CARDIOVASCULAR DISEASE

Cardiovascular disease (CVD) affects the arteries, the blood vessels that carry oxygen-rich blood to the heart and other parts of the body. The commonest and most important CVD is atherosclerosis in which plaques containing cholesterol, fibrous tissue and other cells build up in the walls of arteries. Atherosclerosis causes heart attacks when it affects the arteries of the heart and strokes when the brain arteries are affected.

CARDIOVASCULAR RISK FACTORS

Cardiovascular disease risk factors are characteristics or conditions that increase the risk of developing CVD due to atherosclerosis and may be non-modifiable or modifiable.

Non-modifiable risk factors include age, family history and male gender. The risk of atherosclerosis increases with age, in those with a history of heart attack or stroke in close relatives and is higher in men than women before menopause. Menopausal women have similar CVD risk to men.

Modifiable risk factors include cholesterol, hypertension, diabetes, smoking, overweight, sedentary lifestyle and psychosocial stress.

• Cholesterol is a lipid in the bloodstream and in all the body’s cells. It is important for the healthy functioning of our bodies. The human body makes cholesterol which is needed to form cell membranes and hormones. It is also derived from certain foods like animal meat, milk and milk products like butter and cheese, coconut fat, palm oil and trans fats, often used in foods such as french fries, cakes and cookies. Cholesterol is carried through our blood by particles called lipoproteins consisting of low-density lipoprotein (LDL) and high-density lipoprotein (HDL). High blood levels of LDL lead to deposition of cholesterol in the walls of arteries causing atherosclerosis leading to heart attack and ischemic stroke. HDL cholesterol on the other hand reduces the risk of cardiovascular disease as it carries cholesterol away from the blood stream. A high blood LDL level can be inherited. The condition is known as familial hypercholesterolemia, in which a build-up of LDL cholesterol in the blood is present from birth. This can lead to coronary heart disease at an early age.

• Hypertension or high blood pressure is defined as a systolic blood pressure level of 140 and above and/or diastolic blood pressure of 90 and above. It is a risk factor for coronary heart disease and the single most important risk factor for stroke and brain haemorrhage (bleeding).
• Type 2 diabetes causes damage to blood vessels making them more prone to damage from atherosclerosis and hypertension. People with diabetes develop atherosclerosis at a younger age and more severely than people without and increases the risk of CVD by two to four times. Cardiovascular disease is the leading cause of mortality for people with diabetes. There are a number of reasons for this increased cardiovascular risk. Hypertension, abnormal blood lipids and obesity, all risk factors in their own right for cardiovascular disease, occur more frequently in people with diabetes.

• Smoking has been linked to cardiovascular disease and cancer since the 1940s. This risk is even higher in those who start smoking in childhood. Mortality is 60% higher in smokers and on average smokers die seven years earlier than non-smokers. The risk for CVD increases with both the number of cigarettes and the duration of smoking. Smoking even one cigarette per day is associated with approximately 50 percent increased risk for coronary heart disease and approximately 25 percent increased risk for stroke.[1] Exposure to passive smoke also increases the risk of cardiovascular disease.

• Obesity can be defined by the circumference of the waist, the ratio of the waist to the hips, and the relationship between height and weight referred to as Body Mass Index (BMI). A BMI over 23 kg/m² is defined as overweight, and a BMI of over 28 kg/m² as obese. BMI is not a perfect way of estimating CVD risk but the risk of hypertension, abnormal levels of lipids, diabetes increase with BMI, leading to an increased risk of atherosclerosis and CVD. Increasing BMI or weight has been associated with increased mortality, mainly from cardiovascular complications, and reduced life-span of between 1 to 13 years.

• Diet through its impact on other CV risk factors plays a key role in the development and prevention of CVD. A diet high in saturated fat and trans fat is associated with increased risk of coronary heart disease and stroke. On the other hand, a diet low in saturated fats, with plenty of fresh fruit and vegetables, can reduce CVD risk significantly.
• Socioeconomic status, psychosocial stress, such as poverty, a chronically stressful life, social isolation, anxiety and depression, also increase the risk of CVD.

This article is contributed by Singapore Heart Foundation. For more information on Singapore Heart Foundation, please visit http://www.myheart.org.sg/.