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  1. #1
    Blown_SC is offline Retired Vet
    Join Date
    Feb 2004

    Understanding Hypertension / High Blood Pressure



    This condition is also commonly referred to as "high blood pressure" and it occurs when the pressure of blood flowing through the body's arteries exceeds certain arbitrarily determined numbers. Certain basic laws of physics govern the circulation of blood around the body. The heart is essentially a pump, which is not much different from the pump that causes water to flow through the pipes that make up the plumbing in our homes. The blood vessels represent the plumbing and serve to circulate blood in much the same way that water "circulates" around our homes. The pump generates a pressure, which then forces the blood through the circulation. For the blood to continue to flow through in one direction, the pressure of blood leaving the pump (i.e. heart) must be significantly higher than the pressure of blood returning to it. In physics this difference in pressure is called a gradient. The pressure itself is the result of an inter-play between the force generated by the pumping action of the heart and the resistance to the flow of blood offered by the walls of the blood vessels. When the heart contracts, thus forcing blood into the vessels, the amount of pressure that is generated will depend on how much the vessels are able to widen to accommodate the blood expelled from the heart. If the vessels are unable to widen significantly, resistance to the flow of blood is high and the pressure is correspondingly high. However, if the amount of blood expelled from the heart is smaller than usual, or it is expelled very slowly, the blood vessels are much better able to channel that flow without a dramatic increase in pressure, even if it's walls are not able to distend as fully as they normally do. This very fascinating inter-play is what determines blood pressure, and it is therefore not surprising that blood pressure tends to vary depending on what is occurring in the circulation when it is taken. Although the pressure in blood vessels tends to vary somewhat depending on when it is taken, overall the body tries to keep it within a fairly narrow range. This is because extremes of blood pressure in either direction tend to damage vital organs in the body. The pioneering efforts of some doctors and scientists in the last couple of centuries has led to the ability to measure blood pressure, and therefore to correlate different levels of blood pressure with observed adverse events. It was noted quite early in the evolution of its measurement that it had two components. A system of recording blood pressure was devised that reflects these components. The first component is measurable shortly after the heart empties blood into the arteries and is called the systolic blood pressure, and it is followed shortly after by a second component, which coincides with changes in the size of the blood vessels. This second component is called diastolic blood pressure because it is measured during a period of heart muscle relaxation, in between contractions, that is known as diastole. By convention, both numbers are written down together, one on top of the other. The top number is always the systolic blood pressure. Based on adverse event correlation studies previously referred to, a blood pressure greater than 140/90 was consistently associated with a higher and rising incidence of damage to body organs. For this reason, this pressure was, somewhat arbitrarily, designated the upper limit of normal for blood pressure. While it remains an acceptable guideline for most people, it is now quite clear that for certain high-risk individuals such as diabetic patients, a lower level of blood pressure may be associated with fewer complications .

    There are several different ways of classifying hypertension, with some schemes being more complicated than others. For the purpose of this article, simply dividing it into two large groups should suffice. The first group is referred to as having primary or essential hypertension. The hallmark of this group is that the cause of their hypertension is obscure. They tend to have a strong family history of the disease, making it probable that genetic factors are involved. In these patients, the disease tends to become manifest sometime during middle age and to generally respond to treatment quite well. Other factors that are thought to contribute to the development of this form of hypertension include obesity, salt and alcohol intake, stress and a lack of exercise. Secondary hypertension refers to disease that is clearly attributable to readily identifiable dysfunction of one or more organs. There is a fairly long list of causes including kidney, adrenal, cardiac, hormonal and metabolic disease but an exhaustive list is beyond the scope of this article. The disease tends to manifest much earlier in life and to follow a more aggressive course. Treatment is much more difficult and sometimes requires surgical intervention. However, treatable causes may be completely cured by appropriate therapy unlike essential hypertension, which usually requires life-long treatment.

    As previously mentioned, population studies over time have established generally accepted norms for normal blood pressure. However these numbers were adopted somewhat arbitrarily, and it has become quite clear that other co-existing illnesses may necessitate different standards for control. Hypertension is remarkable in the fact that it is essentially a disease without symptoms in the vast majority of cases. The most effective way to diagnose it is by periodically having your blood pressure checked. When symptoms are present they usually reflect severe disease with target organ dysfunction, or in the case of secondary hypertension, may be the result of symptoms referable to the cause of the hypertension. Some symptoms of severe disease include headaches, blurring of vision, shortness of breath, dizziness, palpitations, chest pain and poor exercise tolerance. Symptoms due to secondary causes are variable and are determined by the specific organ involved. Recently, there has been considerable interest in hooking patients up to a portable device that takes the blood pressure at frequent intervals during a period of several hours to many days. This more intense monitoring of blood pressure is presumed to be more effective at identifying patients with abnormal blood pressure because it can document increased pressure in patients whose blood pressure is normal during a portion of the day. Such patients may have their pressure checked at a time when it is normal even though it remains elevated for the greater part of a twenty four-hour period.

