What Do The Numbers Mean?
Blood pressure is expressed as a fraction, as in 120/80. What do those two numbers represent? The top number is called “systolic”. It represents the force of contraction of the heart sending a pulse wave down the artery. The bottom number (diastolic) measures resistance of the artery to compression, either due to the amount of blood in the artery or the stiffness of the artery wall.
When I take your blood pressure using a stethoscope, I inflate the cuff on your arm until the blood vessel I am listening to is compressed and no blood is flowing through that artery. Then, I slowly let off the pressure until I first hear the sound of your pulse. I am watching the dial on the cuff and make mental note of the number (in millimeters of Mercury pressure) when I can first hear that pulse. This represents the force that your heart is pushing blood through your artery. It is pushing hard enough to get through the compressive force I am applying using the cuff.
I continue listening as I let air out of the cuff until I can no longer hear your pulse. This is the pressure at which compression from the cuff is equal or less than the stiffness of the artery. In other words, I am no longer compressing the artery so the pulse wave passes without resistance or noise.
Most offices (and of course home units) measure blood pressure without a stethoscope. The machine listens and records the numbers. Either way of measuring works fine. I just explained it (above) using a stethoscope because the process and it’s meaning is easier to understand that way. The first number (systolic) is the force of contraction of the heart. The second number (diastolic) is the amount of compression that no longer compresses the artery.
What Is Normal?
Most people know that a normal blood pressure is 120/80 and that healthy women often have a blood pressure ten points lower than men, i.e., 100/70. At one time, it was believed that blood pressure rises with age, but that the threshold for hypertension was 140/90 for people under age 65 and 150/90 for those 65 and older. The guidelines changed in 2017 to much stricter (lower) pressures.
These current guidelinesi are
Normal is a systolic lower than 120 and diastolic lower than 80.
Elevated is a systolic of 120 – 129 and diastolic less than 80
Stage One hypertension is a systolic of 130 – 139 and diastolic of 80 – 89
Stage Two hypertension is a systolic of 140 or higher and diastolic of 90 or higher
Hypertensive crisis is systolic higher than 180 and/or diastolic higher than 120
The impetus for the 2017 guidelines was a study called SPRINT that included over 9,300 participants who were at high risk of cardiovascular events. (There was no group who were treated with diet, exercise and lifestyle interventions to lower their overall risk).
Participants were divided into two groups. One group was controlled with pharmaceuticals to a systolic of 130. The other to a systolic of 120. In the 130 systolic group, there were 8 deaths. In the 120 group, there were six deaths. This was reported as a 25% reduction in mortality risk. That makes it sound like 25 people out of 100 had their lives saved but it was actually only two people out of 4,550. Looked at this way, researchers needed to aggressively treat 4,550 patients to save two lives. In other words, the Number Needed to Treat (NNT) one patient is 2,275 patients. What was the cost both in dollars and side effects?
The dollar cost was estimated by the researchers as between $28,00 and $47,000 per “quality adjusted life year”, whatever that means. Using the lower number, it would cost ($28,000 times 2,275 patients) $63,700,000 to save one life. For that cost, you could hire a personal trainer and give healthy, organic food to all the participants.
As to side effects, researchers noted “higher risk of hypotension, syncope and accelerated reductions in GFR”. Hypotension is low blood pressure. Syncope is fainting. GFR or glomerular filtration rate is a measure of kidney disease. In other words, the intensive drug regimen advocated by the SPRINT study leads to fainting and a reduction in kidney function. Since the study was stopped early, there was no long-term assessment of reduced kidney function on morbidity and mortality.ii
Official Criticisms of the New Guidelines
A lot of physicians, particularly gerontologists were upset by the new guidelines. They pointed out that their elderly patients are at high risk of falling. Blood pressure rises with age to support normal perfusion (oxygen delivery) in the brain. Lowered blood pressure puts their patients at risk of falling, hitting their head and dying of a sub-dural hematoma, or falling and breaking a hip, leading to death by pneumonia.
