Renovascular hypertension in children

Introduction to pediatric renal vascular hypertension 65% to 80% of children with hypertension are secondary hypertension, and renovascular hypertension (RVH) is one of them. Renal vascular hypertension, mainly refers to renal artery stenosis, refers to unilateral or bilateral renal artery and/or its branch lesions cause hypertension caused by renal ischemia. basic knowledge The proportion of illness: 0.002% Susceptible people: children Mode of infection: non-infectious Complications: Hypertensive encephalopathy Congestive heart failure Acute renal failure

Causes of pediatric renal vascular hypertension

Congenital renal artery fibromuscular dysplasia (35%):

It is the main cause of RVH in children and adolescents reported abroad. The lesions occur mostly in the middle or distal part of the renal artery. They are often involved in their branches. There are several common types: (1) Intimal fibrosis: mainly the narrowing of the renal artery trunk. Deformation, angiography showed focal stenosis in the middle, (2) middle fibrosis: intermittent destruction and thickening, more spread to the distal segment of the renal artery, angiography with beaded shadow, (3) fibromuscular hyperplasia: kidney The arterial wall is concentrically thickened. Renal artery angiography shows smooth stenosis of the renal artery and its branches. (4) Subendral fibrosis: severe renal stenosis, irregular angiography and abundant collateral circulation.

Multiple arteritis (25%):

A non-specific chronic vascular inflammatory disease is the main cause of RVH in adults and children in China. This disease is more common in girls over 10 years old. It is rare in infants and young children. The ratio of male to female is 1:8. The basic lesion is the elasticity of the middle layer of the artery. Fibrotic hyperplasia and varying degrees of small round cell infiltration, eventually leading to thickening of the vessel wall, scar formation, loss of elasticity of the vessel wall, stenosis of the lumen or aneurysm-like bulging, mainly invading the aortic arch, thoracic, abdominal aorta and Branch, 60% to 70% involving one or both renal arteries, lesions often located in the renal artery at the beginning of the abdominal aorta stenosis, causing hypertension, other vascular lesions such as hemolytic uremic syndrome, nodular polyarteritis , Ehlers-Danlos syndrome, Kawasaki disease, etc.

Other (20%):

Renal artery thrombosis or embolism, found in the history of trauma or neonatal umbilical vein cannulation, renal artery venous fistula, renal aneurysm, renal artery stenosis after transplantation and congenital renal artery abnormalities (renal arteries uniform small distortion or narrow) Renal dysplasia and renal artery involvement of neurofibromatosis, as well as other renal tumors, renal cysts, the renal artery is affected by the fiber cord, the para-aortic lymph node compression, etc., also according to the location of the lesion is divided into the main invasion of the kidney Arterial disease, intrarenal renal artery disease and lesions outside the renal artery.

Pathogenesis

The renin-angiotensin-aldosterone system (RAAS) plays a major role in renovascular hypertension and can be elucidated using two classical Glodblatt models.

1. The double kidney single clip is similar to the unilateral RVH. The side of the renal artery is clamped to reduce the blood flow of the clamped renal artery, and the secretion of renin is increased by stimulating pressure and chemosensory dense spots, angiotensin II ( After the formation of ATII) increases, it passes:

(1) directly contract the small arteries of the whole body.

(2) Stimulate the release of aldosterone, causing water and sodium retention.

(3) ATII can stimulate the sympathetic nerve, enhance its vitality, stimulate the synthesis of adrenal medulla, and release norepinephrine, causing hypertension, but this mechanism can be partially compensated by the contralateral renal stress urination. In the end, there is no sodium retention, and the result is:

1 increased ischemic side renin secretion.

2 contralateral normal kidney due to elevated blood pressure and negative feedback of sodium retention, inhibition of renin secretion.

3 ischemic renal blood flow decreased.

4ATII-induced vasoconstriction leads to hypertension, and ATII receptor antagonist or angiotensin-metastatic inhibitor (ACEI) can attenuate the effect of ATII, lower blood pressure, but inhibit the feedback inhibition of contralateral renin, and the renin and ATII increase.

