Hypertension
<p ><b>Hypertension</b> (<b>HTN</b>) or <b>high blood pressure</b>, sometimes called <b>arterial hypertension</b>, is a <a href="http://en.wikipedia.org/wiki/Chronic_(medicine)" title="Chronic (medicine)" >chronic </a><a href="http://en.wikipedia.org/wiki/Disease" title="Disease" >medical condition</a> in which the <a href="http://en.wikipedia.org/wiki/Blood_pressure" title="Blood pressure" >blood pressure</a> in the <a href="http://en.wikipedia.org/wiki/Artery" title="Artery" >arteries</a> is elevated. </p>
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This requires the heart to work harder than normal to circulate blood through the blood vessels. Blood pressure involves two measurements, systolic and diastolic, which depend on whether the heart muscle is contracting (systole) or relaxed between beats (diastole). Normal blood pressure at rest is within the range of 100-140mmHg systolic (top reading) and 60-90mmHg diastolic (bottom reading). High blood pressure is said to be present if it is persistently at or above 140/90 mmHg.</p>
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Hypertension is classified as either <a href="http://en.wikipedia.org/wiki/Essential_hypertension" title="Essential hypertension" >primary (essential) hypertension</a> or <a href="http://en.wikipedia.org/wiki/Secondary_hypertension" title="Secondary hypertension" >secondary hypertension</a>; about 90–95% of cases are categorized as "primary hypertension" which means high blood pressure with no obvious underlying medical cause.<sup id="cite_ref-pmid10645931_0-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Hypertension#cite_note-pmid10645931-0" >[1]</a></sup> The remaining 5–10% of cases (secondary hypertension) are caused by other conditions that affect the kidneys, arteries, heart or endocrine system.</p>
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Hypertension is a major <a href="http://en.wikipedia.org/wiki/Risk_factor" title="Risk factor" >risk factor</a> for <a href="http://en.wikipedia.org/wiki/Stroke" title="Stroke" >stroke</a>, <a href="http://en.wikipedia.org/wiki/Myocardial_infarction" title="Myocardial infarction" >myocardial infarction</a> (heart attacks), <a href="http://en.wikipedia.org/wiki/Heart_failure" title="Heart failure" >heart failure</a>,<a href="http://en.wikipedia.org/wiki/Aneurysm" title="Aneurysm" >aneurysms</a> of the arteries (e.g. <a href="http://en.wikipedia.org/wiki/Aortic_aneurysm" title="Aortic aneurysm" >aortic aneurysm</a>), <a href="http://en.wikipedia.org/wiki/Peripheral_arterial_disease" title="Peripheral arterial disease" class="mw-redirect" >peripheral arterial disease</a> and is a cause of <a href="http://en.wikipedia.org/wiki/Chronic_kidney_disease" title="Chronic kidney disease" >chronic kidney disease</a>. Even moderate elevation of arterial blood pressure is associated with a shortened <a href="http://en.wikipedia.org/wiki/Life_expectancy" title="Life expectancy" >life expectancy</a>. Dietary and lifestyle changes can improve blood pressure control and decrease the risk of associated health complications, although drug treatment is often necessary in people for whom lifestyle changes prove ineffective or insufficient.</p>