The American College of Physicians wrote in the Annals of Internal Medicine, “Are the harms, costs, and complexity of care associated with this new target justified by the presumed benefits of labeling nearly half the U.S. population as unwell and subjecting them to treatment? We think not and believe that many primary care providers and patients would agree” iii
In the New England Journal of Medicine, Drs Bakris and Sorrentino concluded that, “The unintended consequence may be that many people, now labeled as patients with hypertension, receive pharmacologic therapy that’s unlikely to provide benefit given their low absolute risk, and they may therefore experience unnecessary adverse events.” They go onto say that while a “target of less than 130/80 mm Hg makes sense for high-risk patients, for everyone else it seems more reasonable to continue defining hypertension as a blood pressure of 140/90 mm Hg or higher.“iv
There is also a risk that the lower blood pressure readings in the SPRINT study were artificially low because of the way they were measured. Patients in the study were measured after sitting alone in a room for five minutes. Then they were re-measured twice and the results averaged. How often has any doctor measured your blood pressure that way? Would those who measured 130 have measured 140 under normal conditions?
Like it or not, doctors will slowly conform to these new guidelines at risk of malpractice, or pressures from insurers and hospital administrators. As Dr Welch put it in a New York Times editorial, “I suspect many primary-care practitioners will want to ignore this new target. They understand the downsides of the relentless expansion of medical care into the lives of more people. At the same time, I fear many will be coerced into compliance as the health care industry’s middle management translates the 130 target into a measure of physician performance. That will push doctors to meet the target using whatever means necessary — and that usually means more medications.”v
High Blood Pressure Is A Risk
Criticism of the new guidelines aside, high blood pressure is a serious risk. Cardiovascular disease is the leading cause of death worldwide. Elevated blood pressure accounts for 62% of stroke and 49% of coronary heart disease cases.vi Statistically, the risk of cardiovascular disease doubles for every 20 points of systolic increase and for every 10 points of diastolic increase (i.e., doubles at or above 140/90).vii Untreated hypertension can shorten life expectancy by 15 to 20 years due to heart attack, stroke and kidney disease. Bear in mind however, that until the SPRNT study, the increased risks have been associated with blood pressures above 140/90.
The Framingham study followed 5,200 individuals from age 28 through 62 for a period of 27.5 years. They divided participants into three groups; under 120/80 BP (normotensive), 120-139 BP (high normal) and greater than 140 BP. What researchers found was, “Significant increases in mortality were observed among hypertensives but not among participants with high-normal BP levels compared with viiinormotensives.”ix In other words, there was no significant increase in morbidly or mortality in the group with systolic blood pressures between 120 and 139.
I am not advocating that we ignore rising blood pressure. I am saying that we need to do everything we can to get our blood pressure to a normal range, but let’s focus first on diet, exercise and lifestyle change. Most of those recommendations can be found in https://drwells.net/cardiovascular-and-metabolic-disease/
What About Hypotension?
Low blood pressure is of course a serious problem as well. Without blood, our hearts, brains and every other organ quickly dies. We need Oxygen and other nutrients to be delivered constantly. Low blood pressure reduces that delivery. The usual first symptoms of low blood pressure include feeling lightheaded, difficulty concentrating, headaches, exhaustion, feeling out of breath and fainting. At very low pressures, the heart stops.
So How Low Is Low?
110/75 Is low normal. No treatment needed.
90/60 Borderline low end of functional. I evaluate patients in this range for hypoadrenia, hypothyroidism, eating disorders or other causes of low metabolic function.
60/40 Too low. This patient could become critical. I consult with the patient’s primary care provider or send my patient to an emergency room. I had a patient below this reading only once. She literally had to hold on to the walls while walking down the hall towards my office. She told me she came for nutritional advice. I asked what she usually eats. She replied, “Instant breakfast and candy.” I asked, “What else?” She said, “No, that’s it. Just the one glass of milk each day for my instant breakfast. The rest of the day I eat candy.” Her history included multiple types of cancer, pneumonia and kidney disease. She was in her early 40’s. The only nutritional advice I could give her was to, “Eat food, a wide variety of real food and lot of it.” I also recommended she get psychological support.
