How does ageing affect the heart — Part 1
Age is an important risk factor for many types of heart disease. (Photo: Pexels)

AS we get older changes take place in the structure and function of the heart. These changes occur in all individuals and may play a role in the development of heart disease in later life.

Age is an important risk factor for many types of heart disease. For example, in developed countries heart failure is found in more than 10 per cent of people above the age of 70 years, atrial fibrillation is found in 10-17 per cent of people above the age of 80 years and 70-80 per cent of all pacemakers are placed in people above the age of 65 years. Age is also a strong risk factor for coronary artery disease with the incidence increasing with age.

What causes changes in the heart as we age?

The underlying factors that change the heart as we age are complex and not well understood. This is an area of active research with many processes being studied. It is likely that there are multiple processes responsible for age related changes. Some of the more popular theories include:

Mitochondrial dysfunction: The mitochondria are parts of the cells responsible for production of energy. As we age, our mitochondria may become dysfunctional leading to the generation of waste products that damage the cell.

Neuro-humoral changes: Ageing is associated with changes in several hormonal systems including the fight or flight system, hormones that regulate salt/water balance and vascular tone. These hormones have direct effects on the muscle of the heart and may lead to scarring of heart muscle, changes in the heart rhythm, increases in heart thickness, structure, and cell death.

Chronic Inflammation: Increase in markers of inflammation is common in the elderly and this inflammation has been associated with increased morbidity and mortality through unclear mechanisms.

Decreased ability to create new heart muscle cells: Humans have a limited ability to generate new heart muscle in response to injury, hence the reason we must always respond with utmost urgency when patients are having a heart attack or with unstable heart related symptoms like chest pain. This limited ability to repair damaged heart muscles further decreases significantly as we age.

How does the structure and function of the heart change with age?

An important change is an abnormal reduction in the number of heart muscle cells. When this occurs, the remaining cells increase in size to compensate for the work of the missing cells resulting in increased thickness of the muscle of the heart. This increased thickness when combined with scar tissue results in a heart which is stiffer and less compliant than normal requiring higher pressures to fill. Another adverse effect of this increase in pressure is enlargement of the atrial chambers. Reductions in the number of cells that form the electrical system of the heart also occur leading to problems with slowing of the heart rate and difficulties with conduction of electricity to all areas of the heart.

In addition to loss of normal heart cells, the deposition of proteins and chemicals within heart tissue can lead to changes in heart function. This can result in increased stiffness of the heart, thickness of the heart, abnormalities of heart rhythm and weakness of heart muscle.

Ageing often results in changes in the heart valves with thickening being common. Calcium deposits can occur. Calcification is often noted in the aortic valve and around the mitral valve. Sometimes these changes may lead to narrowing or leakage of the valves with severe valve dysfunction.

In terms of heart function, as the heart gets older, the walls become less compliant and more difficult to fill with blood. There is also a decrease in the ability of the heart to contract and a reduction in the maximum heart rates that can be achieved. The result is an inability of the heart to increase the delivery of blood and oxygen with exercise, leading to lower exercise tolerance when compared with younger individuals. When these changes are severe, a syndrome of heart failure can result. Ageing is also associated with changes in the arterial blood vessels. Increasing stiffness of these vessels (particularly the aorta) result in resistance to the emptying of the chambers of the heart and an increase in the amount of cardiac work. It also results in higher blood pressure which adversely affects the structure of the heart.

Dr Ernest Madu, MD, FACC and Dr Paul Edwards, MD, FACC are consultant cardiologists for Heart Institute of the Caribbean (HIC) and HIC Heart Hospital. HIC is the regional centre of excellence for cardiovascular care in the English-speaking Caribbean and has pioneered a transformation in the way cardiovascular care is delivered in the region. HIC Heart Hospital is registered by the Ministry of Health and Wellness and is the only heart hospital in Jamaica. Correspondence to info@caribbeanheart.com or call 876-906-2107.

Dr Paul Edwards and Dr Ernest Madu

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