Essential hypertension

Cardiology (12%) Core Clinical Conditions

1A: Able to diagnose and manage

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Definition Aetiology Pathophysiology Risk factor Sign and Symptoms Investigations Diagnosis Management

Definition

Essential hypertension can be defined as a blood pressure (BP) reading of 140/90 mmHg with no known secondary causes.

Aetiology

There are several factors that increases an individual’s blood pressure such as:

Excess salt intake
Aging
Sedentary lifestyle
Renal sodium retention
Insulin resistance
High alcohol intake
Obesity
Smoking
Low calcium, magnesium, potassium intake
Genetics

Pathophysiology

The balance of systemic vascular resistance to cardiac output determines the blood pressure. Numerous physiological processes such as arterial baroreceptors, the renin-angiotensin-aldosterone system, atrial natriuretic peptide, endothelins, and mineralocorticoid and glucocorticoid hormones, are involved in the complex process of controlling blood pressure.

Hypertension may arise as a result of any one of these mechanisms being dysfunctional, causing high systemic vascular resistance, increased cardiac output, or both.

Overtime blood vessels become less flexible and more rigid, which limits vasodilation and raises systemic vascular resistance, raising your blood pressure.

Risk factors

High salt intake >1.5 g/day
Obesity, overweight
Poor diet and sedentary lifestyle
Age
Ethnicity (HTN is more prevalent in black African/Caribbean descent)
Other medical conditions e.g. CKD, Diabetes, sleep apnoea

Sign and symptoms

Generally asymptomatic. However some of the symptoms are:

Headache
Chest pain
Shortness of breath
Dizziness
Visual disturbance

Investigations

Urine test- check for hematuria

Urine albumin:creatinine ratio (check for protein the urine)
Bloods: Hba1c, U&E, cholesterol
Fundoscopy (any presence of hypertensive retinopathy)
12 lead ECG (check cardiac function)
Q-risk assessment (if more than 10% or more consider starting on a statin)

Diagnosis and investigations

If clinic blood pressure is between 140/90 mmHg - 180/120 mmHg you arrange a 24 hr ambulatory blood pressure (ABPM) or a home readings to confirm HTN.

There are different stages of HTN:

Stage 1 Hypertension

Home BP >140/90 ; ABPM>135/85

Stage 2 Hypertension

Home BP >160/100 ; ABPM>150/95

Stage 3 Hypertension

Home BP >180/120

Management

Be aware of the following medications:

ACE inhibitors (ACEi) e.g Ramipril
Angiotensin receptor blockers (ARBs) e.g. Losartan
Calcium-channel blockers (CCB) e.g Amlodipine
Diuretics e.g. Indapamide
Alpha-blockers e.g. Doxazosin
Beta-blockers e.g. Bisoprolol

Stepped approach:

Step 1

ACEi or ARB - if not diabetic and under 55 years old and not of black African or African-Caribbean ancestry.

Note: Offer an ARB to treat hypertension if an ACE inhibitor is not tolerated, perhaps due to cough.

CCB - if above 55 years old and do not have type 2 diabetes and are also of black African or African-Caribbean ancestry.

Note:Offer a thiazide-like diuretic to treat hypertension if a CCB is not tolerated, perhaps due to oedema. Indapamide should be started instead of other thiazide diuretics.

Step 2

If HTN is not well controlled with an ACEi/ARB, offer the following in addition to step 1:

CCB or thiazide-like diuretic

If HTN is not well controlled with a CCB, offer the following in addition to step 1:

ACEi or ARB or a thiazide-like diuretic

Step 3

If HTN is not well controlled with step 2, then offer the following:

ACEi or ARB + CCB + thiazide-like diuretic

Step 4

If HTN is not well controlled with step 3, you can regard them as treatment resistant hypertension. Therefore, you might want to consider:

Discussing adherence
Adding a fourth antihypertensive. For example, a low-dose spironolactone for patients who have a blood potassium level of 4.5 mmol/l or less. Or you can consider an alpha blocker such as doxazosin if the patient’s blood potassium level is above 4.5 mmol/l
Seek specialist advice