B5. Cardiovascular Disease Flashcards
What is cardiovascular disease?
Cardiovascular disease is a general term used to describe diseases associated with the _____and _____ _______. Cardiovascular diseases include __________, ____________and _________ ___________. Most cardiovascular disease starts with ___________ __________.
Coronary heart disease (CHD) is a type of cardiovascular disease.
It occurs when the coronary arteries have lots of ___________in them, which…. It can lead to ___________ ___________.
Cardiovascular disease is a general term used to describe diseases associated with the heart and blood vessels. Cardiovascular diseases include aneurysms, thrombosis and myocardial infarction. Most cardiovascular disease starts with atheroma formation.
Coronary heart disease (CHD) is a type of cardiovascular disease.
It occurs when the coronary arteries have lots of atheromas in them, which restricts blood flow to the heart muscle. It can lead to myocardial infarction.
Atheroma formation
The wall of an artery is made up of several layers. The _______________(inner lining) is usually _________and ____________. If damage occurs to the _______________(e.g. by ____ ______ __________), _______ ______ ____(mostly macrophages) and _____(fat) from the blood, ______together under the lining to form fatty streaks.
Over time, more ______ _______ _____, ______and ___________ _______build up and harden to form a _________ _______called an __________. This plaque partially blocks the ______of the ________and ________ _______ ____, which causes _______ _________to increase.
The wall of an artery is made up of several layers. The endothelium (inner lining) is usually smooth and unbroken. If damage occurs to the endothelium (e.g. by high blood pressure), white blood cells (mostly macrophages) and lipids (fat) from the blood, clump together under the lining to form fatty streaks.
Over time, more white blood cells, lipids and connective tissue build up and harden to form a fibrous plaque called an atheroma. This plaque partially blocks the lumen of the artery and restricts blood flow, which causes blood pressure to increase.
Figure 2: The process of atheroma formation.
Aneurysm
What is it?
What does it start with?
What do atheroma plaques do and what effect does it havve on blood pressure?
What happens when blood travels through a weakened artery at high pressure?
An aneurysm is a balloon-like swelling of the artery. It starts with the formation of atheromas. Atheroma plaques damage and weaken arteries. They also narrow arteries, increasing blood pressure. When blood travels through a weakened artery at high pressure, it may push the inner layers of the artery through the outer elastic layer to form an aneurysm. This aneurysm may burst, causing a haemorrhage (bleeding).
Thrombosis
What is it?
What does it start with?
What does that do?
What accumulates at the site of damage?
What can a blood clot cause?
Thrombosis is the formation of a blood clot. It also starts with the formation of atheromas. An atheroma plaque can rupture (burst through) the endothelium (inner lining) of an artery. This damages the artery wall and leaves a rough surface. Platelets and fibrin (a protein) accumulate at the site of damage and form a blood clot (a thrombus). This blood clot can cause a complete blockage of the artery, or it can become dislodged and block a blood vessel elsewhere in the body. Debris from the rupture can cause another blood clot to form further down the artery.
Myocardial infarction (heart attack)
Where does the heart get supplied with blood?
What does the blood contain?
What happens when there is a blood clot and where does it happen?
What can a heart attack cause?
The heart muscle is supplied with blood by the coronary arteries. This blood contains the oxygen needed by heart muscle cells to carry out respiration. If a coronary artery becomes completely blocked (e.g. by a blood clot) an area of the heart muscle will be totally cut off from its blood supply, receiving no oxygen. This causes a myocardial infarction - more commonly known as a heart attack
A heart attack can cause damage and death of the heart muscle. Symptoms include pain in the chest and upper body, shortness of breath and sweating. If large areas of the heart muscle are affected complete heart failure
can occur, which is often fatal.
Risk factors for cardiovascular disease - High blood pressure
What does it increase the risk of damage to?
What does this in turn have an increased risk of?
What does this do and lead to?
What can increase BP?
- High blood pressure increases the risk of damage to the artery walls.
- Damaged walls have an increased risk of atheroma formation, causing a further increase in blood pressure.
