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HIGH BLOOD PRESSURE SERIES · ARTICLE 3 OF 12
The complications nobody wants to talk about
Stroke, heart attack, kidney disease and dementia.
This is a difficult article. We put it third in the series on purpose. If you understand what high blood pressure does when you leave it alone, the rest of the series — the food, the walking, the medication, the salt — makes much more sense.
We are not writing this to frighten you. We are writing it because, in our experience, knowing the stakes is the single biggest motivator people have. The good news at the end of every section here is the same: high blood pressure, treated, almost completely removes these risks. Untreated, they accumulate quietly for ten or twenty years and then arrive all at once.
What this article is and is not
This article describes what high BP does over a long time when it is left untreated, or treated badly. None of it is inevitable. None of it is automatic. The whole point of treating BP — with food, with movement, with tablets — is to prevent every single thing in this article.
What high BP actually damages
In article 1 we used the garden-hose analogy: when blood is pushed through arteries at too high a pressure, year after year, the walls of the arteries stiffen, scar, and weaken. That damage is the root cause of every complication in this article.
It shows up first and worst in five places — the places where small, delicate blood vessels matter most:
• The brain
• The heart
• The kidneys
• The eyes
• The brain again, in a different way
Each one is preventable. None of them are caused by high BP overnight. All of them are caused by high BP slowly, over many years.
1. Stroke
A stroke is what happens when blood stops reaching part of the brain. Without blood, brain cells start dying within minutes. The part of the body controlled by that area of brain stops working — speech, an arm, a leg, vision, balance.
High blood pressure is the single biggest cause of stroke in South Africa, by a wide margin. There are two kinds.
Ischaemic stroke (a “blockage” stroke)
The arteries in and around the brain become stiff and scarred from years of high pressure. Eventually one of them gets blocked, usually by a clot, and the brain tissue downstream of the blockage starts dying.
About 80% of strokes in South Africa are this kind. They are partly preventable with BP control and the careful use of medications like aspirin in the right people.
Haemorrhagic stroke (a “bleeding” stroke)
One of those weakened, scarred artery walls in the brain finally tears, and blood floods into the brain tissue. This kind of stroke is almost always caused directly by chronic high BP.
It is less common but more dangerous — about 30 – 40% of haemorrhagic strokes are fatal within a month.
Spot a stroke — F.A.S.T.
Face — ask the person to smile. Does one side droop?
Arms — ask them to raise both arms. Does one drift down?
Speech — ask them to say a simple sentence. Is it slurred or strange?
Time — if any of these is wrong, call 10177 immediately. Every minute matters. The earlier treatment starts, the more of the brain can be saved.
What’s reversible
If treatment starts within the first three to four hours, much of the brain damage from an ischaemic stroke can be reversed. Outside that window, recovery is slower and less complete. Six months of physiotherapy and speech therapy can do extraordinary things — but not everything. Some loss is usually permanent.
The way to never need that recovery is to keep BP under control in the years before any stroke happens. Bringing systolic BP down by 10 mmHg cuts stroke risk by roughly 30%. That is not a small number.
2. Heart attack and heart failure
The heart is the muscle that pushes blood through the body. High BP makes it work harder, every single beat, for decades. Two things eventually go wrong.
Coronary artery disease and heart attack
The arteries that feed the heart muscle itself — called the coronary arteries — are particularly vulnerable to the stiffening and scarring caused by high BP. Cholesterol gathers in the weak spots, fatty plaques build up, and eventually one of them cracks. A clot forms on the crack, the blood flow stops, and the part of the heart muscle downstream of the blockage starts dying.
That is a heart attack. The signs:
• A heavy, crushing pressure in the centre of the chest, often spreading to the left arm, the jaw, or the upper back
• Shortness of breath
• Cold sweat
• Nausea
• A sense of doom — many survivors say they knew something was very wrong
If you suspect a heart attack: stop what you are doing, sit down, chew an aspirin if there is one nearby (and you are not allergic), and call 10177. The first hour is critical.
Heart failure
This is the slower, quieter problem. The heart muscle, after years of working too hard, gets tired and weak. It cannot pump efficiently any more. Fluid backs up — into the lungs, into the legs, into the abdomen.
The early signs are easy to miss:
• Getting more tired than usual on stairs or walking uphill
• Swollen ankles by the end of the day
• A persistent cough, especially when lying flat
• Needing more pillows to sleep comfortably
• Sudden weight gain from fluid (a kilogram or more in a few days)
Heart failure is one of the most common reasons elderly South Africans are admitted to hospital. Most of the cases would have been preventable with better BP control twenty years earlier.
What’s reversible
A heart attack that is treated quickly (with stents, clot-dissolving drugs, or surgery) leaves much less damage than one that is treated late. Heart failure, once established, can be slowed and managed but is rarely reversed. The earlier BP is controlled, the less likely either of them happens at all. Bringing systolic BP down by 10 mmHg cuts heart attack risk by roughly 20% and heart failure risk by about 40%.
3. Kidney disease
Your kidneys are full of tiny, delicate blood vessels — millions of them. Each one filters blood and produces urine. Each one needs the right pressure to do its job. Too low, and the kidneys cannot filter. Too high, for too long, and the vessels are slowly destroyed.
