Cardiac Disease Flashcards
What clinical signs and echo findings would you see in a cause of heart worm?
Echo- pulmonary hypertension + pulmonary thromboembolism
End result and signs - right sided congestive heart failure +
pericardial effusion
What is the most common cardiac disease?
Degenerative mitral valve disease
What is the aetiology and signalment in mitral valve dysplasia?
Mitral valve leaflets are too short
Papillary muscles don’t work
Congenital - seen in young large breed dogs
What is the aetiology and signalment of MDVD?
Older small breed dogs
CKCS
Idiopathic nodular thickening of the mitral valve leaflets
What are the haemodynamic effects of MDVD?
Reduced afterload
Increased preload
Reduced stroke volume
Volume overload of the left side of the heart
= eccentric hypertrophy and dilation of the heart
What is the clinical presentation in MDVD?
Grade 1-6, left apical, pan or holo, early sytolic, plateau murmur
+/- palpable thrill
Coughing at night Tachypnoea / dysponea Tachycardia Slow CRT History of lethargy and exercise intolerance Pulmonary crackles
May be a symptomatic
ALWAY REMEMBER TO SIMULTANEOUSLY AUSCULTATE AND PALPATE PULSE
What blood pressure can you expect in MDVD?
Normal
What ECG abnormalities might you see with MDVD?
Supra ventricular premature complexes
Atrial fibrillation
Ventricular premature complexes
(Not VTach, seen in DCM)
What should you sedate a dog in heart failure with?
Butorphanol and alfaxalan top ups
Avoid alpha 2 agonists - cause a reflex bradycardia - massively drop cardiac output
How can you confirm MDVD?
Echocardiography
What findings will you see on echo in MDVD?
Enlarged left atrium and ventricle Mitral valve regurgitation Rounded left ventricle Hyper dynamic systolic function Poor contractility Pulmonary hypertension Tricuspid regurgitation
How can you measure systolic function in MDVD?
Fractional shortening - contractility Ejection fraction - stroke volume E point septal separation - contractility End systolic volume index Systolic time intervals
How can you differentiate MDVD from DCM?
MDVD - left atrium is bigger than the left ventricle, wall is normal thickness
DCM - both the left atrium and ventricle are dilated, thin wall
What clinical pathology results will you see in MDVD?
Pre-renal azotaemia
Elevated cardiac troponin, pro-BNP and pro-ANP
How can you diagnose MDVD in the pre-clinical phase?
Murmur
Holter monitor - VPCs or atrial fibrillation
What is the prognosis of MDVD in the CKCS compared to large breeds?
Better for CKCS - can survive 12m with CHF if well controlled
Poorer for large dogs, deteriorate rapidly
Larger ventricles and atria are poor prognostic indicators, along with ruptured chordae and high pro-BNP
What is the aetiology of endocarditis?
Infection of 1 or more of the endocardium surfaces
- mitral and aortic valves most common
Streps, staphs, e.coli, pseudomonas, bartonella
Bacteriaemia occurs (IV catheter, dental disease)
Multiple emboli - concurrent plolyarthrits, glomerulonephritis, neuro
Bacteria adhere to damage enocardium (eg subaortic stenosis)
Aided by a hyper coagulate state
How does endocarditis present?
New murmur
Diastolic murmur
PUO - classic presentation
Arrhythmias, myocardial infarction, signs of CHF
Medium to large breeds
How can you diagnose endocarditis?
Haematology and biochemistry
Blood culture
Echocardiography - valvular vegetations, regurgitation, systolic dysfunction
Major criteria
What are the major criteria for defining endocarditis?
Positive echocardiogram
- vegetative, oscillating lesions, erosive lesions, abscess
New valvular insufficiency / diastolic murmur
Positive blood culture - 2 positive cultures
How should you treat endocarditis?
IV antibiotics for 1-6w
Fluoroquinolones + metronidazole + potentiated amoxicillin
C-reactive proteins
Anticoagulants
What is the prognosis for endocarditis?
Guarded - recurrent problems and CHF possible
Irreversible valvular damage
What types of primary cardiomyopathy are there?
