I was perhaps nine or 10 years old when I first learned about blood pressure.
My father practiced general dentistry. One year, I accompanied him to a dental convention in San Francisco. For some inexplicable reason, in the massive convention hall, someone was giving away cups of Coca-Cola (a sugary, acidic beverage — one of the most caustic substances to the teeth ever ingested by humans). This was my first time sampling a caffeinated beverage.
As luck would have it, I stopped by another booth demonstrating the then-new technology of an automated blood pressure machine. I don’t remember my results, but I was told, “Your numbers are high. You should see your doctor.”
A repeat blood pressure measurement by my pediatrician turned out normal, and I was told, “You’re really sensitive to caffeine’s effects!” Thus began my understanding that my blood pressure was labile, sensitive to triggers that made it rise appreciably.
As an adult, I often display white coat hypertension: My blood pressure readings are more elevated when taken in a medical setting than at home. I’m an anxious person, and blood pressure measurement releases stress hormones such as adrenaline that can increase my blood pressure. Over the last year, I’ve generated some concerning readings in the doctor’s office in the 150–160/90 range.
Thus, I’ve been on both sides of the stethoscope when confronting white coat hypertension.
What Is White Coat Hypertension?
It’s often difficult for physicians to interpret office-based blood pressure measurements. As I discussed in a prior blog post, various factors related to office-based testing (for example, rushing into an appointment late) can introduce errors.
White coat hypertension — a condition where patients exhibit elevated blood pressure in a clinical setting — occurs in an estimated 15–30% of patients. Home testing isn’t without its pitfalls, either. Incorrect timing of readings, such as during moments of distress or pain, and automated blood pressure cuffs’ inaccuracy, can lead to errors.
As I often emphasize, the seemingly simple task of measuring blood pressure is anything but.
To get the most accurate readings, measure your blood pressure at home using the following criteria:
- Use a high-quality machine such as the OMRON cuff.
- Choose an environment where you can rest comfortably.
- Take three readings every five minutes and average the final two.
- Take your cuff to your doctor’s office to calibrate it with their manual cuff and stethoscope.
When carefully following these rules, I would get readings around 130/80 — much lower than in an office environment, but still not optimal. Furthermore, recent evidence suggests that white coat hypertension, even with normal at-home readings, may confer up to a 36% increased risk for cardiovascular events (such as heart attack and congestive heart failure) as well as up to a 200% increased risk of dying from heart disease.
My primary care doctor told me what I already knew: I needed to get my numbers down.
I’m not alone. In the United States, an estimated half of all adults have elevated blood pressure. Over age 60, the rate rises to almost two-thirds (63%). Unfortunately, the majority of hypertension cases aren’t well-controlled.
Primary vs. Secondary Hypertension
The etiology of hypertension can be divided into primary and secondary hypertension. The latter refers to a specific, identifiable illness that raises blood pressure. Examples include:
- Hormonal disorders such as hyperthyroidism — too much thyroid hormone — and Cushing’s Syndrome — too much cortisol.
- Problems with vascular anatomy such as renal artery stenosis, which starves the kidney of blood supply and causes it to overproduce hormones such as renin, which raises blood pressure.
In only about 5% of hypertension cases can a specific cause be identified. The other 95% of cases are referred to as primary hypertension, also known as essential hypertension. (“Essential” means “we don’t know why,” analogous to the medical terms “idiopathic” or “non-specific.” Medicine has a wonderful vocabulary for camouflaging our lack of knowledge.)
We can’t identify the specific causes of essential hypertension, but we do have a good understanding of its associated risk factors, such as obesity, family history, age, physical inactivity, stress, sleep apnea, and alcohol and cigarette use. Reducing these risk factors can improve blood pressure.
Nonetheless, it’s important to recognize that each risk factor doesn’t correspond to a single disease process responsible for high blood pressure.
What Can Cause Essential Hypertension?
By writing this blog post, I’ve finally wrapped my head around the concept of essential hypertension. Understanding the differences in the philosophy of disease etiology between traditional Western medicine and Chinese medicine provides useful insights:
- Western medicine relies on a linear, reductionist philosophy and works to identify the single cause of a disease (too much of a hormone, a defective protein, a DNA mutation, etc.).
- Chinese medicine views illness as an imbalance of interconnected systems — a hanging mobile that gets knocked askew.
Following the Chinese medicine philosophy, essential hypertension can be represented by an old-fashioned watch run by countless interconnected wheels and gears. As one gear becomes defective, it impacts the gears around it, and so on.
Many gears can become damaged, any of which can wear out the others. The damage can be irreversible and is best prevented early on.
If left untreated, high blood pressure becomes a progressive disease. Many “gears” contribute to this process. Here are four common ones:
Vascular Changes
Arteries are the blood vessels that transport blood from the heart to the rest of the body. Arterioles are mid-sized arteries that direct blood to its appropriate location: for example, to the muscles for physical activity or the digestive tract after a meal.
Arterioles’ walls are lined with smooth muscle tissue, which contracts and relaxes to direct blood to the appropriate location. In response to elevated blood pressure, the smooth muscle lining thickens to exert control over the vessels. The thickening process makes the blood vessels stiffer, requiring greater pressure to move the blood through them, creating a vicious cycle of rising blood pressure.
