Hypertension

What is Hypertension?

Hypertension can be defined as persistent increase of blood pressure in which the systolic pressure is above 140 mmHg and the diastolic pressure is above 90 mmHg.In the elderly population hypertension is defined as systolic pressure above 160 mmHg and diastolic pressure 90 mmHg. It is often called the silent killers because it is usually asymptomatic. Two factors determine blood pressure:

• Change in cardiac output
• Change in Peripheral resistance or both. (A handbook of managing hypertension, Ministry of Health, Ghana 2000) and (Brunner and Sardath, 10th edition, 1994).

INCIDENCE

About 20% of adults develop hypertension than 90% of those who have essential (primary) hypertension which has no identifiable medical cause. The remainders develop elevation in blood pressure with specific cause. Secondary hypertension, such as endovascular narrowing or parenchyma renal disease, certain drugs, organ dysfunctions, tumors and pregnancies. It affects more women than men. In Africa, prevalence of hypertension is higher in urban areas than in rural areas, it tends to affect women over 55years of age. It is also common in the second trimester of pregnancy. Recent studies have revealed that this condition is increasing among teenagers (Brunner and Suddath’s).

Table: 1 Classification of blood pressure

BP Classification	Systolic Blood pressure (mmHg)	Diastolic blood pressure (mmHg)
Normal	<120>	<80>
Prehypertension	120-139	80-89
Stage 1 hypertension	140-159	90-99
Stage 2 hypertension	≥160	≥100

TYPES OF HYPERTENSION

There are three major types of hypertension, these are:

1. Primary Hypertension
2. Secondary Hypertension
3. Malignant Hypertension

Primary hypertension

The primary hypertension is also called essential or idiopathic hypertension. The term is used interchangeably. It normally begins as a benign disease and slowly progresses to an accelerated or malignant state. It is the most common type of hypertension and accounts for 90 - 95% of all cases of hypertension. Although the exact cause of this type of hypertension is unknown, there are predisposing factors. These are:

1. Diet: A diet high in sodium (Na+) and saturated fat increases the risk of developing hypertension. A high intake of sodium such salt increases blood pressure. Also, intake of high levels of saturated fatty diet narrows the lumen of the blood vessels due to the formation of atheroma in the vessels which results in increased blood pressure.
2. Alcohol: Excessive intake of alcohol increases both cardiac output and sympathetic activity which eventually increases the blood pressure and the peripheral resistance.
3. Smoking of Tobacco/Cigarette: Nicotine in tobacco or cigarette have a vasoconstrictive properties and this does cause acute elevations of blood pressure hence, hypertension.
4. Obesity: Weight above desirable levels places extra burden on the heart as it (produces an increase in the number of smooth muscle cells and a collection of lipids within the intima of medium and large –seized arteries) eventually narrows the lumen thereby resulting in reduced blood flow at the distal end of the artery while pressure is an increased at the proximal end. This process leads to increased blood pressure.
5. Sedimentary lifestyle: Physical inactivity decreases high density lipoproteins, the collateral circulation and vessel size and increases total cholesterol level, glucose intolerance and body weight. This increases the risk of developing hypertension.
6. Aging: High blood pressure rises progressively with increasing age .This is because, the number of collagen fibers in the artery and arterioles walls increases overtime making blood vessels stiffer. With the reduced elasticity comes across - sectional area in systolic and so a raised mean blood pressure.
7. Family History: Studies have shown that hypertension is familial thus; persons who are related to hypertensive patients are at risk of developing hypertension.
8. Race: High blood pressure occurs two to three times more in blacks than in whites, especially at diastolic levels above 100 mmhg. Stress.For instances ,emotional stress triggers the release of fatty acids, glucose and clots promoters into the blood stream ,when they tend to such in those rips and stick ,helping to form a plaque .This plaque causes vessels obstruction and structural alteration leading to increased blood pressure. Also, there is vascular response to sympathetic activation during stress and it is typically associated with cardiac output which causes an elevation in blood pressure.
9. Sex: In young adults, hypertension is common among men than women but from age fifty five years and above it is more common in women.

