Hypertension (HTN) is defined as persistently elevated arterial blood pressure.1 HTN is the single biggest risk factor for cardiovascular disease. At least half of all heart attacks and strokes are associated with HTN, making early diagnosis and management of HTN essential.1
There are several types of HTN:
Kidney disease is the most common cause of secondary HTN.
Table 1. Causes of secondary hypertension.
Causes of secondary hypertensionExamples
Kidney disease
Vascular disease
Endocrine disease
Drugs
Other causes
There are several risk factors that increase a person's chance of developing HTN:2
Hypertension (HTN) is a common condition whereby the blood pressure is chronically elevated. It can be asymptomatic, but some warning signs can indicate it. The risk of developing HTN is higher among people of Black African and Black Caribbean origin, and increases with age. Lifestyle factors such as cigarette smoking, excess alcohol consumption, excess dietary salt intake, obesity and lack of physical activity can also increase the risk.
Most cases of HTN are asymptomatic, and may be an incidental finding. Warning signs include headache, visual disturbances, seizures, nausea and vomiting, and chest pain. Symptoms suggesting kidney disease as a secondary cause of HTN are haematuria, 'frothy' urine suggestive of proteinuria, dyspnoea, lower limb swelling, flank tenderness and pain, and weight loss (suggestive of renal cell carcinoma). Symptoms suggesting coarctation of the aorta as a secondary cause are headache, epistaxis, intermittent claudication, lower limb weakness, and cold legs and feet. Symptoms suggesting endocrine disease are muscle weakness, muscle spasms and paraesthesia (hyperaldosteronism), severe headache, palpitations and sweating (phaeochromocytoma), weight gain (particularly abdominal, facial, back of neck and shoulders) (Cushing's syndrome), tall statures, swelling of hands and feet, deepening of voice (acromegaly), weight gain, cold intolerance, low mood (hypothyroidism), and weight loss, heat intolerance, palpitations (hyperthyroidism).
Other important areas in the history include menstrual history (e.g. date of last menstrual period), family history, and medication history.
The majority of patients with HTN will have no findings on examination. All patients with HTN should undergo fundoscopy looking for hypertensive retinopathy suggestive of accelerated or malignant HTN. Typical clinical findings in secondary causes of HTN include enlarged palpable kidneys when balloting the kidneys (autosomal dominant polycystic kidney disease), renal bruits heard when auscultating over the area of the renal arteries (renal artery stenosis), systolic murmur in the left infraclavicular region under the left scapula and radio-femoral delay (coarctation of the aorta), moon facies, abdominal purple striae and bruising (Cushing's syndrome), brittle nails, dry skin, thin hair (hypothyroidism), and fine tremor, palmar erythema, neck goitre (hyperthyroidism).
Diagnosis of hypertension requires the measurement of blood pressure. There are 3 types of blood pressure measurement to consider: clinic blood pressure (patient's blood pressure recorded during the consultation), home blood pressure (patient's readings taken at home), and ambulatory blood pressure monitoring (measurement which takes place over a 24 hour period).
Ambulatory Blood Pressure Monitoring (ABPM) and Home Blood Pressure Monitoring (HBPM) are used to record a patient's blood pressure during normal activities and within the home respectively. The steps required to accurately measure blood pressure are described below and are summarised from the NICE guidelines.
The patient should be quiet and seated with their outstretched arm supported. A sphygmomanometer should be used to manually measure the blood pressure. If the difference between arms is greater than 15mmHg, both readings should be repeated. If the difference remains greater than 15mmHg, subsequent blood pressure readings should then be taken in the arm with the higher readings. If the clinic blood pressure is greater than or equal to 140/90mmHg a second measurement should be taken. If there is a significant difference between the first and second measurements, a third should be taken and the lower of these two should be recorded as the clinic blood pressure.
If the blood pressure is between 140/90mmHg and 180/120mmHg ABPM or HBPM should be offered to confirm the diagnosis of hypertension. At least two blood pressure measurements should be taken an hour during the person's usual waking hours to use the average value of at least 14 measurements for ABPM. Blood pressure should be measured twice daily for HBPM, with two consecutive measurements taken at least one minute apart whilst seated. The measurements should be recorded for at least four days, but ideally for seven days. The measurements from the first day should then be discarded and the average value of the remaining measurements should be used to confirm the diagnosis of hypertension.