Autonomic Nervous System Dysfunction
Prior blog posts have described the sympathetic and parasympathetic nervous systems’ roles in regulating the body’s organs.
The sympathetic and parasympathetic nervous systems control our blood vessels. They coordinate important reflexes such as ensuring adequate blood supply to the brain and maintaining adequate blood pressure when our bodies change positions. These baroreflexes can be reset in response to high blood pressure in such a manner that they raise the blood pressure even further to accomplish their functions.
Hormonal Responses
The Renin-Angiotensin-Aldosterone System (RAAS) is a series of hormones that regulate blood volume and pressure. The system has evolved to maintain adequate blood perfusion of our organs despite potential challenges that may lower blood pressure, such as acute blood loss or dehydration.
While it’s important to have a system that raises blood pressure in an emergency, persistent over-activation of the RAAS can continue the progressive rise in blood pressure by developing a higher set point.
Endothelial Cell Dysfunction
Endothelial cells line each artery’s interior. These cells are hormonally active with local signals that control even the smallest arteries’ constriction or relaxation. For example, nitric oxide is a locally released molecule that causes that region of the artery to open more.
Endothelin is a small protein that causes regional constriction of the artery. These and other locally vasoactive hormones function in a delicate balance to control blood supply through small arteries. High blood pressure disturbs this equilibrium, leading to an eventual predominance of the signals that tighten arteries and raise blood pressure.
Vascular changes, autonomic nervous system dysfunction, hormonal responses, and endothelial cell dysfunction are just four systems among many that regulate blood pressure. Furthermore, they all interact with each other, creating a domino effect that perpetuates a progressive rise in blood pressure if left untreated.
Unfortunately, high blood pressure paves the way for a distressingly long list of complications, including heart attack, stroke, kidney failure, abnormal heart rhythms, sexual dysfunction, blindness, and congestive heart failure. High blood pressure’s dangerous and progressive nature places a premium on early and aggressive control.
My Blood Pressure Treatment
The first step to lowering blood pressure relies on lifestyle modification and, if that fails, initiating drug treatment.
I had already been careful with my lifestyle choices — I was of a normal weight, followed a good diet, wasn’t a smoker or heavy drinker, and was physically active. There was no excess ballast to jettison to lighten my load. Thus, initiating drug treatment would be the next step.
I’ve been extremely fortunate to have lived 61 years without requiring a long-term daily prescription medication. I’ve devoted considerable attention to making healthy choices. I felt being “drug free” was my reward and an important part of my identity. As a physician, I was proud to have talked the talk and walked the walk.
Nonetheless, I’m aware that preventing illness is far more important than pride in not needing any prescription medications.
My primary care doctor prescribed a very low dose of a medication called olmesartan, an angiotensin receptor blocker (ARB). In general, a “start low and go slow” approach to initiating any medication allows the body more time to adapt to drug-induced physiological changes. In the case of blood pressure management, this may require more steps of increasing the medication dosage until the target blood pressure is achieved. However, it reduces the probability of side effects.
In my case, I’m a “lightweight” regarding any ingested substance, more sensitive than others in terms of dose and effect. At an early age, I learned that I can’t even tolerate a cup of Coca-Cola, and as an adult, I developed migraine headache syndrome with multiple food and medication triggers. Fortunately, I haven’t needed many medications, but of those I’ve been prescribed, half have triggered a migraine.
Why start with an angiotensin receptor blocker to reduce blood pressure? This medication category works by interrupting the Renin-Angiotensin-Aldosterone System’s (RAAS) signaling. Given hypertension’s progressive and chronic nature, the prescribed medications are usually taken for many years. Therefore, there can be little tolerance for side effects.
The ARB class of hypertension medications has one of the lowest risks for side effects as well as a solid record of reducing the risk of complications such as heart and kidney disease.
A simple story would entail me starting a low dose of olmesartan and effortlessly reaching a blood pressure at rest of 120/70 with no complications. However, life can be complicated.
Olmesartan comes in tablets ranging in dose from 5 mg to 40 mg. Given my history of medication sensitivity, I started by taking half of a 5 mg pill each evening with no change in resting blood pressure at home of around 130/80. After a week, I progressed to 5 mg each evening and immediately noticed the onset of a mild migraine headache.
I need to start and stop olmesartan a few times to definitively establish causation, but I’m not optimistic about this medication. I’ll probably need to try other ARB medications.
What I’ve Learned From My Blood Pressure Journey
Transiently elevated and moderately elevated at-rest blood pressure readings still confer an unacceptable risk level.
Because of elevated blood pressure’s progressive nature, the longer you wait to initiate treatment, the harder it’ll be to achieve adequate control.
Lifestyle modifications, such as weight loss and exercise, are vital for reducing blood pressure. However, many people, myself included, require medication treatment to achieve a sufficient reduction in blood pressure.
If it isn’t an emergency, it’s best to start antihypertensive medications at a low dose and gradually increase the dosage if tolerated.
Blood pressure medication side effects can occur. Arriving at a well-tolerated and efficacious medication regimen may require trial and error.
Finally, it’s far better to improve your health than to merely perceive yourself as being healthy.