Systolic-Diastolic Spread (Pulse Pressure)
The common normal blood pressure of 120/80 has a 40 point difference between the systolic and diastolic pressures. The same is true of 110/70. This is normal. So what does it mean when there is a 30 point difference as in 110/80? This is called a “narrow pulse pressure”. What about a 60 point difference as in 130/70? This is called a “wide pulse pressure.” A greater than 40 point spread between systolic and diastolic, such as 140/80 where the systolic number is out of normal range is called systolic hypertension. A wide pulse pressure within the normal range is generally ignored but as you will read, it shouldn’t be.
According to Anthony Dart, a Professor of Medicine in Melbourne, “Classically, a wide (high) pulse pressure is a sign of aortic valve regurgitation and a narrow (low) pulse pressure is a sign of aortic stenosis. In the absence of valvular disease, a high pulse pressure may be a sign of stiffness in the arterial walls, and is a risk factor for coronary artery disease and myocardial infarction.” x
In addition to aortic stenosis, a narrow pulse pressure may also be due to congestive heart failure, particularly if the spread is 25 points or less. I should note that a pulse pressure of 30 points is the limit of normal variation and may simply be due to deconditioning. In a sedentary but otherwise healthy individual, regular walking may be all that is needed to correct this. If the spread is 25 points or less, you should see your primary care provider or a cardiologist.
A wide pulse pressure may also indicate valve regurgitation, hyperthyroidism or severe iron deficiency anemia. Having a wide pulse pressure also increases the risk of developing atrial fibrillation. The usual risk for atrial fibrillation is 6%. That goes up to 23% for those with a wide pulse pressure.xi
A wide pulse pressure where the diastolic is lower than 65 indicates an increased risk of myocardial infarction.xii Again quoting from Dr. Dart, “The fall in diastolic pressure seen with pulse pressure widening may be particularly important for coronary perfusion since this occurs predominantly during diastole. In stenotic coronary arteries the reduced diastolic pressure could be expected to lead to impaired myocardial perfusion.” He goes on to say, “Reduced perfusion is likely to be more relevant with a shortened diastolic duration (i.e. fast heart rate) and this may indicate the value of choosing therapy that will limit this reduction.” xiii What he is intimating here is that medication to reduce overall blood pressure that results in a diastolic below 65 while the pulse pressure is greater than 60 and the pulse rate is high (let’s say above 80) may put the patient at greater risk of heart attack.
As referenced in a JAMA network article, “The Hypertension Detection and Follow-up Program reported that all-cause mortality increased by 11% per 10-mm Hg increment in pulse pressure but only by 8% and 5% for similar increases in systolic and diastolic blood pressures, respectively.”xiv In other words, we should all be paying more attention to the pulse pressure spread, instead of just the systolic and diastolic numbers. From what I can tell, this message has not reached most of the medical community, let alone the public. Or, as that JAMA article went on to say, “In older hypertensive patients, pulse pressure, not mean pressure is the major determinant of cardiovascular risk.”xv
To paraphrase a study entitled, “Pulse Pressure, Not Mean Pressure Determines Cardiovascular Risk”, a wide pulse pressure 10 points greater than normal increases the risk of cardiovascular events and premature death by nearly 20%xvi
What About Athletes?
According to research cited in Wikipedia, “For most individuals, during aerobic exercise, the systolic pressure progressively increases while the diastolic remains about the same. In some very aerobically athletic individuals, for example distance runners, the diastolic will progressively fall as the systolic increases. This behavior facilitates a much greater increase in stroke volume and cardiac output at a lower mean arterial pressure and enables much greater aerobic capacity and physical performance. The diastolic drop reflects a much greater fall in systemic vascular resistance of the muscle arterioles in response to the exercise (a greater proportion of red versus white muscle tissue). Individuals with larger BMIs due to increased muscle mass (bodybuilders) have also been shown to have lower diastolic pressures and larger pulse pressures.” xvii
So as we might expect, exercise conditions us to be better at exercise. Even our blood vessels adapt. According to an article in the American Hypertension Association Journal, “In cross-sectional studies, aerobically trained athletes have a higher arterial compliance than sedentary individuals.” xviii The word “compliance’ in this context means that the aorta has greater elasticity. That’s a good thing. However, individuals doing strength training or other maximum exertion exercise (including high-intensity aerobics) increase the stiffness in their aorta and the arteries of their legs, widening the pulse pressure. The authors did not speculate if a wide pulse pressure in athletes might lead to increased risk of cardiovascular events, but did note that moderate aerobic exercise has multiple positive benefits without known adverse consequences. Personally, I think the risk of some stiffening of the aorta with high intensity exercise may not be significant. After all, Jack LaLanne (who among other things did 1,000 pushups in 20 minutes) lived a very full and active life up to his death from pneumonia at age 96. Other than being shot by a jealous husband at that age, I doesn’t get better than that.
