The human circulatory system Part
advanced procedures for treating cardiovascular disease including coronary heart
Doc Brown's GCSE level Biology exam study revision notes
of notes on human circulatory system: heart, lungs & blood vessels
scientific developments to help treat cardiovascular disease and emergency
Reminder: Cardiovascular disease (CVD)
is the scientific medical term for all types of disease that affect
the heart or blood vessels. CVD includes coronary heart
disease (clogged up arteries with fatty deposits), which can
cause heart attacks, stroke, heart failure, and peripheral artery
Appreciate that modern developments in
biomedical and technological research enable us to help when the circulatory
system is not working well.
Points to consider: blood vessel tissue replacement, transplant donated hear,
donor, artificial heart, valve replacement, pacemakers, artificial blood, the
advanced procedures for treating cardiovascular disease and coronary heart disease.
A section of blocked blood vessel
can be replaced by taking a section of healthy blood
vessel and bypassing the affected section.
This is called coronary bypass
Transplanted donated heart or an artificial heart
In the case of a total patient heart
failure and severe cardiovascular disease, surgeons may perform a heart transplant or even a combined
heart and lung transplant if the lungs are diseased to.
The donor organs must come
from other people who have recently died.
However, donor organs might
not be immediately available, or they are not for some other
medical reason not the best option, doctors may fit an
Even after the heart
transplant operation, the new heart does not always start
pumping the blood immediately - stimulation might be required.
Also, the patient has to take suppressive drugs
(immunosuppressant drugs) to stop the body
rejecting the 'foreign' tissue of the new heart (rejection) - these drugs
can have side effects and the patient more vulnerable to
Any major surgery like a hear
transplant operation carries its own risk of bleeding, blood
clots and infection from microorganisms including some
potentially fatal bacterial infections like MRSA.
A transplant can greatly
improve the quality of life (a factor that applies to all
these surgical techniques), BUT the disadvantages are:
it requires major risky
intrusive surgery - unforeseen complications or infection,
patients must take
immunosuppressive drugs for the rest of their life,
the application of
anti-rejection drugs - may cause a greater infection risk
because the body's natural immune defence system is
and, sadly, a shortage of
donors - does require the death of somebody and permission
to use their heart.
BUT, we are balancing
risks versus survival.
Artificial hearts are machines
inserted by surgery into a patients chest to pump the blood around the
circulatory system, ideally temporarily, until a donor heart can be found.
These mechanical devices are
able to pump blood around a person who's heart has failed.
They are usually a temporary
fix to keep the patient alive until a donor heart can be found.
They can also be used to help
a patient recover while the heart is rested and healing.
Artificial hearts can be
permanent solution, with the advantage of reducing the need for
a donor heart.
Artificial hearts have an advantage of
being much less likely to be
rejected by the body, as donor hearts can be, because the immune system
doesn't recognise the plastic or metal parts as an invasive ('foreign') microorganism to
be attacked - like it might with living tissue.
However, any major surgery
in fitting an artificial heart or transplant carries risks eg from bleeding, infection.
Also, artificial heart machines are
subject to wear and tear themselves and are not as efficient as a real heart
and there are still risks from heart attacks and strokes.
Parts of the heart machine
can wear out or the electric motor fail.
The blood flow is not as
smooth causing blood clots leading to strokes.
Heart patients have to
take drugs to thin their blood to make sure this doesn't
Unfortunately, such drugs
cause problems if the patient has an accident and excessive
I'm afraid it just
another case of medical treatment where you are balancing
risks ('bad' outcomes') versus 'good' outcomes!
Surgical techniques - heart valve
Heart valves can be damaged or
weakened by heart attacks, infection or just old age - you can't
stop aging processes!
The damage may cause the valve
tissue to stiffen and prevent the valve from opening and closing
If the valve leaks, blood can
flow in the wrong direction instead of always going forward in
the right direction.
This results in poor
circulation of blood, which causes its own problems.
Tiredness and lack of energy and breathlessness are symptoms
of leaky valves.
Poor circulation can
cause pain in the legs, feet, arms, and hands.
and feet may ache or throb.
When the blood does
not circulate correctly, oxygen and nutrients cannot reach
tissues effectively, which can result in stiffness and
Badly damaged valves can be
replaced with artificial valves or other animal biological
Replacement valves can be
taken from other humans or animals such as cows or pigs.