2. Single kidney single clip: for clamping a case of renal artery, and the contralateral kidney is removed, the isolated kidney is more consistent with this model, so that the action of pressure diuretic sodium does not occur again, resulting in sodium retention, while feedback inhibition Renin secretion, peripheral plasma renin level is normal or decreased after the acute phase, ACEI alone can not prevent the occurrence of hypertension, if the diuretic sodium discharge, blood pressure can be reduced, this RVH can be renin dependent, can also It is volume-dependent, and whether bilateral renal artery stenosis is consistent with this is still controversial. In addition, the kallikrein-kinin-prostaglandin system also plays a role in the pathogenesis of RVH. After kinin is activated by kallikrein, Promotes the synthesis of prostaglandins, which can dilate the systemic arterioles, reduce peripheral vascular resistance, renal vasodilation, and increase renal blood flow.

It promotes the discharge of sodium and water. In the Glodblatt animal model, the activity of kinin kallikrein is reduced. The above factors are involved in the occurrence of hypertension. The occurrence of RVH is related to the speed and period of renal artery stenosis. Renal artery occurs. Hypertension, which is an acute phase, can occur in a few minutes after embolization. At this time, it is mostly renin-dependent hypertension. If you use ACEI, your blood pressure can be quickly and effectively reduced. After a few days or weeks, you will enter the transitional phase. Renin and angiotensin still maintain high levels, but sodium and water retention have been effective. The application of ACEI can still lower blood pressure, but the speed is slowed down, and finally the chronic phase, water, sodium retention and blood volume expansion on the kidney The secretion of the hormone can inhibit the action.

Prevention of renal vascular hypertension in children

The key to prevention is to vigorously prevent and actively treat primary diseases that cause renal vascular hypertension, such as multiple arteritis and atherosclerosis.

Patients with renal vascular hypertension should take the right measures for the right medicine, and should be actively treated for a limited time. It is recommended to use traditional Chinese medicine to relieve vascular obstruction and restore blood flow to the kidneys. On the other hand, it will fundamentally repair damaged kidney tissue and restore normal kidney function. The effect is good after the treatment.

Pediatric renovascular hypertension complications Complications hypertensive encephalopathy congestive heart failure acute renal failure

Renal vascular hypertension with the improvement of diagnostic methods, the continuous improvement of surgical techniques, the improvement of vascular substitute materials, the operative complications are gradually reduced, but due to the differences in medical conditions and doctors' technical proficiency, some complications Occasionally, common complications are as follows.

1, bleeding

Postoperative bleeding is mainly caused by surgical procedures. If the surgeon sutures the vascular technique, the vascular seam is poorly matched, the needle spacing is too large, the knotting is not firm, the ligature is loose or the artificial vascular mesh is oozing.

Precautions: The operator must operate carefully and do not slip. When suturing a blood vessel with a nylon thread or a polyester thread, it is best to play 4 to 5 knots to prevent the ligature from slipping off. The vascular seams should be aligned and evenly spaced to prevent blood leakage. The suture needle should not be too thick. For dry needle eye bleeding, you can use a warm saline gauze to compress for a while; do not rush to suture the bleeding site to prevent the appearance of: "The seams are sewn, the seams are out, and the seams are more and more out of the wolf."

For the application of artificial blood vessels, if the vascular network is larger, there will be more oozing. Therefore, when selecting a blood vessel, it should be a small blood vessel with the same pores.

2, diffuse oozing

This is mainly due to poor blood coagulation, which can be caused by congenital or acquired diseases.

(1) hereditary bleeding disorders

Like hemophilia and hereditary fibrinogen deficiency. Hemophilia is a tendency to hemorrhage after wound trauma, and the clotting time is significantly prolonged. Most of these patients have a history of bleeding from childhood, through detailed preoperative examination of the disease, you can get repeated bleeding gums, nosebleeds, menorrhagia, traumatic local skin and mucous membrane bleeding, tooth extraction bleeding. Too many other medical history. There are several generations of male bleeding abnormalities in relatives, and the possibility of hemophilia should be considered.

(2), acquired acquired coagulation dysfunction, may be caused by the following reasons

1 liver function beads and vitamin K deficiency: such as diffuse bleeding after water, the general cause is difficult to explain, lead A blood for blood coagulation function check. Such as liver dysfunction, partial prothrombin production time may be prolonged; if there is liver disease or vitamin K deficiency, the thrombin time is prolonged.

2 a large amount of blood transfusion: renal revascularization surgery, generally do not need a lot of blood transfusion. Once needed, the function of platelets may also be impeded due to the significant reduction in the number of platelets in the blood. In addition, the activity of the V and W factors in the blood plasma of the library is also greatly reduced, and the free calcium lowers the small H value, the cold temperature and the like, and a large amount of blood can cause a diffuse dish. One believes that the blood of the transport does not exceed 5000ml. If it exceeds this amount, it should lose some fresh blood, reduce the input of dextran, antihistamine drugs that affect the platelet aggregation function.

A large amount of blood transfusion caused by diffuse oozing. Treatment can transport platelets or fresh blood, which can correct platelet function; and supplement some clotting factors to stop bleeding.

3, plug formation

In renal vascular hypertension, renal revascularization surgery, whether it is internal femoral stripping or bypass surgery, intraoperative and post-surgery can form thrombus on the surface of each anastomosis or on the surface of the graft, which is the kidney. Common complications of revascularization.

4. Renal failure after renal recanalization

After renal revascularization and recanalization, it is rare to cause renal failure. However, for patients with complicated renal reconstruction accompanied by hypertension during surgery or preoperative renal disease, renal dysfunction is very common after surgery. In most patients, during the reconstruction surgery, the collateral circulation of the kidney is not destroyed, and the blood perfusion of the kidney is generally ensured. Clamping the main artery of the kidney for 60-90 minutes also showed a significant decrease in renal function. If the collateral circulation is disrupted during surgery or systemic hypotension has occurred, renal perfusion may only reach the marginal cortex, and damage to the renal tubules will be difficult to avoid.

In patients with renal vascular hypertension, special attention should be paid to water and electrolyte balance before surgery. Many of these patients often limit water intake due to drug treatment. Some people argue that when the renal artery is obstructed, proper administration of water, mannitol and diuretics before and after surgery is necessary. Because these measures can temporarily maintain the production of urine, otherwise severe hypoperfusion will occur, and it is difficult to prevent kidney damage.

5. Heart failure, myocardial infarction.

Pediatric renovascular hypertension symptoms common symptoms fatigue edema vertigo hypertension irritability vascular murmur visual impairment eye fundus changes convulsion renal failure

Symptom

Renal vascular hypertension can occur at any age, and many infant cases have been reported. The smallest is only 7 to 10 days. The incidence rate is similar for men and women. The symptoms are different. Small babies may have vomiting, poor developmental nutrition, and congestive heart. Depletion and acute renal failure can be treated because of headache, especially occipital headache, dizziness, irritability, excessive excitement, restlessness and fatigue. Severe patients may have hypertensive encephalopathy, transient visual impairment, convulsions, etc. Can be expressed as abnormal behavior or hyperactivity, etc. Most of the sick children have been present for a considerable period of time due to severe hypertension. At the time of diagnosis, symptoms such as heart, brain, kidney and other target organs have been affected. Patients with aortitis may still be involved. There are symptoms such as low fever, fatigue and joint pain.

2. Signs

(1) Hypertension: Almost half of the children found hypertension during routine physical examination. The systolic or diastolic blood pressure in children exceeded the 95% of the age and gender groups, which was equivalent to the same age, the same sex group average. The value of 2 standard deviations is hypertension; between 95% and 99% of the values, for meaningful hypertension, more than 99% of the values are severe hypertension, RVH patients are severe hypertension, Fundus examination can show different degrees of hypertensive fundus changes: I degree, normal fundus; II degree, focal small artery spasm; III degree, with or without bleeding; IV degree, optic disc edema.

(2) vascular murmur: about 1/3 to 2/3 children (mostly patients with arteritis) can hear vascular murmurs in the middle and upper abdomen and/or the back ribs, and are more easily heard on an empty stomach. Systolic and diastolic continuous murmurs, if the stethoscope moves parallel from the middle to the abdomen, the murmur enhancement is more clinically significant. In addition, attention should be paid to the ischemic symptoms caused by aortitis. If the innominate artery is involved, sputum, sputum occurs. Arterial pulsation weakened or disappeared; if the radial artery involved could cause lameness, cold hands and feet, femoral artery, dorsal artery pulsation weakened or disappeared, children with hypertension need to further check serum endogenous creatinine clearance rate, potassium, sodium, chloride, Blood gas analysis, blood, urinary aldosterone, urinary catecholamine and its metabolites and vanillic mandelic acid (VMA) were measured to initially exclude renal parenchymal hypertension and endocrine, neurological, cardiovascular and other diseases, such as: Aortic coarctation, primary aldosteronism and pheochromocytoma, etc., who are diagnosed with RVH, perform the following tests to determine the presence or absence of renal artery stenosis, and to understand the location of renal artery stenosis, the nature and extent of the lesion, Processing data show that when the cross-sectional area reduction of renal arteries 50% to 80% or more may occur only RVH.

