WHEN I was 14 my biology teacher gave the class a lesson on blood pressure.

He produced a monitor, the old-fashioned kind you still see in some doctor's surgeries with a stethoscope, a dial and a pump. I was picked to test it.

He looked puzzled when the cuff deflated and took another reading, concluding that the machine was broken. The lesson moved on and it was forgotten. By everyone but me. Perhaps some things stick in your mind for a reason.

It was another 16 years before I knew that the machine had been working perfectly that day in biology.

I later came to dread the cuff being wound around my arm at subsequent GP appointments, willing myself to relax as the band tightened, but all the high readings I got were dismissed as 'white coat syndrome.'

However, after I bought my first flat at 30 and moved to the East End of Glasgow, my new GP took one reading and sent me for urgent tests. It wasn't normal, she said, for a young woman to have the blood pressure of an unfit, overweight 70-year-old.

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A chest X-ray and a very intuitive specialist was all it took to diagnose what had caused my blood pressure to average 170/100.

My aorta, the main artery in the human body that takes blood from the heart around the body, was almost entirely blocked off having narrowed increasingly since birth.

Over the years, the condition Coarctation of the Aorta, had caused my blood pressure to soar unchallenged. The very high blood pressure in my upper body had actually caused my ribs to become deformed.

I remember my mind clouding as the specialist told me, gently, I would require open heart surgery, drawing a diagram of the heart's intricate chambers and valves that I struggled to focus on. Things moved quickly after that.

I saw a cardiologist who simply shook her head when I told her I had recently run a half marathon - apparently I could have suffered a major stroke and died during it.

Little things made sense, the agonising cramps in my legs on a long run (because the blood couldn't circulate properly) the purple toe I had as a child, caused by poor circulation in my lower limbs. The heart murmum I had as a baby, that hadn't been followed up.

How do you cope when you know you are facing open heart surgery, unexpectedly as an adult? Like anything health related, and serious, it is far harder for your loved ones. I worried privately but simply put my faith in the doctors and didn't dwell on the possibility that anything could go wrong.

I was first in the queue at 9.30am at the Royal Infirmary, or Hotel Royale as it became known.The last thing I remember was my brother, Ewen, placing drawings my young nephews had created for me in front of my face as I was wheeled down to theatre.

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The highly skilled operation involved the surgeon cutting out the narrowed part of my aorta and sewing in a 2cm plastic tube.

My body had built its own system of arteries to try to bypass my blocked aorta - called collateral, a fact that still amazes me. In the weeks after the surgery, the arteries gradually died, their job done.

Unfortunately, because my condition lay undiagnosed for so long, it has caused other problems. A section of my aorta has grown too big and has formed an aneurysm. It is life-threatening but is closely monitored and if it reaches a certain diameter, then they will operate.

I would say to the parents of any teenager who has high blood pressure or any young adults to make sure they are tested for the heart condition.

When I look at the scar that runs across my back I give thanks for the NHS and the incredible skill of my surgeon, Jim Pollock, who has repaired babies' hearts the size of walnuts as well as mine.

My heart condition was missed at birth and by countless doctors through my teens and twenties.I hope by writing this, it may alert a parent, teenager or adult that high blood pressure isn’t always related to poor lifestyle choices.

For advice and support about congenital heart disease visit www.bhf.org.uk and https://thesf.org.uk/