Secondary Hypertension

It represent 5-10% of hypertensive cases. Here, elevated blood pressure occurs due to an identifiable or specific causes e.g:

1. Renal Disorders stimulates activation of rennin angiotensin aldosterone system resulting in increased rennin. Subsequently; retention of sodium and water, along with vasoconstriction results.in elevated blood pressure.
2. Cardiovascular Disorders.For instance, coarctation of the aorta leads to increase pressure in the blood vessels and may result in hypertension. This usually occurs when the posterior wall of the aorta is thickened
3. Endocrine Disorders. Elevated level of adrenal cortical hormones can result in blood pressure. glucocorticoid result in high blood pressure. Both  glucocorticoid (cortisol) and these mineralocorticoid(aldosterone) promote sodium and water retention by the kidney resulting in elevated blood pressure. Examples of conditions that produce excess of these hormones are primary aldosterone and cushion syndrome. In addition, hypertension in pregnancy is mainly due to hormonal disturbance during pregnancy.
4. Neurologic Disorders. Neurologic disorders such as brain tumors and head injuries put pressure on the posterior hypothalamus, medulla or nerve pathways leading to excess catecholamine production. Increasing levels of catecholamines cause an increase in cardiac output which may result in elevated blood pressure.
5. Pregnancy In pregnancy there may also be pregnancy induced hypertension. This usually occurs when there is abnormal placentation leading to poor placental perfusion. This triggers a response in the circulatory system leading to vasospasm and subsequently hypertension.
6. Medication.Medication such as nervous stimulant oral, contraceptive, steroids pills and synthetics in high blood pressure as part of their side effect.

Malignant Hypertension 

It is a severe form of hypertension which usually occurs as a result of poorly controlled blood pressure. Malignant hypertension is defined as severe hypertension that occurs along with internal bleeding of the retina in both eyes and swelling of optic nerves behind the retinas. It is about four times more common in blacks than whites and occurring more in men than in women. It is especially common in people under 40 years and those of a lower socio-economic class. Malignant hypertension is a medical emergency and if left untreated can lead to serious organ damage or can become rapidly fatal, sometimes even death in three to six months.

CAUSES OF MALIGNANT HYPERTENSION

Like high blood pressure in general, the exact cause of malignant hypertension is not completely understood. The details of how malignant hypertension starts have been an essential research topic for many years, and whiles the complete picture is emerging, we do know some few important things. 

1. Younger patients are at higher risk than older patients, which is the opposite of the risk profile for essential hypertension.
2. Those of African heritage are at higher risk.
3. Anyone with a history of kidney failure or a disease called renal artery stenosis [narrowing of arteries in the kidney] has a greatly increased risk
4. Pregnant women with gestational hypertension or women experiencing certain pregnancy related complications (toxemia of pregnancy) appear to have an increased risk.

In conclusion, malignant hypertension and the serious nature of the disease, however, make it an important problem.

PATHOPHYSIOLOGY

Hypertension is a multifactorial condition. The regulation of blood pressure is by a complex set of interrelated mechanism that comprises of the control of vascular tone and sodium and water balance. The overall control of blood pressure is based on the sympathetic nervous system and the renal rennin-angiotensin system with cardiac output and peripheral vascular resistance serving as the primary regulatory factor which may lead an increase in blood pressure. When there is a decreased blood supply to the kidney such as renal artery stenosis or condition that alters renal function or failure of any kind, there is resultant retention of sodium and water through the production of aldosterone by the kidneys. Also the kidneys release renin which stimulate angiotensinogen (it is impotent or inactive in the liver) to angiotensin I. Angiotensin I is in turn converted to angiotensin II (a potent vasoconstriction agent) by Angiotensin converting Enzyme (ACE). Angiotensin II constrict several arterioles thus increasing peripheral resistance leading to hypertension. Conditions like pheochromocytoma (a tumour of the adrenal medulla). When adrenalin is secreted by the tumour cells or other conditions that increase intracranial pressure there is pressure on the hypothalamus, medulla and nerve pathways resulting in the production of excess catecholamine all leads to increase blood pressure. Catecholamine enhances vasoconstriction and increase cardiac output leading to a corresponding increase in arterial blood pressure hence hypertension.Hypertension occurs without any symptoms, yet can be profoundly damaging to the blood vessels of major organ systems including the brain, heart and kidneys.In early phases, few pathologic changes can be found in the structure of the blood vessels. Over time, however chronically elevated blood pressure causes widespread pathologic changes that interfere with effective blood flow especially to the vital organs. Most important shearing forces from the elevated blood pressure cause by the excess production of catecholamine damage the intimal layer of the blood vessels, leading to increase fibrin accumulation and vessels edema. Both the large and small arteries in the body may become atherosclerotic, tortuous and weak. These changes also narrow the lumen of the blood vessels thereby decreasing blood flow to the organ or tissue supplied. As the damage progresses, the vessel can become occluded or even rupture, causing an abrupt cessation of blood flow to the area. Finally, the pathophysiologic changes decrease local auto-regulatory control of blood flow, as the vessel are less able to control and dilate in response to tissue needs. These greatly increases the risk for coronary artery disease, cerebrovascular disease, renal artery , parenchymal disease and peripheral vascular disease.

