Healthy Retina
Sick RetinaImpotent

Why worry about high bloodpressure?

Hypertension is often called 'the silent killer', because it usually produces no symptoms until it is too late. It is often picked up as a coincidental finding when people visit the doctor for another reason.

Untreated hypertension worsens slowly over the years. Everyone 18 years and older should have their blood pressure checked on a regular basis. You can do this when you see your doctor for another reason, ask to have it done in a pharmacy or buy a blood pressure device (called a sphygmo-manometer) yourself. The price is between 100 and 150 NZ $ for a reliable machine.

It is particularly important to be aware of your blood pressure if you are having risk factors, like a family history of high blood pressure, stroke or heart disease. Other risk factors will be discussed separately below, but very important amongst New Zealanders are diabetes and obesity (overweight)

We should indeed woryy about our blood pressure as it is the single most important factor that causes immense suffering because of stroke, heart attacks and kidney failure and is an important factor to cause blindness. On top of that it is a problem that is treatable and the damage can be largely be prevented.

To enter more into the details of the severe consequences of high blood pressure, I will discuss the topics separately


Stroke is also called: a cerebrovascular accident (CVA). With this we mean that a severe accident happens to the bloodvessels in our brain. Most of us know strokes as a condition that paralyses parts of our body and brings people into wheelchairs. That is indeed often a consequence of stroke.

Basically, a stroke is nothing more than a bloodvessel that gets blocked by a bloodclot or a plaque of fat and the tissues of the brain behind the blockage will get no more oxygen and die.

Depending on where the block sits we can develop different symptoms. Minor strokes, that go unnoticed, or have little consequences (like slurred speech for a limited time, or weakness in an arm or a leg) are often seen in early phases, before the real brain damage has started and are called Transient Ischaemic Attacks (TIA's). TIA' should be a wake up call if they occurr. Adequate treatment should be given and the blood pressure tightly controlled.

There is also a more agressive kind of stroke. Whereas above the so-called ischaemic stroke (the brain does not get oxygen because of an obstruction) is discussed, we can also see that because of the high blood pressure a blood vessel in the brain ruptures and a large bleeding area damages the brain.

This causes large loss of brain function and is in many cases fatal. Compare it to the plumbing in your house bursting because the pressure on the system was overwhelming.

In all strokes high bloodpressure is a major contributing factor. About two-thirds of people who suffer a first stroke have moderate elevated bloodpressure (160/95 mmHg) or above. Hypertensive people have up to 10 times the normal risk of stroke, depending on the severity of blood pressure in the presence of other risk factors.

Ihe important fact to realise is that all this suffering could be prevented if hypertension was treated early and adequately. For doctors it is very sad to see a potentially preventable stroke leading to so much suffering and enormous costs to our healthcare system.

The stroke Foundation recently published the following facts you should know about stroke, realizing that New Zealand has 4 million inhabitants:

  1. Stroke is the second single largest killer in New Zealand (more than 2000 people every year)
  2. Every day, 21 New Zealanders will have a stroke
  3. Stroke is the major cause of adult disability in New Zealand
  4. Stroke is largely preventable, yet 8000 New Zeralanders a year suffer a stroke - a third of which are fatal
  5. There are 56'000 stroke survivors in New Zealand, many of whom have disability and need significant daily support
  6. Stroke recovery can continue throughout life, but there is little ongoing rehabilitation provided for stroke survivors nationally
  7. At least one in three New Zealanders can't recognize the signs of a stroke. delayed recognition means delayed medical intervention. delayed medical intervention can have tragical consequences.
  8. High blood pressure is a major cause of strokes. one in five New Zealanders have high blood pressure, and a third of these don't know it. Reducing your blood pressure can greatly reduce stroke risk. Salt is one of the greatest contributors to raised blood pressure

Heart attacks and Heart Failure

High blood pressure is a major risk factor for heart disease and together they often run in family where people die at an early age.

Heart attack. About half of people who suffer their first heart attack have moderate hypertension (160/95 mmHg) or greater. High blood pressure increases the risk for a heart attack by up to 5 times, depending on the severity of the hypertension.

Heart failure. Uncontrolled high blood pressure (hypertension) is a major cause of heart failure even in the absence of a heart attack. In fact, about 75% of cases of heart failure start with hypertension. It generally develops as follows:


Our eyes are very sensitive organs and you can imagine that they are very vulnerable to high blood pressure. We can see because in the back of our eye is a thin layer of tissue, called the retina, that holds millions of cells that after being activated by light will generate little electric currencies that then runs through nerves to our brains. It is a bit similar to a modern digital camera.

