Cardiovascular Disease Noadswood Science, 2016

Cardiovascular Disease Wednesday, February 07, 2018 Cardiovascular Disease To identify what cardiovascular disease is and how medical techniques can reduce it

Precise Learning Students should be able to evaluate the advantages and disadvantages of treating cardiovascular diseases by drugs, mechanical devices or transplant. In coronary heart disease layers of fatty material build up inside the coronary arteries, narrowing them. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle. Stents are used to keep the coronary arteries open. Statins are widely used to reduce blood cholesterol levels which slows down the rate of fatty material deposit. In some people heart valves may become faulty, preventing the valve from opening fully, or the heart valve might develop a leak. Students should understand the consequences of faulty valves. Faulty heart valves can be replaced using biological or mechanical valves. In the case of heart failure, a donor heart, or heart and lungs can be transplanted. Artificial hearts are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery.

Exercise & Energy How do you think sleeping / watching television / jogging / swimming compare in terms of the energy the body uses? Activity KJ/min Sleeping 4.5 Watching TV 7 Cycling (5mph) 21 Jogging (5mph) 40 Swimming 35 Rowing 58 Walking 14

Cardiovascular Disease Cardiovascular disease is a term used to describe disease of the heart or blood vessels, e.g. coronary heart disease Coronary heart disease is when the arteries that supply the blood to the heart muscle (the coronary arteries) get blocked by layers of fatty materials causing them to narrow and restrict blood flow – this restricted blood flow restricts the oxygen to the muscle which can cause a heart attack

Medicine To reduce cardiovascular disease medical options include: - Stents Statins Donor / artificial hearts Replacement heart valves Artificial blood

Stents Stents are wire mesh tubes that can be inserted inside arteries to widen them and keep them open (useful for people with coronary heart disease)

Stents Stents keep the coronary arteries open making sure blood can pass through to the heart muscles Stents lower the risk of a heart attack and are effective for a long time (with a quick recovery time from surgery) There are disadvantages however – risks during the operation such as heart attack / infections and later blood clots can form (known as thrombosis)

Cholesterol Cholesterol (C27H46O) is a substance found in the blood It is made in the liver and is needed for healthy cell membranes Too much cholesterol in the blood increases the risk of heart disease, and of diseased arteries

Statins Statins are drugs that can reduce the amount of ‘bad’ cholesterol (LDL) as they slow the rate of fatty deposits forming Statins are beneficial for reducing LDL cholesterol and reducing heart attacks, however they need to be taken over long terms and can cause headaches / kidney failure / liver damage (as well as taking some time to become beneficial)

Hearts If a patient has heart failure doctors may perform a heart transplant (perhaps from a donor if available or using an artificial heart) Artificial hearts are mechanical devices which pump blood around the body

Artificial Hearts Artificial hearts are less likely to be rejected by the body than from a donor heart, however the surgery is risky and they do not work as efficiently as a donor heart Blood does not flow through them as well either which means blood thinners must be taken by the patient

Heart Valves Artificial hearts are less likely to be rejected by the body than from a donor heart, however the surgery is risky and they do not work as efficiently as a donor heart Blood does not flow through them as well either which means blood thinners must be taken by the patient

Artificial Blood When someone loses a lot of blood in an accident / during surgery their heart can still pump the remaining blood cells around as long as the volume of their blood is topped up Artificial blood is a blood substitute (e.g. a salt solution (saline)) which is used to replace the volume of blood – this can be used to keep people alive even if they lose 2/3 of their blood until replacement blood can be given / made by the patient

Heart Transplant

Practice Questions What is cardiovascular disease? What causes coronary heart disease What is a stent and describe how it can be used for people with coronary heart disease

Answers What is cardiovascular disease – disease of the heart or blood vessels What causes coronary heart disease – arteries supply blood to the heart muscle get blocked by fatty deposits restricting blood flow What is a stent and describe how it can be used for people with coronary heart disease – a tube inserted inside arteries to widen them which ensures blood flow is not restricted

Practice Questions - Application A patient with heart failure requires a heart transplant but there is no immediate donor available so an artificial heart will be used. Suggest an advantage / disadvantage of artificial hearts

Answers A patient with heart failure requires a heart transplant but there is no immediate donor available so an artificial heart will be used. Suggest an advantage / disadvantage of artificial hearts – less likely to be rejected but surgery can lead to bleeding / infection and they do not work as well as natural donor hearts

Practice Questions - Application The doctor who will carry out the surgey reads an article about artificial hearts and notes the key information: Artificial heart one – has been implemented in more than 1100 patients; is connected to a battery pack outside the body with wires which pass into the skin Artificial heart two – has been implemented into 14 patients; is powered by a battery inserted into the body and can be charged through the skin The doctor recommends artificial heart two – evaluate this decision

Practice Questions - Application Artificial heart one – has been implemented in more than 1100 patients; is connected to a battery pack outside the body with wires which pass into the skin Artificial heart two – has been implemented into 14 patients; is powered by a battery inserted into the body and can be charged through the skin The doctor recommends artificial heart two – evaluate this decision – two is more convenient with no wires and can charge easily and micro-organisms are less likely to cause infection however it has only been tested on 14 patients