Essential or secondary hypertension

Hypertension is used to describe an elevation in blood pressure. Blood pressure does tend to fluctuate depending on the time of day and exertion levels for example, however, when we talk about hypertension we are referring to a chronically raised blood pressure. Hypertension is typically asymptomatic, but it is an important risk factor for cardiovascular and cerebrovascular diseases.

🏘️ Epidemiology

According to the WHO, 1.13 billion people have hypertension globally. Most of which live in low/middle-income counties. In England it has a prevalence of 31% in men and 26% in women.

It is the 2nd biggest global risk factor for disease (after poor diet) and it is the single most important risk factor for the development of cardiovascular disease, increasing the risk of CAD, stroke, HF.

It also is a major risk factor for PAD, CKD, and vascular dementia as well as numerous other diseases throughout the body.

🏃 Physiology and pathophysiology

Blood pressure is an indicator of CVS function. It measures the pressure within our cardiovascular system throughout the cardiac cycle.

The formula for blood pressure is:

• Cardiac output - the more blood that is being pumped through our vessels, the higher the pressure. It is dependant on the heart rate as well as the stroke volume.
• Peripheral resistance - if the blood vessels are more constricted there is higher pressure through them.

Our blood pressure is measured with 2 components, a systolic pressure and diastolic pressure. A normal blood pressure lies between 120/80 - 135/85.

NICE classifies hypertension as a blood pressure of 140/90 (in clinic) or 135/85 (with ambulatory or home readings).

The cause of hypertension can be divided into primary (essential) causes and secondary causes

1. Essential hypertension - also known as primary or idiopathic hypertension. It makes up 95% of hypertensive cases. Its aetiology is multi factorial and not entirely understood but can be due to sympathetic hyperactivity, endothelial dysfunction, inappropriate RAAS activity, excessive sodium intake.
2. Secondary hypertension - due to ROPE.
1. R - Renal disease - most common secondary cause.
2. O - Obesity/other
3. P - Pregnancy/pre-eclampsia
4. E - Endocrine disorders

Renal disease	Endocrine disorders	Other causes
Glomerulonephritis	Primary hyperaldosteronism (Conn’s syndrome)	Glucocorticoids
Chronic pyelonephritis	Phaeochromocytoma	NSAIDs
Adult PCKD	Cushing’s syndrome	Coarctation of the aorta
Renal artery stenosis	Liddle’s syndrome	Combined oral contraceptive
CKD	Congenital adrenal hyperplasia
	Acromegaly

⚠️ Risk factors

😷 Presentation

⭐️ Hypertension is asymptomatic, unless the blood pressure reaches extremely high pressures in hypertensive crisis (such as >200/120mmHg for example).

Typically, it is identified when checking someone’s blood pressure. White-coat hypertension is a concern as a blood pressure in clinic is sometimes higher than when taken at home (it is defined as a blood pressure of 20/10mmHg more than with ambulatory or home readings. This has changed the manner in which hypertension has been diagnosed as we now typically use ambulatory monitors.

The converse may also be true, where patients have masked hypertension. This occurs when they have a normal BP in clinic but higher BP when taken outside of clinic with ambulatory blood pressure monitoring (ABPM) or home blood pressure monitoring (HBPM).

In longstanding hypertension we may see:

• Visual disturbances - due to retinopathy with longstanding hypertension.
• Chest pain - suggestive of CAD.
• Headaches - if it is a hypertensive crisis.
• Sensory or motor deficits - if it presents due to a complication with cerebrovascular disease.

💯 Criteria and staging

The JNC-7 definitions from 2004 for hypertension have been adopted in 2014, and these have set the pharmacological treatment thresholds for hypertension subsequently:

🔍 Investigations

🩸

Blood pressure measurements:

1. 🥇 When considering a diagnosis we should measure blood pressure in both arms.
1. If the difference is >15mmHg, then repeat measurements. If it remains higher then measure the BP subsequently in the arm with the higher reading.

2. If >140/90mmHg → take second measurement during the consultation and record the lower of the 2.
1. If significantly different → take a third measurement.
2. 🏆 If it remains >140/90 then offer ABPM to confirm the diagnosis. If ABPM is not possible then offer HBPM for confirmation.
1. While waiting it is important to do investigations to look for end-organ damage (more on this below) and also to perform a formal risk assessment for CVD using the QRISK2 risk assessment.

ABPM requires 2 measurements per hour during the usual waking hours of the patient. The average value of at least 14 measurements taken are used to confirm the diagnosis.

HBPM requires 4-7 days of recording twice daily (morning and evening). Each recording should be done twice, at least 1 minute apart with the individual seated. We should discard the measurement on the first day and use the average for all the remaining measurements to confirm the diagnosis.

Other investigations to assess for end-organ damage include:

• U&Es - assessing for renal disease as a cause or consequence of hypertension.
• HbA1c - to look for co-existing DM (another important risk factor for CVD).
• Lipids - to look for co-existing hyperlipidaemia.
• ECG - to assess for evidence of left ventricular hypertrophy or evidence of an old infarction.
• Urine dipstick and ACR - once again looking for evidence of DM or renal disease.
• Fundus examination - to assess for hypertensive retinopathy.

🧰 Management

First, let’s discuss who should receive treatment in stage 1 hypertension and stage 2 hypertension. Then let’s look at the treatment algorithm.

Other management factors include:

1. Risk factor modification - low-salt diet (DASH), reducing caffeine intake, restricting alcohol intake, smoking cessation, exercise etc.
2. Complication monitoring

Dear future Sarmad,

Please add in the MOAs and adverse effects of the drugs within these classes when you have the time.

Kind regards,

Sarmad (18/01/2023)

Hypokalaemia in hypertension

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