Case Study: Coronary Heart Disease (CHD) (AQA A-Level Geography): Revision Notes
Case Study: Coronary Heart Disease (CHD)
What is coronary heart disease?
Coronary heart disease is a major health challenge affecting populations worldwide. Understanding its causes, impacts and management strategies is essential for geographers studying population and environment interactions.
Coronary heart disease (CHD) - also known as ischaemic heart disease - is the leading cause of death worldwide, responsible for approximately 9.5 million deaths each year.
CHD belongs to a broader category called cardiovascular diseases (CVD). This group includes cerebrovascular disease (strokes) and vascular dementia. The disease affects different populations at varying rates, influenced by numerous environmental and lifestyle factors.
How CHD develops and causes harm:
A heart attack happens when blood vessels supplying the heart muscle become blocked. This blockage starves the heart of oxygen, potentially leading to heart muscle failure or death. Various risk factors can trigger heart attacks, often working together. These factors affect all populations, though their occurrence varies globally depending on the specific conditions in different regions.
Global distribution patterns
The worldwide pattern of CHD shows significant geographical variation. The highest mortality rates from cardiovascular diseases occur in:
- Eastern Europe
- Northern and Central Asia
- Parts of North Africa
- Parts of South East Asia
This distribution reflects the complex interplay between physical environments, socio-economic development levels, lifestyle choices and healthcare access across different regions.
Links to physical environment
Physical environmental factors play a contributory role in CHD prevalence, though their effects are more limited compared to socio-economic factors.
Air quality
Historically, the changing physical environment has contributed to rising heart disease rates. Industrialisation brought several negative effects on air quality. Studies in the United States have demonstrated that increased exposure to airborne pollutants raises CHD risks. Particulate matter (PM) from industry and transport systems particularly increases these risks.
Research suggests that rural environments with relatively clean air pollution would indicate lower risk. However, clear evidence that this reduces CHD in the developed world remains limited.
Climate
Temperature plays a significant role in CHD mortality rates. Research has identified an optimum temperature range at which CHD mortality is lowest. When temperatures move outside this optimal range - either falling or rising - CHD mortality increases. Extreme temperatures, whether cold or hot, put additional strain on the cardiovascular system beyond what an individual's body is accustomed to handling.
The optimum temperature range varies regionally, depending on the prevailing temperature conditions that local populations have adapted to. For example, the optimum temperature range for low CHD mortality in northern Finland is lower (14.3 to 17.3°C) compared to London (19.3 to 22.3°C).
Cold and damp winters in temperate climates negatively impact the cardiorespiratory system. This increased strain on the heart raises the subsequent risk of heart attack.
Relief and topography
The relationship between landscape and CHD remains unclear compared to other factors. Challenging relief requires more physical effort when walking, which can be advantageous by increasing exercise levels (thereby reducing risk). However, it can also pose a threat for individuals with other underlying risk factors.
Overall, links between CHD and the physical environment show minimal connection, with the possible exception of climate factors. Lifestyle choices within various physical environments emerge as far more important risk factors.
Links to socio-economic environment
Socio-economic factors and lifestyle choices represent the most significant determinants of CHD prevalence in developed countries. Research estimates that 75-85 per cent of people dying from CHD have one or more lifestyle risk factors influenced by negative lifestyles. These include poor diet, physical inactivity and smoking.
CHD development involves multiple factors. Age increases risk, though gender acts as a less important determinant than traditionally thought. Despite the common perception of CHD as primarily affecting men, one in seven women in the UK die from coronary heart disease. The disease is multifactorial - the interaction between genetic, lifestyle and other social factors determines who develops the condition.
Social deprivation
A positive correlation exists between deaths from circulatory diseases and deprivation levels. Studies examining northern UK regions compared with southern regions have found increasing deprivation correlates with higher death rates.
Premature deaths (under 75 years) from CHD occur most commonly in:
- Northern England
- Central Scotland
- South Wales
- South of England (to a lesser extent)
Case Study: Regional Variation in CHD Deaths
The premature death rate from CHD in Glasgow (138 per 100,000) exceeds the rate for Hart in Hampshire (39 per 100,000) by over three times, demonstrating the strong link between deprivation and CHD mortality.
Tobacco use
Smoking causes up to 20,000 CHD deaths each year in the UK. Tobacco lowers 'good' cholesterol (HDL) and makes blood more sticky and prone to clotting. These effects can block blood flow to the heart and brain, triggering heart attacks and strokes.
Alcohol use
Excessive alcohol consumption contributes to several harmful effects:
- Raised blood sugar levels
- Increased fats and bad cholesterol in the blood
- Higher blood pressure - one of the most important risk factors for heart attacks
Interestingly, some studies suggest moderate consumption may reduce risk by raising HDL cholesterol levels.
