Acquired murmurs in dogs Flashcards
What are the 2 causes of acquired murmurs in dogs?
Endocardial disease and myocardial disease
Give examples of endocardial disease
Endocardiosis (usually mitral valve), endocarditis (rare)
In which breed is endocardiosis most prevalent?
CKCS (43% die from heart disease)
Describe the pathophysiology of endocardiosis
- valve leakage
- volume overload of LV
- eccentric hypertrophy of LV
- decreased cardiac output
- RAAS stimulated
- L CHF
- cough, dyspnoea, exercise intolerance, pulmonary hypertension and R CHF
Describe the signalment for endocardiosis
- small breeds
- males > females
What history may come with a dog with endocardiosis?
- asymptomatic
- low grade murmur
- L CHF - cough, dyspnoea, tachypnoea, exercise intolerance
- develop R CHF - ascites, dyspnoea (pleural effusion)
What are the clinical findings in a dog with endocardiosis?
- systolic murmur over mitral +/- tricuspid valve (murmur grade proportional to severity of disease, >4 = CHF)
- early stage of disease - good myocardial function and pulse quality
- +/- dyspnoea
- +/- ascites
- +/- arrhythmias
These radiographic findings are associated with which endocardial disease?
- early stage = LA/LV enlargement, normal R side
- progressed = airway compression, generalised cardiomegaly, venous congestion in heart and lungs
Endocardiosis
What ECG findings are associated with endocardiosis?
- tall R wave = LV enlargement
- wide P wave = LA enlargement
- early stage - supraventricular beats
- ventricular arrhythmias (LV dilated and stretched)
- hypoxia
- occasional VPC
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What echo findings are associated with endocardiosis?
- early stage = thickened mitral valve, may prolapse into L. Normal systolic function
- progressed = thickened valve, remodelling of LV and LA (dilated). Regurgitation on Doppler
What are the tx options for endocardiosis?
Tx depends on the stage of disease
Use a CHF classification system to guide tx
Describe bacterial endocarditis
- affects valves on the L side
- aortic valve is most common site
- mitral valve is second most common site
- aortic stenosis predisposes to development of endocarditis
How do dogs with endocarditis present?
- pyrexia
- joint stiffness - shifting lameness
- new L sided murmur
How is endocarditis diagnosed?
- blood culture (bacteraemia)
- urinalysis and culture
- joint tap
- echocardiography - vegetations
- thoracic radiography - cardiomegaly, CHF
- abdominal US - infarct in organ
- haematology and biochem
What are the treatment options for endocarditis?
- antibiotics and supportive therapy
- guarded prognosis
Describe the aetiology of DCM
- Primary - idiopathic, hereditary (giant breeds)
- Secondary - toxic, taurine deficiency, carnitine deficiency, tachycardia induced (abnormal accessory pathways)
Describe the pathophysiology of DCM
Describe the signalment for DCM
- medium - large breeds, and cocker spaniels
- middle aged - older
- males > females
What hx may a dog with DCM present with?
- exercise intolerance (forward failure)
- L CHF
- R CHF
- ventricular arrhythmias
- asymptomatic
What findings on diagnostic imaging are indicative of DCM?
- radiography - LA and LV enlargement, +/-CHF, pleural effusion
- ECG - wide P wave, tall R wave, AF, ventricular arrhythmias
- echo - mitral valve insufficiency (small murmur), weak IVS movement, poor systolic function, enlarged LV and LA
What are the treatment options for DCM?
- increase systolic function - pimobendan, digoxin, dobutamine
- decrease preload - diuretic, ACE inhibitors
- decrease afterload - ACE inhibitors, inodilator
- arrhythmias - digoxin, Ca channel blocker, B blocker
- prevent further remodelling - ACE inhibitors, spironolactone, pimobendan
In which breeds is ARVC most common?
Boxers, bulldogs
Describe the pathophysiology of ARVC
- arrhythmias cause forward failure = syncope
- poor myocardial function = pulmonary oedema, ascites (backward failure)
- rapid VT = cardiogenic shock
- fatty infiltrate of R side (seen in boxers)
How is ARVC managed?
- pimobendan - supports systolic function
- ACE inhibitors - prevent further remodelling
- sotalol, mexilitine, atenolol, amiodarone - life threatening arrhythmias
What criteria must be met before using anti-arrhythmic drugs?
- runs of VT >180bpm
- multiform VPCs
- close coupling of ventricular ectopics
Describe myocarditis
- hx and CS may not be specific for cardiac disease
- may be secondary to toxoplasma, neospora, parvo, neoplasia
- arrhythmias common
- may develop poor systolic function, secondary dilation with low grade murmurs
- dx difficult - increased serum troponin supportive
- tx - treat primary disease, arrhythmias, CHF
- prognosis guarded
