OVERVIEW

Have you ever found yourself going through medical check-up, and cautioned by the health practitioner about your blood pressure? Well, one may ask why the concern? Interestingly, we would find out more as we progress. However, a common name for hypertension is the ‘silent killer’ because it shows no warning signs or symptoms and most people do not know they have it. Before we even elaborate on what hypertension is, it is best we understand what blood pressure is.

Blood pressure simply refers to the force of the blood pushing against the walls of our arteries (blood vessels that carry oxygen-rich blood). Normally, a person’s blood pressure rises and falls throughout the day. However, when it remains high for a long consistent period of time, it can cause significant damage to the heart and other organs.

In brief, hypertension is a persistent increase in blood pressure greater than 140/90 mmHg in a non-diabetic adult or above 130/80 mmHg for a diabetic adult. This value is based on an average of two or more (consistently) measured blood pressure readings.

TYPES 

The classification of hypertension is based on the cause and the associated blood pressure reading.

Based on the blood pressure reading, these include:

  • Normal blood pressure; <120/80 mmHg
  • Elevated blood pressure; 120-129/<80 mmHg
  • Stage I high blood pressure (Mild hypertension); 130-139/80-89 mmHg
  • Stage II high blood pressure; >140/90 mmHg

*The first value of the blood pressure reading is the systolic blood pressure (blood being pumped out of the heart when the left ventricle contracts) and the second value is the diastolic blood pressure (blood filling the heart when the ventricles relaxes). The unit for blood pressure reading is millimeters of mercury.

Based on the etiology, Hypertension can be classified as:

  • Primary (Essential) Hypertension:

An increase in blood pressure with no known cause. About 80-90% of people with high blood pressure have primary hypertension. Several factors are involved such diets (and lifestyle) narrowing the blood vessels, and increasing resistance of blood flow due to constricted blood vessels. An increase in blood volume could also increase blood pressure. Most of these unknown causes of hypertension, are due to inherited abnormalities affecting arterioles (small arteries) which should help control blood pressure.

  • Secondary Hypertension:

An increase in blood pressure with a known cause. About 5-10% of people with high blood pressure have secondary hypertension. Most causes include kidney disorders, endocrine (hormonal) disorders, renal vein stenosis, obesity, and chronic drug use.

ETIOLOGY

Though primary hypertension has no known cause, the significant causes of secondary hypertension are listed below. These factors can also predispose one to hypertensive complications which would be explained into detail.

  • Kidney Disorders:

The kidney is essential in controlling blood pressure. In view of this, damage to the kidney from inflammation or other disorders affects its ability to maintain sodium and water levels in the body. This increases the volume and pressure of blood. Disorders of the kidney causing high blood pressure include renal artery stenosis (narrowing of the artery supplying the kidneys), pyelonephritis (inflammation of the kidney tubules from ureteral reflux), glomerulonephritis (inflammation involving glomerulus), kidney tumors, polycystic kidney disease, blunt trauma to the kidney and radiation therapy affecting the kidney.

  • Hormonal Disorders:

These include disorders such as hyperaldosteronism (overproduction of aldosterone), Cushing syndrome (increased levels of cortisol), hyperthyroidism (hyperactive thyroid gland) and pheochromocytoma (a tumor in the adrenal gland that produces epinephrine and norepinephrine).

  • Drugs:

These include alcohol (in excess amounts), cocaine, corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs), birth control pills (OCDs), and sympathomimetics (decongestants such as pseudoephedrine and phenylephrine used in cold remedies).

  • Obesity:

An increase in weight could be caused by an inactive lifestyle, chronic stress, smoking, excessive amounts of alcohol intake and increasing salt intake from diet. These can play a major role in hypertension development. Obese persons normally have sleep apnea (difficulty in breathing at night) which aggravates pre-existing high blood pressure. Stress causes a temporal increase in blood pressure. Blood pressure returns to normal when the stress is relieved.

PATHOPHYSIOLOGY

Blood pressure in the body is controlled by the following mechanisms:

  • Change in the amount of blood pumped
  • Change in the diameter of the arteries
  • Change in the volume of blood in the bloodstream

Now hypertension occurs either when the amount of blood pumped per minute increases or when more force needs to be generated by the heart to pump blood due to narrowing of the blood vessels. Soon, blood pressure begins to rise progressively because the constriction of the blood vessels reduces their capacity to control blood pressure.

The kidneys respond directly to blood pressure changes, by removal of sodium and water. This reduces the blood volume and blood pressure. When the ability of kidneys to excrete water and sodium is impaired, blood volume increases and leads to an increase in blood pressure.

The kidneys release some chemicals that control the size of blood vessels and the capacity of blood held within the blood vessels. When kidneys are damaged, these substances are not produced hence increasing blood pressure.