One of the possible causes of arterial stiffness is oxidative damage resulting from an excess of the amino acid Homocysteine. This amino acid is a byproduct of incomplete conversion of Methionine to Cysteine. That conversion is dependent on adequate Vitamin B6 and Folic acid, particularly the folic acid. The most common food source of folic acid is leafy greens. That’s why the name for folic acid or folate is from the same Latin root as “foliage.” Deficiency of these vitamins can cause homocysteinemia or an excessive level of homocysteine in the blood. Up to 40% of patients diagnosed with premature coronary artery disease, peripheral vascular disease, or recurrent venous thrombosis present with elevated levels of plasma homocysteine.xix
There are some people who are genetically unable to utilize folic acid because of an alteration of the gene that converts folic acid to methyltetrahydrofolate. These people are said to have the MTHFR genotype. This genotype is actually pretty common. According to Kaiser Permanente, “Between 10%-15% of the Caucasian population and more than 25% of the Latino population have variants in both copies of the MTHFR gene.”xx Numerous supplement companies sell methylated folate, which can bypass this genetic deficiency. We have it in a 5 mg dosage in our office.
A very interesting study found that, “Folic acid supplementation at 5 mg doses for three weeks reduced pulse pressure by 4.7 +/- 1.6 points.” xxi The authors of that study concluded that, “Folic acid is a safe and effective supplement that targets large artery stiffness and may prevent isolated systolic hypertension.” Interestingly, treatment did not correlate with plasma folate or homocysteine levels and it worked regardless of MTHFR genotype. This suggests that folate reduced arterial stiffness by some unknown mechanism.
Before going out to buy vitamins though, make sure you are getting regular, mild exercise like walking, eating a low-salt, heart-healthy diet and are also reducing stress, losing excess weight, avoiding nicotine, caffeine, excessive alcohol and recreational drugs. These diet and lifestyle modifications will make the biggest difference.
Three Position Blood Pressure
This is a test that is rarely performed but can reveal a lot. It is particularly indicated when the patient complains of feeling lightheaded or has recently suffered falling for an unknown reason. It should also be performed in geriatric patients and others at high risk of falling including patients with vomiting, diarrhea and blood loss. The classic presenting symptom is “feeling lightheaded on arising from a sitting or lying position.”
The procedure is to take blood pressure in a supine or semi recumbent position, then sitting and finally standing. We allow you to lie on the table for 3-5 minutes before taking the first pressure reading. Then let you sit for a minute before taking the sitting reading. We ask if you are feeling dizzy or light-headed and observe you for pallor or sweating. If you have these symptoms or signs associated with sitting up or a blood pressure less than 90/60, we let you lie down and do not proceed to the standing measurement. If it is safe to proceed, we measure your blood pressure as soon as you stand up, then repeat the standing measurement three minutes later.
How To Interpret The Results
According to the Agency for Healthcare Research and Quality. “A decline of ≥20mm Hg in systolic or ≥10 mm Hg in diastolic blood pressure after 3 minutes of standing = orthostatic hypotension.
A heart rate increase of at least 30 beats per minute after 3 minutes of standing may suggest hypovolemia, independent of whether the patient meets criteria for orthostatic hypotension.
