HYPERTENSION
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HYPERTENSION
by bluerose Sun Oct 21, 2007 11:29 pm
Background
Hypertension is one of the most common worldwide diseases afflicting humans. Because of the associated morbidity and mortality and the cost to society, hypertension is an important public health challenge. Over the past several decades, extensive research, widespread patient education, and a concerted effort on the part of health care professionals have led to decreased mortality and morbidity rates from the multiple organ damage arising from years of untreated hypertension. Hypertension is the most important modifiable risk factor for coronary heart disease (the leading cause of death in North America), stroke (the third leading cause), congestive heart failure, end-stage renal disease, and peripheral vascular disease. Therefore, health care professionals must not only identify and treat patients with hypertension but also promote a healthy lifestyle and preventive strategies to decrease the prevalence of hypertension in the general population.
Historical perspectives
Blood pressure was measured for the first time by Stephen Hales in 1773. Hales also described the importance of blood volume in blood pressure regulation. The contribution of peripheral arterioles in maintaining blood pressure, described as "tone," was first described by Lower in 1669 and subsequently by Sénac in 1783. The role of vasomotor nerves in the regulation of blood pressure was observed by such eminent investigators as Claude Bernard, Charles E. Edouard, Charles Brown-Séquard, and Augustus Waller. William Dayliss advanced this concept in a monograph published in 1923. Cannon and Rosenblueth developed the concept of humoral control of blood pressure and investigated pharmacologic effects of epinephrine. Three contributors who advanced the knowledge of humoral mechanisms of blood pressure control are T.R. Elliott, Sir Henry Dale, and Otto Loew.
Richard Bright, a physician who practiced in the first half of the 19th century, observed the changes of hypertension on the cardiovascular system in patients with chronic renal disease. George Johnson in 1868 postulated that the cause of left ventricular hypertrophy (LVH) in Bright disease was the presence of muscular hypertrophy in the smaller arteries throughout the body. Further clinical pathologic studies by Sir William Gull and H.G. Sutton (1872) led to further description of the cardiovascular changes of hypertension. Frederick Mahomed was one of the first physicians to systematically incorporate blood pressure measurement as a part of a clinical evaluation.
The recognition of primary, or essential, hypertension is credited to the work of Huchard, Vonbasch, and Albutt. Observations of Janeway and Walhard led to the recognition of target organ damage, which branded hypertension as the "silent killer." The concepts of renin, angiotensin, and aldosterone were advanced by several investigators in the late 19th and early 20th centuries. The names of Irwine, Page, van Slyke, Goldblatt, Laragh, and Tuttle prominently appear throughout the hypertension literature, and their work enhances our understanding of the biochemical basis of essential hypertension. Cushman and Ondetti developed an orally acting converting enzyme inhibitor from snake venom peptides and are credited with the successful synthesis of the modern antihypertensive captopril.
Definition
Defining abnormally high blood pressure is extremely difficult and arbitrary. Furthermore, the relationship between systemic arterial pressure and morbidity appears to be quantitative rather than qualitative. A level for high blood pressure must be agreed upon in clinical practice for screening patients with hypertension and for instituting diagnostic evaluation and initiating therapy. Because the risk to an individual patient may correlate with the severity of hypertension, a classification system is essential for making decisions about aggressiveness of treatment or therapeutic interventions.
Based on recommendations of the Seventh Report of the Joint National Committee of Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VII), the classification of blood pressure (expressed in mm Hg) for adults aged 18 years or older is as follows*:
• Normal† - Systolic lower than 120, diastolic lower than 80
• Prehypertension - Systolic 120-139, diastolic 80-99
• Stage 1 - Systolic 140-159, diastolic 90-99
• Stage 2 - Systolic equal to or more than 160, diastolic equal to or more than 100
*Based on the average of 2 or more readings taken at each of 2 or more visits after initial screening
†Normal blood pressure with respect to cardiovascular risk is less than 120/80 mm Hg. However, unusually low readings should be evaluated for clinical significance.
Prehypertension, a new category designated in the JNC VII report, emphasizes that patients with prehypertension are at risk for progression to hypertension and that lifestyle modifications are important preventive strategies.
Hypertension may be either essential or secondary. Essential hypertension is diagnosed in the absence of an identifiable secondary cause. Approximately 95% of American adults have essential hypertension, while secondary hypertension accounts for fewer than 5% of the cases.
