michigan hypertension core curriculum - State of Michigan

Essential (Primary) Hypertension:
Diagnosis of Hypertension
Essential hypertension is a misnomer. There is nothing ‘essential’ about hypertension; perhaps
“essential BP”, but not hypertension. This section will describe ‘primary hypertension’.
Blood pressure (BP) is inherently variable within a reasonably predictable range. Hypertension
is defined as elevated average BP over time, preferably with a minimum of 3 properly performed
readings on different days and is never based on a single measurement. Your BP at rest is lower
than your BP during activities. There is a natural diurnal variation for people with usual work-sleep
cycles resulting in increased BP just prior to awakening continuing to be elevated in the morning while
decreasing in the evening. BP also decreases in the early afternoon, which is why post-lunch lectures
are difficult, and the nadir in BP occurs at 2-3AM, during sleep. This data is routinely obtained by
24-hour ambulatory blood pressure monitors. The decrease in BP during sleep is known as the ‘dip’
and is absent in some conditions and when absent results in increased cardiovascular (i.e., strokes,
myocardial infarctions, death) events. Several selected conditions known to attenuate or eliminate the
normal nocturnal decline in BP include: 1) chronic kidney disease (CKD), 2) obesity, 3) high sodium
and/or low potassium diets, and 4) sleep disordered breathing.
Too much pressure is potentially deleterious for any system. For example, an overinflated car
tire allows you to drive to the store without any difficulty; however the increased pressure prematurely
wears out the tire. The human circulatory system is similar. Prolonged BP elevation results in
accelerated atherosclerosis and vascular remodeling that heighten the risk of stroke (brain), myocardial
infarction (heart), myocardial hypertrophy (heart), kidney failure (kidney), and abdominal aneurysms
(general circulatory). Contrary to pervasive myths, there is no specific BP reading that prognosticates
without fail a cardiovascular catastrophe. When marked BP pressures are detected, repeated
measurements and careful short-term follow-up are critical.
Hypertension Phenotypes (Isolated Systolic, Isolated Diastolic, Isolated Systolic/Diastolic)
BP is represented by two numbers (i.e., 120/50 mmHg). The highest number is the systolic
BP and the lower is the diastolic BP. The BP is typically measured by either the auscultatory or
oscillometric methods. The following is a discussion of hypertension phenotypes. Hypertension is
classified into distinctive phenotypes. Mixed systolic/diastolic hypertension is most common in middle
aged patients when both the diastolic and systolic BP are elevated above 140/90 mmHg in the office.
Isolated systolic hypertension (ISH) is most common after 50 years old, although there is an unusual,
benign form in the youth. 1,2 ISH is also the most risky hypertension phenotype despite the fact that
the diastolic BP is not elevated. Isolated diastolic hypertension is least prevalent (and also least
risky) hypertension phenotype. The different categories of hypertension have different pathological
mechanisms which will be discussed in the Pathophysiology Section.
Pre-hypertension is present when BP readings are between 120-139/80-89 mmHg. 3 These
individuals are at risk for the development of hypertension. Thus, lifestyle modification (i.e., exercise,
weight loss, salt and alcohol restriction) is recommended. Borderline or high normal BP is when the
office readings are consistently between 135-140/85-90 mmHg in patients without CKD, diabetes, or
ischemic heart disease.
White Coat Hypertension (office hypertension) is present when the office BP is >140/90 mmHg,
yet the outside the office the BP is