2 Indications and current treatments
2.1 Hypertension is usually asymptomatic, but it is a common and preventable cause of premature morbidity and death. It is a major, but modifiable, risk factor for cardiovascular disease (including stroke and myocardial infarction) and chronic kidney disease. The cause of primary hypertension, which is the most common form, is not fully understood. However, it is likely to involve multiple factors including an increase in sodium retention and a reduction in renal blood flow mediated by the sympathetic nervous system. Secondary hypertension, which is less common, is caused by conditions affecting the kidneys, arteries, heart or endocrine system.
2.2 The NICE guideline on hypertension defines resistant hypertension as blood pressure that remains higher than 140/90 mmHg after treatment with the optimal or best tolerated doses of an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin‑II receptor blocker (ARB) plus a calcium-channel blocker (CCB) plus a diuretic. First-line treatment of hypertension includes lifestyle changes, such as diet and exercise. Antihypertensive medications are used if high blood pressure persists. Implanting a baroreceptor stimulation device may be considered if hypertension fails to respond adequately to these measures.