DCM Flashcards

1
Q

What is the typical signalment of DCM?

A

• 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)

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2
Q

What actually is DCM?

A

• 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)

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3
Q

What are the pathological findings in DCM?

A

Flabby heart
4 chamber dilation
Attenuated wavy cardiac fibres
Fibrofatty infiltration - these are the dogs with arrythmias

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4
Q

What do you find on echo with DCM?

A

Dilated, rounded thin walled left ventricle with v poor pump function

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5
Q

What atrial arrythmias do you see with DCM?

A

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

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6
Q

What ventricular arrhythmias are found with DCM?

A
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
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7
Q

What do you have to consider before making a diagnosis of idiopathic DCM?

A

• 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

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8
Q

How prevalent is DCM in the doberman?

A

Up to six clinically affected

But if you screen for it up to 60%

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9
Q

What are the clinical signs of DCM?

A

• 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.

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10
Q

What are the clinical signs of occult ‘pre’ DCM?

A

• 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.

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11
Q

What are the findings on echo of DCM?

A
Dilated LV in systole and diastole
Low fractional shortening
\+/- LA dilation if near or in heart failure
Possibly secondary mitral regurgitation
\+/- RHS dilation
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12
Q

What are the possible features of overt DCM?

A
  • Left or Bi-Atrial enlargement
  • Increased Mitral M-mode EPSS
  • Arrhythmias
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13
Q

How would you interpret different results on a holter monitor being used to screen for DCM?

A

• < 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.

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14
Q

How can radiography be used for DCM investigations?

A

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

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15
Q

Why take BP?

A

May be in cardiogenic shock

Worry if BP < 100 - give positive inotrope if so

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16
Q

How can clin path help with investigations?

A

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

17
Q

What is ARVC?

A

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

18
Q

What are the three types of presentation of ARVC?

A

• 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.

19
Q

how do you treat ARVC?

A

If DCM like with CHF - treat as if it were that
Acute arrythmias - lidocaine
Long term oral meds for arrhythmia - sotalol

20
Q

What are the secondary nutritional DCM like phenotypes?

A

• 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).

21
Q

What are the secondary myopathies similar to DCM?

A

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

22
Q

What is the standard Tx for DCM?

A

Quad therapy
Frusemide as diuretic
Pimobendan as +ve inotrope and vasodilator
Spironolactone and ACEi to combat RAAS

23
Q

Which dogs and good and bad prognosis?

A

Dobies - MST 8 weeks after onset of CHF

Cockers - very good even when in heart failure

24
Q

How can you treat cardiogenic shock in DCM?

A

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

25
Q

How does an ACEi improve survival time in DCM cf MMVD?

A

Improves survival more in DCM

26
Q

When do you treat A fib?

A
When HR/ 24 is >140 rate (NOT RHYTHM) control is indicated
Use digoxin (vagomimetic effect)
\+/- diltiazem via Ca channel blockade in AV node

To check ventricular rate response, asses HR in cons. in <150 likely OK, if higher, need to use a holter to properly assess

27
Q

How and when do you treat ventricular arrhythmias assocaited with DCM?

A

If haemodynamically signifcant or judged to be life threatening
may need it even if not syncopal
Normally with sotalol
If this is not effective can give mexilitine but this is £££
Should always check with holter 2–4 weeks after to ensure efficacy of treatment and exclude proarrythmias

28
Q

Does slow AF need treating

A

Not normally
Rate normally a lot lower (within normal limits)
Only occasional pulse deficits
Variable pulse volume evident

29
Q

How can you try to treat cardiac cachexia?

A

Fish oil supplement (high Omega-3):
- Eicosapentonoic acid / - Docosahexanoic acid. In 3 to 2 ratio
Counteracts inflammatory cytokines associated with CHF
Improves appetite, reduces muscle and weight loss.
May also be anti arrhythmic

30
Q

What should you treat pre-clinical DCM patients with?

A

Pimobendan - gives on average 9 months extra preclinical life
Some retrospective evidence for ACEi also