Defective heart valves can be
replaced by m an-made artificial mechanical valves that work in the same
mechanical way as a real heart and the
surgery is much simpler and less risky, but still risks of blood clot
Replacing a valve is a less
complicated surgery, so less drastic, and therefore less risky,
than doing a full heart transplant operation.
Advantages of artificial
Disadvantages of artificial
They can damage red blood
cells. Patients need anti-clotting agents because of blood clot
Advantages of biological
Red blood cells not damaged.
Disadvantages of biological
Biological valves can harden
and need replacing.
For some patients the problem is
an inability of their body to control the heart rate.
The steady beat of the
contraction and relaxation of the heart muscles is obviously
Artificial pacemakers can be
fitted under the skin and a wire connects it to a vein to the right
The pacemaker sends electrical
impulses to stimulate and control the heartbeat.
Advantage of artificial
No major surgery is required.
Disadvantage of artificial
Our immune system may
reject the pacemaker ('foreign' materials) and may need
Use of artificial blood
Blood loss from a serious
accident can lead to death indirectly - loss of available blood means less
oxygen and nutrients are getting the cells of all the tissues and organs -
If you can keep the volume of
blood 'topped up' life can be preserved for sometime.
blood can be used temporarily as a blood substitute when a patient has lost
a lot of blood, but, as long as the heart can still pump the diluted fluid
(diluted plasma) containing the remaining red blood cells around the
The simplest artificial blood
(blood substitute) is a saline solution - an aqueous
sodium chloride salt solution NaCl(aq).
Its safe to use, but must NOT
contain air bubbles, and it can keep people alive even if they
have lost 2/3 rds of their red blood cells!
This can now give enough time
e.g. to get the patient to hospital and prepared for surgery if
necessary and also time for the body to produce more red blood
This can be followed up by a
blood transfusion if the patient cannot make enough red blood cells in time!
Research is being done to
develop artificial blood containing molecules that can carry oxygen just
like haemoglobin in red blood cells, but limited progress so far.
This is an ideal solution, to
produce a product that can temporarily act like the haemoglobin
molecules to transport oxygen to the bodies cells - a sort of
This would avoid the need for
a blood transfusion, and presumably the body would gradually
produce enough red blood cells to allow the circulatory systems
to work normally.
Summary of learning objectives and key words or phrases
Be able to describe and understand CVD treatments involving
blood vessel tissue replacement, transplanting a donated heart, issues with
donors, the use of artificial heart valves replacement, pacemakers, the
values of artificial blood
used in advanced procedures for treating cardiovascular disease and coronary heart
TOP OF PAGE
Index of biology notes on
the human circulatory system - the heart, lungs and blood vessels
Big website and use [SEARCH
BOX] below, maybe quicker than the indexes
INDEX of all my BIOLOGY NOTES
HOME PAGE of Doc Brown's Science
website Links to all indexes
UK KS3 Science Quizzes for
KS3 science students aged ~11-14, ~US grades 6, 7 and 8
Biology * Chemistry
* Physics UK
GCSE level students aged ~14-16, ~US grades 9-10
Advanced Level Chemistry
for pre-university age ~16-18 ~US grades 11-12, K12 Honors
Find your GCSE/IGCSE
science course for more help links to all science revision notes
brown - comments - query?
mobile phone or ipad etc. in 'landscape' mode?
Doc Brown's school biology revision notes: GCSE biology, IGCSE
biology, O level biology, ~US biology science grade 8, grade 9 and
grade 10 school science courses or equivalent for ~14-16 year old students of
biology IGCSE AQA GCSE Biology Edexcel GCSE Biology IGCSE OCR Gateway Science
Biology OCR 21st Century Science Biology Some of these biology revision notes
might be suitable for UK KS3 Science-Biology courses for ages 12-14 (~US biology
science grades 6, grade 7 and
SITEMAP Website content © Dr
Phil Brown 2000+. All copyrights reserved on biology revision notes, images,
quizzes, worksheets etc. Copying of website material is NOT
permitted. Exam revision summaries and references to science course specifications
Using SEARCH some initial results may be ad links you
can ignore - look for docbrown