HYPERTENSION (high blood pressure)
Hypertension is defined as a blood pressure ≥140/≥90 mmHg. The following definitions were suggested in 2003 by the seventh report of the Joint National Committee (JNC 7) based upon the average of two or more properly measured readings at each of two or more visits after an initial screen.
- Normal blood pressure: systolic <120 mmHg and diastolic <80 mmHg
- Prehypertension: systolic 120-139 mmHg or diastolic 80-89 mmHg
- Hypertension:
- Stage 1: systolic 140-159 mmHg or diastolic 90-99 mmHg
- Stage 2: systolic ≥160 or diastolic ≥100 mmHg
ESSENTIAL (PRIMARY) HYPERTENSION (High Blood Pressure)
Pathogenesis — The pathogenesis of essential hypertension is poorly understood. A variety of factors have been implicated.
Hypertension is about twice as common in subjects who have one or two hypertensive parents and multiple epidemiologic studies suggest that genetic factors account for approximately 30 percent of the variation in blood pressure in various populations
Complications — Hypertension is associated with a number of serious adverse effects. The likelihood of developing these complications varies with the blood pressure. The increase in risk begins as the blood pressure rises above 110/75 mmHg in all age groups. However, this relationship does not prove causality, which can only be demonstrated by randomized trials showing benefit from blood pressure reduction.
The increase in cardiovascular risk associated with hypertension is importantly affected by the presence or absence of other risk factors .
- Hypertension is quantitatively the major risk factor for premature cardiovascular disease, being more common than cigarette smoking, dyslipidemia, and diabetes, the other major risk factors . In older patients, systolic pressure is more powerful determinants of risk than diastolic pressure .
- Hypertension increases the risk of heart failure at all ages with the hazard increasing with the degree of blood pressure elevation
- ventricular hypertrophy is a common problem in patients with hypertension , and is associated with an enhanced incidence of heart failure, ventricular arrhythmias, death following myocardial infarction, and sudden cardiac death
- Hyperrtension is the most common and most important risk factor for stroke, the incidence of which can be markedly reduced by effective antihypertensive therapy.
- Hypertension is the most important risk factor for the development of intracerebral hemorrhage.
- Hypertension is a risk factor for chronic kidney disease and end-stage renal disease. It can both directly cause kidney disease, called hypertensive nephrosclerosis, and accelerate the progression of a variety of underlying renal diseases.
- Marked elevations in blood pressure can cause an acute, life-threatening emergency.
Malignant hypertension — Malignant hypertension refers to marked hypertension with retinal hemorrhages, exudates, or papilledema. These findings may be associated with hypertensive encephalopathy.
Hypertensive urgency — Severe hypertension (as defined by a diastolic blood pressure above 120 mmHg) in asymptomatic patients is referred to as hypertensive urgency. There is no proven benefit from rapid reduction in BP in asymptomatic patients who have no evidence of acute end-organ damage and are at little short-term risk.
