A Statin Nation. Dr Malcolm Kendrick

      Before starting with more exciting topics, such as what causes heart attacks and strokes – and what doesn’t – there is the unfortunate requirement of attempting to make clear what I am talking about. A recurring theme in this book is that medical terminology is often hopelessly confusing. It can act as a barrier rather than an aid to understanding. So, here is my initial attempt to attain some form of clarity.

      This book is primarily focused on two often fatal conditions – heart attacks and strokes. Whilst there are many different diseases that can damage the heart and the brain, in the majority of cases the problem is a disease of the arteries supplying blood to these organs.

      With heart attacks, the arteries affected are the coronary arteries. The disease is often referred to as coronary artery disease (CAD). Other common terms regularly, confusingly and interchangeably used are coronary heart disease (CHD) or ischaemic heart disease (IHD) (ischaemia is a general term that means lack of blood supply, leading to lack of oxygen supply). CAD, CHD and IHD are different terms for describing the same thing.

      With strokes, the main problem is with the carotid arteries that supply blood to the brain. These arteries branch from the aorta, the single artery that leaves the heart. The carotid arteries separate from the aorta around the base of the neck. One carotid artery goes up the left side of the neck, the other goes up the right. (There are also vertebral arteries going into the back of your brain, through the spinal column, but they are less likely to cause problems, though they can.)

      Whilst the underlying cause of a stroke, as with a heart attack, is disease in the carotid arteries, you will never come across the term carotid artery disease, carotid brain disease or even ischaemic brain disease. Why? That is just the way it is. Equally, I have never heard anyone refer to a stroke as a form of ‘brain disease’. It is funny how thinking and terminology, even in closely related areas, can develop in completely different ways.

      The actual disease in the blood vessels that leads to most heart attacks and strokes is usually referred to as atherosclerosis. This is the development of lumps, or thickenings, in the artery wall. These thickenings are most often called atherosclerotic plaques.

      You may have come across the term arteriosclerosis. I have never worked out what this is, and I don’t think anyone else has either. I think it is the same thing as atherosclerosis, even though some people say it is not. So, I will just leave this to one side.

      Atherosclerosis, or atherosclerotic plaques, do not just occur in the coronary and carotid arteries. You can suffer from atherosclerosis in arteries almost anywhere else in the body. Arteries that supply the kidneys, the bowel, liver, adrenal glands … I recently admitted a lady with severe abdominal pain who had suffered a ‘bowel attack’. An artery supplying blood to a section of her large bowel had blocked off completely and her bowel infarcted (infarction is the sudden loss of blood supply due to a blockage, usually a blood clot, leading to death of the downstream tissue). About 0.6 metres of bowel was later removed surgically. I hate to admit it, but I got the diagnosis completely wrong. On the plus side, at least I sent her to hospital, recognising that she wasn’t very well. I thought she had bowel cancer and had obstructed.

      In short, the underlying disease that we are looking at with heart attacks and strokes is actually vascular disease, which can manifest itself in almost all organs of the body. Vascular disease, due to atherosclerosis, often comes under the umbrella of CVD. This can be shortened to CV, as in CV (cardiovascular) mortality.

      I think I also need to explain a bit more about the vascular system. Essentially, this consists of the heart, the arteries and the veins. The heart begins life where an artery and vein merge together. This area then enlarges, develops valves and an electrical conduction system, etc., transforming itself into the fully formed and highly complex organ that we call the heart.

      It is the first organ in the body to function, and it starts pushing blood around the body twenty days after conception. As with most aspects of foetal development it is just unbelievable how it happens, and that it happens, almost perfectly. Mind-boggling.

      The heart pumps blood into the arteries at relatively high pressure. Veins bring blood back to the heart at much lower pressure. Arteries have much thicker and more muscular walls than veins, primarily because they need to withstand much higher blood pressure. The other main difference between arteries and veins is that the bigger veins have valves in them to stop the blood simply dropping back down to your ankles. If a valve in your leg gives way, you can end up with a bulging varicose vein because of gravity, and increased pressure acting on the vein beneath the failed valve.

      Apart from these small differences, arteries and veins have an identical structure. There is a single layer of cells that lines the inner surface. This layer is usually referred to as the endothelium, made of single endothelial cells, which are wide and flat, a bit like miniature wall tiles, although the endothelium can be several cells thick in certain places. Underneath the endothelium there is a muscular/elastic layer, the media. Surrounding the media is a tough outer layer, the adventitia, which holds everything together.

      When arteries branch and become smaller and smaller, they are called arterioles. Smaller veins are the venules and the smallest blood vessels are capillaries, which join the arterioles to the venules. These are so narrow that red blood cells must be squashed and distorted in order to squeeze through.

      A little-known fact (little known to most doctors I have spoken to, anyway), is that the larger arteries and veins have their own blood vessels to supply them. They are the vasa vasorum, which means blood vessel of the blood vessels. Yes, blood vessels need their own blood vessels to get the nutrients they need. Something I never learned at medical school, for sure; or maybe I was asleep during that lecture.

      DIAGRAM 1