High blood pressure in children

Introduction to children's hypertension The normal blood pressure of children varies with age. The younger the blood, the lower the blood pressure. It is currently considered that blood pressure is higher than the same age systolic (high pressure) or diastolic (low pressure) 20 mm Hg, or preschool children > 110 / 70 mm Hg, school age children > 120 / 80 mm Hg should consider high blood pressure, Essential hypertension is rare in children, accounting for 20% to 30%, but in recent years there is an increasing trend; secondary hypertension is more, accounting for 65% to 80%. In children with secondary hypertension, kidney disease accounts for 79%, followed by cardiovascular disease, endocrine disease, nervous system disease and poisoning. basic knowledge The proportion of sickness: 0.01% Susceptible people: young children Mode of infection: non-infectious Complications: Hypertensive encephalopathy Hypertensive crisis Angina

Causes of hypertension in children

(1) Causes of the disease

According to the cause of hypertension, it is divided into primary hypertension and secondary hypertension. More than 80% of children with hypertension are secondary hypertension. Primary hypertension is also called hypertension. The cause is unknown and high. Blood pressure is the main manifestation of an independent disease. The factors related to the disease are:

1. Secondary hypertension Children with hypertension secondary to other diseases are secondary hypertension, secondary hypertension is also known as symptomatic hypertension, the cause of hypertension is clear, is the clinical manifestation of a disease First, secondary hypertension is the most common hypertension in infants and children. It can be an acute or chronic process. Neonatal hypertension is associated with the application of umbilical artery catheter and renal artery embolism. Children with hypertension and kidney disease, aortic coarctation , endocrine diseases or drugs, etc., common causes are as follows:

(1) Kidney disease: 80% of secondary hypertension may be related to kidney disease, which is the most common form of hypertension in children, or renal hypertension, including: renal parenchymal disease (acute and chronic glomerulonephritis) , chronic pyelonephritis); congenital kidney disease (polycystic kidney, renal hypoplasia); renal tumor: secondary renal disease (connective tissue disease, diabetes); renal vascular disease (renal artery and venous stenosis, obstruction); kidney Peripheral lesions (inflammation, abscess, tumor, trauma, bleeding); hemolytic uremic syndrome.

(2) vascular lesions: such as aortic coarctation (higher limb blood pressure), multiple arteritis.

(3) Endocrine diseases: Adrenal cortical diseases, including: hypercortisolism (Cushing's syndrome), primary aldosteronism, pheochromocytoma, neuroblastoma (secreting catecholamines, is 2 years old) The following common causes of hypertension in infants and young children, hyperthyroidism, hyperparathyroidism (hypercalcemia).

(4) craniocerebral lesions: intracranial tumors, hemorrhage, edema, encephalitis, etc. can cause increased intracranial pressure with high blood pressure, or affect the stability of the autonomic nervous system to make the sympathetic nerves excited.

(5) Poisoning and drugs: lead, mercury poisoning, vitamin D poisoning, adrenocortical hormone, cocaine, stimulants, etc.

2. The cause of primary hypertension is unexplained as essential hypertension, which is related to the following factors:

(1) Genetics: According to relevant statistics at home and abroad, the heritability of hypertension is 60%-80%. With the increase of age, the genetic effect is more obvious. The detection of norepinephrine in normal blood pressure children whose parents are suffering from essential hypertension The concentration of dopamine was significantly higher than that of the control group without a family history of hypertension, indicating that there may be hereditary sympathetic hyperactivity in essential hypertension, and there is often a significant family history of essential hypertension, 1987-1994. The data of the identification and primary prevention of high blood pressure patients in children and adolescents showed that hypertension had a history of 6.57 times that of family history, and family history of adult hypertension was as high as 40% to 60%. May be associated with hereditary calcium and sodium transport disorders (when too much Na is ingested, the cells cannot excrete excessive Na, Na in the smooth muscle cells of the vascular wall, and Na2 + Ca2 exchange increases intracellular Ca2, through membrane depolarization Increased excitability, eventually leading to vasoconstriction, increased peripheral resistance), renin-angiotensin system imbalance and insulin resistance, the latter caused by hyperinsulinemia It may change the activity of cellular Na-K-ATPase, increase the content of Na in cells, stimulate the activity of sympathetic nerves, increase the reabsorption of water and sodium by the kidney, increase the sensitivity of blood pressure, and stimulate growth factors (especially vascular smooth muscle). And increase the secretion of endothelin and other factors, high blood pressure children with normal blood pressure have similar physiological reactions with parents, such as stress, heart rate increased during competition, blood pressure increased significantly higher than no family history, in addition, urinary catecholamine Increased metabolites, sodium load response to weight gain and elevated blood pressure is also significantly higher than those without family history, children with abnormal family history, blacks than whites, adults based on plasma renin activity levels High and low, different types of hypertension were treated differently, but this guidance was not seen in the same large number of adolescents with essential hypertension, red blood cell sodium transport, platelet and leukocyte free calcium concentration, urinary vasodilator Sympathetic receptors can also predict future development of hypertension.

