21.9 Ageing and the cardiovascular system LEARNING OBJECTIVE 21.9 Explain the effects of ageing on the cardiovascular system. General changes in the cardiovascular system associated with ageing include decreased compliance (distensibility) of the aorta, reduction in cardiac muscle fibre size, progressive loss of cardiac muscular strength, reduced cardiac output, a decline in maximum heart rate, and an increase in systolic blood pressure. Total blood cholesterol tends to increase with age, as does low-density lipoprotein (LDL); high-density lipoprotein (HDL) tends to decrease. There is an increase in the incidence of coronary artery disease (CAD), a major cause of heart disease and death in older people. Congestive heart failure (CHF), a set of symptoms associated with impaired pumping of the heart, is also prevalent in older individuals. Changes in blood vessels that serve brain tissue — for example, atherosclerosis — reduce nourishment to the brain and result in malfunction or death of brain cells. By age 80, cerebral blood flow is 20% less and renal blood flow is 50% less than in the same person at age 30 because of the effects of ageing on blood vessels. CLINICAL CONNECTION Coronary heart disease and cardiac stent
Coronary heart disease is the most common form of cardiovascular disease in Australia and New Zealand. It is also the leading single cause of death in both countries. A typical example might be a 70-year-old male who lives in the hill suburbs of Dunedin in New Zealand. He and his wife are keen walkers, and until about a year ago they would walk back up the hill from the city with their groceries. In recent times, he has needed to take several breaks because he gets a tightness in his chest, and if he continues walking he experiences chest pain. If he stops and rests before continuing he feels better. One day while digging his garden he starts to have tightness and chest pain, but this time a break doesn’t help — the pain becomes worse, radiating down the left arm and up the neck. He gets shortness of breath and an ambulance is called. The severity of the chest pain, its tightness and its spread suggests narrowing of the coronary arteries, which could lead to an infarction of the heart muscles (myocardium), otherwise known as a heart attack. In the emergency department, patients with such a history get an emergency angiogram, which is a study of the arteries, or a cardiac catheterisation, which is a diagnostic test that involves inserting a small, flexible tube into the femoral artery in the groin or the radial artery in the wrist. If catheterisation is chosen, a small flexible catheter is inserted into the femoral artery in the groin and fed
upwards and positioned at the entrance to the coronary arteries. A special dye containing iodine is injected into the catheter and into the coronary arteries, and an outline of the coronary vessels visualised. If a narrowing is seen, then a coronary angioplasty is done. The process is similar to the catheter for
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- Three '17
- Francesca fernandez