Other Information

1) Coronary Artery Disease

Over the past thirty years, the economy of Hong Kong has developed rapidly. As the same time the disease pattern among Hong Kong people has demonstrated some similarities to other developed countries. Cardiovascular disease which is very common in develop countries has become the second most common cause of death in Hong Kong. Although common cardiovascular diseases such as hypertension, coronary artery disease and stroke mostly occur among the middle-aged and elderly, medical research showed that the risk factors of the disease such as lifestyle and dietary habits may be identified in adolescence or even earlier. The research also suggested that healthy lifestyle and eating habits could reduce the risk of cardiovascular diseases.

Coronary arteries

Coronary arteries are importance branches of the aorta. They maintain blood flow to the heart muscle, provide nutrients and oxygen to maintain the heart function. As a result of aging, the aorta and its major branches, including the coronary arteries developed atherosclerosis in inner wall, leading to narrowing of the blood vessels. Coronary heart disease is result of severe narrowing of the coronary arteries, causing insufficient blood supply to the heart muscles. When the coronary artery narrows to critical point, the heart muscles will have insufficient blood supply. During vigorous exercise, the insufficiency of blood flow becomes more severe. As a result the patient may develop chest pain or angina. If the coronary artery is blocked completely the heart muscles supplied by the vessel will be damaged. This leads to permanent ischaemic injury to the heart muscles or myocardial infarction. Without prompt treatment patient may die of heart failure or abnormal heart rhythm.

Risk Factors of Coronary Artery Disease

Medical researches have demonstrated the following risk factors of coronary heart disease:

i. Smoking
ii. Hypertension
iii. High blood lipid levels
iv. Diabetes Mellitus
v. Genetic factors

The first four-risk factors are closely related to lifestyle and can be modified. While the genetic propensity to coronary heart disease can not be corrected these individuals should be more aware of their diet and lifestyle in order to lower the chance of developing the disease. Conclusions from medical researches show that the risk factors of atherosclerosis can be found in young age. Therefore, we believe that prevention should start in childhood.

Therapy for Coronary Artery Disease

There are several modalities for the treatment of coronary artery disease, including thrombolysis, percutanous transcatheter angioplasty, coronary artery stenting and coronary artery bypass graft surgery. The principle is to recannulate narrowed arteries or make a bypass around the blocked artery, so that blood supply to heart muscle can be re-stored.

After treatment some patients may have complications like heart failure and abnormal heart rhythm. They require long term medication to prevent progression and recurrence of the disease.

In conclusion coronary artery disease carries high mortality. The complications and long term morbidity of the condition are also serious. There is no effective treatment reverse this disease. Therefore, the best approach to coronary artery disease is prevention, preferably starting from early childhood.



2) Prevention of Cardiovascular Diseases

Prevention of Cardiovascular Diseases should start from childhood. The following measures are effective in modify risk factors:

1.Healthy diet

Excessive intake of fat may result in high levels of blood lipids and cholesterol. It accelerates the development of atheroma and causes coronary artery disease. With the promotion from various health organizations and the government a wide variety of low fat and low cholesterol food are available on the market. However a healthy diet not only consists of low fat, low cholesterol food, it should be balanced. Consumption of sugar and salt should be modest. Excessive sugar intake results in obesity and excessive salt intake leads to high blood pressure. A healthy diet also encourages more vegetable, fruit and fiber intake, which helps to lower the blood cholesterol level.

The Dietitian's advice:

The food pyramid provides a guide to appropriate consumption of different foods. It is importance to have foods from all the classes to form a balanced diet. Deficiency of a class of foods may have adverse effects on the growth of children.

2. Smoking prevention and cessation

Smoking is a cause of lung cancer. It also accelerates the progression of atherosclerosis. Evidence has shown that the risk of coronary artery disease is also increased for the passive smokers. To reduce prevalence of smoking in the general public the government has introduced anti-smoking measures, including limitation of public smoking areas and restrictions on selling cigarettes to teenagers.

There are social and psychological backgrounds of teenage smoking. Parents who smoke are more likely to have children who become smokers in the future. Young people may try cigarette smoking out of curiosity. It is important to promote health education and let young people to know the damaging effects of smoking. Secondary prevention must also be emphasized. Teachers and parents should try to the young smokers and help them to quit smoking.



3. Regular Exercise

Regular Exercise can reduce the risk of coronary heart disease in several ways.

- Exercise lowers blood pressure in hypertension
- Exercise improve physical fitness and prevent overweight
- Exercise lowers the cholesterol level in the blood

The sport facilities in Hong Kong are relatively inadequate compared with other countries. Also physical education is often regards as a less important subject in school, therefore many children are not active in exercise. In addition, many parents themselves do not exercise regularly and spend too much time in watching television and other non-physical activities. These are the reasons why children fail to develop the habit of regular exercise.


What kind of exercise can prevent coronary artery diseases?

To prevent coronary heart disease, aerobic exercise should be taken regularly. Aerobic exercise is a form of physical activity using oxygen to convert fat and carbohydrate to energy. When performing aerobic exercise the heart and lungs work very hard to provide enough oxygen to the muscles, therefore aerobic exercise can maintain the fitness of heart and lungs minimize the risk of coronary heart disease and high blood pressure.

Aerobic exercise has the following characteristics:

1. Whole body activities involving dynamic exercise of large muscle group sustained for several minutes
2. Level of exercise not excessive


What kinds of activities is aerobic exercise?

Soccer, basketball, tennis, badminton, ice skating, stairclimbing, jogging, aerobic dance, rowing, cycling, walking, volleyball, handball, hiking, rope skipping, swimming


What is the appropriate level of aerobic exercise?

The principle is not to stress the body to the limit. If the activity is too strenuous, the muscles develop fatigue and exercise cannot be carried on further.

There are two methods to assess the appropriate level of exercise:

1. Self-Rating of Perceived Exertion
Healthy individual can judge whether the exercise is too much by themselves. Development of tiredness and breathlessness indicates that the maximum level of aerobic exercise is attained.
2. Heart Rate
When doing aerobic exercise, the heart rate will increase. Teenagers performing aerobic exercise should have the heart rate increased to 140-160 beats per minute.


How much exercise should children and teenagers perform?


The American Heart Association recommends that at least 30 minutes of exercise should be done intermittently or continuously every day.


4. Weight control


In 2000 the Department of Health reported that the incidence of obesity among primary school students was 14.1%. It has been shown that the obese teenager is very likely to become obese adult. Therefore prevention of obesity should start in early childhood. Body weight can be maintained by having healthy diet and regular exercise.

The adverse effects of obesity
- Obesity is a risk factor for hypertension and diabetes mellitus and causes high level of cholesterol
- Obesity has a negative impact on the individual's self-image, which may affect their psychosocial development

The etiology of obesity
Excessive intake of food and too little exercise
Hereditary factors
Endocrine disorder
Side effect of drugs e.g. steroid

The diagnosis of obesity
Obesity means excessive body fat. However as the total amount of fat inside the body is different to quantify other indices are used. The following are the two commonly used indices:

I)Relation of body weight to height

1)Body Mass Index = Weight (kilogram) / Height2 (metre) 2.
If the index exceeds 85th percentile it indicates obesity.
2)Weight to Height Ratio

A normal individual should have an appropriate proportion of weight and height. If the percentile of body weight in comparison to the percentile of height is too high, it suggests overweight or obesity.

II)Skin fold thickness

The thickness of skin directly reflects the amount of fat in the subcutaneous tissue and indirectly the total body fat. Conventionally two sites are used for measurement of skin fold thickness: below the scapula and at the back of the arm.



5. Hypertension

Hypertension is a very common cardiovascular disease, especially among the elderly. However, it also exists in children. About 1% of the children are affected, 90% of which are caused by secondary factors.

Chronic hypertension will lead to heart failure, cerebral vascular accidents, renal disease and other problems. Without treatment, the morbidity increases proportionally with the level of blood pressure.

How is hypertension diagnosed?

Normal blood pressure increases with age and body weight. The blood pressure of individual children should be compared with normal value of similar age group and body size. Children whose average systolic or diastolic pressure recorded on three different occasions exceeded 95th percentile are diagnosed as hypertensive. They need further investigations to find out any secondary causes.

Primary causes:	Genetic factors
Secondary causes:	Renal diseases e.g. nephritis and congenital renal malformation Atherosclerotic disease e.g. renal artery stenosis Endocrine disorders e.g. Adrenal gland tumour Drug: e.g. steroids

Measures to prevent hypertension and coronary artery disease are similar:

a)Reduce salt intake and maintain healthy dietary habit
b)Avoid overweight
c)Regular exercise
d)Check blood pressure yearly