What Is Hypertension?
A consistent blood pressure is necessary in the delivery of blood to the organs of the body. Adequate blood pressure ensures that oxygen within the blood is delivered to tissues. One’s blood pressure depends on a complex interaction of many factors:
- Kidneys: The kidneys can maintain a normal pressure by altering how much urine is excreted. Additionally, special sensors called “baroreceptors” within the kidneys can sense high or low blood pressure and release certain hormones that can increase the blood pressure by constricting the blood vessels throughout the body.
- Carotid Artery: Sensors within the carotid arteries located within the neck can sense changes in blood pressure and send information to the brain to increase or decrease the blood pressure and work done by the heart.
Blood pressure readings consists of 2 numbers, the “systolic” on top and the “diastolic” on bottom.
Normal blood pressure is defined as a systolic pressure <120 mmHg and a diastolic pressure <80 mmHg. Therefore, 120/80 (or less) has been designated what is normal for good health.
What the Numbers Mean
- Systolic pressure is the force of blood from the heart to the body, a factor of the heart’s output with each contraction and the resistance down the line this force encounters
- Diastolic blood pressure is based on the baseline resistance of the tissues to which the blood is pumped
Types of Hypertension
Hypertension refers to an elevated systolic or diastolic pressure. An individual’s blood pressure is not static. It fluctuates constantly from the daily challenges of life–stress, danger, emotion, exertions, sex, fear of doctors, etc. Such temporary elevations are normal responses, so an isolated high number at any one point in time is meaningless unless it remains consistently high over time via multiple measurements.
In primary hypertension (“essential” hypertension), the cause is unidentifiable, however typically is a combination of genetics, age, environment, obesity, race, diet, and physical inactivity.
When there is a known or definitive cause or group of causes, hypertension is termed “secondary hypertension,” that is, it is secondary to another cause. Causes include:
- Medications: estrogen, NSAIDs, antidepressants, corticosteroids, stimulants, and other substances, including illicit abuse of methamphetamines and cocaine can raise blood pressure.
- Kidney disease: Including acute and chronic kidney disease, can alter the kidney’s ability to help manage blood pressure, one of its other main functions.
- Aldosteronism: Aldosterone, a hormone from the adrenal gland, directly affects the kidney’s function to eliminate salt (sodium), which impacts blood pressure. (This is why a low-salt diet is prescribed in hypertension.) When the aldosterone overacts to increase reabsorption of salt and water, the blood pressure will rise.
- Obstructive sleep apnea (OSA): OSA prevents the 10% “dip” in blood pressure we should all experience during sleep. Missing this nightly dip affects the average blood pressure over each 24 hours.
- Endocrine disorders: Diabetes, thyroid, and parathyroid disorders all have hormones that can exaggerate the effects that increase blood pressure.
Complications of Hypertension
High blood pressure damages the blood vessels within the body. In arteries, injury from hypertension can result in the buildup of plaque (atherosclerosis) which can obstruct blood flow. The obstruction of blood flow can impair blood being delivered to key areas of the body such as the heart, brain, kidneys or other vital organs. Hypertension can also causes the heart to enlarge, injury to the kidneys resulting in increased risk for peripheral artery disease, heart attack or stroke.
How Is Hypertension Diagnosed?
A blood pressure measurement is as simple as applying a blood pressure cuff, inflating it, and listening over the artery with a stethoscope. When the pressure in the cuff is enough to stop arterial pulsations or have them resume (systolic blood pressure), and when the pressure from the cuff against the artery is low enough to prevent the turbulence of arterial blood flow from vascular resistance (diastolic blood pressure), each of these pressures give the two numbers use in blood pressure.
There is no official line that one can cross to have hypertension, that is, clinically relevant to impact health. But the blood pressure relationship with cardiovascular disease is a gradual one which has no isolated red flags at any one point. Therefore, it is important to observe for hypertension via several readings over time and vigilance for any complications of hypertension.
Diagnosis of Hypertension
Criteria are different for different providers, but in general:
- Serial office setting blood pressures: at least 3 readings spaced out over weeks to months.
- Since a BP reading in the office setting can be spuriously high due to nervousness or a hurried day to fit the appointment into one’s day, out-of-office settings like with home monitoring are beneficial toward diagnosis.
- Home monitoring affords an excellent appraisal by adding as many readings as the patient can do. More information is always better than less information.
- Ambulatory blood pressure monitoring (ABPM) can be indicated in cases in which home monitoring is not possible or is inaccurate.
This involves on-going readings using a cuff and a digital device for recording. If the mean daytime BP is ≥130/≥80, the diagnosis is made.
