Hypertension
Hypertension comes from two words: hyper meaning above normal
and tension meaning pressure.
Hypertension is defined as a persistent rise in blood pressure above what is considered normal for the Person’s age (140/90mmHg).
A Person qualifies to be having hypertension (high blood pressure) when
either diastolic or systolic pressure or both consistently rises above normal when measured on at least 3 separate visits.
Blood pressure: This is the pressure exerted when blood flows into the arteries. It is measured in mmHg using a sphygmomanometer (blood pressure machine)
Diastolic pressure; This is the pressure exerted on the arteries when the heart relaxes
Systolic pressure: This the pressure exerted on the arteries when the heart contracts
Classification of blood pressure
The blood pressure in adults is classified as shown in the table below. The purpose of this classification is to aid proper intervention in the management of hypertension
Bp classification | Systolic Bp Diastolic Bp(mmHg) |
Normal | <120 and <80 |
Pre hypertension | 120 – 139 or 80 – 89 |
Stage 1 hypertension | 140 -159 or 90 – 99 |
Stage 2 hypertension | ≥160 or ≥100 |
Isolated systolic hypertension | ≥140 and <90 |
Proper Measurement of blood pressure
In order to obtain appropriate results, the following must be followed:
- Measure the blood pressure using the right blood pressure machine i.e. the cuff should not be too small or too large for the patient
- Allow the patient to rest for at least 5 to 10 minutes before measuring the blood pressure since exercise increases the blood pressure
- The patient should not be talking while the blood pressure is being measured since wrong results (higher) may be obtained when the patient talks
- The arm of the patient should be positioned at the level of the heart
- At least 2 – 3 measurements should be made at different visits for those with pre hypertension and stage 1 hypertension before the patient is confirmed to be having hypertension
- Inform the patient of his or her blood pressure results and what they mean
- Record the patient’s blood pressure on the medical form and a copy of results should be given to the patient
Types of hypertension
Hypertension is divided into two depending on the cause:
- Essential (primary) hypertension
- Secondary hypertension
Essential hypertension
This is the elevation of blood pressure without a known cause It contributes up to 90% of all cases of hypertension seen in Uganda.
It was called essential hypertension because they thought elevation of blood pressure in elderly patients was necessary to overcome peripheral resistance created by the rigidity of blood vessels caused by aging.
Risk factors for hypertension
Any person may develop hypertension but the following categories of people with the risk factors listed below have higher chances of developing hypertension
- Family history (close relative like father, mother, or sister) with hypertension or cardiovascular disease.
- Patients with diabetes mellitus
- People who are inactive all the time (lack of exercise)
- Persons who are overweight or obese (body mass index) ≥30kg/m2
- People who smoke cigarette
- Advancing age ( people above 60yrs )
- Patients whose cholesterol (fat content in the blood) level is higher than normal.
Secondary hypertension
This is the elevation of blood pressure due to a known cause. The cause may be any of the following:
- Kidney disease
- Use of drugs such as steroids, oral contraceptives.
- Pregnancy (pre eclampsia and eclampsia)
- Obstructive sleep apnoea
- Coarctation (narrowing of the aorta)
- Diabetic renal disease
Note: secondary hypertension is treated by eliminating or treating the cause but sometimes drugs may be used to control the blood pressure
Management of Hypertension
Non pharmacological measures
- Educate the patient and care giver about hypertension and its chronic nature.
- Advise the patient to lose weight if he /she is overweight or obese
- Encourage the patient to do regular exercise such as walking ,riding a bicycle, jogging etc for at least 30 minutes per day and for at least 5 days in a week
- Tell the patient to quit smoking if she or he does as smoking reduces the effectiveness of drugs for hypertension
- Encourage the patient to have a diet containing more of fruits and vegetables.
- Advise the patients who drink alcohol to take it in moderate quantities i.e. 2 bottles of beer per day since excessive amount rises the blood pressure
- Advise the patient to eat food containing less salt (low sodium intake)
- Advise the patient to avoid eating food containing saturated fats
Drug therapy
Drug treatment is recommended for those patients who have not responded to non drug measured and for those who report when the blood pressure is already very high. One drug (monotherapy) is recommended initially for patients with mild hypertension.
In case of poor response another drug may be added or substituted
Patients who present when already in stage 2 may be started on two drugs at once in lower doses then adjusted depending on the response.
Choice of antihypertensive
When choosing a drug for treating hypertension, consider the following in order to safely use the drugs and effective control of blood pressure.
- Patients with other existing diseases or conditions such as pregnancy asthma, diabetes, heart failure, pregnancy, and angina pectoris. This is because some antihypertensive are not recommended to be used in some of the above conditions.
