This document discusses the anatomy and function of the heart. It begins by reviewing heart formation during embryogenesis from mesoderm layers. It describes the circulation pathway of oxygenated and deoxygenated blood through the heart chambers and valves. Common congenital heart defects are explained, including ventricular septal defects which cause a hole between the ventricles. Signs of VSDs include heart murmurs and difficulties maintaining weight from the extra blood flow to the lungs. Untreated large VSDs can lead to heart failure or pulmonary hypertension.

1. Learning Objectives
• Review anatomy of the heart
• Formation of the Heart
• Congenital heart defects
• Clinical Anatomy - Cardiac Disorders

2. Blood Flow
Heart  Lungs 
Heart  Body

3. Vena Cava - AORTA -
vein artery
Atria
Ventricles

5. UNoxygenated
blood enters the
atrium on the right
side of the heart.
Unoxygenated
blood comes in
from the top of the
body through the
superior vena
cava.
Unoxygenated
blood comes in
from the lower
body though the
inferior vena cava.

6. While the
unoxygenated
blood is in the
right atrium,
the tricuspid
valve is closed
to keep the
blood from
flowing down
to the
ventricle.

7. The
atrium
contracts
and the
tricuspid
valve
opens,
forcing
the blood
down into
the
ventricle.

8. The tricuspid
valve closes
again so that
blood cannot
move back up
into the atrium.

9. The ventricle
contracts.
This forces
the
unoxygenated
blood through
the
pulmonary
valve and into
the
pulmonary
arteries.

10. The right pulmonary
artery takes the
unoxygenated blood
to the right lung.
The left pulmonary
artery takes the
unoxygenated blood
to the left lung.
THE PULMONARY
ARTERIES ARE THE
ONLY ARTERIES
THAT CARRY
UNOXYGENEATED
BLOOD.

11. In the lungs,
the carbon
dioxide in the
blood
diffuses into
the alveoli.
The oxygen
in the lungs
diffuses into
the blood.
This is
called gas http://www.webmd.com/hw/health_guide_atoz/tp10237.asp
exchange.

12. Oxygenated
blood from the
lungs enters the
heart through the
left atrium.
The mitral valve
is closed to keep
the blood from
going into the
ventricle.

13. Oxygenated blood
from the right lung
returns to the heart
through the right
pulmonary vein.
Oxygenated blood
from the left lung
returns to the heart
through the left
pulmonary vein.
THE PULMONARY
VEINS ARE THE
ONLY VEINS THAT
CARRY
OXYGENATED
BLOOD.

14. The left atrium
contracts.
This forces
the
oxygenated
blood through
the mitral
valve into the
Left ventricle.

15. The mitral
valve closes
again. This
keeps the
oxygenated
blood from
moving back
up into the
atrium.

16. Oxygenated
blood is forced
into the aorta
to be carried
to the rest of
the body.

17. Oxygenated
blood is carried
to all body cells
where oxygen
diffuses into the
cells and carbon
dioxide diffuses
into the blood.
Blood carrying
carbon dioxide
then returns to
the heart.

18. And the
cycle
begins
again.

19. Meanwhile…
While the blood is
moving oxygen and
carbon dioxide
around, it is also
moving nutrients,
other wastes,
hormones, and
antibodies at the
same time.

20. How does
the Heart
Form?

21. Formation of the Heart
• Mesoderm divides into two layers
• Mesoderm = one of the primary germ
cell layers in the early embryo
• Heart precursor cells come from one of
those two mesoderm layers
(cardiogenic mesoderm)
• Heart precursor cells form a single
heart tube by day 22 of embryogenesis

22. Formation of the Heart
• These cells differentiate into the
endocardium and myocardium
• Endocardium = innermost layer that
lines the heart chambers and valves
valves
• Myocardium = the muscular layer of
the atria and ventricles
• The heart tube grows and elongates
• Primitive heart begins to form around
day 22‐ 23

23. • The heart tube begins to bulge into
primitive heart chambers and
undergoes right ward looping
• Followed by proper valve positioning
and chamber formation

24. What is
Cyanosis?

25. CYANOSIS
 a physical sign causing bluish
discoloration of the skin and mucous
membranes.
 caused by a lack of oxygen in the blood.
 associated with
cold temperatures,
heart failure,
lung diseases, and smothering.
It is seen in infants at birth as
 a result of heart defects,
defects
 respiratory distress syndrome,
 or lung and breathing problems.

26. • The blue discoloration of cyanosis is seen
most readily in the beds of the fingernails
and toenails, and on the lips and tongue.
• It often appears transiently as a result of
slowed blood flow through the skin due to
the cold. As such, it is not a serious
symptom.
• However, in other cases cyanosis is a
serious symptom of underlying disease.

27. Congenital Heart Defects
• Abnormalities in heart present at birth
• Affects 8:1000 live births
• Examples:
• Ventricular Septal Defect
• Atrial Septal Defect
• Coarctation of the Aorta
• Tetralogy of Fallot
• Transposition of the Great Arteries

29. Ventricular Septal Defect (VSD)
• Most common congenital cardiac
anomaly
• There is a hole between the two
ventricles
• Hole can vary in size and location
• Oxygenated blood forced through hole
from left ventricle to right ventricle then
returns to the lungs even though it
already carries oxygen
• Consequences
• Volume load causes enlargement of
both ventricles and the pulmonary
artery and exposes right ventricle
and pulmonary arteries to high
pressures

30. Remember:

32. o Small VSDs may close on their own and usually
does not cause major problems.
o These are the kinds that can close at any time
during childhood.
o A membranous VSD is found in the upper
portion of the interventricular septum.
o A muscular VSD is found in the lower part of
the septum.
o Medium and large sized VSDs are unlikely to
close spontaneously.
o Surgery or other interventional procedures
may be required to close these defects.
Inlet and Outlet VSDs are less common types
and are present where the blood enters or
leaves the ventricles.

33. VSD Signs and Symptoms
• Heart murmur
• Difficulty maintaining weight
• Increased breathing rate
• Lower energy and easy tiring
Ventricular Septal Defect - Animation
http://www.medindia.net/animation/Ventricular_Septal_Defec

34. • Some of the infants may show poor
weight gain, shortness of breath or even
bluish discoloration of the lips, nails or
skin.
• Most of the small VSDs may go
unnoticed.
• A murmur can be heard with a
stethoscope when the baby is a few
weeks old.
• Untreated moderate to large VSDs may lead to
severe complications in a child.
• Heart failure may result from the constant
overload of the right ventricles.
• Arrhythmias and Pulmonary hypertension can
also be an outcome of the high volume of blood
flowing through the right ventricle.
• It is rare that these defects can go unnoticed
and so complications are rather rare.