Download diseases of the cardiovascular system

MATTERS OF THE HEART
“The heart has reasons that
reason does not understand.”
-Jacques Benigne Bossuel
DISEASES OF THE
CARDIOVASCULAR SYSTEM
CANINE DILATED CARDIOMYOPATHY
90% of cases occur in Doberman Pinschers and Boxers
OTHER BREEDS INCLUDE WOLFHOUNDS, GREAT DANES, AND COCKER
SPANIELS
CANINE DILATED CARDIOMYOPATHY:
PATHOPHYSIOLOGY
 DECREASED CONTRACTILITY FROM
AN UNKNOWN CAUSE (viral?, carnitine
deficiency?)
Decreased contractility = decreased cardiac
output
CO (CARDIAC OUTPUT) = SV (STROKE VOLUME) X HR (HEART RATE)
The amt. of blood that leaves
The heart
Amt. of blood ejected with
Each cardiac contraction
(affected by afterload, preload,
and inherent contractility)
How often the heart
contracts
CANINE DILATED CARDIOMYOPATHY:
PATHOPHYSIOLOGY
THE BODY COMPENSATES BY:
1. INCREASING THE HEART RATE
*this is done by sympathetic nervous system
stimulation
2. TRYING TO INCREASE STROKE VOLUME
BY INCREASING PRELOAD (this means that
the body increases filling of the heart)
*This is done by activation of the Reninangiotensin-aldosterone system which leads to
sodium and water retention
THE WALLS OF THE HEART ARE WEAK, FLABBY, AND DILATED – THIS
DILATION MAY CAUSE SEPARATION OF THE MITRAL VALVE LEAFLETS
LEADING TO MITRAL REGURGITATION
CANINE DILATED CARDIOMYOPATHY: CLINICAL
SIGNS
LETHARGY, EXERCISE INTOLERANCE, COUGHING, WEIGHT LOSS, TACHYPNEA,
SYNCOPE, SOFT MURMUR (WHERE?)
PLEURAL EFFUSION, ASCITES, HEPATOMEGALY, WT. LOSS
CANINE DILATED CARDIOMYOPATHY
Enlarged, round heart
DOBERMANS ARE DEEP CHESTED AND MAY NOT APPEAR TO HAVE SUCH AN
ENLARGED HEART ON RADIOGRAPHS
CANINE DILATED CARDIOMYOPATHY
PULMONARY EDEMA
PLEURAL EFFUSION
PATIENT MAY SHOW SIGNS OF LEFT-SIDED, RIGHT-SIDED, OR HEART
FAILURE FROM BOTH SIDES
CANINE DILATED CARDIOMYOPATHY:
PATHOPHYSIOLOGY
 Constant stimulation of the heart by the sympathetic
nervous system causes ventricular arrhythmias and
myocyte death
 Most common arrhythmias: VPC’s and ventricular tachycardia,
esp. in boxers & Dobies; other dogs may have APC’s and atrial
fibrillation
ONE VPC
MULTIPLE VPCs
CAUSING TACHY-CARDIA
CANINE DILATED CARDIOMYOPATHY:
ECHOCARDIOGRAM
http://www.youtube.com/watch?v=7TWu0_Gklzo&feature=related
http://www.youtube.com/watch?v=NSnh3qN2kR4&NR=1
PERFORMING AN ECHOCARDIOGRAM IS THE DEFINITIVE WAY TO DIAGNOSE
DILATED CARDIOMYOPATHY
CANINE DILATED CARDIOMYOPATHY:
DIAGNOSTICS
Laboratory tests
Atrial Natriuretic peptide increase
Released from atria in response to excess stretch
Brain natriuretic peptide increase
 released from ventricles in response to excess
stretch
 Pro-BNP release
Troponin 1 (cTn1) increased
Released when heart muscle is damaged
CANINE DILATED CARDIOMYOPATHY:
TREATMENT
INCREASES CONTRACTILITY
DIGOXIN
FUROSEMIDE
REDUCES FLUID
RETENTION
ENALAPRIL
DIURETIC-ELIMINATES EXCESS
FLUID
CANINE DILATED CARDIOMYOPATHY:
TREATMENT
COENZYME Q10
TAURINE – USED IN COCKER
SPANIELS AND CATS, MAINLY
L-CARNITINE
DIETARY SUPPLEMENTS THAT MAY HELP IMPROVE HEART FUNCTION, ESP
IF THERE IS A DEFICIENCY
CANINE DILATED CARDIOMYOPATHY:
CLIENT INFO
DCM is a progressive diseases that is
almost always fatal
Most dogs die within 6 months -2 years
Death may occur suddenly due to arrhythmias
FELINE DILATED CARDIOMYOPATHY
A globular-shaped heart with
severe dilation of all four
chambers. Depressed
ventricular contractile
performance occurs.
Ventricular dilation distorts the
atrioventricular valves leading to
mitral regurgitation and atrial
enlargement
ABNORMALLY THIN VENTRICULAR WALLS
ATROPHIED PAPILLARY MUSCLES
FELINE DILATED CARDIOMYOPATHY
In the 1980’s DCM in cats was one of the
most commonly diagnosed heart diseases.
It was discovered that this was caused by
a deficiency of TAURINE, an amino acid.
Since that time commercial foods have
added taurine to feline diets, which has
significantly decreased the number of
cases of feline DCM