    Hypertension has been described as the most important public health problem in the United States of America. In large population screening studies involving predominantly white people, close to 50% of screened people without symptoms had blood pressures greater than 140/90. An astonishing one in five people had pressures greater than 160/95. All told, over sixty million Americans have high blood pressure and more than a third are completely unaware of it! All available data suggests that the numbers are much worse for African Americans, particularly black males. One indication of the magnitude of the problem is the epidemic of kidney failure that is sweeping through black communities in urban America. While diabetes is a major cause of the kidney failure in these communities, the problem is undoubtedly exacerbated by untreated hypertension. African Americans also have disproportionately high levels of sudden death, stroke, and congestive heart failure, all of which are traceable to high blood pressure.

    Hypertension is considered such a silent and deadly killer because the first indication of the disease is often a devastating and irreversible complication. Complications affect virtually all organs and are related to damage to blood vessels supplying these organs caused by prolonged abnormally high pressure. The following represents a non exhaustive summary of specific hypertension related complications;

    This is probably the most devastating complication of hypertension. It frequently occurs completely without warning and may be the result of either a blood clot or a rupture of a blood vessel with bleeding into the substance of the brain. Occasionally there are warning signs such as blurred vision, headache, nausea and vomiting. Unfortunately, even when warning signs occur, patients who have not been conditioned to view these symptoms as indicative of an impending "brain attack" usually ignore them! Strokes frequently result in paralysis with prolonged or irreversible disability, or death.

    Kidney Failure
    Damage to the kidneys' blood vessels leads to progressive decline in the function of these organs, culminating in the inability to effectively filter the body's waste. Chronic renal failure is irreversible and eventually requires that a machine take over the excretory functions of the kidney. Once dialysis is initiated, it leads to other problems, which shorten the life expectancy of the patient.

    Heart Disease
    Hypertension is probably the single most important predisposing factor to heart disease. The range of heart problems caused or exacerbated by high blood pressure includes congestive heart failure, heart attacks, irregular heartbeats, and sudden death.

    Peripheral Vascular Disease
    Damage to blood vessels supplying the arms and legs leads to poor circulation which manifests as severe and prolonged pain in the affected extremities, as well as diminished exercise tolerance. In many cases the extremity is eventually lost to gangrene and the doctor has no choice but to have it amputated. Diabetes, high cholesterol, and smoking worsen these circulatory problems.

    A few common sense life style adjustments can go a long way in mitigating the worst consequences of hypertension;

    A low salt, low saturated fat diet is strongly recommended for patients with high blood pressure. Some researchers believe that abnormalities of salt metabolism underlie essential hypertension. While this has not been found to be universally true, there is clear experimental evidence to support the notion that a sub-set of patients has difficulties with salt metabolism. Keeping the cholesterol and saturated fat levels low is important because high levels of both substances exacerbate the damage that hypertension causes to the walls of blood vessels.

    Obese patients tend to have higher blood pressures than their non-obese peers do. They also have greater difficulty controlling their hypertension with medication. When some patients lose weight their blood pressure becomes better controlled on the same medication regimen they were taking prior to losing weight.

    Regular exercise improves blood pressure control. The exercise regimen does not have to be extremely taxing to have a beneficial impact. Vigorous walking several times a week may be all that is required.

    Stress clearly worsens blood pressure control. A stressful work or home environment may make it difficult to control blood pressure. Stress reduction techniques such as biofeedback may augment medication in the control of blood pressure.

    Alcoholism and Substance Abuse
    Alcohol and illegal substances such as cocaine raise blood pressure and may make it difficult to control blood pressure.

    A variety of medications when taken by susceptible individuals can raise blood pressure and make control difficult. Such medications include oral contraceptives, steroids , decongestants and appetite suppressants.

    Co-existing Medical Conditions
    Obstructive sleep apnea raises blood pressure and is an excellent example of a co-existing medical condition that can either unmask hypertension or make known high blood pressure more difficult to treat.

    In November of 1997, the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure issued its sixth report which recommended that hypertension be staged as follows;

    Stage 1: Systolic Blood Pressure of 140-159 mmHg or Diastolic Blood Pressure of 90-99 mmHg.
    Stage 2: Systolic Blood Pressure of 160-179 mmHg or Diastolic BP of 100-109 mmHg.
    Stage 3: Systolic Blood Pressure of 180 mmHg or greater or Diastolic BP of 110 mmHg or greater.

