High Blood Pressure

07 October 2013

Hypertension: "High blood pressure; transitory or sustained elevation of systemic arterial blood pressure to a level likely to induce cardiovascular damage or other adverse consequences."

High blood pressure (BP) or hypertension is a medical condition in which the blood pressure is chronically elevated. Hypertension is the most important modifiable risk factor for coronary heart disease (CHD), stroke (CVA), congestive heart failure (CHF), end-stage renal disease and peripheral vascular disease.

Worldwide, hypertension is seen in about 1 billion people and the prevalence has been estimated to increase by more than 29% by the year 2025. This condition is associated with increased obesity and aging population. Due to the associated morbidity, mortality and economical burden to the society, hypertension remains as a significant public health challenge.

As hypertension rarely causes specific symptoms, it is undetected until an individual’s blood pressure is measured or screened by a physician or until it had caused complications such as stroke or heart attack. The primary goal of treatment is to lower the blood pressure to a normal level through appropriate combination of drugs that achieves this goal.

Classification of high blood pressure

Hypertension is classified as:

  • Primary hypertension and
  • Secondary hypertension.

Primary or essential hypertension which accounts for more than 90% of cases of hypertension is diagnosed in the absence of an identifiable secondary cause. Primary hypertension is more common in adolescents and adults, and has multiple risk factors. Secondary hypertension indicates that the high Blood pressure is a consequence of another condition such as a kidney disease or adrenal disease.

The following is a classification of BP for adults above 18 years:

Systolic blood pressure
Normal Less than 120 mm/hg
Pre hypertension 120 to 139 mm/hg
High BP Stage 1 140 to 159 mm/hg
High BP Stage 2 160 or higher

Diastolic blood pressure
Normal Less than 80 mm/hg
Pre hypertension 80 to 89 mm/hg
High BP Stage 1 90 to 99 mm/hg
High BP Stage 2 100 or higher

Symptoms of high blood pressure

Although patients with isolated hypertension are usually asymptomatic, occasionally they have symptoms such as

  • Dizziness
  • Headache (especially pulsating headaches behind the eyes that occur early in the morning)
  • Blurred vision
  • Facial flushing or tinnitus (ringing sound in the ears)

Hypertension which is very severe with a systolic blood pressure (SBP) >240 mmHg or diastolic blood pressure(DBP) >120 mmHg is called accelerated hypertension. Accelerated hypertension is associated with confusion, visual disturbances, nausea and vomiting. When hypertension causes increased intracranial pressure (pressure exerted by the cranium on the brain tissue and brain fluid), it is called malignant hypertension or hypertensive crisis and is a medical emergency that requires immediate reduction of the blood pressure. This condition may present with end-organ damage.

Over time, untreated high blood pressure can damage organs such as the heart, kidneys or eyes leading to complications such as:

  • Angina, heart attack or heart failure
  • Stroke
  • Kidney failure
  • Peripheral arterial disease
  • Retinopathy (eye damage)


Causes of high blood pressure

Essentially, Blood pressure is the outcome of cardiac output and peripheral vascular resistance (Blood pressure=cardiac output×peripheral vascular resistance). Therefore, maintenance of a normal blood pressure is dependent on the balance between the cardiac output and peripheral vascular resistance.

Essential HypertensionThe pathogenesis of essential hypertension is multifactorial and highly complex. Many factors (and risk factors) have been implicated in the genesis of essential hypertension, which include the following:

  • Increased sympathetic nervous system activity.
  • Increased production of sodium-retaining hormones and vasoconstrictors.
  • Deficiencies of vasodilators such as prostacyclin and nitric oxide.
  • Inappropriate or increased renin secretion, resulting in increased production of angiotensin II and aldosterone.
  • Genetic predisposition.

Secondary Hypertension The common identifiable causes of secondary hypertension are the following:

  • Chronic kidney disease
  • Renovascular disease
  • Cushing’s syndrome (hypersecretion of the hormone cortisol)
  • Pheochromocytoma (adrenal tumor)
  • Drugs such as nonsteroidal antiinflammatory drugs (NSAIDs)

Risk factors for high blood pressure

The risk factors associated with increase in the blood pressure include the following:

  • Long term increased sodium(salt) intake
  • Reduced dietary potassium, calcium and magnesium
  • Diabetes mellitus and insulin resistance
  • Smoking
  • Excessive alcohol consumption
  • Lack of physical activity
  • Obesity
  • High stress levels

Diagnosis of high blood pressure

A complete history, physical examination and certain diagnostic tests are recommended, once the presence of hypertension has been confirmed.

An accurate blood pressure measurement is the key to diagnosis of hypertension. An average of three Blood Pressure readings, each taken 2 min apart is preferable to ascertain the diagnosis. Blood pressure should be measured in both the supine and sitting positions. Patients should be encouraged to abstain from smoking and caffeine intake for at least 30 min before the measurement.

Once the diagnosis of hypertension has been established, it is necessary to identify the presence of any risk factors, secondary causes of hypertension and any evidence of end-organ damage.

Initial, screening tests should be simple. Following are required for initial assessment.

  • Detailed history
  • Physical examination
  • Measurement of body mass index
  • Assessment of routine blood chemistry
  • Blood sugar
  • Lipid profile
  • Urinalysis

Further investigations are carried out in order to outline other cardiovascular risk factors and to detect target organ damage with only limited screening for secondary hypertension.

The cardiovascular risk of hypertension can be determined from the evidence of the following:

  • Target organ damage to the eyes, heart and kidneys.
  • Coexisting illness such as diabetes or hypercholesterolemia.
  • Lifestyle risk factors such as obesity and smoking.

Management of high blood pressure

Recommendations for pharmacologic treatment are based on the presence of symptomatic hypertension, evidence of end-organ damage and unresponsiveness to lifestyle modifications. Drug selection is largely determined by individual’s needs including the presence of any coexisting illness.

Treatment of high blood pressure

The goal of treatment for most hypertensive patients is to lower the SBP below 140 mmHg and the DBP below 90 mmHg. 

Self monitoring of blood pressure at home

You can measure your blood pressure on a real time basis, without having to visit a clinic at home and keep a recording chart or register.

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