High blood pressure is important for 2 reasons. The first is that high blood pressure could be a symptom of something else that is going on within the body and the second is that the number itself can do harm.
Much of modern day high blood pressure management focuses on the second point I.e a high number can do you damage and therefore if we lower the number aggressively we can minimise further damage. It is generally uncommon for doctors to try and look for what may lie underneath and the reason they don’t is because in the majority of the cases you don’t find anything specific underlying the high blood pressure that one can reverse and therefore putting patients on through rigorous investigation is not deemed cost-effective and it is more cost effective and perhaps even more profitable to simply tell the patient to lose weight, cut down on their salt, and take medications. These patients are often billed as having primary hypertension i.e there is no underlying cause. Unfortunately the problem with this approach is that 5-10% of patients actually have an underlying and potentially reversible cause of hypertension and if we don’t aggressively look for it we miss it and subject the patient to a lifetime of medications when actually they may not be needed.
These patients who have an underlying cause for high blood pressure are termed as having secondary hypertension and today’s video is on the subject of secondary hypertension. As mentioned earlier, 5-10% of all patients with hypertension have secondary hypertension. When you take patients between the ages of 18-40, the prevalence of secondary hypertension is close to 30% and certainly if anyone is below 30y, then it is vital that they be aggressively investigated for causes of secondary hypertension.
Lets talk about blood pressure first and as you know I love analogies so ill try and use an analogy to help you understand blood pressure and also how certain pathologies can cause high blood pressure.
When I want to understand blood pressure, I like to think of a hose pipe attached to a tap. The tap is a little bit like the heart, the hose pipe all our blood vessels and the kidneys a bit like the hole at the end of the hose pipe. When we think of blood pressure we are essentially thinking of the pressure within that hosepipe. What determines the pressure in the hosepipe?
How much water is within the hosepipe
The circumference of the hosepipe
The stretchability of the hosepipe
The size of the hole at the end of the hosepipe
In primary hypertension the assumption is that for whatever reason (be that genetic, age , bad luck or lifestyle), the hosepipe is less stretchy and this is why the pressure is high. However if we think about it there are so many other ways by which we could increase the pressure within that system could become elevated (secondary hypertension).
If for some reason the water within the hosepipe is increased, then the pressure within the system would also be increased - this could happen for example with hormonal changes which may increase the amount of fluid we retain or even medications that we may take which could cause more fluid retention within the system or even something that increases how fast or hard our heart beats for a prolonged duration of time.
If we reduced the circumference of the hosepipe - so any narrowing throughout the length of the hosepipe could increase the pressure upstream from the narrowing.
If we reduced the stretchability of the pipe either due to hormonal changes or medications then that would increase pressure
Finally if we made the hole at the end smaller then the pressure would increase. The hole at the end represents our kidneys and therefore if there is any damage to our kidneys that that would have an impact on our blood pressure
24 апр 2021
