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.
Monday, November 5, 2007
More Young Adults Take Anticholesterol, Hypertension Medications, Report Finds
The percentage of young adults who take anticholesterol and hypertension medications has increased significantly in recent years, according to a report released on Tuesday by pharmacy benefit manager Medco Health Solutions, the AP/Washington Times reports.
According to the report, the percentage of adults ages 20 to 44 who took anticholesterol medications increased from 2.5% in 2001 to more than 4% in 2006, a 68% increase. About 4.2 million young adults took anticholesterol medications in 2006, the report found.
In addition, the report found that the percentage of young adults who took hypertension medications increased from 7% in 2001 to more than 8% in 2006, a 21% increase. About 8.5 million young adults took hypertension medications in 2006, according to the report.
In comparison, the percentage of adults older than age 65 who took anticholesterol medications increased by 52% from 2001 to 2006, and the percentage of seniors who took hypertension treatments increased by 9.5%, the report found. About half of seniors took anticholesterol medications in 2001, and more than one-fourth took hypertension treatments, according to the report.
Some experts attributed the results of the report to increased rates of obesity, hypertension and high cholesterol among young adults. In addition, they said that more physicians have begun to promote use of anticholesterol and hypertension medications among young adults as a preventive measure.
American Heart Association President Daniel Jones said, "This is good news, that more people in this age range are taking these medicines."
Robert Epstein, chief medical officer for Medco, said, "It was a surprise to us," adding, "Maybe the fact that we're seeing more young people with high cholesterol and blood pressure is indicative of the epidemic of obesity and overweight that we're seeing in this country" (AP/Washington Times, 10/30).
According to the report, the percentage of adults ages 20 to 44 who took anticholesterol medications increased from 2.5% in 2001 to more than 4% in 2006, a 68% increase. About 4.2 million young adults took anticholesterol medications in 2006, the report found.
In addition, the report found that the percentage of young adults who took hypertension medications increased from 7% in 2001 to more than 8% in 2006, a 21% increase. About 8.5 million young adults took hypertension medications in 2006, according to the report.
In comparison, the percentage of adults older than age 65 who took anticholesterol medications increased by 52% from 2001 to 2006, and the percentage of seniors who took hypertension treatments increased by 9.5%, the report found. About half of seniors took anticholesterol medications in 2001, and more than one-fourth took hypertension treatments, according to the report.
Some experts attributed the results of the report to increased rates of obesity, hypertension and high cholesterol among young adults. In addition, they said that more physicians have begun to promote use of anticholesterol and hypertension medications among young adults as a preventive measure.
American Heart Association President Daniel Jones said, "This is good news, that more people in this age range are taking these medicines."
Robert Epstein, chief medical officer for Medco, said, "It was a surprise to us," adding, "Maybe the fact that we're seeing more young people with high cholesterol and blood pressure is indicative of the epidemic of obesity and overweight that we're seeing in this country" (AP/Washington Times, 10/30).
Study Results Of Cardiovascular Risk For Living Kidney Donors
Living kidney donors show no increase in their risk of heart attacks or other cardiovascular events in the years after donation, according to the largest-ever study of the issue, presented at the American Society of Nephrology's 40th Annual Meeting and Scientific Exposition in San Francisco.
Although donors are more likely to be diagnosed with high blood pressure (hypertension) during follow-up, it is unclear whether this represents a true risk of living kidney donation, according to Lawson Health Research Institute scientist, Dr. Amit X. Garg. Dr. Garg is also an Associate Professor in Medicine and Epidemiology with the Schulich School of Medicine & Dentistry at The University of Western Ontario in London, Ontario, Canada.
Dr. Garg and colleagues analyzed follow-up data on 1,278 patients who became living kidney donors in Ontario between 1993 and 2005. Rates of major cardiovascular events -- including myocardial infarction (heart attack), stroke, angioplasty, or bypass surgery -- were compared to those of 6,369 healthy adults. To ensure comparability, the two groups were closely matched for age, sex, income, and use of health care services before donation.
During a follow-up period of one to thirteen years (average six years), 1.3 percent of the living kidney donors died or experienced a cardiovascular event. This was not statistically different from the 1.7 percent rate in the comparison group.
The only significant difference was a higher rate of hypertension among living kidney donors: about 16 percent, compared with 12 percent in the comparison group. "Donors were diagnosed more frequently with hypertension, but they also saw their primary care physicians more often than controls, and so had more opportunities to be diagnosed," says Dr. Garg. On average, the donors had one additional medical visit per year.
Living kidney donation has become an important source of organs for transplantation. However, it is essential to know the extent and nature of any health risks of donation. "Knowledge of any potential risks associated with becoming a living kidney donor would guide future donor selection, informed consent, and best practices to follow and care for living donors," comments Dr. Garg. "Risk estimates in the literature are currently quite variable, and there is global consensus that we need better estimates."
The new study refines past estimates by providing long-term follow-up data on a large group of living kidney donors -- 50 times larger than any previous study. Encouragingly, the results show no long-term increase in cardiovascular risk after donation.