- Atheromas can also cause blood clots to form
- A blood clot could block flow of blood to the heart muscle, possibly resulting in myocardial infarction
- So anything that increases blood pressure also increases the risk of cardiovascular disease, e.g. being overweight, not exercising and excessive alcohol consumption.
Risk factors for cardiovascular disease - High blood cholesterol and poor diet
Why is cholesterol a risk factor?
What is associated with high BC levels?
If the blood cholesterol level is high (above 240mg per 100 cm³) then the risk of cardiovascular disease is increased. This is because cholesterol is one of the main constituents of the fatty deposits that form atheromas. Atheromas can lead to increased blood pressure and blood clots, which could cause a myocardial infarction.
A diet high in saturated fat is associated with high blood cholesterol levels. A diet high in salt also increases the risk of cardiovascular disease because it increases the risk of high blood pressure.
Figure 1: The link between high blood pressure, atheroma formation and myocardial infarction.
Figure 2: The link between a diet high in saturated fat or salt, atheroma formation and myocardial infarction.
Cigarette smoking
What does it have that increases risk of heart attack?
What does it also decrease and why is that bad?
Both carbon monoxide and nicotine, found in cigarette smoke, increase the risk of cardiovascular disease and myocardial infarction.
Carbon monoxide combines with haemoglobin and reduces the amount of oxygen transported in the blood, and so reduces the amount of oxygen available to tissues. If the heart muscle doesn’t receive enough oxygen it can lead to a heart attack.
Smoking also decreases the amount of antioxidants in the blood- these are important for protecting cells from damage. Fewer antioxidants means cell damage in the coronary artery walls is more likely, and this can lead to atheroma formation.
Figure 3: The link between smoking, atheroma formation and myocardial infarction.
Reducing the risk
Most of these factors are within our control-a person can choose to smoke, eat fatty foods, etc. However, some risk factors can’t be controlled, such as having a ________ ______________to coronary heart disease or having high blood pressure as a result of another condition, e.g. some forms of diabetes. Even so, the risk of developing cardiovascular disease can be reduced by removing as many risk factors as you possibly can.
Most of these factors are within our control-a person can choose to smoke, eat fatty foods, etc. However, some risk factors can’t be controlled, such as having a genetic predisposition to coronary heart disease or having high blood pressure as a result of another condition, e.g. some forms of diabetes. Even so, the risk of developing cardiovascular disease can be reduced by removing as many risk factors as you possibly can.
Interpreting data on risk factors and cardiovascular disease - Example LDL cholesterol level
Figure 4 shows the results of a study involving 27 939 American women. The LDL cholesterol level was measured for each woman. These women were then followed for an average of 8 years and the occurrence of cardiovascular events (e.g. heart attack, surgery on coronary arteries) or death from cardiovascular diseases was recorded. The relative risk of a cardiovascular event, adjusted for other factors that can affect cardiovascular disease, was then calculated.
Describe data?
Draw conclusions?
Check if conclusions are valid?
Other things to think about?
- Describe the data - The relative risk of a cardiovascular event increases as the level of LDL cholesterol in the blood increases,
from 0.9 at > 97.6-115.4 mg di¹ to 1.5 at> 153.9 mg di¹. - Draw conclusions - The graph shows a positive correlation between the relative risk of a cardiovascular event and the level of LDL cholesterol in the blood.
- Check any conclusions are valid - Make sure any conclusions match the data, e.g.
- This data only looked at women-no males were involved, so you can’t say that this trend is true for everyone.
- You can’t say that a high LDL cholesterol level is correlated with an increased risk of heart attacks, because the data shows all first cardiovascular events, including surgery on coronary arteries.
- Also, you can’t conclude that a high LDL cholesterol level caused the increased relative risk of a cardiovascular event-there may be other reasons for the trend.
- Other things to think about - A large sample size was used (27 939). Data based on large samples is better than data based on small samples. This is because a large sample is more representative of the whole population (i.e. it shares more of the various characteristics of the population).
