECG Holter Echo
What side effects can result from HF medications that clients should watch for at home?
Appetite
Energy level
Vomiting, diarrhea
Hydration
Mentation
What is the prognosis of HCM?
Good (several years for most) asymptomatic cats
Poor long term prognosis if CHF develops
Sudden death can occur (10-25% of HCM related deaths)
ATE also a potential complications
RCM is a primary myocardial disease that is characterized by _________ dysfunction
Diastolic
T/F: both HCM and RCM are due to diastolic dysfunction and increase in ventricular wall thickness
False
Both are due to diastolic dysfunction
HCM—>increased ventricular wall thickness
RCM—>normal ventricular wall thickness
What changes occur to the heart in RCM?
Focal or diffuse fibrosis in the endocardium and/or myocardium
Walls are usually normal thickness but focal thinning/thickening is possible
Atrial dilation in most common
How does the diastolic filling differ between HCM and RCM?
HCM: prolonged myocardial relaxation -> decreased passive filling
DCM: restrictive filling —> ventricle is stiff impairing atrial systolic filling
What is the signalment of RCM?
Adult onset
Av age 7
No sex or breed predisposed
What are possible PE findings in cats with RCM?
Can have no auscultable abnormalities
Gallop/low grade murmur possible
HR normal/low/high
Premature beat possible
Femoral pulses normal unless ATE
Abnormal lung sounds
Hypothermic if ATE or low output HF
How do you treat cats with RCM?
Asymptomatic with atrial enlargement: antithrombic (clopidogrel) ACE inhibitor (enalapril or benazepril ) \+ pimobdenan if systolic dysfunction is present
Symptomatic: same treatment for HCM with HF
What is the prognosis for cats with RCM?
Symptomatic - mean survivial is 4-9months