Further study is needed to determine whether the apparent increase in the risk of high blood pressure is truly an effect of living kidney donation, or if it merely reflects the increased medical scrutiny after donation. "These results emphasize the importance to counsel and follow all kidney donors to manage modifiable factors in an attempt to prevent hypertension and future cardiovascular disease," adds Dr. Garg.
Although donors are more likely to be diagnosed with high blood pressure (hypertension) during follow-up, it is unclear whether this represents a true risk of living kidney donation, according to Lawson Health Research Institute scientist, Dr. Amit X. Garg. Dr. Garg is also an Associate Professor in Medicine and Epidemiology with the Schulich School of Medicine & Dentistry at The University of Western Ontario in London, Ontario, Canada.
Dr. Garg and colleagues analyzed follow-up data on 1,278 patients who became living kidney donors in Ontario between 1993 and 2005. Rates of major cardiovascular events -- including myocardial infarction (heart attack), stroke, angioplasty, or bypass surgery -- were compared to those of 6,369 healthy adults. To ensure comparability, the two groups were closely matched for age, sex, income, and use of health care services before donation.
During a follow-up period of one to thirteen years (average six years), 1.3 percent of the living kidney donors died or experienced a cardiovascular event. This was not statistically different from the 1.7 percent rate in the comparison group.
The only significant difference was a higher rate of hypertension among living kidney donors: about 16 percent, compared with 12 percent in the comparison group. "Donors were diagnosed more frequently with hypertension, but they also saw their primary care physicians more often than controls, and so had more opportunities to be diagnosed," says Dr. Garg. On average, the donors had one additional medical visit per year.
Living kidney donation has become an important source of organs for transplantation. However, it is essential to know the extent and nature of any health risks of donation. "Knowledge of any potential risks associated with becoming a living kidney donor would guide future donor selection, informed consent, and best practices to follow and care for living donors," comments Dr. Garg. "Risk estimates in the literature are currently quite variable, and there is global consensus that we need better estimates."
The new study refines past estimates by providing long-term follow-up data on a large group of living kidney donors -- 50 times larger than any previous study. Encouragingly, the results show no long-term increase in cardiovascular risk after donation.
Further study is needed to determine whether the apparent increase in the risk of high blood pressure is truly an effect of living kidney donation, or if it merely reflects the increased medical scrutiny after donation. "These results emphasize the importance to counsel and follow all kidney donors to manage modifiable factors in an attempt to prevent hypertension and future cardiovascular disease," adds Dr. Garg.
How is high blood pressure defined?
Blood pressure can be affected by several factors, so it is important to standardize the environment when blood pressure is measured. For at least one hour before blood pressure is taken, avoid eating, strenuous exercise (which can lower blood pressure), smoking, and caffeine intake. Other stresses may alter the blood pressure and need to be considered when blood pressure is measured.
Even though most insurance companies consider high blood pressure to be 140/90 and higher for the general population, these levels may not be appropriate cut–offs for all individuals. Many experts in the field of hypertension view blood pressure levels as a range, from lower levels to higher levels. Such a range implies there are no clear or precise cut–off values to separate normal blood pressure from high blood pressure. Individuals with so–called pre–hypertension (defined as a blood pressure between 120/80 and 139/89) may benefit from lowering of blood pressure by life style modification and possibly medication especially if there are other risk factors for end–organ damage such as diabetes or kidney disease (life style changes are discussed below).
For some people, blood pressure readings lower than 140/90 may be a more appropriate normal cut–off level. For example, in certain situations, such as in patients with long duration (chronic) kidney diseases that spill (lose) protein into the urine (proteinuria), the blood pressure is ideally kept at 130/80, or even lower. The purpose of reducing the blood pressure to this level in these patients is to slow the progression of kidney damage. Patients with diabetes (diabetes mellitus) may also benefit from blood pressure that is maintained at a level lower than 130/80. In addition, African Americans, who have an increased risk for developing the complications of hypertension, may decrease this risk by reducing their systolic blood pressure to less than 135 and the diastolic blood pressure to 80 mm Hg or less.
In line with the thinking that the risk of end–organ damage from high blood pressure represents a continuum, statistical analysis reveals that beginning at a blood pressure of 115/75 the risk of cardiovascular disease doubles with each increase in blood pressure of 20/10. This type of analysis has led to an ongoing "rethinking" in regard to who should be treated for hypertension, and what the goals of treatment should be.
Even though most insurance companies consider high blood pressure to be 140/90 and higher for the general population, these levels may not be appropriate cut–offs for all individuals. Many experts in the field of hypertension view blood pressure levels as a range, from lower levels to higher levels. Such a range implies there are no clear or precise cut–off values to separate normal blood pressure from high blood pressure. Individuals with so–called pre–hypertension (defined as a blood pressure between 120/80 and 139/89) may benefit from lowering of blood pressure by life style modification and possibly medication especially if there are other risk factors for end–organ damage such as diabetes or kidney disease (life style changes are discussed below).