Dilated cardiomyopathy
Arrthymogenic right ventricular cardiomyopathy
Hypertrophic cardiomyopathy - rare in dogs, terriers, pointer
- 2ndry to left ventricular outflow tract obstruction
Atrial cardiomyopathy - springers, Labrador
- atrial walls thin leading to atrial standstill
What secondary cardiomyopathies occur?
Myocarditis - viral, automimmnue, infectious, traumatic
Tachycardiomyopathy - most common
- seen with AF, VTach and SVTach
Other causes Nutritional - taurine or l-carnitine deficiency Systemic hypertension Drugs and toxins Metabolic and endocrine
What is the aetiology and signalment of DCM?
= impaired systolic function + dilated cardiac chambers
Seen in middle aged medium to large breed dogs
Idiopathic but likely to be genetic
Dilation of all 4 chambers and increased heart to body weight ratio
What is the most common cardiomyopathy in dogs?
DCM
What is the cardiac decompensation in DCM?
Dilation of the AV value annulus = mitral regurgitation
Fibrosis and arrhythmias due to cardiac remodelling
Increased hydrostatic pressure = congestion
Toxicity to myocyte a due to sympathetic drive
How does DCM present in the Doberman?
Slowly progressive
Inherited
Ventricular arrhythmias and sudden death
Cardiomegaly
Screening recommended every 4 months - short survival after development of CHF
What is the aetiology and signalment seen with arrhythmogenic right ventricular cardiomyopathy?
= loss of cardiac myocytes, replaced with fibro-fatty tissue
Boxers
What is the clinical presentation of ARVC?
Asymptomatic with VPCs
Symptomatic with VPCs
Ventricular dilatation, myocardial dysfunction and dysrrthymias
May present as sudden death
May also present as syncope and exercise intolerance
Cough, tachypnoea, dysponea, abdominal distension, increased water intake, heart murmur
What presentation would you expect in a dog with DCM?
Large breed or cocker spaniel
Grade 1-3 systolic heart murmur, some dogs have none
Gallop sound
Adult dog with a history of collapse
What would you find on the rest of your clinical exam in a case of DCM?
Cardiac cachexia Pale mm and slow CRT Tahcyponea, dysponea Weak femoral pulses Chest percussion - pleural effusion Jugular distension Abdominal effusion Respiratory crackles
What are the two presentations of DCM?
Preclinical - sudden death and ventricular arrhythmias
Clinical - forwards and backwards heart failure
What arrhythmias are seen with DCM?
AF
SVTach
VTach
VPCs
What is the definitive diagnosis of DCM?
Echocardiography
Left and right sided chamber enlargement
Thin walls
Reduced contractility and systolic function
Mild to moderate mitral valve regurgitation
How many VPC on a holster monitor in 24h would make you suspicious of cardiomyopathy?
Doberman - more than 50 VPCs
Boxer - 100-300 VPCs
Likely affected 300-1000
Affected greater than 1000
What drug is indicated in pre-clinical DCM?
Pimobendan
+/- Benazepril - used in people
What conditions should you consider treating in DCM?
Supraventricular tachycardia Ventricular tachycardia Pulmonary hypertension Preclinical disease Congestive heart failure
What is the prognosis for DCM?
Better with cocker spaniels with taurine deficiency, especially if over two - contractility improves after taurine supplementation
Dobermanns can live 2-4y with preclinical DCM
Survival only around 4m after development of CHF
What are common causes of a secondary myopathies in cats?
Hypertension
Hyperthyroidism
How should you investigate hypertension in a cat?
Haematology and biochemistry
Total T4
Urinalysis
What complications can hypertension cause?
Retinal detachment
Neurological problems
Renal damage
What is the pathology and presentation in feline HCM?
Marked concentric hypertrophy of the left ventricle = reduced diastolic function & reduced compliance
Present as sudden death, sleeping more or dysponeic
Persians, Maine coons, ragdoll, Norwegian forest cat
What other diseases must you rule out to make a diagnosis or hypertrophic cardiomyopathy?
Aortic stenosis Systemic hypertension Hyperthyroidism Chronic renal failure Acromegaly Diabetes mellitus
What diagnostic signs will you see on echo in a cat with HCM?
