Download diseases of the cardiovascular system

CONGENITAL
DEFECTS
CHIHUAHUAS, MALTESE, POODLE, POMERANIAN, SHELTIE
PUPPIES COMMONLY AFFECTED
Normally, the ductus arteriosus carries blood from the pulmonary artery
to the aorta during fetal development. It bypasses the lungs of the fetus.
The duct should close in the first
12-24 hours after birth. If it does
not, the blood begins to shunt
from the aorta into the
pulmonary artery and
hyperperfuse the lungs.
The left side of the heart will
have an increase in blood return
and become volume overloaded.
THIS IS CALLED A LEFT-TO-RIGHT SHUNT
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CLINICAL SIGNS:
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A loud murmur best heard over the left base
Sometimes called a “machinery” murmur or a
continuous murmur
If the shunt is small some animals may be asymptomatic
In large shunts the animal will develop left-sided heart
failure
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Pulmonary edema
Cough
Exercise intolerance
Tachypnea
Weight loss
ECG: wide range of arrhythmias including APCs and
VPCs
Echocardiography (ultrasound)
Radiographs: left atrial and ventricular enlargement
EXCELLENT PROGNOSIS WITH SURGICAL CORRECTION: LIGATION O
THE DUCTUS ARTERIOSUS
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CLIENT INFO:
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64% OF ANIMALS WILL DIE WITHIN 1 YEAR IF
NOT TREATED SURGICALLY
Dogs with this condition should not be used for
breeding
Atrial Septal Defect
During fetal life, the foramen ovale is an openingi n the interatrial septum, allowing
shunting of blood from the right atrium to the left atrium in order to bypass the
nonfunctioning fetal lungs. It should close at birth. If it doesn’t, after birth, the blood
will shunt from left to right resulting in overload of the right side of the heart.
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CLINICAL SIGNS: ATRIAL SEPTAL
DEFECTS
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Result in overload of the right side of the heart →
dilation and hypertrophy of the right-sided
chambers
Systolic murmur
Right-sided heart failure
Radiographs: right ventricular enlargement
Echo: right ventricular dilatation
Blood is shunted from the oxygen-rich left ventricle into the right ventricle. The blood
goes through pulmonary circulation and right back into the left atrium and ventricle
resulting in volume overload of the left side of the heart. The right ventricle may dilate
as well.
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CLINICAL SIGNS: VENTRICULAR SEPTAL
DEFECTS:
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Animals with small defects may have minimal or no
signs
Larger defects may result in acute left-sided heart
failure, usually by 8 weeks of age
A harsh holosystolic murmur
CLIENT INFO:
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Repair of these defects requires open-heart surgery or
cardiopulmonary bypass. These procedures are
uncommon in the dog and cat
Most of these animals will eventually experience
development of congestive heart failure
Chihuahuas, English Bulldogs, are commonly affected. CAUSE: polygenic inheritance
In pulmonic stenosis, the right ventricular outflow tract is narrowed
either at the valve itself, just below it, or just after it.
The most common form of pulmonic stenosis involves
a deformed pulmonary valve such that the valve leaflets
are too thick, the opening is too narrow, or the valve cusps
are fused.
The heart must pump extra hard to get blood through
This unusually narrow, stiff valve.
The right ventricle becomes thickened from all this extra work. The right atrium
May become dilated and hypertrophied.
NORMAL CANINE CHEST RADS
THIS DOG HAS PULMONIC STENOSIS –
THE HEART LOOKS “PREGNANT” IN THE
FRONT DUE TO RIGHT VENTRICULAR
ENLARGEMENT
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CLINICAL SIGNS:
Syncope
 Tiring on exercise
 Right-sided congested heart failure
 Left basilar (base) murmur
 Right ventricular enlargement
 Radiographs: right ventricular enlargement,
dilation of the pulmonary artery, pulmonary
underperfusion
 Echo: right ventricular hypertrophy and
enlargement, dilation of the main pulmonary
artery
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A special balloon is inserted into the
valve where it is inflated and the
obstruction is broken down.
Unfortunately, medical management is not
very beneficial in these cases. Beta-blockers
may be used to relax the heart muscle and
possibly dilate the stenosis.
Newfoundland, Boxer, Golden Retriever, and Bull Terrier are most commonly affected
LESION DEVELOPS IN THE FIRST 4-8 WEEKS OF LIFE
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There is a scar-like
narrowing just below
the aortic valve. The
heart must pump extra
hard to get blood
through the narrowed
area. The blood is
pushed through in a
turbulent fashion
creating a heart
murmur.
THE HARD WORK RESULTS IN LEFT VENTRICULAR HYPERTROPHY, LEFT
ATRIAL ENLARGEMENT, AORTIC DILATION
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CLINICAL SIGNS:
Fatigue
 Exercise intolerance (low cardiac output)
 Syncope
 Systolic murmur at the left heart base
 ECG: evidence of left ventricular enlargement - ↑
QRS height
 Echo: left ventricular hypertrophy, subvalvular
fibrous ring, aortic dilation
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TREATMENT
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Balloon catheter dilation – has been done with
variable and temporary results
Medical management: THE GOAL IS TO SLOW
THE HEART RATE AND DECREASE
CONTRACTILITY; PROPRANOLOL (BETABLOCKER WILL DO THIS)
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CLIENT INFO:
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Should not be used for breeding
Acute, left-sided congestive heart failure is possible
Sudden death is not uncommon
DCM
HCM
PDA
Aortic stenosis
•1 – dogs
•Enlarged Heart
bronchile
constriction
•Dilated Flappy
muscle
•Nutritional: no
taurin in cats
•1 – Cats
•Saddle
thrombus
•Rarely in dogs
(hereditary)
•Noncompliant
heart muscle
•Aorta –
pulmonary a –
lungs back L
side
•Stenotic aortic •Stenotic
valve causes LV pulmonic valve
hypertrophy
•Pregnant heart
•High pressure
in aortic valve
can lead to
aortic dilatation
•L sided heart
failure (HF)
•LV
hypertrophy
•Sudden death
if aorta
ruptures
•Increased HR
•Cough
•Increased HR
•Weakness in
hindlimbs,
acute pain, rear
cold feet
•Pulmonary
edema
•Digoxin:
increased
contractibility
•Beta blocker:
Slow HR
•Diuretic
•Blood thinner
•Treat
•No breeding
surgically or die
Pulmonic
stenosis
•RV
hypertrophy
•R sided HF
•Balloon
valvuloplasty