by Malcom Kendrick, MD
A review has found that lowering blood pressure below the "standard" target of 140/90 mm Hg is not beneficial in terms of reducing mortality or morbidity. (1) July 2009.
Although I am most focused on the apparently untreatable medical madness surrounding cholesterol lowering and statins, I have long been interested in the parallel 'Looking Glass World' of blood pressure lowering. A recent study ( quoted above ) re-ignited my interest. It showed what I have long known, which is that ( unless it is extremely high ), lowering blood pressure is a particularly futile exercise in ‘sweeping a symptom under the carpet'.
You may have noticed that there are many parallels between blood pressure and cholesterol levels:
1: When they are raised above normal, they are both considered to be causes of cardiovascular disease.
2: The ‘experts' now agree that you cannot have a blood pressure level, or cholesterol level, that is too low.
3: Billions are spent every year in an attempt to lower them.
4: The level considered to be ‘high,' thus dangerous requiring treatment, has fallen remorselessly over the years.
5: No-one knows ( in most cases ) why the levels go up - or are high to start with.
There is only one real difference that I can discern between them. In contrast to a very high cholesterol level ( which is harmless ) a very high blood pressure level is definitely dangerous.
The average blood pressure of an adult is somewhere about 120/70. The 120 figure represents the highest pressure achieved ( measured in the arm ), just after the heart has finished contracting. The 70 figure represents the lowest the pressure drops down to, just before the heart contracts again. The higher number is known as the systolic blood pressure, the lower is the diastolic. It's a Latin thing, or maybe Greek. The early medics did love their ancient, dead, languages.
If the blood pressure reaches, say, 200/120 ( which it can, and even higher ), this is associated with a greatly increased risk of stroke, heart failure and other forms of cardiovascular disease - and kidney failure. No one disagrees with this. Not even me....for a change. And lowering an extremely high blood pressure can be life saving. No argument here, either.
But - or perhaps there are many different buts here - things become far from straightforward when it comes to moderately raised blood pressure. What, for instance, are we supposed to be treating when we lower it? A raised blood pressure is not itself a disease. It is not even ( unless it gets very high ) a symptom of a disease; because raised blood pressure ( except at extreme levels ) does not cause any symptoms.
When you get down to it, a raised blood pressure is a measurement made using a machine. Unlike your measured height, however, the blood pressure is not something that remains constant. If you exercise it will go up. If you relax it will go down. Or, to put this another way, the blood pressure is reactive.
One thing that the blood pressure cannot be is proactive. By which I mean that the blood pressure cannot just rise, all by itself, for no reason whatsoever. If the blood pressure rises there must be some underlying reason, or cause, for it.
In some cases, the underlying cause can be found. If you have a narrow renal artery, for example, this reduces blood supply to the kidney. The kidney thinks this means that the blood pressure is too low, and it releases hormones designed to raise the blood pressure - to a level high enough blast the blood supply past the narrowing. If you open up the renal artery surgically, the blood supply is restored at normal pressure, the kidney stops releasing extra hormones, and the blood pressure normalizes.
In around five per cent of cases of high blood pressure, a cause like this is found. In the other ninety five per cent, no cause is found. At which point something very strange happens. Instead of calling this ‘a raised blood pressure where no cause can be found,' the medical profession turned, once again, to the ancient dead languages in order to create a disease. This disease is called Essential Hypertension. This actually means ‘a raised blood pressure where no cause can be found.' But you have to admit that it sounds rather more impressive.
More importantly, perhaps, a process occurred whereby essential hypertension turned from a measurement, into a disease, rather than the body's natural reaction to some underlying problem. And once it became a disease, a whole series of drugs were developed in order to treat it. Some reduce the blood volume, some relax the blood vessels, some block production of hormones produced by the kidneys to raised blood pressure, others stop the heart pumping so hard.
They come by names such as thiazide diuretics, beta-blockers, alpha-blockers, angiotensin converting enzyme inhibitors, angiotensinogen II inhibitors etc. etc. After statins, these are the most prescribed type of medications in the world, and hundreds of millions of people take them each and every day.
Clever though they clearly are, in the early days of drug development almost no controlled trials were done to see if they actually did any good. There were a couple of short-term studies on people with very high, out of control, blood pressure. But when it came to people with mild/moderate raised blood pressure (which represents the vast majority of people with high blood pressure), there were no studies at all. Yes, you did read that right. There were no placebo-controlled studies. It was just accepted that if you lowered the blood pressure, you had to be doing good. After all, you were treating the disease known as ‘essential hypertension'.
Does Treating High Blood Pressure Do Any Good? Part 2 of 2
Dr. Malcolm Kendrick (MbChB MRCGP) M.D.
Dr. Kendrick has worked in family practice for almost twenty years.
He has specialized in heart disease and set up the on-line educational website for the European Society of Cardiology.