High Blood Pressure (Hypertension)

Blood is pumped by the heart into the arteries with some pressure. This is known as blood pressure. Blood pressure is defined as the amount of force exerted by the blood on the artery walls. High Blood Pressure or Hypertension is the medical term used to describe elevated blood pressure. It commonly affects around 1 in 7 adults and is a leading risk factor heart attack and stroke.

Blood Pressure is expressed in two numbers. The higher number is known as Systolic Pressure, or the amount of force (as measured in millimetres of mercury) that is exerted against the artery walls during a heartbeat (contraction). The lower number in the Diastolic pressure, which does the force exist while the heart is resting between beats.

What is the Normal Blood Pressure?

A normal adult’s (age 18 or older) blood pressure is as follows:

• Systolic: Less than 130mm of mercury (mm hg).
• Diastolic : less than 85 mm hg.

Blood pressure levels at or above 140mm hg systolic and 90 mm hg diastolic are considered high blood pressure.People with borderline  or ‘high-normal,’ blood pressure (systolic of developing  high blood pressure and they also have higher risk for heart disease than those with optimal (less than 120/80mm hg) blood pressure. When the exact cause of blood pressure is not known, it is known as essential hypertension  and when the exact cause of blood pressure is known it is known as secondary hypertension.

Why high blood pressure is called a silent killer?

Hypertension is called a ‘silent killer’ because it does not cause symptoms unless it is severely high. It’s a silent killer because even extremely fit an apparently healthy person can sometimes have dangerously high blood pressure. Since, the person is not aware of its existence; he / she does not take any treatment. Left untreated, sustained high blood pressure can damage arteries, heart, kidneys, eyes, brain and can cause atherosclerosis.

What are Symptoms of high blood pressure?

Usually there are no warning signs or symptoms of high blood pressure and the person is not aware about it, until blood pressure is checked.  Occasionally, headache can occur, particularly when the systolic blood pressure is elevated beyond 200mm hg, or when blood pressure is rising rapidly. In most cases, hypertension is diagnosed on routine  blood  pressure  examination, or when   a major  complication arises. However, in severe high blood pressure, headaches, visual  disturbances, nausea, and vomiting  may occur.  Malignant high blood pressure, which is rapid rise of blood pressure to very high levels, can also cause the above mentioned symptoms.

If the person does not receive treatment for high blood pressure, damage may occur to the heart, kidney, eyes, or brain and can produce problems such as:

• Coronary artery disease ; heart attack, or heart failure.
• Kidney (renal) failure.
• Peripheral vascular disease (reduced blood supply to the extremities).
• Problems in the eye (retinopathy).
• Paralysis due to stroke due to reduced blood supply.

How Blood Pressure is measured?

A blood pressure monitor is also known as a sphygmomanometer. A blood pressure measurement  is taken by temporarily stopping the flow of blood in an artery (usually by inflating a cuff around the upper arm) and then  listening  for the sound  of the blood beginning to flow through  the artery again as air is released from the cuff. As blood flows back into the artery, it can be heard through a stethoscope placed on the skin over the artery inside the elbow. Blood pressure is recorded as two measurements.

• The reading when the sound of blood flow is first heard is called the systolic pressure. Systolic pressure represents the peak blood pressure that occurs when the heart contracts.
• The reading  when the sound of blood flow can no longer be heard is the diastolic  pressure. Diastolic pressure  represents  the lowest is the diastolic  pressure. Diastolic  pressure represents the lowest blood pressure that occurs when the heart relaxes  between  beats.

These two pressures are expressed in millimeters of mercury (mm hg) because the original  devices that measured blood pressure used a column of mercury.

How frequently blood pressure should be checked up?

• Healthy  adults with normal blood pressure  (less than 130mm hg systolic and less than 85mm hg diastolic) should have their blood pressure checked  at least once every 1 to 2 years. This can be done during any routine  medical  checkup.
• Adults with borderline  high (high-normal) readings (130mm hg systolic and less than  85-89mm hg diastolic) should have their blood pressure checked as often as recommended  by their doctor, or at least annually. This can be done during any routine medical checkup.
• Adults with other risk factors for heart or blood or blood vessel disease or evidence of disease caused by high blood pressure need to have their blood pressure every four months.

What are major causes of high blood pressure?

There may not be obvious reasons why the blood pressure is so high. When there is no single clear-cut cause of high blood pressure it is called essential hypertension. However, there are certain factors, which if present  in a patient, contribute to the development of high blood pressure. These are known as risk factors. Some of the common risk factors for the development of essential hypertension are as follows:

• Sedentary lifestyle – Exercise helps maintain normal blood pressure, but few people get the amount of exercised  they require to stay healthy.
• Smoking – Smoking doubles the risk of high blood pressure, ischaemic  heart disease and trebles the chances of dying by the age of 60 years.
• Obesity: Obesity  increases blood pressure.
• Diet: Fats, cholesterol-rich foods and salt  can all raise blood pressure.
• Birth control: Many women have increased blood pressure when they take birth  control pills. Occasionally it is necessary to stop or change these pills because they may cause dangerously high blood pressure.
• Alcohol: Alcohol can increase blood pressure, and also damage the liver  and heart.
• Stress : Although  stress is clearly related to elevated blood pressure, pinning down the cause of the stress may be difficult.
• Family history of high blood pressure: Chances of developing high blood pressure  in the offspring increase, if either of the high parents  has high blood pressure but if both the parents have high blood pressure than the chances of developing  high blood  pressure are as high as 75 percent.
• Ageing: Blood pressure increases with age due to hardening of the arteries.
• Increased sodium (salt) intake. Persons who consume more than normal amounts of salt are more prone to develop high blood pressure.
• Depression
• High cholesterol: (total cholesterol over 200mg/dl (mg/dl); high-density lipoprotein (HDL), or good, cholesterol less than 40mg/dl).
• Diabetes
• Low intake of potassium, magnesium, and calcium.

Is development of high blood pressure hereditary?

Genetics seem to be one of the causes of high blood pressure. Presence of high pressure in either a single or both the parents makes one more prone to development of hypertension. The genetic factors are likely to act by making the individuals more susceptible to environmental influences, such as stress, faulty diet, lack of exercise, and so on.

What are the common lab tests for investigation in patients with high blood pressure?

Blood tests and urine tests are done to determine if there is any cause for high blood pressure and to find out whether there has been any damage to organs and to check for complications. Common lab tests include measurements of:

• Potassium
• Sodium (a component of common salt)
• Blood sugar
• Blood uera
• Serum creatinine
• Lipid profile
• Cholesterol
• HDL cholesterol
• LDL cholesterol
• Triglycerdies
• Electrocardiography (ECG)

An ECG is recommended for all patients with hypertension  to screen for any increase in muscle mass of the heart (left ventricular hypertrophy). A routine ECG also identifies coexist reduced blood supply to the heart (myocardial ischaemia).

• Echocardiography: Echocardiography is done to determine  whether high blood pressure has started to damage the heart.

In most people who have high blood pressure without any complications, routine lab test results  will be normal. Sometimes, findings suggest  the presence of kidney disease, diabetes, or a hormonal disorder. If secondary high blood pressure is suspected, then additional tests may be done to determine the cause. Both systolic  or diastolic  blood pressure are important : When assessing risk is important to take both values into consideration. In particular, marked elevation of either systolic or diastolic pressure should not be ignored, even if the other parameter values have different importance. Diastolic  blood pressure is the best predictor of coronary heart risk in these under the age of 50 years. Both systolic and diastolic pressures are equally predictive in the 50-60 age range.After 60 years of age systolic and pulse pressure ( difference  between systolic and diastolic pressure) become dominant. Therefore after the age of 50 years. Lower than diastolic pressure the higher the risk of coronary heart disease.