A blood pressure drop immediately after standing that resolves at 3 minutes does not indicate orthostatic hypotension. However, this finding may be useful to confirm a patient’s complaint of feeling dizzy upon standing and may lead to patient education about using caution when arising from a lying or sitting position.” xxii
This test can also be supporting evidence in identifying hypoadrenia or poor sympathetic tone. Normally, under the influence of the sympathetic nervous system and adrenals (which are themselves an extension of the sympathetic nervous system), blood vessels and muscles constrict slightly when we rise from lying to sitting or from sitting to standing. This constriction ensures adequate blood flow to the brain. Thin people (usually female) with poor muscle tone and chronic low blood pressure are more at risk. The evidence for adrenal insufficiency in people with postural hypotension is inferred from it’s presence in people with Addison’s Disease (adrenal failure).xxiii Postural hypotension in isolation does not confirm a diagnosis of hypoadrenia.
Those over age 65 should also be evaluated for carotid artery occlusion using sonography. The combination of postural hypotension and carotid artery occlusion is a common cause of falling in the elderly. “Falls are the leading cause of fatal injury and the most common cause of nonfatal trauma-related hospital admissions among older adults.” xxiv
What Does It All Mean?
Like anything else, context is key. If you have a lot of risk factors, you may need to control your blood pressure more aggressively than someone with fewer risk factors. If your pressure is too high, the place to start is always with diet, exercise and other lifestyle choices like eliminating smoking, caffeine, alcohol and substance abuse. Medications should be a second line of defense (unless your blood pressure is critically high) but taking medication doesn’t eliminate the need to make the hard lifestyle changes. There is no substitute for good habits.
Like the other vital signs, we don’t just look at blood pressure in a vacuum. If you have a high BMI or waist to weight ratio, let’s address that. If you have low temperature and pulse, let’s address your low metabolism so you can lose weight. Low thyroid function is also implicated in elevated blood pressure because thyroid hormone is the main driver for producing Nitric Oxide in the endothelium (lining of the blood vessels). Nitric Oxide lowers blood pressure by relaxing blood vessels and increasing perfusion. Exercise also stimulates more nitric oxide production. The foundations of good health always come back to proper diet, exercise and lifestyle. We all know this but we don’t always follow what we know, instead reaching for a quick fix, whether it is a nutritional supplement or a drug. By monitoring vital signs, we can provide ourselves with accountability and knowledgable guidance on our path to recovery.
What I recommend is that you get a home blood pressure machine and take your blood pressure first thing in the morning and after other activities such as exercise. Keep a log of your blood pressures and associated activities. Find out what helps and what hurts. If your blood pressure is higher one morning, ask yourself, “What did I eat last night? Was it salty?” Measure your blood pressure after a stressful conversation. Measure it after whatever it is you do to relax. What you can measure, you can change. Just making these measurements and writing them down will provide the knowledge you need to improve. In my sixties, I found that salty food does indeed increase my systolic blood pressure and exercise reduces it. The generic advice, “Eat less salt” is not as actionable as knowing that every time I eat a particular dish from my favorite restaurant, my pressure is up the next morning. No one else could have told me to stop eating that and expect me to follow their advice. The generic advice of “Get regular exercise” is not as useful as knowing that my systolic pressure drops 20 – 30 points after intense exercise and stays down most of the day. Measurement can be motivational if you log the results and correlate blood pressure measurements with your activities and diet. To a great extent, you can be your own doctor. You can learn what works for you on a daily basis instead of just at your annual physical. We are happy to provide coaching, encouragement and advice, but no one else can fix it for you.
David Wells, D.C., L.Ac.
xii Owens P, O’Brien E. Hypotension in patients with coronary disease: can profound hypotensive events cause myocardial ischaemic events? Heart 1999;82:477-81. 10.1136/hrt.82.4.477
xiv Abernethy JBorhani NOHawkins CM et al. Systolic blood pressure as an independent predictor of mortality in the hypertension detection and follow-up program. Am J Prev Med. 1986;2123- 132
xvi Blacher J, Staessen JA, Girerd X, Gasowski J, Thijs L, Liu L, Wang JG, Fagard RH, Safar ME (Apr 2000). “Pulse pressure not mean pressure determines cardiovascular risk in older hypertensive patients”. Arch Intern Med. 160 (8): 1085–9.