(2) Personality: A type A personality (the main manifestation of type A personality behavior is extremely competitive, time-critical and sexy, easy to be irritated or easy to attack others). The incidence of cardiovascular disease in adolescent behavior types Higher than other types.

(3) Diet: sodium ions have a certain boosting effect, while many fish eaters are less likely to suffer from hypertension. Therefore, high-risk groups should limit the high-sodium salt diet, encourage more fish, and eat too much salt in the diet. Causes high blood pressure, and low blood pressure occurs when the salt intake is less than 3g per day. The daily salt intake of children aged 11-14 years in Chicago is nearly 8g (136.7mmol sodium), which can cause high blood pressure, but laboratory and clinical Studies have found that changing salt intake and blood sodium levels can only affect the level of some individuals, especially those with genetic sodium deficiency, which is sensitive to salt exposure, so the salt-causing disease is conditional. The potassium content in the diet is too low, too much saturated fatty acids and low calcium can contribute to high blood pressure.

(4) Obesity: Obesity increases the capillary bed due to the accumulation of adipose tissue, causing an increase in circulating blood volume and cardiac output, aggravation of the heart burden, and prone to hypertension and cardiac hypertrophy over a long period of time. Blood pressure can be reduced by reducing body weight. It also proves that obesity has a significant effect on blood pressure. Children's blood pressure is significantly positively correlated with body weight, height and body mass index. The weight is the most obvious. The longitudinal survey of 1164 normal children in Beijing urban area is 8 years old. The detection rate of hypertension in obese children for 5 consecutive years is 5 times that of non-obese children. Among them, 465 6-year-old children found that with the increase of obesity, the blood pressure percentile increased to 13 years old obese children with hypertension. The detection rate was as high as 14.7%, compared with 4% in the control group. The blood pressure survey of 2,445 students aged 7-18 years in the United States showed that the body mass index continued to be above the 90th percentile. The index is 9 to 10 times below the 50th percentile. Obesity is the main influencing factor of primary hypertension in children.

(5) Exercise: Studies on children's athletes show that physical exercise increases cardiac output, slows heart rate, consumes excess calories, and thus effectively controls obesity, hyperlipidemia, and low cardiovascular adaptability, which are related to cardiovascular and cerebrovascular diseases. The formation and development of risk factors provide a good basis for the early prevention of cardiovascular and cerebrovascular diseases in adults.

(6) Others: There is a difference in prevalence among ethnic groups. Blacks in the United States are more than Caucasians. In addition, long-term mental stress, excessive sympathetic excitability, lack of sleep, smoking, etc., due to excessive adrenaline production and Adrenalin also raises blood pressure.

2. Secondary hypertension

(1) Kidney substantial lesions:

1 acute and chronic glomerulonephritis (including renal lesions of connective tissue disease) urine routine, urine concentration function, blood urea creatinine value, urine count, blood lupus erythematosus cells, anti-nuclear antibody determination, serum protein electrophoresis, serum complement Determination, if necessary, renal biopsy.

2 pyelonephritis urine routine, middle urine culture, intravenous pyelography.

3 polycystic kidney, renal hypoplasia renal function test, intravenous pyelography.

4 renal embryo tumor abdominal mass, urine routine, intravenous pyelography.

5 hemolytic uremic syndrome blood routine, platelets, reticulocytes, blood bilirubin, blood electrolytes, urine routine, renal function test.

(2) Renal vascular disease:

1 renal artery stenosis, embolization of abdominal or lumbar vascular murmur, intravenous pyelography, isotope kidney map, renal artery.

2 renal vein embolization angiography, renal vein renin activity assay.

(3) Cardiovascular diseases:

1 aortic constriction upper limbs high blood pressure, lower limb blood pressure, lower limbs than the upper limb pulse weak delay, echocardiography, aortic angiography.

2 major arteritis in the vascular part of the sound, the surrounding pulse is weak or disappear, aortic angiography, other renal artery stenosis.

(4) Endocrine disorders:

1 secondary to a history of adrenal corticosteroids or ACTH long-term medical treatment, Ke Xing Zheng face, obesity.

