Hypertension

Hypertension is a condition in which blood vessels carrying blood around the body have permanently raised pressure. The condition is also referred to as high blood pressure.

Hypertension increases the risk of damage to organs within the body, such as the kidneys, heart, brain and eyes. It is difficult to define high blood pressure, as blood pressure has a skewed normal distribution within the population. Consequently, the hypertension classifications are based upon pressures above which the risk of adverse outcomes are greater (140/90mmHg or higher or 135/85mmHg or higher, depending on the setting) (World Health Organisation (WHO), 2021; National Institute for Health and Care Excellence (NICE), 2021).

Hypertension alone is often asymptomatic. Headache is no more common than in the general population. However, in malignant hypertension (otherwise known as accelerated hypertension) there may be symptoms such as:

• headache
• nausea
• confusion and,
• blurred vision (Brettler, 2022)

Malignant hypertension is a rapid rise in blood pressure resulting in damage to the blood vessels. People with malignant hypertension may present with severe hypertension (systolic blood pressure above 200mmHg) and signs of retinal haemorrhage or papilloedema. These warrant hospital admission (NICE, 2019).

The blood pressure in the vessels is determined by the cardiac output and peripheral resistance. Increased cardiac output or increased resistance within the vessels will increase blood pressure (Brettler, 2022).

Causes of hypertension can be divided into primary (essential hypertension) and secondary.

Secondary causes of hypertension are much rarer and should be considered in all people with hypertension under the age of 40.
Secondary causes include:

• renal disease, including glomerulonephritis, chronic pyelonephritis and polycystic kidneys
• Cushing’s syndrome
• Conn’s syndrome
• pregnancy
• phaeochromocytoma
• hyperparathyroidism
• steroids

Primary (or essential) hypertension accounts for around 85-95% of cases of hypertension. The aetiology is complex and multifactorial. Key processes that have been identified are:

• disturbance of autoregulation (increased cardiac output, matched by increased resistance)
• increased body sodium (via intake and retention)
• hormonal dysregulation, notably the renin-angiotensin- aldosterone axis
• endothelial (vascular cell lining) changes

Ultimately, these factors bring about structural changes that similarly cause small vessel atherosclerosis (plaque

The gold standard in the diagnosis of hypertension is made following ambulatory blood pressure monitoring (ABPM) or home blood pressure monitoring (HBPM). ABPM is where blood pressure is tested intermittently via an automated cuff and device over a 24-hour period.

Home blood pressure monitoring (HBPM) consists of a person taking blood pressure measurements at home twice daily, for a minimum of 7 days. Hypertension is confirmed if there is a clinical blood pressure of 140/90mmHg or higher and an ABPM daytime average or HBPM average of 135/85mmHg or higher (NICE, 2019).

Management strategies in hypertension differ according to the severity of the hypertension, the age of the patient and other cardiovascular risk factors.

All people diagnosed with hypertension should be offered lifestyle advice, including smoking cessation, reduction of alcohol intake and discussion about diet and exercise.

The severity of hypertension can be classified according to the following stages: