Hypertension: a very basic introduction Flashcards
Hypertension: a very basic introduction?
- Hypertension is one of the most common medical conditions encountered in the developed world.
- Whilst there is a degree of normal variation in blood pressure according to the time of day and whether we are exerting ourselves hypertension describes a chronically raised blood pressure.
- The main relevance of hypertension lies in the fact that it is an important risk factor for the development of cardiovascular disease such as ischaemic heart disease and stroke.
- Unless the blood pressure is very high it is unusual for patients to experience any symptoms.
What is a ‘normal’ blood pressure?
Normal blood pressure can vary widely according to age, gender and individual physiology.
- Most healthy people have a blood pressure between 90/60 mmHg and 140/90 mmHg.
NICE define hypertension as follows:
- a clinic reading persistently above >= 140/90 mmHg, or:
- a 24 hour blood pressure average reading >= 135/85 mmHg
Why do some patients have an elevated blood pressure?
- Patients with hypertension may be divided into two categories.
- The vast majority (around 90-95%) have primary, or essential, hypertension.
- This is where there is no single disease causing the rise in blood pressure but rather a series of complex physiological changes which occur as we get older.
- Secondary hypertension may be caused by a wide variety of endocrine, renal and other causes.
Secondary hypertension - Renal Disease?
- Glomerulonephritis
- Chronic pyelonephritis
- Adult polycystic kidney disease
- Renal artery stenosis
Secondary hypertension - Endocrine disorders?
- Primary hyperaldosteronism
- Phaeochromocytoma
- Cushing’s syndrome
- Liddle’s syndrome
- Congenital adrenal hyperplasia (11-beta hydroxylase deficiency)
- Acromegaly
Secondary hypertension - Other causes?
- Glucocorticoids
- NSAIDs
- Pregnancy
- Coarctation of the aorta
- Combined oral contraceptive pill
Symptoms and signs?
As mentioned earlier, hypertension does not typically cause symptoms unless it is very high, for example > 200/120 mmHg. If very raised patients may experience:
- headaches
- visual disturbance
- seizures
It also also important when assessing a patient with newly diagnosed hypertension to ensure they do not have any end-organ damage?
- fundoscopy: to check for hypertensive retinopathy
- urine dipstick: to check for renal disease, either as a cause or consequence of hypertension
- ECG: to check for left ventricular hypertrophy or ischaemic heart disease
Investigations?
Following diagnosis patients typically have the following tests:
- urea and electrolytes: check for renal disease, either as a cause or consequence of hypertension
- HbA1c: check for co-existing diabetes mellitus, another important risk factor for cardiovascular disease
- lipids: check for hyperlipidaemia, again another important risk factor for cardiovascular disease
- ECG
- urine dipstick
Management?
The management of patients with hypertension involves several aspects:
- drug therapy using antihypertensives
- modification of other risk factors to reduce the overall risk of cardiovascular disease
- monitoring the patient for the development of complications of hypertension
Angiotensin-converting enzyme (ACE) inhibitors?
- Inhibit the conversion angiotensin I to angiotensin II
- Cough Angioedema Hyperkalaemia
- First-line treatment in younger patients (< 55 years old) Less effective in Afro-Caribbean patients Must be avoided in pregnant women Renal function must be check 2-3 weeks after starting due to the risk of worsening renal function in patients with renovascular disease Drug names end in ‘-pril’
Calcium channel blockers?
- Block voltage-gated calcium channels relaxing vascular smooth muscle and force of myocardial contraction
- Flushing
Ankle swelling
Headache - First-line treatment in older patients (>= 55 years old)
Thiazide type diuretics?
- Inhibit sodium absorption at the beginning of the distal convoluted tubule
- Hyponatraemia
Hypokalaemia
Dehydration - Although technically a diuretic, thiazides have a very weak diuretic action
Angiotensin II receptor blockers (A2RB)?
- Block effects of angiotensin II at the AT1 receptor
- Hyperkalaemia
- Angiotensin II receptor blockers are generally used in situations where patients have not tolerated an ACE inhibitor, usually due to the development of a cough
Drug names end in ‘-sartan’
Drug therapy is decided by well established NICE guidelines, which advocate a step-wise approach?