Examination of renal vascular hypertension in children

Blood routine, urine routine, urine bacteriological examination, blood urea, creatinine, potassium, sodium, calcium, chloride and blood gas analysis should be listed as routine examination, most patients above the test results are normal, when severe hypertension has secondary kidney Proteinuria, elevated blood urea and creatinine may occur in the lesions, electrocardiogram is mostly left ventricular high voltage or left ventricular hypertrophy, X-ray chest radiograph shows left ventricular enlargement, and RVH-induced whole heart failure is generally increased throughout the heart. Large, pulmonary congestion.

Diagnosis and diagnosis of renal vascular hypertension in children

diagnosis

Screening check

(1) Rapid continuous intravenous pyelography (IVP): 1 , 2, 3, 5, 10, 15 min after injection of contrast agent, to understand the size of the kidneys, kidney development and excretion, the positive criteria are:

1 The long diameter of the ischemic kidney is shortened by 1 to 1.5 cm (normally, the left kidney is slightly larger than the right kidney by 0.8 cm).

2 delayed renal pelvis and renal pelvis development, no development and / or reduced development concentration.

3 late contrast agent excretion delay, the coincidence rate of this method in children is 42% to 65%, false negatives are mostly renal artery stenosis or renal artery branch stenosis, intravenous diuretics can also be administered during examination, can make the pelvis The contrast agent rapidly "eluting", the kidney has a small glomerular filtration rate, and the contrast agent is discharged slowly, thereby expanding the difference between the two kidney excretion contrast agents, and is beneficial to improve the diagnosis of RVH.

(2) Color Doppler ultrasonography: two-dimensional ultrasound images can be used to understand the difference in the size of the kidneys, such as one side of the renal artery stenosis, the kidney is significantly smaller than the healthy side, and the double renal artery can be explored by Doppler ultrasonography. Diameter, blood flow and flow rate, to understand the presence or absence of renal artery stenosis, a rapid, non-invasive, reproducible screening test.

(3) Radionuclide examination: preliminary understanding of the blood perfusion, secretion and excretion function of bilateral kidneys. In recent years, 99mTc-DTPA renal dynamic imaging has been applied to reflect the two more comprehensively. The size of the lateral kidney, the peak time of renal perfusion, the degree of renal function and the degree of difference between the two kidneys, can also be used in the ACEI inhibition test to enhance the degree of difference in the perfusion, secretion and excretion of the tracer in the kidneys between the kidney and the kidney. The sensitivity and specificity of the test are improved.

(4) Plasma renin activity and angiotensin inhibition test:

1 Peripheral plasma renin activity (PRA) determination: renin secretion has circadian rhythm, PRA activity is the lowest at 8 o'clock in the morning, the highest secretion from noon to 8 o'clock, PRA and hypertension do not have a simple parallel relationship, due to RVH The time of existence, unilateral or bilateral and severity, the PRA value varies greatly, the patient's PRA can be significantly increased, a few are normal or reduced, in addition, the measurement is also affected by sodium intake, body position, age and use The effects of various factors such as pressure control need to be detected after 2 weeks of antihypertensive and diuretic withdrawal, and the use of antihypertensive diuretics may cause serious complications of hypertension, as well as primary hypertension and kidney in children. Substantial hypertension, PRA can also be elevated, so the sensitivity and specificity of the diagnosis of RVH are very poor.