High blood pressure
Approximately 47 per cent of heart attacks worldwide are attributed to hypertension (high blood pressure). Consistently high blood pressure forces the heart to work harder. This extra strain causes the coronary arteries to slowly become narrowed from a build-up of fat, bad (non-HDL) cholesterol and other substances.
Atherosclerosis - the slow process where plaque (deposits of fat, cholesterol and other substances) gradually narrows the coronary arteries.
Poor nutrition
A WHO report identified that diets high in saturated fat, sodium and sugar, but low in complex carbohydrates, fruits and vegetables, increase CHD risk.
Overweight and obesity
Obesity functions as an independent risk factor for CHD. It also associates with other risk factors including high blood pressure, high cholesterol and diabetes.
Diabetes
Men with Type 2 diabetes face two to four times greater risk of developing CHD compared to those without diabetes. Women with Type 2 diabetes face three to five times greater risk. High blood glucose levels from diabetes damage blood vessels and the nerves controlling the heart.
Infrequent exercise
Physical activity significantly reduces risk. Research estimates that approximately 35 per cent of CHD mortality in the United States results from physical inactivity. Even for people with no other risk factors, sedentary lifestyles increase the likelihood of developing CHD or other risk factors such as obesity and high blood pressure.
Ethnicity
Racial and ethnic background appear to influence heart disease risk, though the picture involves complex interactions between lifestyle habits. For example, in the UK, south Asian people show higher likelihood of developing heart disease and experiencing higher premature death rates from CHD compared to white Europeans.
In the United States, African Americans face greater risk. Researchers suggest a genetic predisposition to salt sensitivity makes African Americans more susceptible to high blood pressure. However, Hispanics generally display higher rates of obesity, diabetes and other CHD risk factors, yet show lower rates of heart disease and fewer deaths from CHD compared to other groups. This pattern suggests a mixture of genetics and lifestyle choices determines outcomes.
Family history
Inherited genetic conditions can pass through families, affecting people of any age and potentially proving life-threatening. First degree relatives with premature CHD face increased risk of developing the disease themselves.
Urbanisation and cardiovascular diseases
According to the World Heart Federation, one major factor increasing CHD risk in developing societies involves the rapid urbanisation taking place. Negative impacts of urbanisation particularly affect children growing up in fast-developing cities:
- Areas with insubstantial housing conditions and poor access to healthcare services, healthy foods and safe, green places free of environmental toxins and pollutants for outdoor activity
- Crowded living environments can spread diseases such as rheumatic fever, which if untreated causes rheumatic heart disease
- City dwellers face greater likelihood of exposure to marketing and advertising for unhealthy foods, tobacco and alcohol
- Higher levels of particulate matter air pollution in urban areas
- Urban environments may discourage physical activity and encourage sedentary habits
- Individuals consume more prepared and heavily processed convenience foods often high in sugar, salt and saturated fats
- City dwellers become tobacco users more frequently than rural dwellers
- Children in cities may be particularly susceptible to second-hand smoke given the number of smokers in urban areas along with crowded living conditions
Impacts of CHD
Impacts on health and well-being
The most common symptom of CHD is angina - a low level but fairly constant chest pain that can spread to other parts of the upper body. The pain can increase when the heart experiences more stress, for example from physical activity. Patients can relieve these symptoms with nitrate tablets or sprays, beta blockers (to slow heart beat), calcium channel blockers (to relax arteries), aspirin or other clot-preventing drugs.
The two other main symptoms of CHD are heart attacks and heart failure. Heart attacks can permanently damage heart muscle and, if not treated straight away, prove fatal. Heart failure can also develop when the heart becomes too weak to pump blood around the body effectively. This causes fluid to build up in the lungs, making it increasingly difficult to breathe.
Recovery from heart attacks is possible, allowing patients to lead a normal life. However, those at high risk or who have suffered a heart attack must undergo surgery to reduce the risk. Surgery itself can prove stressful and risky.
Rehabilitation programmes for those recovering from heart attacks or surgery focus on exercise, education about lifestyle choices, and relaxation and emotional support to build confidence. Those suffering from heart attacks can lose confidence in undertaking physical activity. CHD sufferers at all disease stages may require continued medication for the rest of their lives. This may include warfarin (an anticoagulant which 'thins' the blood) which may have subsequent side-effects. In some cases, electronic devices are fitted to patients to regulate heart beat and blood flow.