2 Cortisol urinary 17-steroid steroid determination, plasma and urinary free cortisol determination, dexamethasone inhibition test, abdominal B-ultrasound and CT examination.

3 primary aldosteronism blood electrolyte determination, blood and urine aldosterone determination, plasma renin activity determination, abdominal B-ultrasound and CT examination.

4 pheochromocytoma venous pyelography, 24-hour urinary vanilla acid (VMA) determination, benzyl oxazoline test, abdominal B-ultrasound and CT examination 5 neuroblastoma abdominal or thoracic mass, anemia, intravenous pyelography, 24-hour urinary dopamine determination, abdominal B-ultrasound and CT examination.

(5) Central nervous system disorders:

1 intracranial tumor, hemorrhage, edema cerebrospinal fluid examination, fundus examination, brain CT examination.

2 encephalitis nervous system examination, cerebrospinal fluid examination.

(6) Poisoning:

1 lead poisoning red blood cell spot color, cerebrospinal fluid examination, long bone skull X-ray examination.

2 Determination of urinary mercury in mercury poisoning.

(two) pathogenesis

The regulation of normal blood pressure is a complicated process, mainly depends on cardiac output and peripheral resistance, and the cardiac output itself is affected by various factors, such as extracellular fluid volume, heart rate and myocardial contractility; total peripheral resistance is also Affected by various factors, such as the receptor and receptor of the sympathetic nervous system, angiotensin, prostaglandin, bradykinin, etc., in addition to self-regulation mechanism, so the occurrence of hypertension mainly affects the above factors, The occurrence of essential hypertension is related to factors such as heredity, personality, and obesity diet, but how to influence the above factors has not been fully elucidated.

Secondary hypertensive renal vascular renal disease, due to decreased renal blood perfusion pressure, stimulate the secretion of a large amount of renin in the paragonadal cells; renin is a proteolytic enzyme that catalyzes the production of angiotensinogen from the liver Hydrolysis to angiotensin I, which is then converted to angiotensin II by the conversion enzyme in the pulmonary circulation, which has a strong vasoconstriction effect, leading to hypertension; and indirectly stimulates the secretion of aldosterone by the spheroidal band of the adrenal cortex, which increases blood volume expansion. Blood pressure, acute glomerulonephritis and most renal diseases, due to increased blood and sodium retention blood volume, resulting in hypertension, hypercortisolism, due to a large number of secretion of glucocorticoids caused by sodium retention and stimulate angiotensin production Lead to high blood pressure, pheochromocytoma, excessive secretion of adrenaline and norepinephrine by tumor cells, increase blood pressure and heart rate by increasing myocardial contractility and heart rate, and raising blood pressure, aorta Constriction increases blood pressure due to mechanical obstruction and increased renin.

The basic pathophysiology of hypertension is the increase of peripheral vascular resistance caused by systemic small arterial spasm. Long-term small arteriospasm leads to arteriosclerosis, while renal arteriosclerosis aggravates renal ischemia, which causes blood pressure to rise continuously. After sexual change, it gradually develops into renal insufficiency. Long-term hypertension increases left ventricular afterload, leading to left ventricular hypertrophy. In the advanced stage of hypertension, it may be due to renal dysfunction. Sodium and water retention leads to increased blood volume and aggravates the heart. The load further enlarges the left ventricle and gradually develops into left heart failure. On the other hand, persistent cerebral arteriolar spasm causes cerebral edema, causing optic disc edema, visual impairment, headache, vomiting, convulsions and syncope.

Pediatric hypertension prevention

Prevention of hypertension in children should be considered as the primary cause of prevention of adult death - part of cardiovascular disease and stroke, prevention of hypertension should be started from childhood, the purpose of prevention is to reduce the incidence of hypertension, lower blood pressure to reduce or avoid Organs are involved, improve the quality of life, prevent comprehensive measures should be adopted. For children with high blood pressure, positive family history and obese children should be the key targets for prevention. Regularly measure blood pressure, and ensure the normal growth and development of children in the diet. Overweight, and should start from infants and young children, avoid feeding too much milk or excessive heat card, avoid too much high-fat and high-cholesterol diet in daily diet, increase the intake of unsaturated fatty acids, eat more vegetables, encourage low-salt diet, adhere to Physical exercise, avoid the stimulation of excessive mental stress, such as excessive learning burden, often watch TV and movies rich in horror or horror content, reduce the noise in the environment, ensure enough sleep time, avoid smoking, drinking and so on.

Pediatric hypertension complications Complications hypertensive encephalopathy hypertensive crisis angina

Can be complicated by hypertensive encephalopathy, and even hypertensive crisis, angina pectoris, heart failure, pulmonary edema, cerebral edema, renal insufficiency, etc., secondary hypertension has different primary pathogenesis, complications are different, see related content.

Symptoms of hypertension in children Common symptoms Visual impairment Multi-urinary appetite decreased edema convulsions Hypertension Ventilation ataxia Dizziness slow growth

Hypertension itself is similar to primary or secondary, clinical manifestations are similar, the symptoms caused by hypertension depends on the rapid development of hypertension, the degree of blood pressure and the extent of target organ involvement, and the clinical symptoms vary greatly. Children with primary hypertension are more common in adolescents, mostly mild hypertension, often without obvious symptoms, only found in physical examination or athlete screening, often accompanied by moderate, mild obesity, elevated blood pressure in secondary hypertension Can be mild to severe, generally asymptomatic, clinical manifestations of the symptoms and signs of the primary disease, such as chronic nephritis children often due to growth retardation to the diagnosis, when the blood pressure rises significantly, or persistent and / or rapid Type of high blood pressure, may have dizziness, headache, nosebleed, loss of appetite, vision loss, etc., severe cases of vomiting, convulsions, ataxia, hemiplegia, aphasia, coma and other symptoms of hypertensive encephalopathy, such as symptoms of sudden rise in blood pressure Intensified, accompanied by angina pectoris, heart failure, pulmonary edema, convulsions, etc., called hypertensive crisis, which is due to temporary small arteriospasm causing significant increase in peripheral vascular resistance, making blood pressure Speed due to the increase, must be urgently addressed in order to save lives, so infant convulsions or heart failure and unexplained irritability, headache older children should be routine blood pressure.

According to abnormalities in the fundus, pediatric hypertension can be divided into 4 degrees, I degree is normal fundus, II degree is focal small arteriolar contraction, III degree has exudation with or without hemorrhage, IV degree is optic disc edema , III degree or IV degree fundus changes suggest malignant hypertension, and can quickly progress to the possibility of hypertensive encephalopathy.

Some diseases may have special symptoms, such as pheochromocytoma may have sweating, palpitations, tachycardia, weight loss, etc.; hypercortisolism may be weak, obese, body shape changes, hairy, freckle, slow growth, etc. Primary aldosteronism has low periodic muscle tension, weakness, hypokalemia, hand and foot spasm, polyuria, polydipsia, etc.; the clinical features of adrenal gland abnormalities are masculine and high blood pressure coexist.

The positive signs are different due to their primary disease. During the physical examination, the blood pressure of the extremities must be measured and the carotid artery and limbs pulse should be measured. The blood pressure of the upper limbs of the aortic coarctation is higher than the blood pressure of the lower limbs by 2.67 kPa (20 mmHg). In severe cases, the femoral artery pulsation disappears. Lower extremity blood pressure can not be measured, at the same time must pay attention to abdominal waist and neck large blood vessel murmur, about half of children with renal vascular disease can hear vascular murmur, should also pay attention to abdominal percussion, such as the tumor may be hydronephrosis, more Cystic kidney, pheochromocytoma, neuroblastoma or renal embryonal tumors.

Examination of hypertension in children

The following checks should be routinely performed:

1. Urine routine, urine culture, urine catecholamine qualitative.

2. Blood routine examination.

3. Determination of serum electrolytes, especially potassium, sodium, calcium, phosphorus.

4. Determination of blood lipids: total cholesterol, triglyceride, high density lipoprotein cholesterol, low density lipoprotein cholesterol, apolipoprotein A, apolipoprotein B.

5. Determination of plasma creatinine, urea nitrogen, uric acid, fasting blood glucose.

6. Determination of renal venous plasma renin activity ratio: preoperative preparation if necessary: oral furosemide 1mg / (kg · d), 2 times / d, a total of 1 ~ 2 days, and given a low sodium diet, stop With -blockers, a single dose of captopril was given orally 30 minutes before, and the results showed that the activity of renal vein renin was more than 1.5 times higher than that of the contralateral side.

7. Determination of plasma renin activity: Determination of plasma renin activity after oral administration of a single dose of captopril, such as greater than 12 ng / (ml · h), can diagnose renal vascular hypertension, pay attention to not taking antihypertensive drugs such as diuretics .

