Essential Hypertension and Hypertensive Emergencies

Regarding Essential Hypertension and Hypertensive Emergencies answer the following questions;

1. What is the estimated prevalence of systemic hypertension in the U.S. population?
2. What is the most common cause of systemic hypertension?
3. How is hypertension classified?
4. What is the natural history of untreated hypertension?
5. Does medical therapy improve outcomes in hypertension?
6. What is a hypertensive crisis?

Answers;

1. What is the estimated prevalence of systemic hypertension in the U.S. population?
Hypertension in the United States affects approximately 65 million Americans. How ever, the prevalence increases with age, so that more than 60% of the population older than 70 years has hypertension. The Framingham Heart Study has demonstrated that 55-year-old normotensive
individuals have a 90% lifetime risk of developing hypertension. The incidence of hypertension and its severity is greater in blacks than whites in every age-group beyond adolescence.

2. What is the most common cause of systemic hypertension?
No cause is found for approximately 90% of patients with hypertension. These patients are said to have essential hypertension. Although the mechanism of essential hypertension is unknown, there are apparently both genetic and environmental factors.


3. How is hypertension classified?

• Normal blood pressure is less than 120/80 mm Hg. 
• Blood pressures of 130 to 139 mm Hg systolic and 80 to 89 mm Hg diastolic are considered prehypertension. Individuals w ith prehypertension have twice the lifetime risk of developing hypertension as their normotensive counterparts. 
• Stage 1 hypertension is defined as a systolic blood pressure of 140 to 159 mm Hg and a diastolic blood pressure of 90 to 99 mm Hg, 
• Stage 2 hypertension is a systolic blood pressure of 160 mm Hg and greater and a diastolic blood pressure of 100 mm Hg and greater 

4. What is the natural history of untreated hypertension?
Uncomplicated hypertension often remains asymptomatic for 10 to 20 years or more. How ever, there is a direct relationship between the levels of both systolic and diastolic blood pressures and the incidence of stroke, CAD, and HF. Indeed, for every 20 and 10 mm Hg increment in systolic and diastolic pressure respectively, individuals aged 40 to 70 years have a doubling of cardiovascular risk from blood pressures of 115/75 to 185/115 mm Hg. The overall risk of premature cardiovascular disease increases substantially when additional cardiovascular risk factors are present. In fact, the
likelihood of a vascular event over the next 10 years can be estimated for any patient on the basis of their age, sex, and other risks . If patients with hypertension are not treated, approximately 50% die of coronary disease, 33% of stroke, and 10% to 15% of renal failure.

5. Does medical therapy improve outcomes in hypertension?
Clinical trials of antihypertensive therapy have demonstrated an average mean reduction of 40% for stroke, 50% for HF, and 20% to 25% for MI.

6. What is a hypertensive crisis?
A hypertensive crisis is an acute life-threatening complication of accelerated hypertension. In patients with chronic hypertension and hypertensive crisis, the blood pressure is generally 180/120 mm Hg or greater, but may be lower in patients whose blood pressure was previously normal (e.g., eclampsia).
Malignant hypertension is present when there are retinal hemorrhages, exudates or papilledema, and/or malignant nephrosclerosis. When there are signs of cerebral edema, hypertensive encephalopathy is said to be present.

Examples of hypertensive crises include:

• Accelerated/malignant hypertension
• Hypertensive encephalopathy
• Atherothrombotic cerebral infarction w ith severe hypertension
• Aortic dissection
• Acute pulmonary edema or left ventricular failure
• Acute MI
• Eclampsia
• Drug-induced hypertension (cocaine)