Clinically, one’s level of blood pressure (BP) is determined by the average of 2 or more separate BP readings at two or more separate times. The criteria for its diagnosis as well as the proper technique for obtaining an accurate BP must be used for the diagnosis to be valid.
Blood pressure is composed of two measurements:
- Systolic pressure: The pressure in arteries during systole (contraction of the heart muscle).
- Diastolic pressure: The pressure in arteries between cardiac contractions, representing the resting vascular resistance of the tissues.
- Normal blood pressure: Systolic <120 mmHg and diastolic <80 mmHg (<120/<80)
- Elevated blood pressure: Systolic 120 – 129 mmHg while diastolic is still <80 mmHg (120-129/<80)
- Hypertension stage 1: Either systolic 130 – 139 mmHg or diastolic 80 – 89 mmHg
- Hypertension stage 2: Either systolic ≥ 140 mmHg or diastolic ≥ least 90 mmHg
Since there are two numbers involved (systolic/diastolic), the higher (more abnormal) number determines which stage is present.
- Treated hypertension: A normal BP in those requiring medication to keep it normal.
Because BP can vary from moment to moment and depend on patient position, respiration, or activity, inaccuracies can be corrected by having patients undergo “ambulatory” or home BP monitoring.
Primary vs Secondary Hypertension
Blood pressure slowly rises with age, but blood pressure disorders arise due to smoking, obesity, alcohol consumption, stress, thyroid disease, dyslipidemia (unhealthy elevations of cholesterol and triglyceride), genetics, high sodium diet, stimulants, hormones, kidney disease, diabetes, adrenal tumors, and many other causes. These are referred to as “secondary” hypertension.
The most common type of hypertension, however, is “primary” hypertension, for which a definitive cause is not identified.
Complications of Hypertension
Hypertension is usually a co-morbidity within a spectrum of cardiovascular conditions, such as atherosclerosis and abnormal lipid elevations. These contribute to obstructive plaques in arteries which limit perfusion to the heart and other organs. The most notorious of complications include heart attack (myocardial infarction) and stroke; also ominous, however, are claudication (blockage of blood flow to arteries of the extremities causing pain), paresthesias (abnormal sensations from damage to nerves), and ischemia to organs supplied by compromised arteries, e.g., mesenteric ischemia which threatens the viability of the entire intestinal tract, renal hypertension, or myocardial ischemia from atherosclerosis of the coronary arteries.
Typically, due to secondary hypertension, a hypertensive emergency is with a BP ≥ 180/≥ 120 and there is evidence of organ damage occurring. There can be neurologic symptoms, nausea, chest pain from myocardial ischemia, dyspnea due to pulmonary edema, or back pain due to aortic dissection.