Impacts on economic well-being
The economic impacts of heart disease are substantial and affect multiple levels:
Individual and family level:
- Cost of healthcare to the individual and their family
- Loss of income due to time off work
Government level:
- Cost of providing healthcare, treatment and medication
Economy-wide level:
- Cost to the economy because of lost productivity
These costs prove difficult to quantify precisely, but estimates provide insight into the scale:
Economic Costs of CHD:
- In the UK, healthcare costs relating to heart and circulatory diseases (all cardiovascular diseases) totalled $9 billion in 2018
- The total cost to the UK economy (including premature death, disability and indirect costs) reaches around $19 billion per year
- Heart disease costs the US economy around $220 billion each year (including healthcare costs, medicines and lost production)
Management and mitigation strategies
WHO has identified two types of cost-effective interventions for implementation to prevent and control CVDs. They recommend using these in combination to reduce disease burden.
Population-wide interventions
These interventions affect the whole population and aim at primary prevention - stopping the disease before it develops.
Individual level interventions
These interventions target those at high total CVD risk and focus on treatment of symptoms for those with established disease.
At the national level, governments bear responsibility to protect the health of citizens. They employ a combination of approaches to implement these measures.
Government responsibilities include:
- Providing health education for the public to raise awareness of CHD causes and promote healthy lifestyles
- Introducing policy and legislation to discourage certain activities and lifestyles that lead to poor health, or encourage activities which improve health
- Providing affordable medication and healthcare to control symptoms or treat the disease
Health education
Interventions only prove effective if they gain public support and understanding. Health education is essential to promote healthy choices. Schools provide an ideal starting point for many health campaigns, as implanting messages in a receptive learning environment may create more lasting effects.
The World Heart Federation (supported by WHO) has initiated numerous activities to assist schools around the world and co-ordinate World Heart Day events and activities on 29 September each year. Activities and events include:
- Blood pressure testing
- Encouraging physical exercise
- Scientific conferences
- Promoting a heart-healthy diet
Health Education in Practice:
In the UK, dieticians promote the benefits of eating oily fish, fruit and vegetables, and consuming less saturated fats for a heart-healthy diet.
Policy and legislation
Only governments can legislate for disease prevention and control. WHO recommends the following population-wide policies:
Tobacco - comprehensive smoking control policies including:
- Taxation on tobacco products
- Advertising bans
- Designating smoke-free areas in public places
- Enforcing health warnings on packets
Foods - taxation on foods high in saturated fat, sugar and salt; requiring food processors and companies to label food products by levels of fat, sugar and salt
Alcohol - taxation and other measures to reduce harmful use
School meals - ensuring children receive healthy balanced meals
Physical activity - providing cycle paths, walking routes and other incentives to increase activity levels
Medical treatment and secondary prevention
Many different medicines are used as secondary prevention to treat CHD. Usually they aim to reduce blood pressure or widen the arteries. Examples include:
Blood thinning medicines - reduce heart attack risk by preventing blood clotting, for example aspirin
Statins - reduce cholesterol levels by blocking its formation
Beta-blockers - block the effects of a particular hormone in the body, which slows down the heartbeat and improves blood flow
Nitrates - widen the blood vessels
Angiotensin-converting enzymes (ACE) inhibitors - treat high blood pressure, for example ramipril
Calcium channel blockers - reduce blood pressure by relaxing the muscles that make up artery walls, causing the arteries to become wider, for example amlodipine
Diuretics - flush excess water and salt from the body
If blood vessels narrow due to fatty deposit build-up and symptoms cannot be controlled, costly surgical procedures may become necessary. These include:
- Coronary heart by-pass
- Valve repair and replacement
- Balloon angioplasty, where a small balloon-like device is threaded through an artery to open the blockage
Medical devices such as pacemakers or prosthetic valves may be fitted to treat some types of CHD. In the most extreme cases, a heart transplant may be necessary.
Remember!
Key Points to Remember:
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CHD is the world's leading cause of death, accounting for around 9.5 million deaths annually, with the highest rates in Eastern Europe, Central Asia and parts of Africa and South East Asia.
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Socio-economic and lifestyle factors dominate - 75-85% of CHD deaths involve lifestyle risk factors such as smoking (20,000 UK deaths yearly), poor diet, physical inactivity (35% of US CHD mortality), high blood pressure (47% of heart attacks) and obesity.
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Physical environment plays a limited role - climate (temperature extremes), air quality (particulate matter pollution) and urbanisation affect CHD rates, but lifestyle choices prove far more significant.
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The economic burden is substantial - UK costs total $19 billion yearly ($9 billion healthcare), whilst the US faces $220 billion in annual costs from healthcare, medicines and lost productivity.
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Effective management requires multiple strategies - combining population-wide interventions (health education, policy on tobacco/food/alcohol, physical activity promotion), individual treatments (medications like statins, beta-blockers, ACE inhibitors) and surgical procedures (bypass, angioplasty, transplants) to prevent, control and treat the disease.