For some people, blood pressure readings lower than 140/90 may be a more appropriate normal cut–off level. For example, in certain situations, such as in patients with long duration (chronic) kidney diseases that spill (lose) protein into the urine (proteinuria), the blood pressure is ideally kept at 130/80, or even lower. The purpose of reducing the blood pressure to this level in these patients is to slow the progression of kidney damage. Patients with diabetes (diabetes mellitus) may also benefit from blood pressure that is maintained at a level lower than 130/80. In addition, African Americans, who have an increased risk for developing the complications of hypertension, may decrease this risk by reducing their systolic blood pressure to less than 135 and the diastolic blood pressure to 80 mm Hg or less.
In line with the thinking that the risk of end–organ damage from high blood pressure represents a continuum, statistical analysis reveals that beginning at a blood pressure of 115/75 the risk of cardiovascular disease doubles with each increase in blood pressure of 20/10. This type of analysis has led to an ongoing "rethinking" in regard to who should be treated for hypertension, and what the goals of treatment should be.
How is the blood pressure measured?
The blood pressure usually is measured with a small, portable instrument called a blood pressure cuff (sphygmomanometer). (Sphygmo is Greek for pulse, and a manometer measures pressure.) The blood pressure cuff consists of an air pump, a pressure gauge, and a rubber cuff. The instrument measures the blood pressure in units called millimeters of mercury (mm Hg).
The cuff is placed around the upper arm and inflated with an air pump to a pressure that blocks the flow of blood in the main artery (brachial artery) that travels through the arm. The arm is then extended at the side of the body at the level of the heart, and the pressure of the cuff on the arm and artery is gradually released. As the pressure in the cuff decreases, a health practitioner listens with a stethoscope over the artery at the front of the elbow. The pressure at which the practitioner first hears a pulsation from the artery is the systolic pressure (the top number). As the cuff pressure decreases further, the pressure at which the pulsation finally stops is the diastolic pressure (the bottom number).
The cuff is placed around the upper arm and inflated with an air pump to a pressure that blocks the flow of blood in the main artery (brachial artery) that travels through the arm. The arm is then extended at the side of the body at the level of the heart, and the pressure of the cuff on the arm and artery is gradually released. As the pressure in the cuff decreases, a health practitioner listens with a stethoscope over the artery at the front of the elbow. The pressure at which the practitioner first hears a pulsation from the artery is the systolic pressure (the top number). As the cuff pressure decreases further, the pressure at which the pulsation finally stops is the diastolic pressure (the bottom number).
Hypertension: Blood Pressure Basics
What is hypertension? What causes hypertension and what are the symptoms?
Blood pressure is the force of blood pushing against blood vessel walls. The heart pumps blood into the arteries (blood vessels), which carry the blood throughout the body. High blood pressure, also called hypertension, is dangerous because it makes the heart work harder to pump blood to the body and it contributes to hardening of the arteries or atherosclerosis and the development of heart failure.
What Is "Normal" Blood Pressure?
There are several categories of blood pressure, including:
People whose blood pressure is above the normal range should consult their doctor about methods for lowering it.
What Causes Hypertension?
The exact causes of hypertension are not known. Several factors and conditions may play a role in its development, including:
There are usually no symptoms or signs of hypertension. In fact, nearly one-third of those who have it don't know it. The only way to know if you have hypertension definitely is to have your blood pressure checked.
If your blood pressure is extremely high, there may be certain symptoms to look out for, including:
Blood pressure is the force of blood pushing against blood vessel walls. The heart pumps blood into the arteries (blood vessels), which carry the blood throughout the body. High blood pressure, also called hypertension, is dangerous because it makes the heart work harder to pump blood to the body and it contributes to hardening of the arteries or atherosclerosis and the development of heart failure.
What Is "Normal" Blood Pressure?
There are several categories of blood pressure, including:
- Normal: Less than 120/80
- Prehypertension: 120-139/80-89
- Stage 1 hypertension: 140-159/90-99
- Stage 2 hypertension: 160 and above/100 and above
People whose blood pressure is above the normal range should consult their doctor about methods for lowering it.
What Causes Hypertension?
The exact causes of hypertension are not known. Several factors and conditions may play a role in its development, including:
- Smoking
- Being overweight
- Lack of physical activity
- Too much salt in the diet
- Too much alcohol consumption (no more than 1 to 2 drinks per day)
- Stress
- Older age
- Genetics
- Family history of high blood pressure
- Chronic kidney disease
- Adrenal and thyroid disorders
There are usually no symptoms or signs of hypertension. In fact, nearly one-third of those who have it don't know it. The only way to know if you have hypertension definitely is to have your blood pressure checked.
If your blood pressure is extremely high, there may be certain symptoms to look out for, including:
- Severe headache
- Fatigue or confusion
- Vision problems
- Chest pain
- Difficulty breathing
- Irregular heartbeat
- Blood in the urine
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