Chapter 86

### Introduction

The greatest danger to a man is that someone will discover hypertension and some fool will try to reduce it.

John Hay 1931

Hypertension is a serious community disorder and the most common condition requiring long-term drug therapy in Australia. It is a silent killer because most people with hypertension are asymptomatic and unaware of their problem. Epidemiological studies have demonstrated the association between hypertension and stroke, coronary heart disease, kidney disease, heart failure and atrial fibrillation. Treatment may be lifelong, hence the need for careful work-up.

• Target organs (including some specific examples) that can be damaged by hypertension include the heart (failure, LVH, ischaemic disease), the kidney (kidney insufficiency), the retina (retinopathy), the blood vessels (peripheral vascular disease, aortic dissection) and the brain (cerebrovascular disease).

• Deaths in hypertensive patients have been shown to be due to stroke 45%, heart failure 35%, kidney failure 3% and others 17%.1

• Factors increasing chances of dying in hypertensive patients are: male patient, young patient, family history, increasing diastolic pressure.1

### Definitions and classification

• The various categories of BP are arbitrarily defined according to BP values for both diastolic and systolic readings (see Table 86.1).2,3

When a patient’s systolic and diastolic BPs fall into different categories, the higher category should apply.

Table 86.1

Definition and classification of blood pressure adults aged 18 years and older measured as sitting blood pressure (mmHg)2,3

For adults aged 18 years and older hypertension is:

• diastolic pressure >90 mmHg and/or

• systolic pressure >140 mmHg

• Isolated systolic hypertension is that of ≥ 140 mmHg in the presence of a diastolic pressure <90 mmHg.

• Hypertension is either essential or secondary (see Table 86.2).

• Essential hypertension is the presence of sustained hypertension in the absence of underlying, potentially correctable kidney, adrenal or other factors.

• Malignant hypertension is that with a diastolic pressure >120 mmHg and exudative vasculopathy in the retinal and kidney circulations.

• Refractory hypertension is a BP >140/90 mmHg despite maximum dosage of tw o drugs for 3–4 months.

Table 86.2

Causes of hypertension

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