Untreated hypertension can impact on and damage the entire circulatory system:
- The force exerted by high blood pressure causes microscopic tears in the walls of blood vessels. These turn into scar tissue.
- The damaged areas and scar tissue in the blood vessel walls accumulate materials circulating in blood, such as, cholesterol, platelets and fats. This leads to a build-up of plaque on blood vessel walls, causing them to narrow.
- Hypertension speeds up hardening of the arteries, making the blood vessel walls less flexible
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Stroke
Vascular dementia
This occurs when narrowing of the arteries to the brain causes decreased and insufficient blood supply to brain cells, causing them to become damaged or die.
Retinopathy
Hypertension places a strain on the blood vessels in the eye, causing them to narrow and/or bleed. This can result in retinal haemorrhages and the development of ‘cotton wool’ spots in the eye, both of which damage vision. Papilloedema can occur as a result of leakage and ischaemia, further reducing eyesight.
Myocardial infarction
Untreated hypertension damages blood vessels and predisposes an individual to clot and plaque formation. Myocardial infarction is caused by a blockage in a coronary artery.
Heart disease
Heart disease can result from untreated hypertension, as the ensuing plaque build-up can lead to the cardiac arteries gradually narrowing and hardening.
Heart failure
By damaging the circulatory system, hypertension adds to the workload of the heart, causing the heart to enlarge. An enlarged heart cannot effectively supply the required amount of blood to the body.
Embolism
We have seen that hypertension causes changes to blood vessels walls. A common cause of embolism is the formation of a clot at the site of a damaged blood vessel, which then breaks off and travels through the bloodstream to another part of the body, often the lungs.
Kidney disease
Hypertension damages the blood vessels supplying the kidneys. This results in the kidneys not filtering fluid and waste products properly, leading to an increase of fluid volume in the blood. This, in turn, causes a further increase in blood pressure.
Aneurysm
An aneurysm occurs when the walls of a blood vessel that has been weakened by hypertension begin to balloon out. These weakened areas can bust, resulting in a haemorrhage.
Erectile dysfunction
Hypertension stops the arteries that carry blood to the penis from dilating effectively. This causes the smooth muscle in the penis to lose its ability to relax. As a result, not enough blood flows into the penis to make it erect.
Peripheral arterial disease
This is a manifesting of the systemic atherosclerosis exacerbated by hypertension. The arteries supplying the legs and feet become narrowed and hardened, leading to insufficient blood circulating in these areas.
Pulse point
As you may remember from the Introduction, the risk associated with increasing blood pressure is continuous, with each 2 mmHg rise in systolic blood pressure associated with a 7% increased risk of mortality from ischaemic heart disease and a 10% increased risk of mortality from stroke.
You might wonder whether the opposite is also true and whether the benefits associated with reduced blood pressure are also greater with lower blood pressures. A recent trial (SPRINT) found that intensive blood pressure (SBP less than 120 mmHg) was associated with a significant reduction in cardiovascular events compared with standard blood pressure control (Wright et al, 2015).
(Ref: Wright JT, Williamson JD, Whelton PK et al. A randomized trial of intensive versus standard blood pressure control (PDF). N Engl J Med 2015;373 (22): 2103-2116)
Page last reviewed: 17 Sep 2020