Thickened left ventricular wall and septum
= more than 1/3 of chamber diameter
Enlarged papillary muscles
Bulging left atrium
Smoke in the the left atrial appendage
SAM of MV
Mild mitral valve regurgitation (exacerbates hypertrophy)
What are the radiographic signs of HCM?
Cardiomegaly
Enlarged left atrium
DV - typical valentines heart - left side of the heart is pushing the atrial septum over to the right
Signs of CHF - patchy alveolar pattern seen in cats with CHF
(Less predictable distribution)
Congested pulmonary veins
What signs might you see on electrocardiography in HCM?
Left fasicular bundle branch block
Atrial fibrillation
Left ventricular enlargement - tall T waves
What produces the murmur in HCM?
Atrial septum bulge obstructs the LVOT
= high ventricular outflow tract velocity and biphasic acceleration
SAM of the mitral valve
What kind of murmur is produced in HCM?
Diastolic, Gallop murmur - hear S3 and S4
Harsh murmur
What are the two presentations of HCM?
Asymptomatic but have a murmur
Left sided congestive heart fairlure
How does a cat with FATE present?
Extreme pain - methadone ASAP!!
Paraplegic
Hypothermia of the limbs
Blue nail beds
- due to thrombus at the aortic bifurcation – external iliac arteries
How should you treat clinical HCM and CHF?
Furosemide IV - venodilator and reduces blood volume (preload)
Benazepril - ace inhibitor (licensed for renal disease)
Per untold - venodilators
Prevent thromboembolism - clopidogrel
Furosemide and enalapril have been proven to reduce the risk of an adverse outcome in cats with CHF due to HCM
How can you treat preclinical HCM?
Beta blockers - Propanolol, emsomolol
- reduce LVOT and SAM
- slows heart rate and improves diastolic function
- CI in CHF
Pimobendan - Ca channel blocker
Benazepril - ace inhibitor
Diltiazem - positive lusiotrope = improves diastolic filling
There is no evidence that any drug slows down the progression to CHF
How does DCM usually present in cats and what must you rule out?
Usually collapse and in cardiogenic shock
Must rule out taurine deficiency as a cause - supplement
How should you manage DCM due to taurine deficiency in cats?
Taurine Pimobendan Benazepril Furosemide Digoxin
O2 therapy
Warmth
Drain the pleural effusion
What are the two forms of restrictive myopathy seen in cats?
Endomyocardial - large atrium and bridging scars
Unclassified - has features of different types of cardiomyopathy
Usually have normal ventricular wall measurements, chamber size and function
However the left atrium is dilated and diastolic is reduced due to restrictive pathology
How does ARVC usually present in cats?
Ventricular arrhythmias and right sided congestive heart failure
What are the consequences of HCM?
Left sided congestive heart failure
FATE
Hypertension
Arrhythmias
What does increased pro BNP suggest?
Ventricular stretch
What does increased cardiac troponin I suggest?
Ischaemic episode, neoplasia, myocarditis
= damage to myocardium
When should you recommend a cardiology work up to an owner?
Grade 3+ mitral valve regurgitation
Grade 4+ mitral valve regurgitation
How should you work up a dysponeic patient with a history of MDVD?
Auscultate - determine progression of murmur
Palpate pulses, CRT mm colour
Give oxygen
Sedate with butorphanol for thoracic radiographs
T fast scan to check for pericardial effusion
Give IV furosemide after ruling out pericardial effusion
Take baseline bloods
How should you work up a MDVD with a chaotic heart rhythm no is collapsed?
ECG
Oxygen
T fast to rule out pleural / pericardial effusion
IV furosemide
What underlying conditions lead to VPCs and ventricular tachycardia, therefore must be treated first?
CHF - myocardial hypoxia and ischaemia Catecholamines - stress and pain Hypokalaemia Acidosis Abdominal disease - GDV - pancreatitis - splenic lesions - pyometra - sepsis - perforated GI ulcer
What underlying factors do you need to identify and exclude before treating a bradyarrhythmia?
High vagal tone
Hyperkalaemia - addisons, urinary obstruction, anuric RF
Hypothyroidism
Drug side effects