Serial blood pressure readings are not needed when a patient presents with a BP ≥180 systolic/≥120 diastolic or who has end-organ damage with an initial reading of ≥160 systolic/≥100 diastolic.
- Blood tests: electrolytes, calcium, and serum creatinine; fasting glucose; complete blood count; thyroid stimulating hormone (TSH), lipid profile
When hypertension is found to be secondary to causes identified in blood work, ECG, or from renal disease, other testing may be necessary:
- Renal function: urinary albumin to creatinine ratio, since increased albumin in the urine is a risk factor for cardiovascular disease. Also, many electrolyte imbalances call for renal and endocrine testing.
- Hemoglobin a1C for diabetics
- T3 and T4 thyroid levels when the TSH is elevated
- Cardiac echogram if hypertension is suspected of having untoward effects on the heart and to evaluate for atherosclerosis
- Peripheral vascular echograms to identify arteriosclerosis and venous insufficiency
If hypertension is considered primary hypertension, that is, without an identifiable cause, management of the blood pressure is based on:
- Lifestyle changes
- Change in medications to equally effective ones that do not have hypertension as a side effect
- Weight management and obesity reduction to impact metabolic syndrome
- Diet/nutritional counseling for both salt restriction and to impact dyslipidemia (cholesterol) as part of a metabolic syndrome. Statin medication is prescribed when conservative and lifestyle changes fail
The DASH diet (Dietary Approaches to Stop Hypertension) is high in vegetables, fruits, whole grains, poultry, fish, nuts and low-fat dietary products; it is low in sweets, red meats, and sweetened beverages.
- Smoking cessation
- Stress reduction via counseling to identify stressors in a patient’s life and strategies to deal with them
- Antihypertensive medication when conservative and lifestyle changes fail
If hypertension is considered secondary to some other cause, management requires treatment for that cause in attempts to either mitigate its negative influence, eliminate it via reversing it, or delay its hypertensive tendencies. Antihypertensive medication is also used.
Goals in the Management of Hypertension
Blood pressure goals are an essential part of the management of hypertension. A goal of <130/<80 is often set first. Some physicians move these numbers a few mm of mercury lower, based on physician preference, reasonable expectations, and comorbidities. Other goals, in those conditions that contribute to hypertension–diabetes, metabolic syndrome, obesity, smoking, inactivity, etc.–need to be established as well.
- Thiazide diuretics, which decreased intravascular volume
- Calcium-channel blockers (long acting)
- Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), which step in to lessen the renal impact of hypertension
Choice of medications or combinations can be decided upon based on monotherapy treatment success or failure, race, side effects, and the presence of diabetes or ischemic heart disease.
How Can I Prevent Hypertension?
Prevention as it applies to hypertension centers on both a reduction in cardiovascular events once hypertension is diagnosed and prevention of hypertension in those at risk for it.
Preventing Hypertension in Those at Increased Risk
Patients who are obese, have diabetes, are inactive/sedentary, or who have a strong family history of hypertension should address the alterable aspects of their risk:
- Smoking cessation
- Avoid drug abuse
- Strict glycemic control and maintenance of hemoglobin A1c target goals
- Identify stressors and seek counseling to deal with them
- Lipid blood testing to identify dyslipidemia as soon as possible and treat it
Prevention of the Progression and Complications of Hypertension After Diagnosis
- Management of coronary artery disease with increased surveillance (echocardiography, ECG) and treatment when indicated via angioplasty or bypass procedures
- Management of claudication (pain from exertion in the extremities, inferring arterial obstructive disease) with arterial plaque removal, revascularization, or bypass procedures
- Management of venous insufficiency to prevent thromboembolic events (that can lead to pulmonary emboli), via vein ablation or removal to decrease the venous load, and via anticoagulation to prevent thrombotic emboli to distal targets
Another aspect of prevention is in avoiding errors in diagnosis based on spurious data. Especially in cases in which one is considering medicinal manipulation, accuracy is important.
- The blood pressure cuff must be the proper size to render a reasonably accurate blood pressure reading. For example, a cuff too small on an obese arm will result in numbers that are higher than what they would be on a larger, more appropriate cuff size; a cuff too large on a thin arm will do the opposite
- “White coat syndrome:” this is a sympathetic stimulus that results in a transient blood pressure elevation in nervous or fearful individuals. Prevention is via home monitoring or ambulatory BP monitoring
- Temporary, solvable conditions, such as medication with hypertension as a side effect. Prevention is by exchange for an equally efficacious medication
- Improperly taking a blood pressure: other factors that influence the blood pressure, making it inaccurate, are breathing fluctuations during the reading, crossing one’s legs, being in an animated conversation, and arm positioning