Lec 1 - 3 Flashcards by Sam Lumby

Define heart disease

The presence of any harmful or potentially harmful cardiac finding outside of normal limits

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Define heart failure

Heart disease that is severe enough to overwhelm compensatory mechanisms of the cardiovascular disease

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What does DAMNIT-V stand for?

Degenerative, developmental
Autoimmmune, allergic, anomalous 
Metabolic
Neoplastic, nutritional 
Inflammatory, infectious, immune-mediated, iatrogenic, idiopathic
Toxic, traumatic 
Vascular

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What is an innocent murmur?

Haemic or physiological murmur

Doesn’t indicate that anything is wrong

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What is the most common cardiac disease?

Chronic valvular heart disease for small to medium dogs

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What form of canine cardiomyopathy is the most common?

Dilated from and usually affects large and giant breeds

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What type of chronic valvular disease is the most common in dogs?

Mitral 62%

Mitral and tricuspid 32.5%

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What are 3 common synonyms for chronic valvular heart disease?

Mitral/tricuspid endocardiosis
Myxomatous AV valve disease
Progressive myxomatous degeneration of the heart valves

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In valvular endocardiosis, what can also rupture?

The chordae tendinae

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What are some of the aetiologies of chronic valvular heart disease in dogs?

Dyscollagenosis (genetic degeneration of collagen)
Response to injury lesions
Inherited predisposition (polygenic inheritance)
Uncertain

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Describe the pathophysiology of chronic valvular heart disease in dogs?

Nodular valvular lesions grow
Eventually get leakage/ insufficiency/ regurgitation of blood
From the ventricle to the atrium
Start hearing a murmur
Progresses over years
Extra volume of blood regurgitating into the atrium (LS vol. overload)
Heart beats harder
Atrial walls stretch and remodel
Keeps worsening over time
Volume overload leads to ventricular dilation and eccentric hypertrophy
RAAS kicks in
Eventually atrium and veins can’t remodel/ compensate enough
Pulmonary lymphatic drainage increases
Eventually this can’t keep up and oedema develops
Venous pressure rise
Develops into congestive heart failure

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Is a dog with a mitral murmur always in heart failure?

No.

However it will progress over many years and eventually it will lead to failure

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Can you judge a murmur’s severity by loudness?

No.

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In chronic valvular heart disease the heart muscle is damaged and enlarged and makes what other cardiac condition more likely?

Spontaneous depolarisation

Rhythm disturbances
Supraventricular more likely than ventricular

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What are 2 clinical exam findings that you can find in a dog with right sided congestive heart failure, apart from listening to heart?

Excessive jugular pulse which will rise over 1/3 up the neck - especially if you press on the cranial abdomen
Ascites
(Also the liver enlarges so that may be palpated if lucky)

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What will cause chronic passive congestion of the liver?

Mitral and tricuspid valve failure

Right sided heart failure

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What type of chronic valvular heart disease is most likely to cause pleural effusion in dogs?

Biventricular failure

Although usually will only see pulmonary oedema

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How can mitral regurgitation and development of left heart failure predispose to right heart failure? (especially if there is the beginning of lesions on the tricuspid valve)

Backup of blood in lungs since LS not pumping properly
Get increased pressure in lungs
Harder for the right side to pump against this

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What is the consequence of a ruptured chordae tendinae?

Sudden onset of pulmonary oedema
Pale
Collapsed

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What is the consequence of an atrial tear of the septum?

Blood goes from the left to right side of the heart
Goes into RSHF suddenly
Ascites

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What is the consequence of sudden tachyarrhythmia (usually supraventricular)

Faint

Die

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What do clinical features seen in a dog with chronical valvular heart disease depend on?

The stage at which the animal is presented

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What are some common findings during a clinical exam of a dog with chronic valvular hear disease?

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Murmur - New or worsening
Cough at night, early morning, at exercise
Exercise intolerance
Weakness
Syncope
Dyspnoae, tachypnoea, orthopnoea 
Sudden death

What specific things should you look at/do in a physical examination of an animal with suspected heart disease?

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Capillary refill time
Mucous membrane colour and temperature
Heart and lung sounds
Presence of an apical beat/thrill
Heart rate and rhythm
Arterial pulse character and rhythm (femoral artery)
Jugular pulse and distension

What heart rates are classified as bradycardia in a -medium, large and small dog, and cats?

``` Heart rate under - Medium dog - 70 Large dog - 60 Small dog - 90 Cat - 120 ```

What heart rates are classified as tachycardia in a -small dog, and cats?

Heart rate over - Small dog - 160 Cat - 220 (unless very stressed)

What causes the first heart sound?

Closure of the AV valves | -mitral and tricuspid

What causes the second heart sound?

Closure of the aortic and pulmonic valves

Where is the first heart sound the loudest?

Over the heart apex | tip

Where is the second heart sound the loudest?

Over the heart base | top

What causes a 'split' heart sound?

When the pairs of valves don't close at exactly the same time

What is the cause of a murmur?

Turbulent blood flow within the heart

How should you describe a murmur? (4 things)

Loudness/grade (out of 5/6) When during the cardiac cycle Where it can be heart Quality - musical, frequency, blowing etc.

When during the cardiac cycle are you most commonly going to hear a murmur?

Systolic contraction

What are 4 causes of syncope?

Bradyarrhythmia Tachyarrhythmia (heart doesn't fill properly) Long bout of coughing (prevents venous return) Severe left mainstem bronchus collapse

What are 5 differential diagnoses for chronic valvular heart disease in dogs?

