DEFINITION OF HYPERTENSION:

*Hypertension or (high blood pressure),sometimes called "arterial hypertension", is a chronic medical condition in which the blood pressure in the arteries is elevated to an extent that clinical benefit is obtained from blood pressure lowering.

*Blood pressure is summarised by two measurements, systolic and diastolic, which depend on whether the heart muscle is contracting (systole) or relaxed between beats (diastole) and equate to a maximum and minimum pressure, respectively. Normal blood pressure at rest is within the range of 100-140mmHg systolic (top reading) and 60-90mmHg diastolic (bottom reading). High blood pressure is said to be present if it is persistently at or above 140/90 mmHg.

CARDIOVASCULAR COMPLICATION ASSOCIATED WITH HYPERTENSION: The most common and important of these are: Myocardial infarction Stroke Cerebral/brain stem infarction Cerebral haemmorhage Lacunar syndromes Multi-infarct disease Hypertensive encephalopathy/malignant hypertension Dissecting aortic aneurysm Hypertensive nephrosclerosis Peripheral vascular disease

The risk of heart failure is increased six-fold in hypertensive subjects. Meta-analysis of clinical trials has indicated that these risk are reversible with relatively modest reductions in blood pressure of 10/6mmHg associated with a 38% reduction in stroke and 16% reduction in coronary events, while a 5mmHg reduction in blood pressure is associated with a 25% reduction in risk of renal failure.

EPIDEMIOLOGY OF HYPERTENSION:

* Essential hypertension (primary hypertension)* Secondary hypertension

Essential hypertension (also called primary hypertension or idiopathic hypertension) is the form of hypertension that by definition has no identifiable cause. It is the most common type of hypertension, affecting 95% of hypertensive patients,it tends to be familial and is likely to be the consequence of an interaction between environmental and genetic factors.Genetic factors clearly play a part as the condition clusters in families, with hypertension being twice as common in subjects who have a hypertensive parent.

Prevalence of essential hypertension increases with age, and individuals with relatively high blood pressure at younger ages are at increased risk for the subsequent development of hypertension. Hypertension can increase the risk of cerebral, cardiac, and renal events.Secondary hypertension (secondary high blood pressure) is high blood pressure that's caused by another medical condition. Secondary hypertension differs from the usual type of high blood pressure (essential hypertension), which is often referred to simply as high blood pressure. Secondary hypertension can be caused by conditions that affect:

Kidneys (renal disease) Heart Endocrine system steroid excess:hyperaldosteronism(Conn's syndrome) hyperglucocorticoidism(cushing's syndrome) growth hormone excess:acromegaly catecholamine excess:phaeochromocytoma

Secondary hypertension can also occur during pregnancy:pre-eclampsia Vascular causes Renal artery stenosis:fibromuscular hyperplasia;renal artery atheroma;coarction of the aorta

Drugs Sympathomimetic amines Oestrogens (e.g. combined oral contraceptives pills) Cyclosporin Erythropoietin NSAIDs Steroids

Proper treatment of secondary hypertension can often control both the underlying condition and the high blood pressure, which reduces the risk of serious complications including heart disease, kidney failure and stroke.

Hypertension is more common in black people of African Caribbean origin, who are also at particular risk of stroke andrenal failure. Hypertension is exacerbated by other factors, for example high salt or alcohol intake, poor diet, lack of exercise and obesity.

