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examBoard: Pearson Edexcel
examType: IGCSE
lessonTitle: Coronary Heart Disease
Coronary heart disease (CHD) is one of the leading causes of death worldwide. It occurs when the blood vessels that supply the heart muscle with oxygen and nutrients become narrowed or blocked. This can lead to serious health problems, including heart attacks. Understanding how CHD develops and what we can do to prevent it is crucial for maintaining good health.
Key Definitions:
Before we dive into coronary heart disease, let's understand the heart's structure and how it's supplied with blood.
The heart is a muscular organ about the size of your fist. It has four chambers: two atria (upper chambers) and two ventricles (lower chambers). The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs. The left side receives oxygenated blood from the lungs and pumps it to the rest of the body.
The heart muscle itself needs oxygen and nutrients to function. It receives these through the coronary arteries, which branch off from the aorta (the main artery leaving the heart). The two main coronary arteries are the left and right coronary arteries, which further divide into smaller branches to supply all parts of the heart muscle.
Coronary heart disease develops when the coronary arteries become narrowed by a gradual build-up of fatty material called atheroma. This process is called atherosclerosis. As the coronary arteries narrow, they can't deliver enough oxygen-rich blood to the heart, especially during physical activity when the heart needs more oxygen.
Atherosclerosis is a slow, progressive disease that may start in childhood but typically becomes dangerous in middle age or later. It develops in several stages:
The inner lining of an artery (endothelium) gets damaged due to factors like high blood pressure, smoking, or high cholesterol.
Cholesterol, fat, calcium and other substances in the blood begin to stick to the damaged area, forming plaque.
The plaque grows larger, narrowing the artery and restricting blood flow. It may also become unstable and rupture.
When coronary arteries become narrowed or blocked, several serious conditions can result:
Angina is chest pain or discomfort that occurs when the heart muscle doesn't get enough oxygen-rich blood. It may feel like pressure or squeezing in the chest. Angina is often triggered by physical activity or stress and relieved by rest. It's a warning sign that you're at increased risk of a heart attack.
A heart attack (myocardial infarction) occurs when a coronary artery becomes completely blocked, usually by a blood clot forming on a ruptured plaque. This cuts off blood supply to part of the heart muscle, which begins to die without oxygen. Heart attacks require immediate medical attention to prevent permanent heart damage or death.
Several factors increase your risk of developing CHD. Some you can control (modifiable), while others you cannot (non-modifiable).
The Framingham Heart Study, started in 1948, is one of the most important epidemiological studies in medical history. Researchers followed over 5,000 residents of Framingham, Massachusetts and their descendants for decades to identify risk factors for heart disease. This study was the first to identify many of the major risk factors we now know, including high blood pressure, high cholesterol, smoking, obesity, diabetes and physical inactivity. The study introduced the concept of "risk factors" into medical vocabulary and revolutionised our understanding of heart disease prevention.
Doctors use various tests to diagnose coronary heart disease:
Treatment aims to relieve symptoms, reduce risk factors and prevent complications. Options include:
Various medications can help manage CHD, including statins to lower cholesterol, antiplatelet drugs to prevent blood clots, beta-blockers to reduce heart workload and nitroglycerin to relieve angina symptoms.
For severe cases, procedures may be needed: angioplasty (widening narrowed arteries with a balloon) and stenting (inserting a mesh tube to keep arteries open), or coronary artery bypass grafting (CABG) to create new routes for blood to flow around blocked arteries.
Essential for managing CHD: quitting smoking, eating a heart-healthy diet, regular physical activity, maintaining a healthy weight, managing stress and controlling conditions like high blood pressure and diabetes.
Prevention is always better than cure. Here are key strategies to reduce your risk of developing CHD:
Eat plenty of fruits, vegetables, whole grains and lean proteins. Limit saturated and trans fats, salt and added sugars. The Mediterranean diet, rich in olive oil, nuts, fish and vegetables, has been shown to reduce heart disease risk.
Aim for at least 150 minutes of moderate-intensity activity (like brisk walking) or 75 minutes of vigorous activity (like running) each week. Exercise strengthens the heart, improves circulation and helps control weight, blood pressure and cholesterol.
Research shows that making multiple lifestyle changes can dramatically reduce heart disease risk. A study published in the New England Journal of Medicine found that people who followed five healthy lifestyle factors (not smoking, maintaining a healthy weight, regular physical activity, moderate alcohol consumption and a healthy diet) had an 82% lower risk of coronary heart disease compared to those who followed none. This demonstrates that many cases of CHD are preventable through lifestyle choices.
Remember, understanding coronary heart disease is the first step toward prevention. By making informed lifestyle choices, you can significantly reduce your risk of developing this serious condition.
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