This document discusses diseases of the cardiovascular system. It begins with an introduction to the anatomy and function of the heart and circulation. It then discusses examination methods for the heart and the cardiac cycle. It explains principles of circulatory failure including heart failure and peripheral circulatory failure. Abnormal heart rhythms like tachycardia and bradycardia are also summarized. Treatment methods for different cardiovascular diseases and failures are provided.

1. Diseases of
Cardiovascular system
Karima Al Salihi

2. Introduction
1. The cardiovascular system consists of the heart
and blood vessels.
2. The heart is a cone shape organ composed from
right and left atria, right and left ventricles in all
domestic animals.
3. The right atrium receives blood from systemic and
coronary veins then flow into the right ventricle
which pumping blood into the pulmonary circulation
to liberate C0 2 & take 02 to & from alveoli of the
lungs.

3. 4. The left atrium receives the
freshly oxygenated blood from the
lungs through pulmonary vein to
flow into the left ventricle which
provides the driving force for
pumping arterial blood into the
systemic circulation through aorta.

4. Function of cardiovascular system
(1) The heart provides the driving force for the maintenance of
continuous circulation of blood through the cardiovascular
system so that normal exchanges of
fluid, electrolytes, oxygen and other nutrients and excretory
substances can be occurs between the vascular system and
tissues.
(2)The principal force responsible for the passage of fluid
through the capillary wall is
the difference between the capillary pressure
and the osmotic pressure of the plasma protein.

5. (3) Where the capillary pressure is greater,
outward filtration occurs.
Where the osmotic pressure of the plasma is
greater, inward filtration or absorption occurs.
Subsidiary factors are the hydrostatic pressure in
the tissue spaces and osmotic pressure of the
relative small amount of protein the escapes through
the capillary walls into the tissue spaces.
Failure of the circulation in any degree interferes with
these exchanges and is the basis for circulatory
failure.

7. Anatomy of the heart:

8. (1) The heart is a muscular organ suspended by its
own vessels in the lower two-thirds of the thoracic
cavity. The left ventricle is in contact with the chest
wall in an area extending from the third to the six ribs.
(2) A small area of the right ventricle is in contact with
the chest wall from the fourth to about the six ribs. In
cattle the heart is only separated by the thickness
of the diaphragm from the reticulum, which
occupies the lower anterior part of the abdominal
cavity formed by the curve of the diaphragm,
makes it possible for penetrating foreign bodies
to enter the pericardial sac and cardiac muscle.
The great vessels entering and arising from it fix
the base of the heart.

9. (3) The right atrio-ventricular opening
guarded by the tricuspid valve lies
opposite to the fourth intercostal space.
The pulmonary orifice lies opposite to the
third intercostal space slightly above
atrioventricular opening.
(4) The left atrio-ventricular opening
guarded by the bicuspid valve or mitral
valve, which is opposite to the fifth
intercostal space. The aortic orifice lies
opposite to the fourth intercostal space.

10. Methods of the examination of the heart:
(1)Palpation of the cardiac region to detect
the thrill and cardiac displacement.
(2) Percussion in cardiac area gives dull
sound.
(3) Auscultation of the heart must be
prolonged and also it is necessary to lift the
forelimb forwards as the heart lies above
the elbow joint in the left side by about fist
of hand in large animals.

11. Cardiac cycle:
•When relaxation of the ventricles is just commencing, both
atria will fill with blood from the great veins entering the heart
(cranial and caudal vena cava in the right side and pulmonary
veins in the left side). The cycle of contraction commences
in the atria for passing the blood into the ventricles.
(1) Systolic sound (Lub):
•It is produced by contraction of the ventricles and closure of
the atrio-ventricular valves in association with tension of
the chordae tendinae.
•During cardiac systole the blood forced along the
pulmonary artery to the lungs and aorta through the arteries
to the systemic circulation. The atria are relaxed and filled
with blood from great veins then the contraction is completed
and ventricles relax.

12. (2) Diastolic sound (Dub)
•It is produced by closure of aortic and
pulmonary valves and relaxation of ventricles
resulted in decrease of heart content and blood
pressure in the great vessels.
N.B: The vibration of any portion of the heart will
be transmitted through the fluid filling its chambers.
Therefore heart sounds are complex involving
vibration of all the substance of the heart and its
contained fluid. The vibration of the cardiac skeleton is produced
by the closure of the valves of the heart.

14. Principles of circulatory failure:
•The function of cardio-vascular system is
to maintain the circulation of the blood so that the
normal exchanges of fluid, electrolytes, oxygen and
other nutrient and excretory substances can be
made between the vascular system and tissues.
• Failure of the circulation in any degree interferes
with these exchanges and is the basis for
circulatory failure. The two functional units of the
system are the heart and blood vessels. Any
disease of one of them may giving rise to two forms
of circulatory failure:

15. (1) Heart failure: It is inadequency due to involvement of the
heart itself resulting in CHF, later on deprives tissues of their
oxygen & acute heart failure occur.
(2) Peripheral circulatory failure, in which the vascular
system fails to return the blood to the heart resulting in CHF
& oxygen tissue deprivation. Abnormalities of cardiac rate
and rhythm:
(1) Tachycardia:
It is an increase of heart rate resulting from an increased rate
of discharge of impulses from the sinoauricular node, which
has its own intrinsic rate of discharge. Tachycardia may be:
1) Simple due to excitement, fever, pain or some drugs
administration.
2) Paroxysmal due to myocardial diseases. It is short
attacks with sudden onset and end.

16. Treatment:
(1) Keep the animal in quite place
(2) Administration of nerve sedative such as
chloral hydrate (20-40 gm in water orally or
rectally) or morphine (0.3-0.5 gm/ horse,
0.03-0.05 gm /dogs).
(3) Blood substitute may be given by slow
intravenous injection.
(4) Digitalis and quinidine sulfate (l-2gm in 16
ml water three times daily) is recommended
to terminate dangerous attacks of paroxysmal
tachycardia.

17. (2) Bradycardia:
It is an abnormal decrease in heart rate than
normal
Causes:
(1) Heart diseases such as degeneration,
atrophy and myocarditis.
(2) Nervous disorders (meningitis, encephalitis
and hydrocephalus).
(3) Vagus stimulation as in GIT disorders. It is
temporary effect and disappears after
administration of atropine SC or correction of
diet.

18. Treatment:
•Complete rest of the affected animal to
avoid occurrence of acute heart failure &
treat the real cause.
•Manifestations of circulatory failure:
•It is usually depend on the manner and
rapidity of its onset and on its duration.
They may be:
(1) Congestive heart failure. (2) Acute
heart failure.
(3) Peripheral circulatory failure.