James A Garfield

Cardiovascular disease remains a common cause of morbidity and mortality in the adult. In this article I plan to describe the common age-related changes in cardiovascular structure and function and try to suggest ways by which we can seek to reduce our risk factors for cardiac disease.

The cardiac output or work of the heart will be affected by changes in preload (filling of heart), postload (resistance to flow), contractility, coronary blood flow and the heart rate. Each of these is impacted upon by age-related physiological changes.

The early diastolic filling rate progressively slows after the age of 20, so that by 80, the rate is reduced up to 50%. Despite the slowing of left ventricular filling early in diastole, end-diastolic volume is not usually reduced in healthy, elderly persons. In healthy older persons, more filling occurs later in diastole to compensate for the slowed early filling.

In a number of studies an increase in afterload has been shown with increasing age. Several factors contribute to this including increasing frequency of systolic hypertension, occurrence of peripheral vascular disease and reduced elasticity of the aorta..

Contraction and relaxation are prolonged in senescent cardiac muscle. This coupled with the reduced beta-adrenergic stimulation of the heart with age may explain its relative inability to increase heart rates with exercise.

The resting, sitting cardiac output is not reduced in healthy older men although it does decreases slightly in women. Both sexes show an age-associated decreases in the maximum exercise capacity and maximal oxygen consumption decline with age but to a variable extent among individuals. Elderly persons in good physical condition can match or exceed the aerobic capacity of unconditioned younger persons.

The aging heart is vulnerable therefore to decompensation in response to hypoxia, the onset of atrial fibrillation, increased metabolic demands or changes in intravascular fluid volumes. Underlying heart disease resulting from coronary vessel disease, hypertension, atherosclerosis and valvular heart disease is also likely to have a greater impact on health and life.

What are the common risk factors for heart disease as we age and how can we modify them?

1. Gender: Males throughout their lifetime are at higher risk of heart disease although the difference becomes much smaller with age because of an increase in coronary artery disease in older women. Most of this age-related increases in coronary artery disease appears to be prevented by hormone replacement therapy.

2. Cholesterol: The total serum cholesterol is a measure of the circulating fat in the blood stream and is made up of high density lipoproteins (HDL), low density lipoproteins (LDL) and triglycerides (TG). HDL is often referred to as the Agood cholesterol@ since a higher level appears to lower the risk of heart disease. Factors which improve one HDL include maintaining an ideal weight, physical exercise, and avoiding smoking. LDL conversely is referred to as the Abad cholesterol@ since elevated levels are associated with atherosclerosis. LDL cholesterol can be reduced by a low fat diet, weight loss and medication.

3. Blood Pressure: We usually define a blood pressure as abnormally high, in individuals over 60 years of age, when either or both the systolic pressure is more than 160 mm Hg and the diastolic pressure is more than 90 mm Hg. A high blood pressure increases the postload and resistance to cardiac output, cause ventricular hypertrophy and predisposes to atherosclerosis. Factors that can reduce blood pressure include exercise, avoidance of obesity, salt restriction and medication

4. Cigarette smoking: Smoking on average reduces life expectancy by two to five years. Stopping smoking will reduce the coronary risk to that of a non-smoker within four years.

5. Diabetes Mellitus. Poorly controlled diabetics have an increased risk of atherosclerosis and cardiac disease. Better control will probably reduce this risk.

6. Exercise: Individuals who regularly exercise have been demonstrated to have aerobic capacities similar to sedentary individuals 10 years younger. In a study of Harvard alumni modest exercise started at age of 75 years resulted in nearly six months of extra life. The described benefits of exercise are seen with even relatively modest amounts of exercise. For example 5-10 minutes of stretching exercise associated with aerobic exercise for 20 minutes, three times a week. Before commencing this sedentary seniors or those with known cardiac disease should seek medical advice.

7. Sodium intake: Evidence is mounting that lifestyle and diet can modify age-associated increases in arterial stiffness and pressure. For example, dietary sodium has a greater effect on arterial pressure with age.

8. Obesity: Individuals with obesity have double the risk of coronary heart disease.

It should be clear therefore that a number of the recognised risk factors are potentially modifiable through changes in diet and lifestyle. Indeed, recent studies indicate that, in some instances, the impact of lifestyles on cardiovascular function may be far greater than that of aging!