CLINICAL MANIFESTATION

Hypertension is usually referred to as the “silent killer” because it is frequently asymptomatic and usually detected on a routine physical examination of blood pressure. The signs and symptoms present as;

• Visual disturbances
• Epistaxis 
• Dizziness
• Palpitation
• Fatigue
• Body weakness
• Memory loss
• Chest pain
• Dyspnea
• Peripheral oedema
• Seizures
• Restlessness
• Weak peripheral pulse
• Vomiting
• Coma
• Hematuria
• Elevation of blood pressure of 140/90 mmHg or more.
• Headache 

COMPLICATIONS

If hypertension is not identified early for prompt and effective treatment, it results in complications. These complications usually relates to the various organs and structures which are dependent to the heart. The organs commonly affected are;Heart, Brain, Kidneys, Eyes. This complication includes;

1. Left heart failure.
2. Left ventricular hypertrophy.
3. Renal failure.
4. Myocardial infarction.
5. Cerebro-vascular accident.
6. Nocturia.
7. Cerebral oedema
8. Arrhythmias.
9. Hypertensive retinopathy.
10. Hypertensive encephalopathy.
11. Impotence in men.
12. Sudden death.

DIAGNOSTIC INVESTIGATIONS

1. Urinalysis to detect protein, red blood cells and white blood cells suggesting renal disease.
2. Blood chemistry (i.e. analysis of sodium, potassium, fasting glucose and total and high-density lipoprotein) may be high indicating renal dysfunction.
3. Electrocardiography (ECG) which may reveal left ventricular hypertrophy and also the electrical activity of the heart.
4. Chest x-ray, this demonstrates cardiomegaly. It may also reveal aortic aneurysm.
5. Excretory urography may reveal renal atrophy indicating chronic renal disease.
6. Monitoring of blood urea nitrogen (BUN and creatinine levels, whether normal or elevated above 1.5mg/dl which suggest renal disease.
7. Urinary catecholamine levels are used to diagnose pheochromocytoma.

DIAGNOSTIC MEASURES

1. Presenting signs and symptoms e.g. Palpitations, fatigue, peripheral edema etc.
2. Physical examination
3. History of patient e.g. a history of hypertension in the family

MEDICAL MANAGEMENT

The main objective of any treatment program selected for individuals is to keep blood pressure within normal range. With the essential hypertension, there is no specific care rendered but drug therapy, lifestyle modifications and dietary restrictions as treatment of choice. Treatment of secondary hypertension is directed towards correcting primary conditions and curbing hypertension effects. Drug treatment include;

• Anti-hypertensive example Nifedipine.
• Diuretics: Thiazide diuretic example drochlorothiazide (Esidrex).
• Loop diuretics example spironolactone.
• Adrenergic inhibitor such as Reserpine, Methyldopa (Aldo Matt, Propranolol, intradermal.
• Vasodilators example hydralazine, hydrochloride, Apresolinol.
• Angiotensin converting enzyme inhibitors example Captopril, Capoten.Calcium blockers antagonist/example Nifecard, Adalat, Cordipin.

Non – Pharmacological Management

• Dietary changes
• Lifestyle modifications

Dietary Changes

1. Sodium intake should be restricted 
2. Increase fiber intake
3. Increase potassium as it increases extracellular potassium and sodium level
4. Caloric and fat restriction
5. Adequate intake of fruits and vegetables

Lifestyle Modification

1. Weight reduction by at least 15 of the optimum weight.
2. Regular exercise. Regular aerobic exercise such as jogging, walking and swimming can help control blood pressure. It can cause about 10mmHg decrease in systolic blood pressure. 
3. Avoidance of cigarette smoking
4. Avoidance  of alcohol intake
5. Stress management

PREVENTION OF HYPERTENSION

Hypertension is a life-threatening condition and as such best to prevent its occurrence. A positive outlook towards health is reflected in the individual’s lifestyle and habits. Health promotion focuses on educating the entire public to form a positive and more comprehensive attitude towards health.

PRIMARY PREVENTION

Health education is the most ideal action taken in primary prevention of hypertension. These thwart the habit or lifestyle of the general public as the causes and effects of hypertension likewise how the environment becomes a risk factor in the promotion of the disease are taught.

Primary prevention of hypertension includes:

1. Early identification of the condition and providing prompt and appropriate treatment. This is done through regular screening of individuals to detect any abnormality and if present ,prompt doctor’s attention for adequate treatment to be given.
2. Stress management by avoiding unhealthy arguments.
3. Weight reduction
4. Moderation of alcohol intake
5. Avoid smoking cigarette.
6. Regular physical exercise
7. Fat and sodium restriction

SECONDARY PREVENTION

This has to do with, prevention of complications of the conditions by using drugs. It can also be achieved through lifestyle modification.

SURGICAL MANAGEMENT

Surgical interventions may become necessary in the case of tumors (pheochromocytoma) and sclerotic changes of the renal arteries which may be the cause of secondary hypertension. This surgical intervention is known as adrenalectomy.