Hypertension is high blood pressure. It is a common medical condition where the high blood pressure can be either due to no cause or due to a number of causes.
Hypertension is a risk factor for the development of stroke and is also a cause for heart disease. Epidemiological studies have shown that over half the people over 60 years of age suffer from hypertension. According to the National Institute of Clinical Excellence, ever 2 mmHg rise in systolic blood pressure increases the risk of heart attacks by 7% and that of stroke by 10%.
In this article, we take a look at hypertension in a bit more detail.
Definition of hypertension
A normal blood pressure is defined as a systolic blood pressure between 120-140 mmHg and a diastolic blood pressure of 60-90 mmHg. Hypertension is defined as a consistently high blood pressure over 140/90 mmHg.
Causes of hypertension
Hypertension is classified into 2 types, depending on the cause –
1. Primary (essential) hypertension – In this form of hypertension, there is no cause identifiable or any possible causes have been ruled out. Primary hypertension includes a genetic cause and takes into consideration environmental factors.
2. Secondary hypertension – This occurs due to a number of causes –
- Renal causes – Polycystic kidney disease, Liddle syndrome
- Endocrine disease – Phaeochromacytoma, Cushing syndrome, congenital adrenal hyperplasia, primary hyperaldosteronism (Conn’ syndrome), acromegaly, hyperthyroidism, hyperparathyroidism
- Vascular causes – Renal artery stenosis, coarctation of the aorta, vasculitis
- Drugs and toxins – Cocaine, alcohol, nicotine, non-steroidal anti-inflammatory drugs
- Obstructive sleep apnoea
Grades of hypertension
The table below defines the different degrees of hypertension as defined by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (7th report) –
Systolic Blood Pressure (mmHg)
Diastolic Blood Pressure (mmHg)
120 – 139
80 – 89
140 – 159
90 – 99
Patients with hypertension can remain without symptoms for years. Most symptoms of hypertension relate to the effects that high blood pressure can have on different organs in the body. These include
- Heart – thickening of the heart walls, angina, heart attacks (coronary artery disease), weakening of the heart muscle (heart failure)
- Brain – Cerebrovascular disease (stroke), dementia
- Peripheral vascular disease
- Kidney failure
In patients with severe hypertension, patients can complain of severe headache and blurring of vision.
Hypertension is usually diagnosed during a routine clinic visit when 3 blood pressure readings taken two minutes apart show elevated readings consistently. However, this is sometimes insufficient, as patients who see a doctor can develop a condition called ‘white coat hypertension’, where the blood pressure can be elevated when a patient is in the clinic, and normal at home.
Investigations are aimed at determining the cause of hypertension as well. Here are some of the tests that can be conducted –
1. Electrocardiogram – This can show changes suggestive of a heart attack, angina or changes in the heart muscle due to high blood pressure.
2. 24 hour ambulatory blood pressure recording – Here a blood pressure cuff is applied around the arm and the blood pressure is measured a number of times over a 24 hour period, including when the patient is asleep. This will provide the treating physician with a good idea of what the resting blood pressure is at home, what the maximum blood pressure is and how long it remains elevated for during the period of measurement.
3. Special tests – While a detailed discussion regarding each investigation required for all the secondary causes of hypertension. The table below illustrates a few tests performed –
cause for hypertension
|Renal artery stenosis||Renal ultrasound with Doppler studies|
|Coarctation of the aorta||CT scan of aorta|
|Phaeochromocytoma||24 hour urinary metanephrine|
|Obstructive sleep apnoea||Sleep studies|
4. Echocardiogram – This is an ultrasound scan of the heart and allows for diagnosis of a weak heart or thickened heart muscle.
Treatment of hypertension depends on the cause, but in most cases it is all about reducing the blood pressure.
1. Lifestyle modifications – This involves stopping smoking, reducing alcohol intake and getting plenty of exercise. However, the most important step is to cut down or not add any salt to the food. The salt intake primarily involves reducing sodium intake, while maintaining intake of potassium levels along with other minerals and nutrients.
2. Drug treatments
There are a variety of drug treatments that are prescribed for patients. The drugs have plenty of evidence supporting their use in preventing future heart disease and complications due to hypertension.
- Beta blockers – These drugs include Atenolol, Bisoprolol and Metoprolol. In addition to reducing the blood pressure, they also reduce the heart rate and reduce the amount of work the heart has to do when it is pumping. This makes it very useful as treatment for patients with high blood pressure and heart disease.
- ACE inhibitors – Angiotensin Converting Enzyme inhibitors are a commonly prescribed treatment for hypertension. It is often offered as first line treatment for patients under the age of 55 years. However, it should be used with caution in patients with kidney disease, and can cause a dry cough. Drugs include Ramipril, Perindopril and Trandalopril.
- Calcium channel blockers – Include Diltiazem and Nifedepine
- Angiotensin receptor blockers – Often used when ACE inhibitors cause side effects. Drugs include Losartan, Valsartan and Telmisartan.
- Alpha blockers – These drugs are also useful to manage hypertension. Drugs include Prazocin.
- Diuretics – These are commonly called ‘water tablets’ though the primary aim in using them is to reduce blood pressure rather than get rid of large amounts of fluid in the body. Drugs include Bendrofluazide and Indapamide.
Below is a table that illustrates how treatment is prescribed.
These are just some of the treatments that are offered. Drug therapy may be offered as a single drug or man drugs may be prescribed in combination with each other. Usually in stage 1 hypertension, only one drug may be required, but in stage 2 hypertension, a combination of treatments are prescribed.
This brief review covers the common causes of hypertension and the treatments that are available. By controlling blood pressure, complications of hypertension such as heart attacks and strokes can be prevented.