Optical control of high blood pressure by lipid Profile:

Optimal control of blood pressure requires good control of blood pressures as well as good control over lipid profile as is depicted in the following table :

Treatment of Hypertension

• In about 10 percent cases, a specific cause can be ascertained and these cases can be treated by correcting  the underlying cause. In the remaining 90 percent, the hypertension  cannot be cured, but it can be controlled by slat restriction,  lifestyle  changes and drugs. High blood pressure treatment, whether it involves lifestyle changes or medication is usually  a lifelong process.

The need for treatment is decided by the level of blood pressure and by other  factors which may also affect the risk  of damage to blood vessels, e.g. diabetes or continued  smoking. In some people, lifestyle changes  alone may be enough  to control hypertation. Therefore  the treatment  can vary from person  to person.

Whether  medications fro borderline high pressure are required or not depends  on whether  other risk  factors for heart disease  or storke are present  and whether  other organs in the body have already been affected by high blood  pressure. If there are no additional  risk factors for heart disease or stroke  and there are no additional risk factors for heart disease  or stroke  and there does not appear to be any organ  damage, lifestyle modification may be enough  to control the hypertension.

If blood pressure readings are quite high, medications are usually required in addition to lifestyle changes.

Common Drugs used in Hypertension:

In the past few decades , a large number of anti-hypertensive  drugs have been developed  which  have revolutionized  the treatment of hypertension. These drugs can be classified into the following  categories :

• Diuretics : These drugs lower blood pressure by increasing  the excretion of sodium and water through the kidneys. The most commonly  used diuretics in treating hypertension  are the thiazides.
• Beta blocking  drugs: These drugs reduce the constriction of blood vessles  and reduce the heart rate. They may be prescribed  alone or in combination  with other drugs.
• Vasodilators: These drugs relax the muscles in the blood  vessels  walls,  causing  them  to dilate, or widen.  Vasodilators  are usually prescribed along with  a diuretic  or beta blocking drugs.
• Centrally acting  drugs : These agents decrease  the heart  rate and lower the amount of blood with each  beat. They are usually taken with  a thiazide diuretic.
• Angiotensin converting enzyme (ACE) Inhibitors: These drugs  block  the formation   of angiotensin, a naturally occurring  substance that constricts blood vessels. They also decrease the body’s ability to retain salt and water. ACE inhibitors are also used to treat congestive  heart failure.
• Calcium  channel-blocking  agents: Small amounts of calcium are needed  by arterial  smooth muscles and other muscles to constrict. By blocking  the entry of calcium ions into  the vessel walls, the constriction of the blood  vessels is decreased  and blood pressure fall. A number of calcium channel-blocking drugs are being  used  to treat both high  blood pressure and angina.

Drugs prescribed for hypertension should be taken  exactly as instructed, and usually life long. Although  they will lower blood pressure,  they do not cure the disease; once stopped, the blood pressure will go up again, sometimes even higher than before. Side effects or adverse reactions are common and include  dizziness when  standing (orthostatic hypotension), fatigue, depression,  and impotence, among others, should be reported to the treating   physician.

What is the Salt Connection of Hypertension?

Salt in small amounts is necessary  for the body  but too much can be harmful. It increases the amount of fluid retained in the body and thus has a direct effect on the blood pressure. The human body needs less than 5 grams  of salt per day. An average person consumes anywhere between 10 and 15 grams of salt per day. The total daily consumption  of sodium should be no more than 2 grams of sodium  (=5 grams of salt) per day. We get most of our sodium through sodium  chloride, i.e. table salt.

Dietary salt restriction results in a fall n blood pressure and reduces swelling  and breathlessness in heart failure patients. Some patients are particularly sensitive  to the effects of sodium on blood pressure. Salt reduction is important for control of blood pressure and heart failure.

What is Potassium connection of Hypertension?

Potassium supplementation  is not effective in reducing blood pressure and is not recommended for treatment of high blood  pressure. However, no adverse effects of additional potassium intake have been identified, and it may provide a safe substitute for dietary sodium salt.