8. Endocrine examination: plasma norepinephrine, adrenaline and thyroid function tests, such as blood pressure treatment failed to control, or the corresponding special symptoms and signs of secondary hypertension, after comprehensive analysis, can selectively carry out the following special examinations :

9. ECG, chest lateral photo and kidney ultrasound.

10. Intravenous pyelography: rapid sequence method, it can be seen that one side of the kidney excretion contrast agent is later than the contralateral side, the kidney outline is irregular or significantly smaller than the contralateral side (the diameter difference is more than 1.5cm), the contrast agent density is greater than the contralateral side, or the upper ureter and There is an indentation of the renal pelvis (caused by dilated ureteral artery compression). Since the size and position of the kidney can only be estimated semi-quantitatively, and there are false positives and false negatives, it is currently not used.

11. Radionuclide kidney map: 131I. Hippuran (131I. sodium urate) kidney map, measured 131I. Hippuran excretion rate from urine, reflecting effective renal plasma flow, 99mTc-DTPA (99m-diethylenetriamine pentaacetic acid Kidney scan, reflecting glomerular filtration rate, renal renal artery stenosis, renal plasma flow is asymmetric, one side is greater than the contralateral 40% to 60%; one side of the radionuclide delay appears; the concentration of both kidney nuclide is consistent, excretion consistent .

12. Captopril-radionucleotide kidney diagram principle: Captopril is an angiotensin-converting enzyme (ACE) inhibitor, which prevents angiotensin II-mediated contraction of the small arteries after glomerular glomeruli. Therefore, after taking captopril, the radionuclide renal graph examination showed that the glomerular filtration rate of the affected side decreased sharply, but the plasma flow did not change significantly. Method: oral single dose of captopril, children 0.5 mg/kg Before taking the drug, the radionuclide renal graph was performed 60 min and 90 min after the administration. The results showed that the intake and excretion of DTPA on the affected side decreased after taking captopril, while the 131I.-Hippuran intake did not change, and the affected side GFR/RPF was obvious. reduce.

13. Renal angiography: It can be confirmed that the stenosis is bilateral or unilateral, the stenosis is in the renal artery or its branches, and the balloon angioplasty can be performed at the same time. If the serum creatinine is >119mmol/L, the contrast agent The total amount should be limited and properly hydrated and expanded.

14. CT and MRI examinations.

Diagnosis and diagnosis of hypertension in children

First identified as primary or secondary hypertension, diagnosed as primary hypertension exclusion, except for a variety of possible secondary factors, combined with the corresponding history, symptoms and signs, the corresponding laboratory and auxiliary examination To identify the cause of secondary hypertension as early as possible.

Essential hypertension is slow and often asymptomatic due to onset, and is easily overlooked. Therefore, blood pressure should be included as a routine part of regular child physical examination for early detection. If there is suspected hypertension, blood pressure should be measured regularly. If the blood pressure continues to rise for more than a few weeks or months, other tests should be performed to exclude secondary hypertension. The primary hypertension can depend on the age of the child (usually in the elderly over 10 years old), and the blood pressure rises slightly. High, low to moderate obesity, positive family history, no symptoms and signs of the primary disease to prompt diagnosis.

The diagnosis of secondary hypertension is mainly to find the primary disease. According to the age of the child, the degree of hypertension, or the symptoms and signs, those with intermittent fever should pay attention to repeated infection of the urinary tract (reflux nephropathy), height, If the weight is lower than normal, there is a chronic disease. Pay attention to whether there are any masses or abdominal vascular murmurs on both sides of the abdomen. The blood pressure of the extremities is measured to exclude the aortic constriction. Generally, the lower extremity blood pressure is 10-20 mmHg (1.33 to 2.67 kPa) higher than the upper limb. The reduction or disappearance of limb blood pressure is more common in multiple arteritis. Screening should include blood, urine routine, serum electrolytes, blood urea nitrogen, serum creatinine, uric acid, etc., suspected infection should be used for urine culture, and chronic hypertension should be used for cardiac ultrasound. And ECG examination, pay attention to the presence or absence of left ventricular hypertrophy.

Renal imaging examination can be found in related content. Ultrasound examination can understand kidney size, morphology, collecting duct system, kidney lesions or space-occupying lesions. Intravenous pyelography can not detect the difference of renal perfusion. Radionuclide kidney map can identify renal function. Or scar, renal Doppler ultrasound and angiography can show the main artery or branch of the artery, and abnormal blood flow of arteries and veins. When angiography, blood can be taken from the renal vein and inferior vena cava to check the renin activity.

Peripheral blood renin activity can be used for the screening of renal parenchyma and renal vascular diseases. The normal value decreases with age. The values of the laboratories vary greatly. Too low indicates that the mineralocorticoid acts too much. Or renal vascular involvement, further laboratory tests are required depending on the cause of hypertension.

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