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Physicians wordwide hardly diagnose a disease as frequently as high blood pressure. According to information from the Robert Koch Institute in Germany, almost one in three adults are affected with the silent killer Three out of four 70 to 79 year olds have high blood pressure.
The diagnosis often comes completely unexpected for those affected because high blood pressure usually causes no symptoms. Every fifth patient is unaware of their illness and consequently is not treated, which can have fatal consequences.
Why is blood under pressure at all? What are the causes which increase this pressure? What are the consequences of a permanent increase in blood pressure on the organism? In the following article, we explore the basis of blood pressure.
The human body is composed of about 60 trillion cells. Each of these cells needs oxygen and nutrients in order to perform their functions. The supply of these substances is carried through the blood circulating in the body for this purpose: Arteries carry oxygenated blood to the farthest corners of the body. Veins carry deoxygenated blood back to the heart and then to the lungs where the oxygenation process repeats.
The absorbed nutrients from food are first transported to the liver and then distributed via the blood throughout the body.
The blood also has many more functions and serves as the transport of heat or the immune system.
Thus, the blood must constantly be kept in motion because without oxygen and nutrients the whole system would collapse within a short time.
In order to bring the oxygen-rich blood from the heart into the peripheral organs and limbs, a strong pump is necessary–the heart. This muscle can not be voluntarily contracted by us as can our skeletal muscle tissue. Instead, the heart is autonomously controlled by a natural pacemaker known as the sinus node.
The heart consists of two “halves”: In the right ventricle flows deoxygenated blood from the body from where it is pumped into the lungs where an oxygenated/deoxygenated gas exchange takes place. From there, it flows into the left ventricle and is then pumped back as oxygenated blood into the arteries.
The heart changes rhythmically between contraction and relaxation. With each contraction of the heart, blood is pumped from the left ventricle into the arteries that supply the body and from the right ventricle to the lungs where the gas exchange takes place.
This so-called ejection phase of the heart follows the expansion phase during which the heart muscle relaxes and expands. Oxygen-rich blood flows from the lungs into the left ventricle and deoxygenated blood flows from the body into the right ventricle.
Similar to water pumped through a pipe system, each contraction of the heart pressurizes the arterial vascular system. Too high of a pressure and we initially often do not note a permanent increase, but it can lead to damage of the vascular system.
The currently common method for measuring the blood pressure dates back to the Italian physician Scipione Riva-Rocci. For this reason, we often find the abbreviation “RR” for blood pressure.
In the method according to Riva-Rocci, an artery on the wrist or upper arm is clamped using a tourniquet and the pressure is then reduced slowly. When the pressure of the cuff is equal to the pressure in the arteries the blood can flow again.
It generates pulsating knocking sounds, known as Korotkoff sounds, through the vessel. This pressure corresponds to the maximum pressure during the ejection phase of the heart and is also referred to as systolic pressure.
The Korotkoff sounds can either be listened to with a stethoscope directly to the artery or, as in the case of the vast majority of monitors for self-measurement, at home to automatically evaluate acoustically.
If the pressure of the tourniquet cuff falls to the pressure during the expansion phase of the heart, the Korotkoff sounds disappear again. This lowest reading which acts on the vascular system pressure is referred to as diastolic pressure.
The systolic pressure is thus the one that is triggered by the maximum contraction of the heart.
The diastolic pressure is the “base pressure” in the arteries which is also present during the expansion phase of the heart.
Blood pressure is still expressed in the unit Torr. This standard of measurement would otherwise be rarely used today since the common unit of pressure (such as for air pressure) is now the Pascal. Nevertheless, the Torr remains in use today in the EU and Switzerland to indicate blood pressure.
A Torr is equivalent to the pressure that is generated by a column of mercury one millimeter high. The chemical symbol for mercury in chemistry is Hg, so the abbreviation for the unit is Torr mmHg.
Of course, in the measurement for blood pressure with modern appliances, no mercury is used; the unit of measurement remains the same, however.
The indication of the blood pressure is usually in the form of “120mmHg/80mmHg”, stated as “120 to 80”, wherein the first value is always the systolic and the second value is the diastolic pressure. The systolic value is often colloquially referred to as “upper,” the diastolic as “lower” value.
Below a systolic blood pressure of 100mmHg is called low blood pressure or hypotension. This is generally safe and should only be treated in the case of pregnancy or lapses into unconsciousness.
Systolic values between 100mmHg and 120mmHg are optimal and reduce the risk of cardiovascular disease. Normal values range from 120mmHg-129mmHg/80mmHg-84mmHg. From 139mmHg/89mmHg is high-normal blood pressure and is already a warning sign. Values that are higher than 139mmHg/89mmHg are classified as high blood pressure.
Blood pressure test results are independent of age. Thus, the notion of a systolic value of “100 plus age is normal,” is a fallacy. It is completely wrong!
If test scores are greater than 200mmHg systolic or 120mmHg diastolic, a doctor must be called immediately; it is an emergency!
Table 1 shows both systolic and diastolic readings written in order respectively as pairs.
Systolic [mmHg] Diastolic [mmHg]
The higher of the two values is always used for classification. For example, a blood pressure of 135mmHg/99mmHg, is considered as light high blood pressure, although the systolic value is still in the high normal range.
It may also occur that only the upper value is too high while the diastolic value is in the normal or high normal range. This so-called isolated systolic hypertension occurs mainly in the elderly.
It is important to note that a single test of blood pressure is not sufficient to diagnose high blood pressure as being too high. A single test is only a snapshot. It is subject to many personal and environmental fluctuations.