``` Primary respiratory disease Cardiomyopathy Infective endocarditis Sick sinus syndrome Late-presenting congenital disease ```

How do you make a diagnosis of chronic valvular heart disease in a dog?

``` Systolic murmur in small to medium dog (esp. mitral) +/- cough Exercise intolerance Weakness, syncope Dyspnoea, tachypnoea Lung crackles Ascites etc. Radiography looking for cardiomegaly +/- Echocardiography, ECG (not essential for common CVHD) ```

What should you offer the client to perform if you find a murmur in a happy, healthy dog?

Baseline thoracic radiographs Arterial blood pressure measurement Baseline basic blood work and urine analysis (PCV, TPP, creatinine) -If all normal then re-examine in 6-12 months and keep an eye on it

What are the treatment principles for canine chronic valvular heart disease?

Control signs of CHF Limit the excessive neurohormonal activation that contributes to disease progression Try to decrease LV size Promote forward flow of blood Halt progession of valvlular degeneration (not yet possible)

How should you treat a dog with chronic valvular heart disease that has no other clinical signs?

Client education Routine health maintenance Monitoring Avoid high salt foods

How should you treat a dog with chronic valvular heart disease that is showing mild to moderate heart failure?

``` As a dog with no clinical signs PLUS Exercise restriction until under control ACEI - vasodilator, apposes RAAS) And/or Pimobendan - inodilator Frusemide - enough to improve breathing (NOT on its own) Moderate dietary salt restriction +/- Digoxin for tachyarrhythmias If frusemide stops working - Spironolactone ```

One week after starting or increasing the dose of an ACEI, what must you do?

Check that the drug has not raised serum creatinine substantially Also measure Na/K

How should you treat a dog with chronic valvular heart disease with a severe, acute presentation?

``` Supplemental 02 Cage rest Close monitoring Drain large effusion I/V Frusemide Oral pimobendan +/- Oral ACEI Nitroglycerine ointment and nitroprusside infusion (vasodilators) Dopamine/dobutamine infusion (positive inotropes) ```

What are two synonyms for infective endocarditis?

Bacterial/fungal endocarditis | Vegetative (valvular)endocarditis

What are the vegetations in infective endocarditis made of?

Made of fibrin and platelets | With some bacteria/pathogen inside

In infective endocarditis, where to the circulating organisms colonise and damage?

The endocardium and heart valve

What two valves are most commonly affected in infective endocarditis?

Mitral or aortic

Is infective endocarditis associated with chronic, degenerative AV valve disease?

What is a prerequisite of getting infective endocarditis?

A blood-borne infection

What are the 4 most common infective agents responsible for infective endocarditis?

Staphylococcus Streptococcus E.coli Pseudomonas aeruginosa -Bartonella in hard-to-diagnose cases maybe

Describe the pathogenesis of infective endocarditis?

Blood-borne infection Damages mitral and aortic valves most commonly Valve leaflet endothelium ulcerates Platelets adhere to sub-endothelial collagen Fibrin deposition Enlargement - vegetations Flimsy, friable at first and turn into calcified and fibrous Cause valvular insufficiency and/or stenosis Young vegetations can break off and lodge in kidneys mainly (also brain if aortic valve affected) Process is quick and develop Left sided CHF in days

What are some clinical features that you will see in a patient with infective endocarditis?

``` Fever usually New/changing heart murmur Stiffness, lameness, +/- joint swelling Lethargy anorexia, weight loss GI signs +/- signs of congestive heart failure +/- syncope Very unhappy, sick animal ```

In infective endocarditis what causes stiffness, lameness and possible joint swelling?

Antigen-antibody complexes enter the joints. | Makes synovial fluid less viscous

What kind of murmur are you most likely to hear in a dog with infective endocarditis?

Diastolic murmur At the heart base (aortic valve affected)

How do you diagnose a dog with suspected infective endocarditis?

Echocardiograph - see flopping vegetations or valve destruction New murmur that is definitely new Positive blood cultures ECG and blood tests not that helpful

How do you collect blood for culture in a suspected infective endocarditis case?

Sterile venipuncture Large volume over 10mL if possible From different veins more than an hour apart Blood goes into a special culturing bottle for aerobic incubation

How do you treat a dog with infective endocarditis?

Aggressive therapy with bactericidal antibiotics that are capable of penetrating fibrin E.g. Beta lactam & aminoglycoside OR a fluoroquinolone IV for the first week 6-8 weeks (watch for aminoglycoside toxicity since nephrotoxic) Supportive care - CHF, arrhythmias

Lec 1 - 3 Flashcards

(57 cards)