This is called chronic kidney disease, or CKD. It progresses in stages. Early stages have no symptoms at all. Later stages bring tiredness, swelling, itching, nausea, and a metallic taste in the mouth. By the time symptoms appear, kidney function is often below 30%.
The endpoint of CKD is dialysis — three-times-a-week sessions on a machine that does the kidneys’ job — or a kidney transplant. Public-sector dialysis in South Africa is heavily rationed; in many provinces there is a waiting list, and not everyone gets on it.
How to catch it early
Two tests, both available free at any public clinic:
• A urine dipstick, looking for protein in the urine. Early kidney damage leaks tiny amounts of protein.
• A blood test for creatinine, which is used to calculate something called eGFR — an estimate of how well your kidneys are filtering.
If you have high BP or diabetes, both tests should happen at least every year. Catching CKD at Stage 1 or 2 can completely prevent progression to dialysis.
What’s reversible
The early stages of kidney damage from high BP can be halted, and in some cases partly reversed, by getting BP firmly under control. Once you reach Stage 4 or 5, function does not come back — but progression can be slowed dramatically with the right medication. The right medication usually includes one of the BP drug groups we will discuss in article 9, which are particularly good for kidneys.
4. The eyes
The retina at the back of the eye is densely packed with tiny blood vessels. An eye doctor or an optometrist can look at these vessels directly with a small light and a lens. They are the only blood vessels in your body that can be examined without cutting you open.
High blood pressure damages these vessels in a recognisable pattern — narrowed arteries, leaks, bleeds, and tiny dead patches. This is called hypertensive retinopathy.
Mild retinopathy has no symptoms. Severe retinopathy causes blurred vision, dark patches in the visual field, and in the worst cases, sudden vision loss.
Many people first find out they have high BP when they go for an eye check for new glasses, and the optometrist sees the damage at the back of the eye. It is worth saying — if you are 40 or older, an annual eye check is a good idea regardless of whether your vision feels fine.
What’s reversible
Early hypertensive retinopathy reverses completely once BP is controlled. Severe retinopathy may leave permanent vision damage in the affected patches, but progression stops.
5. Vascular dementia
This is the complication people talk about least and one of the most frightening. Dementia is the slow, progressive loss of memory, judgement, language, and personality. It used to be thought of as Alzheimer’s disease — a brain condition more or less separate from the heart and blood vessels.
The research of the last twenty years has changed that picture entirely. Many cases of dementia are partly or entirely vascular — caused by years of small, often unnoticed bits of damage to the small blood vessels in the brain. The biggest single risk factor for vascular dementia in middle and late life is untreated high blood pressure in your forties, fifties and sixties.
The path looks like this: chronic high BP slowly damages the small blood vessels in the brain. Tiny strokes happen, sometimes too small to notice. The damage accumulates. Cognitive function declines, sometimes step by step, sometimes gradually.
The same damage also makes “ordinary” Alzheimer’s-type dementia worse and more disabling when it does start.
What’s reversible
Dementia, once established, does not reverse. The whole point is to never get there. Good BP control in your forties, fifties and sixties is, alongside not smoking and staying physically active, the single biggest thing you can do to protect the brain you will need at 75.
How much of this does treatment actually prevent?
The numbers below come from large international studies that have followed millions of people over decades. They describe the effect of bringing systolic BP (the top number) down by 10 mmHg through any combination of lifestyle and medication.
Outcome Risk reduction Stroke About 30% Heart attack About 20% Heart failure About 40% Kidney disease progression About 25% Death from any cardiovascular cause About 13% Vascular dementia (over 20 years) About 25 – 30%
These are not small numbers. They are some of the biggest risk reductions in all of medicine, from a single change. And many people need more than 10 mmHg of reduction — going from 150 / 95 to 130 / 80, for example, is closer to 20 mmHg, which roughly doubles every benefit in the table.
Every milligram of mercury you bring your BP down protects your brain, your heart, your kidneys and your eyes.
The bigger picture
Untreated high blood pressure is not a “maybe one day something might happen” condition. It is a slow, certain accumulation of damage. The damage is invisible for many years and then arrives all at once, in the form of a stroke, a heart attack, or kidney failure. By that point, much of the damage cannot be reversed.
The whole rest of this series — the food, the walking, the medication — is about preventing every single complication in this article. Most of them are preventable in most people, most of the time, if BP is brought down and kept down. The treatment is cheap, accessible, and effective.
The next article in the series gets practical: how to measure your own blood pressure properly. What the numbers really mean. How to choose a home monitor. How often to test. How to keep a record that you can actually take to your clinic.
Where to get more help
Heart and Stroke Foundation South Africa — heartfoundation.co.za · 021 422 1586.
In an emergency — 10177 for an ambulance, or get to your nearest hospital emergency department immediately.
South African Renal Society — sa-renalsociety.org — patient information on kidney disease.
Phila Today Diabetes Series — articles on diabetic complications cover much of the same damage from a different angle. They are useful companion reading.
Phila Today High Blood Pressure Series — next: understanding your BP reading — what the numbers mean and how to measure at home.
Phila Today · Article 3 of 12 in the High Blood Pressure Series