Ever since I first encountered the medical field, something struck me as off about their relentless focus on blood pressure. Before long, I began to notice that the blood pressures the same acquaintances (e.g., relatives or friends) shared with me varied immensely. As I was pondering this, a long-time Eastern spiritual teacher shared with me their belief that the West’s relentless focus on blood pressure was due to it being much easier to measure than blood perfusion (healthy blood flow).
Then, as I became more acquainted with the medical field, I began to notice a consistent pattern—whenever a drug existed that could treat a number or statistic, as the years went by, the acceptable number kept on being narrowed, making more and more people eligible to take the drugs that treated the number.
For example, as I discussed recently, once the statins drugs entered the market (which unlike their predecessors, could effectively lower cholesterol), the acceptable blood cholesterol levels kept on being lowered, and before long almost everyone was told they would die from a heart attack unless they started a statin—despite statins have an almost non-existing mortality benefit (e.g., taking them for 5 years at best makes you live 3-4 days longer) and causing (often severe) side effects for roughly 20% of users. Broadly recommending these drugs hence appears unconscionable, but as I showed in that article, these unjustifiable guidelines were a product of clever pharmaceutical marketing and targeted bribery of public officials.
In this article, I will attempt to show how something similar happened in the field of blood pressure. As this is an immensely controversial position to take (e.g., measuring and documenting blood pressure is one of the most routine procedures during a medical visit), I’ve done my best to clearly present the evidence for this perspective so you can make your own determination.
Conventional Blood Pressure Perspectives
Since blood vessels are elastic structures filled with fluid, that fluid holds them under pressure. Blood pressure in turn is typically measured by determining how much external force is needed to exceed the artery’s pressure and compress it so that blood no longer flows through it. Low blood pressure (hypotension) is a problem because it prevents blood from reaching the areas where it’s needed (e.g., orthostatic hypotension or POTS describes a common condition where people become lightheaded as they stand up due to insufficient blood being pushed into the brain), but in most cases, medicine instead focuses on the consequences of high blood pressure. Within the existing model, those consequences are:
•Weakened blood vessels become more likely to break open and leak as higher blood pressure pushes against them. This for instance is why Emergency Rooms aggressively lower the blood pressure of patients who show up with symptoms of “hypertensive emergency” such as a severe headache and a significantly elevated blood pressure. Likewise, whenever a critical blood vessel ruptures (e.g., the aorta or one in the brain), once the bleed has been confirmed, the first step in managing it is to lower the patient’s blood pressure (so less blood leaks out) after which they are sent to surgery.
•Excessive pressure on the arteries strains and damages them, causing the lining of the vessels to become damaged and gradually develop atherosclerosis.
•Excessive blood pressure damages the internal organs (termed end-organ damage), leading to premature failure and early death (e.g., from a heart attack or kidney failure).
Because of this, high blood pressure is viewed as one of the greatest preventable causes of cardiovascular disease and thus a chief focus of all medical visits is ensuring a patient achieves a sufficiently lowered blood pressure.
Unfortunately, that chain of logic has quite a few gaps in it (see if any jump out to you). We will now examine each of them.
Variable Blood Pressure
Blood pressure (BP) is immensely variable. For example, pressures at the periphery (where BP is typically measured), which when studied is found to vary by around 14 points This thus frequently leads to individuals being erroneously diagnosed with hypertension and put on blood pressure lowering medications despite having normal blood pressures (leading to those medications making them hypotensive).
This phenomenon in fact is so common (constituting 15-30% of hypertension diagnoses) that it is often referred to as “White Coat Hypertension,” a name derived from the fact stress is one of the things which commonly elevates blood pressure, and since visiting a doctor is a stressful experience, many patients hence have temporarily elevated blood pressures there. Because of this, the guidelines suggest having patients who are diagnosed with hypertension have multiple measurements to confirm it (e.g., with home blood pressure monitoring). Unfortunately, this often does not happen in practice.