- Affordability and accessibility of the medicine by the patients
- Establish whether the patient is allergic to the drug or not
- Establish the Presence of target organ damage
Choice of antihypertensive in different conditions
Condition | Recommended antihypertensive | |
1st choice | 2nd choice | |
Pregnancy | Methyldopa (Aldomet) | Atenolol ,Nifedipine |
Diabetes mellitus | Captopril ,Lisinopril | Nifedipine ,Amlodipine |
Asthma | Amlodipine, Nifedipine | |
Preeclampsia or eclampsia of pregnancy | Hydralazine (Apresoline) | Labetalol |
Angina pectoris | Nifedipine ,Amlodipine | Atenolol ,Propranolol |
Heart failure | Frusemide, Lisinopril, Captopril | Carvedilol |
Resistant hypertension
This is the persistent elevation of blood pressure above 140/90mmHg despite the use of 3 or more appropriate drug combination including a diuretic at full doses
Causes
- Patients above 60 years
- Poor drug compliance(taking the drugs wrongly)
- Continuous presence of risk factors such as smoking ,excessive alcohol intake and obesity
- Concurrent use of drugs that elevate blood pressure for example flu (common cold) preparations(decongestants),painkillers like diclofenac
- Presence of secondary causes of hypertension for example kidney failure
Malignant hypertension, hypertensive emergency, hypertensive urgency
Malignant hypertension
Malignant hypertension is a condition characterized by sudden severe rise in blood pressure resulting into small vessel damages
Clinical presentation include confusion, headache, visual loss and comma
It is a medical emergency that requires hospital admissions and rapid control of blood pressure over 12 to24 hours to normal level
Hypertensive emergency
This is severe elevation of blood pressure more than 180/120mmHg) with signs of damage to target organs such as the brain and kidney.
The patient must be admitted in the hospital if possible in intensive care unit and pressure must be lowered immediately to prevent damage to the kidney, heart and brain.
Blood pressure should be gradually lowered since cerebral hypo perfusion can occur if the blood pressure is lowered by more than 40% in the initial 24 hours
Drugs used to treat hypertensive emergencies in Uganda include intravenous hydralazine or Labetalol
Hypertensive urgency
This is a situation in which blood pressure is very elevated but there is no potential organ damage
The blood pressure must be reduced within 1 – 2 days and oral medications are recommended used for example Nifedipine (Sublingual), Captopril, Labetalol tablet e.t.c.
Drugs used in the treatment of hypertension
Drugs used in the treatment of hypertension in Uganda include:
- Beta blockers
- Calcium channel blockers
- Diuretics
- Angiotensin converting enzyme inhibitor(ACE inhibitors)
- Angiotensin II antagonist
- Centrally acting hypertensive
- Direct acting vasodilators
1. Beta blockers
Beta blockers are the most commonly used drugs in the treatment of hypertension in Uganda because they are affordable and available in most of the places countrywide.
Examples |
Propranolol(Inderal) |
Atenolol (Totamol) |
Carvedilol |
Labetalol |
Mechanism of action
Beta blockers block beta 1 receptors in the heart which results in slowing of the heart rate and reduction in the force of heart contraction. This action results in lowering of blood pressure.
Indications.
- Hypertension
- Angina pectoris
- Migraine headache
- Congestive heart failure (Carvedilol)
- Post myocardial infarction
Side effects
- Impotence
- Wheezing
- Cold extremities
- Bradycardia
- Reduced exercise tolerance
- Tiredness
- Heart failure
Contraindications
- Patients with asthma
- Patients with acute heart failure
- Heart block
- Chronic obstructive airway disease
- Patients with diabetes mellitus since they mask signs of hypoglycemia
- Depression
Pregnancy and breast feeding
- Generally common beta blockers are recommended for use in pregnant mothers though prolonged use may lead to growth retardation in fetuses
- Beta blockers may be used in breast feeding mothers
2. Calcium channel blockers
Calcium channel blockers are among the first line drugs used in the treatment of hypertension. They can be used alone or in combination with other antihypertensive such as beta blockers, Angiotensin converting enzyme inhibitors or diuretics .These drugs can be used safely in patients who also have other co existing conditions such as asthma, hyperlipidaemia, diabetes mellitus and renal dysfunction.
Examples |
Nifedipine |
Amlodipine |
Felodipine |
Mechanism of Action.
Calcium channel blockers decrease the entry of calcium ions into the smooth muscles causing vasodilatation and lowering of the blood pressure.
Indications
- Hypertension
- Angina pectoris
Side effects
- Flushing
- Oedema
- Headache
- Postural hypotension
- Dizziness
- Weakness
- Heart burn
- Tachycardia
Contraindications
- 2nd or 3rd degree heart block
- Known hypersensitivity to any of the members
- Severer heart failure
- Severe hypotension
Pregnancy and breast feeding
Calcium channel blockers especially Nifedipine is used in the treatment of hypertension in pregnant mothers
3. Diuretics
Diuretics are among the first line drugs used in the treatment of hypertension.
