The Basics of High Blood Pressure

February 16, 2023

In healthcare, we talk about Primary and Secondary Prevention. Secondary Prevention is the proverbial “closing the stable door after the horse has bolted”. If someone has a heart attack, they are at a high risk of another within a year. Secondary Prevention measures applied correctly can greatly improve the situation.

The three pillars of primary prevention
Primary Prevention is about stopping the initial event from happening in the first place. As this involves targeting a much larger section of the populace, it is a much bigger potential earner for the pharmaceutical industry. Advertising efforts reflect this. The three biggest pillars of primary prevention are smoking cessation and management of hypertension and cholesterol.
Smoking cessation is by far the most important, with benefits across almost every single organ in the body. Cholesterol treatment is a huge business, but the actual benefits are somewhat controversial in a general population. Cardiologists think everyone should be on a statin even before birth! Doctors who are aware that the heart is surrounded by a whole human being are less convinced – pointing out data that shows no overall benefits to general mortality or morbidity.  

Blood pressure readings can fluctuate
When it comes to blood pressure, however, the consensus is a genuine consensus (this is surprisingly rare, even amongst real doctors!). High blood pressure is bad, and low blood pressure is good as long as it is not too low, as this can lead to fainting. The actual goal posts move around slightly as drug companies try to find studies to push the targets down, after which independent research relaxes them again. A sensible line can be drawn at <150/<90 in a clinic (whitecoat) setting, and <130/<80 for home readings. It is important to remember that blood pressure is a dynamic value that fluctuates according to time of day and circumstances. As a general rule, if you have different readings, use the lowest one to judge whether you have high blood pressure or not. For example, if you get readings of 150/95, 110/70, and 130/100 throughout the day – your blood pressure is 110/70. Nevertheless, a one-off reading of >180/>120 is going to need attention. Otherwise, I would expect three consecutive elevated readings, spaced at least two weeks apart, before initiating treatment.

Ironing out misconceptions about blood pressure
There are a few misconceptions about blood pressure. Firstly, it does not have any direct symptoms. People especially associate it with headaches, but it is the pain and stress of the headache that is elevating the blood pressure. It is not the high blood pressure that is causing the headache. It doesn’t exactly help to clarify the issue that a lot of blood pressure pills cause headaches as a side effect.
Secondly, it is also not really an out-of-hours emergency. It usually takes over a decade to start causing problems – hence it can wait till the next clinic hours.
Thirdly, it is not a disease per se. It is a regulatory setting in the body, wandering off course. If you have an infection, you take a week’s antibiotics, then stop and the disease is gone. If you take medication for high blood pressure for a week and then stop, you get the blood pressure back! Once treatment is needed, it usually ends up being a life sentence.

High blood pressure leads to other health issues
Persistent elevated blood pressure causes a multitude of health issues – mostly simply by putting everything under more strain. For example, the heart has to work 50% harder to pump circulation around a 150/100 system than around a 100/70 system one. It stands to reason that it would wear out 50% faster. Blood vessels are also under more strain, with big vessels forming aneurysms, and small vessels leaking, creating issues in the eyes and kidneys.
As is usually the case, treatment can be both non-pharmacological and pharmacological. Non-pharmacological measures are easy to remember.
  • Don’t add salt to your food
  • Cooking with salt in moderation is fine but pouring a salt cellar’s worth of salt over your smokey bacon is not! This is worth about 10mm Hg.  
  • Don’t drink heavily!
  • A glass of wine a day is good, but a bottle of wine a day – not so much! This is worth 10-60mm Hg.  
Exercising, losing weight, stopping smoking, meditating and the like, are all highly commendable, but will not directly lower blood pressure. They may ameliorate its bad effects, however.

Drugs and tests for high blood pressure
Pharmacological treatments abound - I can think of seven anti-hypertensive drug classes off the top of my head (don’t test me on this!). There are also plenty of contributions from the alternative brigade, though where they have a genuine effect on blood pressure, it is usually because they are herbal versions of older and obsolete diuretics. The market is so crowded that antihypertensives are often marketed more for their side effects, than for lowering blood pressure. Viagra and Regaine are examples of this.
There is also a surprising Placebo contribution. New drugs must undergo a placebo controlled, double blind trial. It is not unusual for the placebo arm to match the real drug for efficacy in the beginning. It is only as the study wears on that the placebo loses its potency and the real drug starts to gain ground.
*Side note: Never trust a study that ceases after only a month!
The old school drugs are prone to causing a lot of side effects. For example, Beta blockers might improve your ability at pool or darts but will also prevent you from enjoying the fruits of victory. The newer classes are much better in this respect. Both efficacy and side-effects can vary widely across individuals, and it is not a case of one size fits all. Starting antihypertensives is best done via a Primary Care Physician and will probably take a few months to get right. Once stabilized, it is still worth reviewing (including blood tests) every six to nine months. 

Dr Julian Martin Chadwick - Internal Medicine Physician
Columbia Asia Hospital - Saigon