Note: one common source of error when measuring blood pressure is the wrong sized cuff being used for the patient. Another is that patients frequently have significantly different blood pressures in each arm. This helps to explain why it is commonly estimated that 25% of those diagnosed with hypertension do not have it.
Likewise, there is a surprisingly poor correlation between peripheral blood pressure and the central blood pressure inside the aorta. For example, one large study found a significant difference between the blood pressure within the aorta and the arm, and that the aorta pressure had a much stronger correlation to the likelihood of cardiovascular disease.
Note: different classes of blood pressure medications have very different effects on central versus peripheral blood pressure.
What Affects Blood Pressure?
If fluid at a set pressure tries to move through a tube, as the tube shrinks, the pressure it creates (e.g., on the walls of the tube) will increase, while if the tube enlarges, the pressure it exerts will decrease. The body in turn continually controls where blood in the body goes by changing the heart rate and fully or partially constricting the arteries, allowing it to shunt blood to where it is most needed (e.g., by dilating arteries in that area).
Blood pressure is thus a product of two factors: the amount of blood in the arteries and the constriction or relaxation of the arteries containing it.
Note: since arterial BP is greater than venous BP, it’s what’s measured externally (as veins compress long before arteries do and only arterial blood has a signature pulsatile wave created by the heartbeat).
Since each beat of the heart pushes blood into the arteries and hence increases the pressure within them, two different blood pressure values exist—the baseline pressure (known as the diastolic pressure) and the pressure when the heart contracts (known as systolic pressure). The blood pressure values you see (e.g., 140/90), represent that maximum and minimum.
Note: one reason why this stretching is important is because when the vessels contract back to their normal size once the systolic pressure fades, that recoil pushes blood further along into the circulation.
Blood pressures lowering medications in turn work by loosening the arterial walls, reducing the total blood in circulation, weakening the contraction of the heart, or a combination of all three.
What Causes High Blood Pressure?
Most cases of high blood pressure (90-95% of them) are what is known as “essential hypertension” or “primary hypertension” which is a fancy (and rarely questioned) way of saying “elevated blood pressure without a known cause.” More importantly, the fact there is no known cause for most cases of elevated blood pressure has been a widespread belief in medicine for decades. Typically, the only cause we hear about is “eating salt,” despite the fact that the most detailed review of this subject found that drastic salt reduction typically results in less than a 1% reduction in blood pressure.
For the remaining 5-10% (known as secondary hypertension), recognized causes include reduced blood flow to the kidneys (which sets off a signal to raise the blood pressure because the kidney believes there isn’t enough blood perfusion), sleep apnea, or having a rare tumor which dumps large amounts of adrenaline into the blood (which constricts blood vessels and increases the heart rate).
Note: a kidney (especially the left) being in the wrong position (which is quite common) can functionally compress the renal artery. However, until an actual stenosis (narrowing) of the artery, this can be quite difficult to identify with conventional measurements. Additionally, as I showed in a recent article on the importance of sleep, poor sleep is immensely damaging to cardiovascular health and those effects extended to blood pressure (e.g., one study found a single night of partial sleep deprivation raised SBP [systolic blood pressure] by 6, another found SBP raised by 6 and DBP by 3 while a third study found it raised SBP 4.5 and DBP by 2.6 alongside using fMRI imaging to show it also impaired the brain’s control of blood vessel function).
Since the cause of hypertension isn’t known, medicine thus focuses on specific risk factors that are known to be associated with it such as being over 65, having diabetes, eating too much salt, insomnia, obesity, not exercising, stress, being an alcoholic or other people in your family having high blood pressure. Keep these risk factors in mind as you read the next section.
Note: of these causes, I and many of my colleagues believe one of the most underappreciated ones is anxiety, as frequently, effectively treating it can resolve a case of high blood pressure, which would otherwise receive (often indefinite) pharmacologic treatment.
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