REGUALTION OF BLOOD PRESSURE:The endogenous regulation of arterial pressure is not completely understood, but the following mechanisms of regulating arterial pressure have been well-characterized: Baroreceptor reflex: Baroreceptors in the high pressure receptor zones detect changes in arterial pressure. These baroreceptors send signals ultimately to the medulla of the brain stem, specifically to the Rostral ventrolateral medulla (RVLM). The medulla, by way of the autonomic nervous system, adjusts the mean arterial pressure by altering both the force and speed of the heart's contractions, as well as the total peripheral resistance. The most important arterial baroreceptors are located in the left and right carotid sinuses and in the aortic arch.[31] Renin-angiotensin system (RAS): This system is generally known for its long-term adjustment of arterial pressure. This system allows the kidney to compensate for loss in blood volume or drops in arterial pressure by activating an endogenous vasoconstrictor known as angiotensin II. Aldosterone release: This steroid hormone is released from the adrenal cortex in response to angiotensin II or high serum potassium levels. Aldosterone stimulates sodium retention and potassium excretion by the kidneys. Since sodium is the main ion that determines the amount of fluid in the blood vessels by osmosis, aldosterone will increase fluid retention, and indirectly, arterial pressure. Baroreceptors in low pressure receptor zones (mainly in the venae cavae and the pulmonary veins, and in the atria) result in feedback by regulating the secretion of antidiuretic hormone (ADH/Vasopressin), renin and aldosterone. The resultant increase in blood volume results an increased cardiac output by the FrankStarling law of the heart, in turn increasing arterial blood pressure.These different mechanisms are not necessarily independent of each other, as indicated by the link between the RAS and aldosterone release. Currently, the RAS is targeted pharmacologically by ACE inhibitors and angiotensin II receptor antagonists. The aldosterone system is directly targeted by spironolactone, an aldosterone antagonist. The fluid retention may be targeted by diuretics; the antihypertensive effect of diuretics is due to its effect on blood volume. Generally, the baroreceptor reflex is not targeted in hypertension because if blocked, individuals may suffer from orthostatic hypotension and fainting.CLINICAL PRESENTATION OF HYPERTENSION

Hypertension is often an incidental finding when subjects present for screening or with unrelated conditions. Severe cases may present with headache, usual disturbances or evidence of target organ damage (stroke, ischemic heart disease or renal failure).

Malignant HypertensionMalignant hypertension is extremely high blood pressure that develops suddenly and rapidly and causes some type of organ damage. "Normal" blood pressure is below 120/80. A person with malignant hypertension has a blood pressure that's typically above 180/120. It's considered a hypertensive emergency and should be treated as a medical emergency.Causes Malignant HypertensionIn many people, high blood pressure is the main cause of malignant hypertension. Missing doses of blood pressure medications can also cause it. In addition, there are certain medical conditions that can cause it. They include: Collagen vascular disease, such as scleroderma Kidney disease Spinal cord injuries Tumor of the adrenal gland Use of certain medications, including birth control pills and MAOIs Use of illegal drugs, such as cocaineYou are at high risk for malignant hypertension if you have had: Kidney failure Renal hypertension caused by renal artery stenosisSymptoms of Malignant HypertensionThe main symptoms of malignant hypertension are a rapidly increasing blood pressure of 180/120 or higher and signs of organ damage. Usually the damage happens to the kidneys or the eyes.Other symptoms depend on how the rise in blood pressure affects your organs. A common symptom is bleeding and swelling in the tiny blood vessels in the retina. The retina is the layer of nerves that line the back of the eye. It senses light and sends signals to the brain through the optic nerve, which can also be affected by malignant hypertension. When the eye is involved, malignant hypertension can cause changes in vision.Other symptoms of malignant hypertension include: Blurred vision Chest pain (angina) Difficulty breathing Dizziness Numbness in the arms, legs, and face Severe headache Shortness of breathIn rare cases, malignant hypertension can cause brain swelling, which leads to a dangerous condition called hypertensive encephalopathy. Symptoms include: Blindness Changes in mental status Coma Confusion Drowsiness Headache that continues to get worse Nausea and vomiting SeizuresHigh blood pressure, in general, makes it difficult for kidneys to filter wastes and toxins from the blood. It is a leading cause of kidney failure. Malignant hypertension can cause your kidneys to suddenly stop working properly. If this happens, the condition is called malignant nephrosclerosis.Exams and TestsMalignant hypertension is a medical emergency.A physical exam commonly shows: Extremely high blood pressure Swelling in the lower legs and feet Abnormal heart sounds and fluid in the lungs Changes in thinking, sensation, muscle ability, and reflexesAn eye examination will reveal changes that indicate high blood pressure, including: Bleeding of the retina Narrowing of the blood vessels in the eye area Swelling of the optic nerve Other problems with the retinaKidney failure, as well as other complications, may develop.Tests to determine damage to the kidneys may include: Arterial blood gas analysis BUN Creatinine UrinalysisA chest x-ray may show congestion in the lung and an enlarged heart.This disease may also affect the results of the following tests: Aldosterone level Cardiac enzymes (markers of heart damage) CT scan of the brain Electrocardiogram (EKG) Renin level Urinary sedimentDiagnosis of HypertensionYou can get your blood pressure measured by a health care provider, at a pharmacy, or you can purchase a blood pressure monitor for your home.Blood pressure is most often measured with a device known as a sphygmomanometer, which consists of a stethoscope, arm cuff, dial, pump, and valve.Blood pressure is measured in two ways: systolic and diastolic. Systolic blood pressure is the maximum pressure during a heartbeat. Diastolic blood pressure is the lowest pressure between heartbeats.Blood pressure is measured in millimeters of mercury (mm Hg) and is written systolic over diastolic (for example, 120/80 mm Hg, or "120 over 80"). According to the most recent guidelines, a normal blood pressure is less than 120/80 mm Hg. Hypertension is blood pressure that is greater than 140/90, while prehypertension consists of blood pressure that is 120 to 139/80 to 89.Blood pressure may increase or decrease, depending on your age, heart condition, emotions, activity, and the medications you take. One high reading does not mean you have high blood pressure. It is necessary to measure your blood pressure at different times, while you are resting comfortably for at least five minutes. To make the diagnosis of hypertension, at least three readings that are elevated are usually required.In addition to measuring your blood pressure, your doctor will ask about your medical history (whether you've had heart problems before), assess your risk factors (whether you smoke, have high cholesterol, diabetes, etc.), and talk about your family history (whether any members of your family have had high blood pressure or heart disease).HOME OR AMBULATORY BLOOD PRESSURE MEASUREMENTS

