Blood vessels don’t forget

Here BHF Professor, Mark Hanson, from University of Southampton gives us an insight into his research into blood pressure, and how we’re all a chip off the old block.

Blood vessels don’t forget

Like the plumbing in a house, our circulation is made up of a network of pipes. They deliver blood, oxygen and nutrients to every tissue in our bodies. However, unlike the rigid pipework in a house, our blood vessels are sensitive and responsive. They expand and contract to regulate our blood pressure and blood flow according to the needs of our bodies.

Our vessels control blood pressure day to day, month to month, keeping it surprisingly steady in each of us. But just like many other aspects of our bodies, people differ in their pressures and flows. So how do blood vessels know how to cope with our differences?

Part of the answer is that they learn on the job. What teaches them? It turns out to be growing up – our life in the womb before we are born, and then our early years as infants and young children.

As our bodies grow, so do our blood vessels. And as they grow they are exposed to many things - diet, hormones, stress, and more. Many of these things come from the mother, in signals which cross the placenta or in her milk. This is why a healthy lifestyle and diet is so important during pregnancy and childhood.

The settings our blood vessels learn affect how they respond to the challenges of our lives later – what we eat, how much we exercise, whether we smoke or drink too much alcohol, and so on. As we get older, these settings have a great influence on whether we remain healthy or get cardiovascular disease, and explain partly why the risk of disease varies between individuals.

We’re beginning to understand how the memory of our early lives is stored in our blood vessels. What happens in the womb doesn’t change the DNA we inherit from our parents, but it does appear to affect the way DNA works in the lining and muscular walls of our blood vessels. These changes are called epigenetic processes.

Our new knowledge about epigenetics holds out hope for future prevention of cardiovascular disease. Epigenetic changes occur in early life, so by measuring them we may be able to tell how large the risk of disease will be in a person many years later. Or we might be able to devise new treatments, personalised to each of us, and monitor how well they work.

Epigenetic ‘marks’ on our DNA are like memories of our early lives which stay with us for years – our blood vessels don’t forget.

What do my numbers really mean?

What do my numbers really mean?

I have my blood pressure checked fairly regularly. Generally, as long as my doctor doesn’t look worried by the digits he types into my medical records, I’m happy.

Sometimes I might ask what the reading is: “blah blah over blah” he replies cheerily. I nod my head and smile, none the wiser.

I’m familiar with the style of blood pressure readings, and know that there’s a big number ‘over’ a small number, but I wanted to find out what those numbers really mean…

Put simply, blood pressure is the pressure of blood in your arteries - the tubes that carry your blood from your heart to your brain and the rest of your body. You need a certain amount of pressure to get the blood around your body.

Your heart pumps in a regular rhythm squeezing oxygen-rich blood out of the big main artery – the aorta – which divides and branches into smaller and smaller vessels, nourishing every organ and tissue in the body.

The pressure of blood flowing through your arteries varies according to whether the heart is pumping or relaxing. Each time your heart pumps it contracts and blood is squeezed out, it creates a surge of pressure in the arteries. It’s this peak in pressure against the inside walls of your arteries that gives the top reading, which in medical terms is called your ‘systolic’ pressure.

After each beat/pump of your heart it has to relax to refill with blood, and the pressure of blood in your arteries falls, and this is the bottom reading. This is called your ‘diastolic’ pressure.

So, taking these two measurements give a reading of how much pressure your blood places on the inside walls of your arteries. This is blood pressure.

You should have your blood pressure measured so that you know what your target is. If you don’t have heart or circulatory disease, diabetes or kidney disease your target is to have a blood pressure below 140/85mmHg. (mmHg stands for millimetres of mercury, which are the units that are used to measure blood pressure).

However, if you have heart or circulatory disease – including being told you have coronary heart disease, angina, heart attack or stroke, have diabetes or kidney disease then your blood pressure should be below 130/80mmHg.

Ideally though your blood pressure would be quite well below these levels.

Know Your Numbers week starts today. We’ve got lots of booklets and info online about the ways to help your maintain a healthy blood pressure.

Cold Heart

It’s a routine familiar to many of us. We wake up in the morning, peer round the curtains and check what the weather is doing.

If it’s cold we reach for our hat and scarf, and if it’s warm, shorts and sunglasses are order of the day.

But if you’ve got heart disease the weather can play a much more important role. In fact, a new study, funded largely by the BHF, has found colder than average temperatures may increase someone’s risk of heart attack.

Cold weather

Extreme cold weather can affect the heart by increasing heart rate and blood pressure. And chilly temperatures could also affect blood cells which could increase the risk of developing blood clots. A blood clot is often involved in the blocking of a coronary artery leading to heart attack.

So, if the weather forecast predicts plummeting temperatures then heart patients must remember to wrap up warm and wear several layers of clothing – including a hat, gloves and nice thick socks.

And it’s also very important to avoid sudden exertion. If you’re a heart patient and you need to shovel snow off your driveway or push the car, leave it to someone else. Even better, stay indoors and keep the heating on.

And remember to keep an eye on vulnerable friends, family and neighbours during those cold snaps.

Hot weather

At the opposite end of the spectrum, hot weather can also play its part in the lives of heart patients.

The advice is simple; don’t stay in the heat for long periods and make sure you drink plenty of fluids.

But why is drinking water so important? Hot weather can cause excessive sweating which increases the loss of fluid from your body and, in turn, reduces your total blood volume.

It means the workload on your heart and the demand for oxygen is increased, which can lead to angina if you have coronary heart disease.

It’s a running joke that we all love to talk about the weather, but it can play an important part in the life of anyone suffering from heart disease – the UK’s biggest killer.

By Ellen Mason, senior cardiac nurse

Your Heart Matters

We've just launched Heart Matters, a brand new free service for you if you're looking to improve, or look after, your heart health.

When you sign-up you'll receive a special Heart Matters pack (pictured right) including a 'heart risk' tape measure, a guide to heart health and a 5-a-day Food Diary.

You also get access to a dedicated Heart Matters HelpLine, staffed by cardiac nurses and heart health advisers, regular issues of 'heart health' magazine, plus the chance to receive regular support emails on issues including getting active, healthy eating and well being.

Find out more about Heart Matters at the new website

And don't forget to let us know what you think about our new free service by posting a comment below...

Taking heart information out to the nation

Our latest video podcast has just been released, and it's a report from our recent BHF Live! events which took place in north east England.

Our nurses' team and a special BHF Live! truck toured supermarkets offering members of the public free heart health information, plus cholesterol, blood pressure and overall fitness tests.

You can see how they all got on by watching the video below. We hope you enjoy it...