Hypertension is one of the most common worldwide diseases afflicting humans. Because of the associated morbidity and mortality and the cost to society, hypertension is an important public health challenge. Over the past several decades, extensive research, widespread patient education, and a concerted effort on the part of health care professionals have led to decreased mortality and morbidity rates from the multiple organ damage arising from years of untreated hypertension. Hypertension is the most important modifiable risk factor for coronary heart disease (the leading cause of death in North America), stroke (the third leading cause), congestive heart failure, end-stage renal disease, and peripheral vascular disease. Therefore, health care professionals must not only identify and treat patients with hypertension but also promote a healthy lifestyle and preventive strategies to decrease the prevalence of hypertension in the general population.
Historical perspectives
Blood pressure was measured for the first time by Stephen Hales in 1773. Hales also described the importance of blood volume in blood pressure regulation. The contribution of peripheral arterioles in maintaining blood pressure, described as "tone," was first described by Lower in 1669 and subsequently by Sénac in 1783. The role of vasomotor nerves in the regulation of blood pressure was observed by such eminent investigators as Claude Bernard, Charles E. Edouard, Charles Brown-Séquard, and Augustus Waller. William Dayliss advanced this concept in a monograph published in 1923. Cannon and Rosenblueth developed the concept of humoral control of blood pressure and investigated pharmacologic effects of epinephrine. Three contributors who advanced the knowledge of humoral mechanisms of blood pressure control are T.R. Elliott, Sir Henry Dale, and Otto Loew.
Richard Bright, a physician who practiced in the first half of the 19th century, observed the changes of hypertension on the cardiovascular system in patients with chronic renal disease. George Johnson in 1868 postulated that the cause of left ventricular hypertrophy (LVH) in Bright disease was the presence of muscular hypertrophy in the smaller arteries throughout the body. Further clinical pathologic studies by Sir William Gull and H.G. Sutton (1872) led to further description of the cardiovascular changes of hypertension. Frederick Mahomed was one of the first physicians to systematically incorporate blood pressure measurement as a part of a clinical evaluation.
The recognition of primary, or essential, hypertension is credited to the work of Huchard, Vonbasch, and Albutt. Observations of Janeway and Walhard led to the recognition of target organ damage, which branded hypertension as the "silent killer." The concepts of renin, angiotensin, and aldosterone were advanced by several investigators in the late 19th and early 20th centuries. The names of Irwine, Page, van Slyke, Goldblatt, Laragh, and Tuttle prominently appear throughout the hypertension literature, and their work enhances our understanding of the biochemical basis of essential hypertension. Cushman and Ondetti developed an orally acting converting enzyme inhibitor from snake venom peptides and are credited with the successful synthesis of the modern antihypertensive captopril.
Definition
Defining abnormally high blood pressure is extremely difficult and arbitrary. Furthermore, the relationship between systemic arterial pressure and morbidity appears to be quantitative rather than qualitative. A level for high blood pressure must be agreed upon in clinical practice for screening patients with hypertension and for instituting diagnostic evaluation and initiating therapy. Because the risk to an individual patient may correlate with the severity of hypertension, a classification system is essential for making decisions about aggressiveness of treatment or therapeutic interventions.
Based on recommendations of the Seventh Report of the Joint National Committee of Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VII), the classification of blood pressure (expressed in mm Hg) for adults aged 18 years or older is as follows*:
• Normal† - Systolic lower than 120, diastolic lower than 80
• Prehypertension - Systolic 120-139, diastolic 80-99
• Stage 1 - Systolic 140-159, diastolic 90-99
• Stage 2 - Systolic equal to or more than 160, diastolic equal to or more than 100
*Based on the average of 2 or more readings taken at each of 2 or more visits after initial screening
†Normal blood pressure with respect to cardiovascular risk is less than 120/80 mm Hg. However, unusually low readings should be evaluated for clinical significance.
Prehypertension, a new category designated in the JNC VII report, emphasizes that patients with prehypertension are at risk for progression to hypertension and that lifestyle modifications are important preventive strategies.
Hypertension may be either essential or secondary. Essential hypertension is diagnosed in the absence of an identifiable secondary cause. Approximately 95% of American adults have essential hypertension, while secondary hypertension accounts for fewer than 5% of the cases.
bluerose- Posts : 43
Join date : 2007-10-14
Location : TP.HCM
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