In the event a routine blood pressure check with the family doctor reveals high scores, at least two more measurements on two different days must be made to negate a random fluctuation. It is best to self assess your blood pressure several times at home to eliminate that the high blood pressure occurs only in the doctor’s office–known as White Coat Syndrome.
Some basic things to consider before each measurement to ensure reliable test results.
A measurement should always be performed only after a rest period of at least five minutes, during which time you become relaxed. If the test is made after a physical activity, such as climbing stairs or walking, the measured values will be skewed too high.
Within 30 minutes prior to measurement you should not drink coffee or smoke because caffeine and nicotine can also distort the test.
A strong urge to urinate drives blood pressure up; before the measurement, you should empty the bladder.
The measurement should always be on the same arm when possible and with the same device. The tourniquet must be on a level with the heart. For the upper arm monitor, the forearm can relax on the tabletop. For a wrist monitor, the hand should rest in your elbow and may include the hand of the opposite shoulder for support. The (tested) wrist must be at heart level.
In order to avoid inaccurate results, any conversation and movement should be avoided.
A second test may take place no sooner than five minutes after the first so that the affected blood vessel can regenerate. An immediate second measurement produces incorrect scores.
For high blood pressure patients, it is important to document the measured values. A blood pressure table (chart or card) is useful for such record keeping. These are obtainable from pharmacies or online from the German Hypertension Society. Some pharmaceutical companies also provide blood pressure charts for self print off their websites.
High blood pressure, also known as hypertension, is derived from the Greek “hyper” meaning high/overly and “tonus” which means tension.
Arterial hypertension denotes an increased pressure in the vessels supplying the body, the arteries. While in the so-called pulmonary hypertension, the vessels of the lungs are affected. Portal hypertension refers to an increased pressure in the large hepatic vein.
Colloquially, one thinks of high blood pressure or hypertension as usually arterial high blood pressure, which can be divided into two major subgroups.
The primary or essential high blood pressure has no identifiable physical cause; it affects about 90% of high blood pressure patients. The causes for the development of primary hypertension are not clear yet. Not one, but many different factors lead to the development of high blood pressure.
As with many other diseases, genetic factors may also play a role in the onset of high blood pressure. A positive family history–that is, closely related family members with high blood pressure–may be an indication of a threat.
In addition to hereditary predisposition, personal lifestyle plays a key role in the pathogenesis of high blood pressure: physical inactivity, an unhealthy diet (obesity), alcohol, smoking, and stress are main risk factors. In the Western world of the 21st century, these risk factors are part of everyday life for many people. Healthy food, balanced lifestyle, and moderate exercise often become secondary concerns in the modern day business/family world.
Why does stress cause high blood pressure? Stress triggers an increased release of the hormone adrenaline which makes our body ready for fight or flight: The heartbeat speeds up. Blood pressure increases. We are tense and ready for physical activity.
For our ancestors, this mechanism was essential for survival in the hunt or in the face of a saber-toothed tiger. The physical exertion during fight or flight dismantled the adrenaline within a short time period making it “well spent.”
Today, however, stress occurs particularly at work. The adrenaline builds up in the body rather than degrading rapidly. Blood pressure can be raised only so long until it becomes problematic.
The rarer secondary high blood pressure, in contrast to primary high blood pressure, results from another organic disease. Most commonly, it is caused by kidney disease resulting from diabetes mellitus: A reduced salt excretion in renal insufficiency automatically leads to less water excretion; more water in the vascular system increases the local pressure.
Other causes of secondary high blood pressure, for example, may be a hormonal disorder as occurs in Cushing’s disease or a congenital malformation of the aorta.
High blood pressure is known in English as the “silent killer” because it often carries no symptoms for years leaving the affected none the wiser. In rare cases, symptoms may occur such as occasional headaches, dizziness, and insomnia; all are, however, very non-specific and are usually dismissed as a temporary malaise.
The long-term consequences of permanently raised blood pressure are severe: As with a pipe system in which the water pressure is permanently too high, damage can also occur in the vascular system by the high blood pressure.
Hypertension is a risk factor for atherosclerosis which is colloquially referred to as hardening of the arteries. This process has nothing to do with lime but is a lesion of the vessel wall: In particular, other factors such as high cholesterol or nicotine may create retention and thickening of the vessel wall leading to the formation of so-called plaques.
These focal changes may be unstable over time and tear. A blood clot formed in the vessel can lead to closure of pulmonary, cardiac, or cerebral vessels resulting in pulmonary embolism, heart attack, or stroke.
Furthermore, the permanently increased blood pressure also leads to direct damage to organs such as the kidney or the heart where the small blood vessels are unable to cope with increased pressure in the long run.
Therefore, the diagnosis of high blood pressure should not be taken lightly even if the disease does not cause acute symptoms. In such cases, a change in lifestyle and taking medications are essential to prevent long-term damage.
High blood pressure or hypertension is the pathological increase in the pressure prevailing in the arteries. Readings above 139mmHg/90mmHg are deemed as high blood pressure. Because of its harmful effect on the vascular system with an associated increased risk of cardiovascular disease, treatment is necessary regardless of any lack of symptoms.
The most common primary hypertension is triggered by many different factors. In addition to genetic predisposition, diet, physical activity, and stress play important roles. The affected can frequently reduce their blood pressure with significant results by a change in lifestyle. A consultation with a physician accompanied with an appropriate prescription, if needed, can lessen or even leave high blood pressure completely eliminated.