Hypertension can be classified into stages 1, 2 or 3 according to the blood pressure (seen in Table 2).
Errors in measuring blood pressure can arise from incorrect patient positioning, poor understanding of measuring technique, incorrect cuff size (the bladder should encircle at least 80% of the arm) and incorrect cuff position (the cuff should be placed 2cm above the brachial artery and the 'artery mark' should be aligned with the brachial artery).
Bedside investigations include urinalysis to look for haematuria and proteinuria, urine albumin creatinine ratio (uACR), which indicates albuminuria, and an ECG to look for signs of cardiac arrhythmias and heart failure.
Relevant laboratory investigations to consider are:
Cardiovascular disease risk can be assessed with QRISK3, an online tool which takes into account factors such as sex, age, ethnicity, smoking status, and presence of comorbidities to generate a percentage which estimates the risk of a patient having a heart attack or stroke in the next 10 years.
The target clinic blood pressure is <140/90mmHg and <135/85mmHg for ABPM/HBPM for patients aged <80 years. For patients aged ≥80 years, the target blood pressure is <150/90mmHg and <145/85mmHg for ABPM/HBPM.
Conservative management should be offered to all patients with HTN, including advice on diet, exercise, lower salt intake, lower caffeine consumption, stopping smoking, and reducing alcohol consumption.
The decision to commence antihypertensive medication depends upon the stage of HTN. For stage one hypertension, discuss drug therapy with patients aged <80 years who have a preexisting cardiovascular disease, kidney disease, or an estimated 10-year risk of cardiovascular disease of ≥10%. For patients aged ≥80 years, consider drug therapy for those with a clinic blood pressure >150/90mmHg, and for patients <60 years with an estimated 10-year risk of cardiovascular disease <10%. For stage two and three hypertension, offer antihypertensive drug therapy to all patients.
Often a single antihypertensive drug is inadequate to control HTN, so a stepwise approach is used to add further drugs until controlled is achieved (Figure 1). A minimum of 4 weeks should be allowed to determine whether a drug or combination of drugs have been successful at reducing the blood pressure.
Patients aged <55 years who are not of Black African or African-Caribbean descent should be offered an ACE inhibitor such as ramipril, or if not tolerated, an angiotensin-II receptor blocker such as losartan. Patients aged ≥55 years and patients of Black African or African-Caribbean descent should be offered a calcium channel blocker such as amlodipine.
Those already taking an ACE inhibitor or angiotensin-II receptor blocker can be offered a calcium channel blocker such as amlodipine or thiazide-type diuretic such as indapamide. Patients already taking a calcium channel blocker should be offered an ACE Inhibitor such as ramipril or a thiazide-type diuretic such as indapamide. If an ACE Inhibitor is not tolerated, an angiotensin-II receptor blocker such as losartan can be used, with Angiotensin-II receptor blockers being preferred for patients of Black African or African-Caribbean descent.
Combination of an ACE inhibitor or angiotensin-II receptor blocker plus a calcium channel blocker and thiazide-type diuretic should be offered.
Patients whose blood pressure is not controlled with steps 1-3 are said to have resistant hypertension. Management depends on the serum potassium level.
Patients should be referred for specialist assessment if they remain hypertensive despite 4 anti-hypertensive drug therapies.
Accelerated or malignant HTN are referred to as hypertensive emergencies and may require hospital admission. NICE recommends the following management if the clinic blood pressure is ≥180/120mmHg.
Refer for same-day specialist assessment if there are:
If none of the above are present, investigate for signs of complications associated with HTN as soon as possible. If complications are present start medical management without waiting for ABPM/HBPM. If complications are not present repeat blood pressure measurements within 7 days.
The goal of managing accelerated or malignant HTN is to reduce the blood pressure over a 24 - 48 hour period. If the blood pressure is reduced too quickly this can lead to organ hypoperfusion.
If hospital admission is necessary, an arterial line is often inserted in patients with accelerated or malignant HTN to allow for continuous blood pressure monitoring.
Intravenous anti-hypertensive agents such as nitroprusside, labetalol and nicardipine can be used to control blood pressure in accelerated or malignant hypertension.
The complications of hypertension can be divided into the following categories, based on the affected organs:
