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Don't Forget to Exercise! And Avoid Unhealthy Diets!

PREVENTION OF CARDIOVASCULAR DISEASES

by Dr PHUA Kai Lit
School of Medicine and Health Sciences
Monash University Sunway Campus
Bandar Sunway, Malaysia

American Public Television programme on Diet, obesity and disease

American Heart Association


WHAT ARE THE CARDIOVASCULAR DISEASES? (CVDs)

Coronary heart disease or CHD (also called ischaemic heart disease)
Hypertension
Congenital heart disease (malformation of heart & major blood vessels around the heart)
Valve defects caused by infections (rheumatic fever causing rheumatic heart disease; infective endocarditis)
Cardiomyopathies and myocarditis
Syphilitic heart disease (cardiovascular complications of advanced syphilis)

RISK FACTORS FOR CVDs

1. Non-modifiable

Age e.g. blood pressure tends to increase with age
Sex e.g. risk increases sharply after menopause for women
Ethnicity e.g. associations between ethnicity and CVDs
Family history e.g.increased risk if close family member has CVD

2. Modifiable, physiological

Blood chemistry e.g. high total serum cholesterol, high plasma triglycerides, elevated LDL (Low Density Lipoproteins)
Hypertension
Diabetes
Obesity

3. Behavioural

Smoking - risk of CVD is 2-3 times higher for smokers
- passive smoking also increases the risk of CVD
Diet - diets high in saturated fats, salt, calories, refined sugar
- diets low in fresh fruits and vegetables
Sedentary lifestyle - lack of exercise
Alcohol - excessive alcohol consumption

4. Environmental

Air pollution - associated with hospital admissions and deaths from pulmonary and cardiovascular diseases
Temperature (cold weather)e.g. myocardial infarction from shovelling snow
Heavy metal poisoning e.g. cardiomyopathy due to cobalt sulphate added to beer
Infectious agents e.g. group A Streptococcus and rheumatic heart disease

(1) - (3) are the most important risk factors. Diet and smoking are especially important
(4) contributes only an estimated 10% to CVD rates in developed countries

The World Health Organisation says that

"Strong evidence exists that dietary factors play a central role in CVD and account for much of the variation in disease rates between countries"

---- diets high in calories, saturated fats, refined sugars, salt, low in fresh fruit and vegetables

---- overnourishment and obesity

---- tobacco smoking (12% of CVD in developed countries attributed to smoking)

PREVENTION (the following are VERY IMPORTANT CONCEPTS)

PRIMARY PREVENTION: Prevent the disease or injury from actually occurring. In the case of CVDs, through actions such as a "Healthy Lifestyle" e.g., healthy diet, regular exercise, preventing overweight, control of stress, etc

SECONDARY PREVENTION: Early detection and prompt treatment of disease. An example is medication to lower blood pressure

TERTIARY PREVENTION: Rehabilitation after a disease has occurred. Attempts are made to restore as much of a person's functions as possible e.g. revascularisation or even heart transplants for severe cases of CVDs

EVIDENCE THAT CVDs CAN BE PREVENTED

1. There are large differences in incidence and death rates for CVDs between different countries and between different social groups within one country.

2. CVD rates can go up or down over time

3. CVD rate changes among immigrant groups e.g. the descendants of Japanese immigrants in the USA experience CHD rates which resemble those of white Americans. Rates among the Japanese in Japan are much lower.

4. Risk factors have been identified

5. There is strong evidence from randomised clinical trials that CVDs can be prevented

APPLICATION OF CONCEPTS OF "PRIMARY PREVENTION", "SECONDARY PREVENTION" AND "TERTIARY PREVENTION" TO CVDs

CORONARY HEART DISEASE (CHD) AND HYPERTENSIVE HEART DISEASE

Primary Prevention:

Healthy Diet
Less salt (also, avoid canned, pickled and processed foods)
Exercise
Stop smoking
Medication to lower blood cholesterol (decrease LDL)
Control hypertension before it leads to left ventricular hypertrophy

Tertiary Prevention: (after myocardial infarction)

Beta-blockers
Stop smoking
Treat for hyperlipidemia
Low dose aspirin
ACE inhibitors (patients with left ventricular dysfunction
Revascularisation e.g. bypass surgery
Thrombolytic drugs
Heart transplant

CONGENITAL HEART DISEASE

Primary Prevention:

Rubella immunisation of susceptible women (avoid pregnancy for 2 months after vaccination)
Avoid radiation during pregnancy
Avoid teratogenic drugs during pregnancy
Avoid cigarettes, alcohol, pesticides, herbicides during first trimester of pregnancy

Secondary Prevention:

Surgery (children with congenital heart disease)

RHEUMATIC HEART DISEASE

Primary Prevention:

Treat group A Streptococcus infection with penicillin or erythromycin
Prevent recurrent attacks of rheumatic fever

Secondary Prevention (for patients with existing valvular diseases):

Antibiotics before dental extraction
Antibiotics before urologic and surgical procedures to prevent infective endocarditis

CARDIOMYOPATHIES AND MYOCARDITIS

Primary Prevention:

Prevent alcohol abuse (cardiomyopathy)

Secondary Prevention:

Treat for viral myocarditis infection
Treat for schistosomiasis
Treat for Chagas' Disease (Latin American form of trypanosomiasis)

SYPHILITIC HEART DISEASE

Primary Prevention:

Prevent syphilis
Treat early stages of syphilis

IN CONCLUSION ...

(1) CARDIOVASCULAR DISEASES CAN BE PREVENTED
(2) YOU SHOULD BE ABLE TO APPLY THE CONCEPTS OF PRIMARY, SECONDARY AND TERTIARY PREVENTION TO CVDs
(3) PREVENTION CAN BE UNDERTAKEN AT THE INDIVIDUAL LEVEL OR THE POPULATION LEVEL

Examples of individual level prevention:
Healthy diet; rubella immunisation for women

Example of population level prevention:
Regulation of the fat and salt content of canned and other processed foods by the Government (ENFORCEMENT)
Ministry of Health campaigns to encourage "healthy eating" and "healthy lifestyle" (EDUCATION)
Raising taxes on tobacco and alcohol (ECONOMIC)
Banning machines used to sell cigarettes (ENVIRONMENTAL MODIFICATION)

An interesting example of a population level intervention:
Singapore's effort to persuade hawkers to reduce the amount of fat and salt in the food they sell

QUESTION FOR YOU TO PONDER: Is it possible to persuade McDonald's, Pizza Hut, KFC etc to make their fast foods more healthy?


REFERENCES

Wallace, R.B. ed. 1998 "Maxcy-Rosenau-Last Public Health and Preventive Medicine" 14th ed. Stamford, Connecticut: Prentice-Hall International Inc.

Cassens, B.J. 1992 "Preventive Medicine and Public Health" 2nd. ed. Philadelphia: Harwal Publishing

Lucas, A.O. and H.M. Gilles 1990 "A New Short Textbook of Preventive Medicine for the Tropics" 3rd. ed. Sevenoaks, Kent: ELBS with Edward Arnold

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