Diuretics for example Bendrofluazide are safe, cheap and effective in the treatment of hypertension. These drugs may be used alone or in combination with ACE inhibitors, beta blockers etc in the treatment of hypertension
Classification of diuretics
Class | Example |
Thiazide diuretics | Bendrofluazide (Aprinox) Metolazone |
Loop diuretics | Frusemide (Lasix) |
Potassium sparing diuretics | Spironolactone |
Mechanism of action
Diuretics work by promoting the excretion of large amount of water in form of urine thereby reducing the blood volume and lowering of blood pressure.
Indications.
- Hypertension
- Heart failure
Note: Thiazide diuretics are mainly used in the treatment of hypertension but may be used in mild cases of heart failure
Loop diuretics are commonly used in the treatment of heart failure and rarely in the treatment of hypertension unless associated with fluid over load (oedema)
Side effects
Class | Common side effects |
Thiazide diuretics |
|
Loop diuretics |
|
Contraindications
Thiazide diuretics are not recommended in patients with
- Gout
- Diabetes
- Hypokalaemia
- Hyperlipidaemia
- known hypersensitivity
Pregnancy and breast feeding
Generally diuretics should be used with caution during pregnancy and breast feeding
4. Angiotensin converting enzyme inhibitors (ACE inhibitors)
ACE inhibitors are drugs of first choice in the treatment of hypertension and also hypertension in diabetic patients. They may be used alone or in combination with diuretics or beta blockers.
Examples |
Captopril |
Ramipril |
Lisinopril |
Enalapril |
Mechanism of action
These drugs interfere with the conversion of Angiotensin I(vasodilator) to Angiotensin II (vaso constrictor) by inhibiting the Angiotensin converting enzyme. This leads to a reduction of peripheral resistance and lowering of blood pressure
Indications.
- Hypertension
- Heart failure
- Diabetic nephropathy
Side effects
The common side effects associated with use of ACE inhibitors include
- Dry irritating cough
- Skin rash
- Taste disturbance
- Angioedema
Contraindications
- Pregnant mothers
- Patients with renal impairment
- Previous history of angioedema
- Known hypersensitivity to any of the drugs in this group
- Breast feeding
5. Centrally acting antihypertensive
These drugs were among the first to be used in the treatment of hypertension in Uganda. They are no longer used so much in the general management of hypertension because of associated side effects and presence of effective drugs with less side effects.
Example
- Methyldopa
- Clonidine
Methyldopa, the only member currently registered in Uganda is used as a drug of 1st choice in the treatment of hypertension in pregnant mother because of its safety in this category of patients
Mechanism of action
These drugs inhibit sympathetic out flow from the brain there by decreasing total peripheral resistance and lowering of blood pressure.
Indications
- Hypertension during pregnancy
- Severe hypertension as a 3rd line drug
Side effects
- Tiredness
- Headache
- Impotence
- Dizziness
- Mental depression
- Sedation
- Rebound hypertension on withdraw
Contraindications
- Severe liver disease
- Known hypersensitivity to methyldopa
6. Angiotensin II antagonists
These drugs are among the new ones used in the treatment of hypertension .They are as effective as ACE inhibitors but are usually recommended in patients who cannot tolerate ACE inhibitors because of side effects such as cough.
Examples |
Losartan |
Telimisartan |
Valsartan |
Candesartan |
Mechanism of action
Angiotensin II antagonists bind tightly at Angiotensin II receptor preventing the action the action of Angiotensin II .This action reduces peripheral resistance resulting into vasodilatation and lowering of blood pressure
Indications
- Hypertension
- Heart failure
Side effects
The most common side effects associated with the use of these drugs include:
- Hypotension
- Dizziness
- Hyperkalaemia
Contraindications
These drugs should be avoided during pregnancy especially during the 2nd and 3rd trimester since they are associated with fetal malformation
- Breast feeding mothers
7. Direct acting vasodilators
Drugs that belong to this group include
- Hydralazine
- Minoxidil
Hydralazine is the only member registered in Uganda and is only recommended in the treatment of hypertension that has not responded to other antihypertensive.
The use of hydralazine in the long term treatment of hypertension is associated with fluid retention and reflex tachycardia which can be offset by combining it with beta blockers (to prevent reflex tachycardia or diuretics to reduce fluid retention)
Mechanism of action
Direct acting vasodilators work directly on the blood vessels causing relaxation (widening of the blood vessel) leading to a reduction in the blood pressure
Indications
- Severe hypertension
- Hypertensive emergences
- Hypertension in pregnancy associated with pre- eclampsia and eclampsia
Side effects
The following side effects are commonly seen when hydralazine is used
- Headache
- Tachycardia
- Flushing
- Dyspnoea
- Oedema
- Postural hypotension
Contraindications
- Angina pectoris
- Patients with heart failure
- Known hypersensitivity