DCM Flashcards
What is the typical signalment of DCM?
• Tend to be large or giant pedigree breeds
• Dobermann, Weimaraner
• Giant breeds: Newfoundland, Great Dane, Irish
Wolfhound, St Bernard, Leonberger, Deerhound,
Dogues de Bordeaux etc.
• Also some small breeds: American & English Cocker
spaniels, Standard Schnauzer.
• Portuguese water dogs: unusual juvenile form in US
• Rare in cross-breed dogs
• Both sexes affected, but males over-represented with
CHF signs (i.e. DCM may progress more rapidly in
males?)
• Boxer dogs: Arrhythmogenic Right Ventricular
Cardiomyopathy (ARVC)
What actually is DCM?
• A primary myocardial disorder
• Poor systolic function (i.e. pump function)
• Leads to progressive dilatation of the left ventricle,
then left heart chambers and sometimes all 4 heart
chambers.
• The left ventricle also becomes rounded, with loss of
the normal elliptical geometry.
• Left ventricular walls appear thin relative to LV
chamber dilatation (i.e. decreased relative wall
thickness) (although there is some eccentric LV
hypertrophy)
What are the pathological findings in DCM?
Flabby heart
4 chamber dilation
Attenuated wavy cardiac fibres
Fibrofatty infiltration - these are the dogs with arrythmias
What do you find on echo with DCM?
Dilated, rounded thin walled left ventricle with v poor pump function
What atrial arrythmias do you see with DCM?
Atrial fibrillation
Associated with severe atrial stretch
mostly seen in dogs with clinical DCM (CHF)
Can see A fib prior to overt heart disaese - especially in giant breeds e.g. Irish Wolfhounds
Normally sounds less chaotic and the heart rat is not as high
What ventricular arrhythmias are found with DCM?
Can get these before changes on echo Mostly doberman/ Great Dane/ Weimeranas Also seen in Boxers with ARVC VPCs of Ventricular tachycardia Signs may include syncope or sudden death
What do you have to consider before making a diagnosis of idiopathic DCM?
• Need to actively exclude other conditions which might result in dilatation of the heart chambers and development of arrhythmias.
• MMVD in large breed dogs often associated with myocardial failure
• Need to exclude other acquired or congenital heart disease (e.g. mitral dysplasia).
• Exclude primary arrhythmias such as supraventricular
tachycardia, which may result in secondary tachycardia induced cardiomyopathy (TICM)
• Ventricular arrhythmias may be associated with abdominal disease. Consider abdominal ultrasound.
• Athletic hearts? (e.g. Springer spaniels)
• Hypothyroidism
How prevalent is DCM in the doberman?
Up to six clinically affected
But if you screen for it up to 60%
What are the clinical signs of DCM?
• L-CHF: cough, tachypnoea, dyspnoea, inspiratory
crackles on auscultation
• Forward heart failure: weak femoral pulses, quiet
heart sounds, cold extremites, pale mucus membranes, slow CRT. History of exercise intolerance or lethargy.
• R-CHF (usually biventricular CHF): ascites, jugular
distension, positive hepatojugular reflux etc. May be
pleural effusion.
• Cardiac auscultation: Quiet heart sounds, soft (
grade 3/6) systolic murmur (MR), S3 diastolic gallops,
premature beats / pauses following, overt arrhythmia.
What are the clinical signs of occult ‘pre’ DCM?
• There may be NO abnormalities on physical
examination.
• Need to screen by echocardiography
• However, be suspicious if there is a soft heart
murmur, any premature beats or arrhythmias, or if
heart sounds seem “too quiet” for conformation and
body condition of the dog.
• If the patient is due to have a surgical procedure
requiring a long anaesthetic, it might be worth
screening for DCM.
What are the findings on echo of DCM?
Dilated LV in systole and diastole Low fractional shortening \+/- LA dilation if near or in heart failure Possibly secondary mitral regurgitation \+/- RHS dilation
What are the possible features of overt DCM?
- Left or Bi-Atrial enlargement
- Increased Mitral M-mode EPSS
- Arrhythmias
How would you interpret different results on a holter monitor being used to screen for DCM?
• < 50 VPCs / 24 hours normal (usually <10)
• >300 VPCs / 24 hours abnormal
• 100 – 300 VPCs / 24 hours: equivocal; recheck after
6 months.
• If fast couplets, triplets or runs of ventricular tachycardia, also abnormal.
How can radiography be used for DCM investigations?
Gold standard for heart failure
R lateral and DV
May see a v sharp cardiac silhouette due to poor systolic function
N.B Dobies do not have as dramatic changes in the heart on rads as the heart appearance starts out v long and thin
Why take BP?
May be in cardiogenic shock
Worry if BP < 100 - give positive inotrope if so
How can clin path help with investigations?
Haem - as may have pallor
Biochem - d/t expected diuresis
Cardiac bbiomarkers - Can be helpful as a screening tool but not diagnostic and not 100% sensitive and specific
Troponin good for prognosis
What is ARVC?
Mostly in Boxers but also seen in English Bulldogs and others
Characteristic histo path of loss of cardiac myocytes and adipocyte infiltrate
Mostly RV, can also affect LV + atria
Familial disease
What are the three types of presentation of ARVC?
• Category 1: Incidental arrhythmias (ventricular
premature complexes; no syncope, normal echo)
• Category 2: Syncope due to ventricular tachycardia.
May or may not be associated with echo changes.
• Category 3: DCM like phenotype, also with
ventricular arrhythmias. Often present with CHF.
how do you treat ARVC?
If DCM like with CHF - treat as if it were that
Acute arrythmias - lidocaine
Long term oral meds for arrhythmia - sotalol
What are the secondary nutritional DCM like phenotypes?
• Taurine deficiency. Not simply cause & effect
(contrast to cats with DCM). Consider it in American
and English Cocker Spaniels, Golden Retrievers,
Newfoundlands.
• Grain-free diets. Recently described, some but not
all associated with taurine deficiency. Important to get
good diet history, especially if an atypical breed is
diagnosed with DCM.
• L-carnitine deficiency. Reported in some Boxers
with DCM phenotype, with low myocardial L-carnitine
levels (but not blood levels).
What are the secondary myopathies similar to DCM?
Drugs / Toxins
• e.g. Doxorubicin / Epirubicin chemotherapy drugs
Arrhythmia induced
• Called tachycardia induced cardiomyopathy
(TICM), e.g. due to sustained supraventricular
tachycardia.
Generalised myopathies also affecting the heart
• E.g. muscular dystrophy in Golden retrievers.
Myocarditis
• DCM phenotype can be end-stage consequence of
prior infectious or immune mediated myocarditis.
Nutritional
What is the standard Tx for DCM?
Quad therapy
Frusemide as diuretic
Pimobendan as +ve inotrope and vasodilator
Spironolactone and ACEi to combat RAAS
Which dogs and good and bad prognosis?
Dobies - MST 8 weeks after onset of CHF
Cockers - very good even when in heart failure
How can you treat cardiogenic shock in DCM?
IV pimobendan
Can also do a dobutamine CRI, but there is a risk of excessive tachycardia/ proarrhythmia - need to monitor with and ECG
Avoid IVFT as you already have increase Na and H20 retention and don’t want to increase it further
