Hypertension

Hypertension, also known as high blood pressure, is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms itself. It is, however, a major risk factor for stroke, coronary artery disease, heart failure, atrial fibrillation, peripheral arterial disease, vision los

Hypertension, also known as high blood pressure, is a long-term medical condition in which the blood pressure in the arteries is persistently elevated.[10] High blood pressure usually does not cause symptoms itself.[1] It is, however, a major risk factor for stroke, coronary artery disease, heart failure, atrial fibrillation, peripheral arterial disease, vision loss, chronic kidney disease, and dementia.[2][3][4][11] Hypertension is a major cause of premature death worldwide.[6]

High blood pressure is classified as primary (essential) hypertension or secondary hypertension.[5] About 90–95% of cases are primary, defined as high blood pressure due to non-specific lifestyle and genetic factors.[5] Lifestyle factors that increase the risk include excess salt in the diet, excess body weight, smoking, physical inactivity and alcohol use.[1][5] The remaining 5–10% of cases are categorized as secondary hypertension, defined as high blood pressure due to a clearly identifiable cause, such as chronic kidney disease, narrowing of the kidney arteries, an endocrine disorder, or the use of birth control pills.[5]

Blood pressure is classified by two measurements, the systolic (first number) and diastolic (second number) pressures.[1] For most adults, normal blood pressure at rest is under 120 millimeters mercury (mmHg) systolic and 80 mmHg diastolic,[12][13] elevated blood pressure is between 120–129 mmHg systolic and under 80 mmHg diastolic and high blood pressure is present if the resting blood pressure is persistently at or above 130/80 (stage 1) or 140/90 (stage 2) mmHg.[5][12][13] Different numbers apply to children.[14] Ambulatory blood pressure monitoring over a 24-hour period appears more accurate than office-based blood pressure measurement.[5][10]

Lifestyle changes and medications can lower blood pressure and decrease the risk of health complications.[7] Lifestyle changes include weight loss, physical exercise, decreased salt intake, reducing alcohol intake, and a healthy diet.[5] If lifestyle changes are not sufficient, blood pressure medications are used.[7] Up to three medications taken concurrently can control blood pressure in 90% of people.[5] The treatment of moderately high arterial blood pressure (defined as >160/100 mmHg) with medications is associated with an improved life expectancy.[15] The effect of treatment of blood pressure between 130/80 mmHg and 160/100 mmHg is less clear, with some reviews finding benefit[12][16][17][18] and others finding unclear or no benefit.[19][20] High blood pressure affects 33% of the population globally.[8] About half of all people with high blood pressure do not know that they have it.[8] In 2019, high blood pressure was believed to have been a factor in 19% of all deaths (10.4 million globally).[8]

Signs and symptoms

Hypertension is rarely accompanied by symptoms.[1] Half of all people with hypertension are unaware that they have it.[8] Hypertension is usually identified as part of health screening or when seeking healthcare for an unrelated problem.

Some people with high blood pressure report headaches, as well as lightheadedness, vertigo, tinnitus (buzzing or hissing in the ears), altered vision or fainting episodes.[21] These symptoms, however, might be related to associated anxiety rather than the high blood pressure itself.[22]

Long-standing untreated hypertension can cause organ damage with signs such as changes in the optic fundus seen by ophthalmoscopy.[23] The severity of hypertensive retinopathy correlates roughly with the duration or the severity of the hypertension.[21] Other hypertension-caused organ damage include chronic kidney disease and thickening of the heart muscle.[8]

Secondary hypertension

Secondary hypertension is hypertension due to an identifiable cause and may result in certain specific additional signs and symptoms. For example, as well as causing high blood pressure, Cushing's syndrome frequently causes truncal obesity,[24] glucose intolerance, moon face, a hump of fat behind the neck and shoulders (referred to as a buffalo hump), and purple abdominal stretch marks.[25] Hyperthyroidism frequently causes weight loss with increased appetite, fast heart rate, bulging eyes, and tremor. Renal artery stenosis may be associated with a localized abdominal bruit to the left or right of the midline, or in both locations. Coarctation of the aorta frequently causes a decreased blood pressure in the lower extremities relative to the arms, or delayed or absent femoral arterial pulses. Pheochromocytoma may cause abrupt episodes of hypertension accompanied by headache, palpitations, pale appearance, and excessive sweating.[25]

Hypertensive crisis

Severely elevated blood pressure (equal to or greater than a systolic pressure of 180 mmHg or a diastolic pressure of 120 mmHg) is referred to as a hypertensive crisis.[26] Hypertensive crisis is categorized as either hypertensive urgency or hypertensive emergency, according to the absence or presence of end-organ damage, respectively.[27][28]

In hypertensive urgency, there is no evidence of end-organ damage resulting from the elevated blood pressure. In these cases, oral medications are used to lower blood pressure over 24 to 48 hours gradually.[29]

In a hypertensive emergency, there is evidence of direct damage to one or more organs.[30][31] The most affected organs include the brain, kidney, heart, and lungs, producing symptoms that may include confusion, drowsiness, chest pain, and breathlessness.[29] In a hypertensive emergency, the blood pressure must be reduced more rapidly to stop ongoing organ damage;[29] however, there is a lack of randomized controlled trial evidence for this approach.[31]

Pregnancy

Hypertension occurs in approximately 8–10% of pregnancies.[25] Two blood pressure measurements, taken six hours apart, of greater than 140/90 mmHg are diagnostic of hypertension in pregnancy.[32] High blood pressure in pregnancy can be classified as pre-existing hypertension, gestational hypertension, or pre-eclampsia.[33] Women who have chronic hypertension before their pregnancy are at increased risk of complications such as premature birth, low birthweight or stillbirth.[34] Women who have high blood pressure and had complications in their pregnancy have three times the risk of developing cardiovascular disease compared to women with normal blood pressure who had no complications in pregnancy.[35][36]

Pre-eclampsia is a serious condition in the second half of pregnancy characterised by increased blood pressure and the presence of protein in the urine.[25] It occurs in about 5% of pregnancies and is responsible for approximately 16% of all maternal deaths globally.[25] Pre-eclampsia also doubles the risk of death of the baby around the time of birth.[25] Usually, there are no symptoms in pre-eclampsia, and it is detected by routine screening. When symptoms of pre-eclampsia occur, the most common are headache, visual disturbance (often "flashing lights"), vomiting, pain over the stomach, and swelling. Pre-eclampsia can occasionally progress to a life-threatening condition called eclampsia, which is a hypertensive emergency and has several serious complications including vision loss, brain swelling, seizures, kidney failure, pulmonary edema, and disseminated intravascular coagulation (a blood clotting disorder).[25][37]

In contrast, gestational hypertension is defined as new-onset hypertension in the second half of pregnancy without protein in the urine.[33]

Exercise during pregnancy is generally safe and may improve outcomes in hypertension during pregnancy,[38] and may prevent gestational hypertension and related complications.[39][40][41]

Children

Failure to thrive, seizures, irritability, lack of energy, and difficulty in breathing[42] can be associated with hypertension in newborns and young infants. In older infants and children, hypertension can cause headache, unexplained irritability, fatigue, failure to thrive, blurred vision, nosebleeds, and facial paralysis.[42][43]

Causes