    The report also recommended placing patients into one of three different risk groups based on a number of life-style and other risk factors for heart disease. The specified risk factors include smoking, elevated cholesterol, diabetes mellitus, age greater than sixty years for either sex, and family history of heart disease in men younger than age fifty five or women younger than age sixty five. The idea is to use a combination of staging and grouping to assess risk and thereby make appropriate treatment decisions for individual patients.

    Risk Group A: No other risk factors for heart disease and no evidence of organ damage from Hypertension.
    Risk Group B: A minimum of one additional risk factor not including diabetes mellitus.
    Risk Group C: Patients with diabetes, target organ damage from hypertension, heart disease, with or without other risk factors for heart disease.

    The practical effect of assessment that combines staging and grouping is to enable earlier and more aggressive treatment of patients with apparently mild elevation of their blood pressures who are never-the-less at great risk for complications due to the nature of their life-style or the presence of co-existing illnesses.

    As previously alluded to, a healthy life-style including a sensible diet, moderate exercise, and the avoidance of alcohol and illegal drugs, is an essential adjunct to medication in the treatment of hypertension. The considerable sums of money that have been invested in research into the treatment of this condition has produced several classes of chemicals that have proven useful in lowering blood pressure. Because of the likely multi-factorial causes of elevated BP, and the presence of genetic influences, some forms of treatment are more effective in particular genetic groups, or for hypertension due to specific causes. A comprehensive discussion of the different classes of anti-hypertensive medications is beyond the scope of this article. However, since the article is directed to African-American populations, it is necessary to comment on classes of pharmaceuticals that are either particularly effective at lowering blood pressure in blacks, or have been found to be relatively less effective when compared to their effect on whites;

    More Effective in Blacks. Studies have shown that blood pressure medications that work by inducing the body to excrete salt and water appear to be disproportionately effective in black patients. While the reason for this is not entirely clear, some researchers believe that it may be due to genetically influenced abnormalities in the body's' handling of salt. It is however very difficult to isolate any one abnormality because cultural factors concerning the intake of salt, as well as other issues likely also contribute to the observed differences. What is clear however, is that some black patients whose blood pressure has been hard to control have achieved significantly better control once a "water pill", known medically as a diuretic, has been added. If you are on blood pressure medications and your control has been poor, you need to ask your doctor whether your regimen includes a diuretic. If you are not on one, he may want to consider adding it provided that there are no contraindications.

    Less Effective in Blacks. The class of medications called Beta Blockers is less effective for BP control in blacks when compared with whites. Once again, the reasons for this observed difference are not clear but there has been speculation, partially supported by research findings, that it is related to differences in the nature of key hormones and chemicals involved in the regulation of blood pressure. Beta blockers have several other beneficial effects on the heart that, in the absence of contraindications, they are frequently prescribed for their other benefits, and a diuretic or other blood pressure lowering medication is added to the regimen to ensure adequate blood pressure control.

    Other Considerations. Although several different classes of anti-hypertensive medications are now available, physicians have to consider many factors before deciding which class of medications to prescribe for a particular individual. Some of these factors include coexisting medical conditions, possible side effects, age, and affordability issues. Thus, it is very important that, as a patient, you discuss with your doctor, all your medical problems, medications, and socio-economic issues that could potentially affect your compliance with the prescribed regimen. Some medications are particularly suitable for patients with particular combinations of health problems. A good example of this would be a patient with diabetes and high blood pressure. There is abundant experimental and clinical evidence of the protective effect on the kidneys, of a class of medications called ACE Inhibitors, in this setting. Unless there are other contra-indications, a drug from this class should be prescribed to all such patients. One must also be mindful of potentially dangerous side effects of some of the medications. For example, Beta Blockers can be dangerous for patients with asthma, circulatory problems affecting the limbs, and diabetes mellitus. The bottom line is that, as a patient, you have a responsibility to stay as informed as possible about your condition. You can do this by asking lots of questions, and taking every opportunity you can find to read up about your condition.


    Thou shall maintain a healthy weight.

    Thou shall not smoke.

    Thou shall limit your alcohol consumption to no more than one to two drinks a day.

    Thou shall be physically active (at least thirty minutes of moderate physical activity 3-4 times a Week.

    Thou shall have your blood pressure checked at least once every six months.

    Thou shall make life style changes to minimize stress.

    Thou shall limit your salt intake to no more than 4-6 grams a day(1-1 ½ teaspoons of table salt Per day).

    Thou shall eat a healthy diet consisting of fruits, vegetables, and limited amounts of saturated fat.

    Thou shall take your medications religiously.

    Thou shall make a commitment to learn as much as possible about your illness.

    From DRveejay11 @ Premier Muscle

  2. #2
    He-man is offline Junior Member
    Join Date
    Oct 2004
    Awsome Read Bro!!!

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