Ambulatory blood pressure measurement (ABPM) measures blood pressure at regular intervals. It is believed to be able to reduce the white coat hypertension effect in which a patient's blood pressure is elevated during the examination process due to nervousness and anxiety caused by being in a clinical setting. Out-of-office measurements are highly recommended as an adjunct to office measurements by almost all hypertension organizations.The ambulatory blood pressure monitor consists of a cuff which wraps round your arm. The cuff is attached to a small electric recording device on a belt or strap worn on your body. The doctor or nurse who supply the device should make sure the cuff is the right size for your arm. You should keep the device safe and dry and not have a bath or shower whilst wearing it. From time to time you will feel a tightening sensation in your arm whilst the cuff is inflating but this will not last very long and most people will not be worried by it. Try not to move your arm whilst the cuff is inflating. If the device cannot record your blood pressure it will try to repeat the process up to three times. The machine is usually set to record twice an hour whilst you are awake and hourly at night.

The ambulatory monitor can be worn whilst going about your everyday activities. So, it will give an accurate impression about how your blood pressure behaves under normal circumstances. The doctor will look at at least 14 readings spread throughout the day to decide whether or not you have hypertension.Home blood pressureThis is an alternative to ambulatory blood pressure measurement. The process for doing this will be exactly the same as that used by the doctor or nurse in the surgery. You will be given a blood pressure monitor to use at home. Wrap the cuff around your arm just above the level of the elbow. (Check the instructions with the monitor to make sure the tubing is in the right position.) You should be seated comfortably with your arm supported (for example, on a table) at the level of your heart. Press the button to inflate the machine and make a note of the reading.

You should measure your blood pressure twice a day, once in the morning and once in the evening. On each occasion you should take two readings, one minute apart. You should take readings for at least four days, and ideally for seven days. The doctor should use all the readings, apart from those taken on the first day, to calculate your average blood pressure.assesment of the hypertensive patient

secondary causeAlthough in the majority of patients hypertension is primary/essential, there are certain features that may lead to a suspicion of an underlying cause (secondary hypertension): Young patient (