Will a so-called ophtalmoscope (see picture on the right) I can look through your pupil at the retina. This is a pain-free procedure that gives me an enormous amount of information about the blood vessels in your eyes, but also about the little blood vessels in general. Nowhere are blood vessels so visible for us than in the eye. If in the eye we see damage of the little arteries then we may assume that it is not much better in the kidneys and around the heart. We call this 'end organ damage'.

In the picture of the right hand side you can see what I will see when I look through my ophtalmoscope in your eye. The retina, holding a large number of tiny bloodvessels that supply the million retina cells with the oxygen they need to do their work. High bloodpressure in these little bloodvessels damages the cells and the bloodvessels can even rupture, causing bleeding or haemorrhages in the eye background.

In the next picture you see the eye background of someone with damage due to high bloodpressure. Note the severe damage, white spots and haemorrhages (bleeding) where the little light receptors have completely disppeared. Of note that this person was only complaining of some blurred vision, whereas there was already substantial damage! This damage can not be repaired but with adequate treatment, usually eyesight can be maintained. Untreated, it will lead to blindness.

Understandably, early diagnosis and treatment of hypertension are pivotal in preventing blindness.

Kidney Failure

As about 30% of all the people that have end-stage kidney disease and require dialysis (artifical kidney) have come to that a=stage because of high bloodpressure, it is easy to understand that the prevention of this needs our top attention. this even doubles if we have diabetes in the same individual.

Our kidneys are very complex organs. They have three major functions.

Number one is to clean our body of waste products. Compare the kidneys to a coffee filter, but realise that we have 1 million tiny filters in each of our two kidneys. These filters are as thin as the wall of the tiniest bloodvessels our body has, the so called capillaries. Because hypertension causes a permanently elevated pressure in these tiny capillaries, you can imagine that these filters get damaged. The function of the filters, passing waste products to the urine and retaining inportant nutrients, like proteins is disturbed. The very first sign that the filters start to fail is when they can no longer hold back the proteins. that is why we are always looking in your urine for the presence of proteins (called 'proteinuria'): an early sign of kidney damage and often a herald to kidney failure.

The number two tasks of our kidney is very obvious: to get rid of the water that we drink. the little filters have sensors, that will tell us how good our body is hydrated. If we drink a lot, the sensors will tell our kidneys to let go of water and we notice that we urinate more. Since the waste products are now dissolved in a large amount of urine, the colour of the urine becomes clearer. In contrast, if we do not drink enough, or if we loose water from the body because of fever, sweating when working hard or in case of diarrhea, the kidneys will retain water and the waste products are more concentrated. this explains the darker, and sometimes somewhat smelly urine that we can produce. the so-called concentrating capacity of the kidneys is truely amazing!

The third function of the kidneys is to produce hormones. An important hormone is erythropoietin. It increases the number of red blood cells, that transport oxygen trhough our body. if the kidneys fail, the number of red blood cells will fall as this hormone is no longer produced. We become 'anaemic' and patients feel lethargic and are often pale.

Hypertension will in the long term cause both our kidneys to fail and our body will longer have the three functions, as mentioned above, available. the only way to treat complete kidney failure is 'dialysis'. A machine takes over the cleaning of the blood. If people are healthy enough, they may qualify for a kidney transplant, where one kidney of another person is placed in the body of the patient with kidney failure.

Obviously, the goal is to prevent kidney failure and the good news is that hypertension, when treated early, is less likely to cause all these problems. Untreated hypertension will neraly always lead to kidney failure.

Sexual dysfunction

Sexual dysfunction is more common and more severe in men and women with hypertension and in smokers than it is in the general population For women this often means a loss of 'libido' (the desire to have sexual intercourse) and for men often problems to have or maintain an erection. Many of the drugs that treat hypertension are thought to cause impotence and loss of libido as side effect. Hence the importance to limit the number of medications as much as possible. In these cases, the problem often disappears when the drugs are stopped. More recent evidence suggests however, that the disease process that causes hypertension is in men often the major cause of erectile dysfunction (it needs a good and healthy bloodvessel structure to have an erection).

Newer antihypertensive drugs, like ACE-inhibitors and Angiotensin Receptor Blockers are much less likely to cause sexual dysfunction. men that have high bloodpressure but not severe heart disease were found to be safe in most studies regarding the use of medication for erectile dysfunction (drugs like Viagra, Cialis, and Levitra).

Alzheimers Dementia

Recently a strong relationship was found between dementia and poor blood vessel quality, in particular in patients with hypertension. Isolated systolic (the upper value of the two bloodpressure figures) hypertension may pose a particular risk for dementia. All other forms of hypertension can cause dementia by an increasing number of very small strokes (see above). There is however no clear evidence yet that treating high blood pressure agressively reduces the occurence of Alzheimers dementia. The vascular (multiple stroke) dementia can probably largely be prevented by early diagnosis and adequate treatment.