Primary hypertension Primary hypertension is a syndrome in which elevated blood pressure is the main clinical manifestation with or without a variety of cardiovascular risk factors, often referred to as hypertension. Hypertension is an important cause and risk factor for a variety of cardiovascular and cerebrovascular diseases, affecting the structure and function of important organs, such as the heart, brain, and kidneys, ultimately leading to the failure of these organs, and remains one of the leading causes of death from cardiovascular disease to date. Blood pressure classification and definition Blood pressure levels in the population are continuously and normally distributed, and there is no clear line of demarcation between normotension and elevated blood pressure. The criteria for hypertension are defined based on clinical and epidemiological data. Hypertension is defined as a systolic blood pressure ≥ 140 mmHg and/or a diastolic blood pressure ≥ 90 mmHg, which is further classified into grades 1 to 3 according to the level of elevated blood pressure. When systolic and diastolic blood pressure belong to different grades, the higher grade is used as the standard. Clinical manifestations and complications (a) Symptoms: Most have a slow, gradual onset and generally lack specific clinical manifestations. About 1/5 patients are asymptomatic and are only detected when blood pressure is measured or when complications such as heart, brain and kidney occur. The common symptoms include dizziness, headache, neck tightness, fatigue, and palpitations, which are mild and persistent. Most of the symptoms may resolve on their own and worsen after stress or exertion. More severe symptoms such as blurred vision and nosebleeds may also occur. There is a correlation between symptoms and blood pressure levels, due to hypertensive vasospasm or dilation. A typical hypertensive headache disappears when the blood pressure drops. Patients with hypertension can have a combination of other causes of headache, often unrelated to high blood pressure, such as mental anxiety headache, migraine, glaucoma, etc. If sudden onset of severe dizziness and vertigo occurs, be aware that it may be a transient ischemic attack or excessive hypotension or upright hypotension, which is likely to occur in people with hypertension combined with atherosclerosis and cardiac decompensation. Patients with hypertension may also present with symptoms of affected organs, such as chest tightness, shortness of breath, angina pectoris, and polyuria. In addition, some symptoms may be the result of adverse reactions to antihypertensive drugs. (B) Signs: Blood pressure fluctuates greatly with the season, day and night, and emotions. Blood pressure is higher in winter and lower in summer; blood pressure has obvious diurnal fluctuations, generally lower at night and rapidly increases in the early morning after waking up and activity, forming a peak in the early morning. Patients’ self-measured blood pressure values at home are often lower than clinic blood pressure values. Signs are generally less frequent in hypertension. Some signs often suggest the possibility of secondary hypertension, such as a lumbar mass suggesting polycystic kidney or pheochromocytoma; delayed appearance or absence of femoral artery pulsation and significantly lower blood pressure in the lower extremities than in the upper extremities suggesting aortic constriction; centripetal obesity, purple lines and hypertrichosis suggest the possibility of Cushing’s syndrome. (iii) Malignant or acute hypertension in a few patients with rapid progression of the disease: diastolic blood pressure persistently ≥130 mmHg with headache, blurred vision, fundus bleeding, exudation and papilledema, prominent renal damage, persistent proteinuria, hematuria and tubuluria. The disease progresses rapidly, and without timely and effective antihypertensive treatment, the prognosis is poor, and death often occurs from renal failure, stroke, or heart failure. The pathogenesis is unclear, and some patients have severe renal artery stenosis as a secondary cause. (iv) Complications: 1, hypertensive crisis 2, hypertensive encephalopathy 3, cerebrovascular disease 4, heart failure 5, chronic renal failure 6, aortic coarctation Diagnosis and differential diagnosis Hypertension is diagnosed mainly on the basis of blood pressure values measured in the clinic, using an approved mercury column or electronic sphygmomanometer to measure blood pressure in the brachial artery area of the upper arm at quiet rest and sitting. Generally, the difference in blood pressure between the left and right upper arms is <1.33 to 2.66/1.33 kPa (10 to 20/10 mmHg), with the right side > the left side. If the difference in blood pressure between the left and right upper arms is large, consider an obstructive lesion in the subclavian artery and distal part of one side, such as aortitis or atheromatous plaque. If necessary, blood pressure should also be measured in the lying and standing positions (after 1 and 5 seconds) in patients with suspected upright hypotension, for example. Whether blood pressure is elevated cannot be determined by just one or two clinic blood pressure measurements; a period of follow-up is needed to observe changes in blood pressure and overall levels. Once hypertension is diagnosed, it is necessary to identify whether it is primary or secondary. Common secondary hypertension (a) Renal parenchymal hypertension (b) Renal vascular hypertension (c) Primary aldosteronism (d) Pheochromocytoma (e) Cortisolism (f) Aortic constriction