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Topic last updated: 05 Nov 2021
    • Biology Biology
    • Ico Human Biology Human biology
    • Ico Physical Education Physical education
    • Ico Science Science
    • 14-16
    • 55

Heart and circulation

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Cardiovascular disease

There are a number of common things that can go wrong with your heart and cardiovascular system. They can be quite minor or life threatening. Up to a third of adult deaths in the UK alone are linked to cardiovascular disease.

Cardiovascular diseases include:

  • High blood pressure (hypertension)
  • Atherosclerosis - this is when a fatty deposit or plaque builds up inside an artery so the artery wall becomes harder and the gap for the blood to flow through gets narrower.

 

Atherosclerosis New

The build-up of plaque in atherosclerosis

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Atherosclerosis is the cause of many serious cardiovascular conditions including:

  • Coronary artery disease is when atherosclerosis takes place in one of the coronary arteries. This reduces the blood supply to the heart muscle itself. The lack of food and oxygen can cause problems including pain and shortness of breath when you exercise, this is known as angina.
  • A stroke happens when a blood clot forms in one of the blood vessels supplying the brain with food and oxygen. This is often the result of atherosclerosis in the vessels. If a blood vessel in the brain breaks and bleeds this can also cause a stroke. Bleeding in the brain is often the result of high blood pressure.
  • A heart attack results if one or more branches of the coronary artery become completely blocked by plaque or by a clot which forms as a result of the plaque. In a heart attack part of the heart muscle is starved of oxygen. In a severe heart attack the patient may die. About 27% of all deaths in countries such as the UK are caused by coronary heart disease.
  • Atrial fibrillation is a form of arrhythmia when the natural rhythm of the heart is disturbed. The atria beat very fast and irregularly so they do not empty properly.
  • Genetic problems with the heart such as long QT syndrome can cause serious problems. This is the most common cause of death due to heart problems in teenagers and young adults.

 

Investigating heart disease

When patients have symptoms which might be caused by heart disease, doctors need ways of finding out what is going on in the heart.

One way to investigate the heart is to take an angiogram. A dye which shows up on X-rays is injected into the blood stream. Images taken as it flows through the coronary arteries show up any blockages.

Another way to investigate the heart is to use an ECG (electrocardiogram). This machine gives images of the electrical activity of the heart. Doctors can use this to see how the heart is beating.

Ecg Plot

Angiograms show up a blocked coronary artery

The previous ECG corresponds to a healthy individual. The animation below demonstrates how ECGs look like under different cardiovascular conditions.

ECGs are used to diagnose heart disease

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Factors affecting cardiovascular disease

Many factors increase your risk of developing cardiovascular disease. Many of them are exactly the same as the risk factors for high blood pressure. Some of them you can do nothing about, yet some of them are in your hands - you have the power to reduce your risk of cardiovascular disease (CVD):

Factors that CAN be controlled:

  • Being overweight - obesity is closely linked to CVD (see graph on the right)
  • Smoking - smoking narrows and hardens the arteries which causes CVD
  • Lack of exercise - if you don't exercise your cardiovascular system is not very fit and your risk of disease increases - your risk goes up
  • High blood cholesterol - this may be genetic or related to the amount of fat in the diet

Factors that CAN'T be controlled:

  • It may run in the family - there is a genetic tendency to develop CVD such as hypertension
  • Age - the older you are, the more likely you are to suffer from CVD
  • Being male - men are more likely to suffer from CVD than women, particularly before women go through the menopause

 

The relationship between obesity and coronary heart disease is shown in the graph below.

Body mass index (BMI) and waist-to-hip ratio (WHR) are two measures broadly used to categorize an individual as underweight, normal weight, overweight or obese.

A quartile is a number that divides the data in four parts of the same size. When talking about quartiles, data are usually ordered from smallest. This way, below the first quartile (Q1), 25% of the lowest values are found, whereas top 25% of the values are found above Q3.

This diagram shows a positive correlation between BMI, WHR and coronary heart disease. The higher the BMI and WHR are, the more likely it is to develop cardiovascular disease.

Cvd Obesity
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The prevention and treatment of cardiovascular diseases
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