EPIDEMIOLOGY

An estimated 26% of the world’s population (972 million people) is hypertensive. There have been high prevalence records in developing nations. A higher percentage of women beyond age 64 have hypertension as compared to men. However, men between 45 and 64 years have higher percentage of hypertensive records than women.

In sub-Saharan Africa, because of the increasing influence in western diet and lifestyle, most adults seem to develop hypertension quite early. Another contributing factor, work-related stress has predisposed most adults to hypertension development.

In adolescents, secondary hypertension is prominent due to the chronic use of drugs and alcohol. These cause kidney disorders which predispose such groups to hypertension.

RISK FACTORS

A person can increase their risks of developing hypertension if they practice any of the following:

  • Eating foods high in sodium (salty foods), saturated fat or cholesterol (fatty or oily foods) or foods low in potassium.
  • Physically inactive.
  • Obesity or increased weight gain.
  • Chronic alcoholism.
  • Smoking or chronic use of tobacco.

The following groups can also be predisposed to hypertension:

  • Pregnant women with a history of hypertension
  • A family history of hypertension
  • A family history of hormonal disorders
  • A family history of kidney disorders

SIGNS AND SYMPTOMS

As stated, hypertension is mostly asymptomatic (without symptoms). However, when complications develop in target organs, symptoms begin to appear. These general signs and symptoms include:

  • Dizziness
  • Headaches
  • Confusion
  • Nosebleeds (Epistaxis)
  • Fatigue
  • Vomiting
  • Nausea
  • Seizures
  • Irregular heart rate (Palpitations)
  • Anxiety
  • Increased sweat
  • Coma

COMPLICATIONS

Before one can fully understand the complications involved with hypertension, it is best to understand the forms of hypertension which cause people to seek medical attention.

  • Hypertensive Urgency:

This is an emergency condition when the diastolic blood pressure is more than 120 mmHg but does not result in any organ damage known to persons or doctors. This usually does not cause symptoms. However, it is identified during a routine physical examination by a health practitioner.

  • Hypertensive Emergency:

A severe form of hypertension which is often fatal. This is a persistent increase in blood pressure more than 180/120 mmHg, with evidence of damage in one or more vital organs (brain, heart, and kidneys) accompanied by a range of symptoms. When left untreated, it could lead to death.

The following are the common complications associated with hypertension:

  • Heart attack (Myocardial Infarction)
  • Heart failure (Congestive Heart Failure)
  • Stroke (Cerebrovascular accident)
  • Kidney failure (Hypertensive nephropathy)
  • Abnormal heart rhythms (Arrhythmias)
  • Eye disorders such as glaucoma (Hypertensive retinopathy)

DIAGNOSIS

In identifying an increase in blood pressure, your health practitioner would do the following:

  • Measure blood pressure with a sphygmomanometer (an instrument used in measuring blood pressure).
  • Eye examination (Direct and Indirect Ophthalmoscopy).
  • Listen to heart sounds and rhythm (Auscultation of the heart).

Other laboratory tests that can be performed to identify secondary causes of hypertension are as follows:

  • Complete blood count
  • Electrocardiography (ECG)
  • Echocardiography
  • Chest X-ray
  • Ultrasound scan of kidneys and adrenal gland
  • Serum lipids
  • Blood urea, electrolytes, and creatinine
  • Blood glucose
  • Urinalysis
  • Serum uric acid

PROGNOSIS

The higher the blood pressure, the more severe the changes in the retina of the eye and the more involvement of other organs, worsens the prognosis. Increased systolic blood pressure predicts fatal or nonfatal events better than diastolic blood pressure. Coronary artery disease (CAD) is the most common cause of death among treated hypertensive patients. Ischemic or hemorrhagic stroke is a common result of partially treated hypertension. Effective control of hypertension prevents most complications and prolongs life.

MANAGEMENT & TREATMENT

In managing hypertension, it is best to ensure lifestyle changes such as:

  • Regular exercise such as a brisk walk every 30 minutes 3 times a week.
  • Reducing weight in overweight and obese persons.
  • Smoking cessation.
  • Diet involving fruits and vegetables reduced salt and fat.
  • Reduction in alcohol use.

In antihypertensive drug therapy, most health practitioners consider the following factors before administration:

  • Age and sex of the person.
  • The severity of high blood pressure.
  • Presence of other conditions such as diabetes or high cholesterol levels.
  • Potential side effects of the drugs.
  • Cost of the drugs
  • Tests to rule out other secondary effects of elevated blood pressure
  • Allergic reactions
  • Race of the patient.

Antihypertensive drugs such as fenoldopam, nitroprusside nicardipine or labetalol are used in hypertensive emergencies to rapidly reduce blood pressure.