2 angiotensin inhibition test: it is convenient to use oral captopril, oral captopril, can block the production of ATII, through the negative feedback effect to significantly increase the secretion of renin, in order to improve the sensitivity of the test Sex and specificity, observed changes in PRA before and after the test. METHODS: Diuretic and antihypertensive drugs were stopped 2 weeks before the test, and the children were given a supine position. Captopril (Kai Bo Tong) was orally administered with 0.7 mg/kg of water and 20 ml orally. Flush with warm boiled water, take it again), take PRA and blood pressure 30 minutes before taking the medicine and 1 hour after taking the medicine. The positive result is:

A. Diastolic blood pressure drops 15%.

B. Before blood administration of PRA>5ngAI/(ml·h), >10ngAI/(ml·h) after administration, the difference between PRA after treatment is >4ngAI/(ml·h), after using captopril, The reduction of ATII production, sodium retention feedback inhibited the release of renin, and increased renin secretion. This test showed that the increase of PRA after treatment was more diagnostic than the decrease of blood pressure. Positive results suggest that surgery can achieve good results, but this test has strict Preoperative preparation and requirements are required to obtain reliable data and are not very clinically applicable.

2. Confirmation examination

(1) Digital Substraction angiography (DSA): This is an electronic computer-assisted X-ray imaging technique. The principle is to apply a digital video image processing system in an angiogram. Go to a urinary tract flat bone, soft tissue and other shadows, because the other tissue shadows are eliminated, leaving only the only image of the renal artery, so that the sharpness of the renal artery development is significantly improved, and the inner diameter of the renal parenchyma can be recognized.

(2) renal angiography: the screening test is positive or the screening test is negative and still highly suspected RVH can be used for this examination, the use of percutaneous cannula for angiography, can better show the kidney including the arcuate artery The lesions, location, extent, degree of stenosis and collateral circulation of the arteries and their branches are reliable methods for the diagnosis of RVH. Based on this, the surgical treatment method can be determined, the surgical effect can be estimated, and intracavitary vasodilation can be performed at the same time as necessary. Intraoperative (PTA) treatment, young children with small blood vessels, but also do not cooperate, sometimes need to be performed with the help of intravenous anesthesia, there is a certain risk, such as wound bleeding, vascular embolism and acute renal failure before the examination Therefore, the patient should be carefully selected, and adequate preparation should be done before surgery. For example, before the angiography, hypertension should be controlled to prevent wound bleeding. Immediately after the angiography, 20% mannitol 20-40 ml should be intravenously administered, followed by rehydration to reduce acute kidney. Complications of dysfunction and vascular embolism.

(3) Magetic resonance angiography (MRA): is a reliable non-invasive examination method. The accuracy of RVH diagnosis can be the same or better than DSA because it is a three-dimensional renal artery vascular image. It can clearly show the renal artery in the aortic opening, and it can avoid the dangers and complications of iodine allergy, hemorrhage, thrombosis and other diseases caused by renal angiography. It is suitable for allergic to angiographic contrast, heart and kidney function. Incomplete or bleeding quality, but for young children, imaging time required to hold 20 to 30s, it is difficult to cooperate.

Differential diagnosis

1. Reninoma (ball paracellular disease): There are also refractory and severe hypertension, elevated plasma renin activity, secondary increase in blood aldosterone, high urinary aldosterone and hypokalemia, which are highly renal-vascular Blood pressure, but its renal venous renin activity showed a significant increase in one side, renal angiography was repeated normal, although the distribution of blood vessels in the kidney may be abnormal, such as abnormal direction of operation, flexion and dilation of small arteries, B-ultrasound, CT examination can be seen Space-occupying lesions.

2. Pheochromocytoma: sudden increase in blood pressure, often with wind upset, similar to renal vascular hypertension, but pheochromocytoma often has sympathetic excitation, such as sweating, pale face, palpitations, etc., urine The catecholamine (VMA) was positive, and the abdominal X-ray film showed calcification in the adrenal gland. Abdominal B-ultrasound could detect the tumor.

3. Chemoceptoma (chemodectoma): also known as non-chromophobic paraganglioma, originated from the aorta or carotid body, mostly occurs in the neck and has no function. Nearly 90 cases have been reported in China since 1958. Recently, Peking University Hospital of Pediatrics also saw a 9-year-old boy with persistent persistent hypertension, with headache onset, symptoms resembling pheochromocytoma, plasma renin activity and AII increase, similar to renal vascular hypertension, B-ultrasound A retroperitoneal mass was found, and the tumor tissue was negative for chromatin after resection, which is the only difference from pheochromocytoma.

4. Primary aldosteronism: The disease first developed hypertension, serum potassium decreased, blood sodium increased, blood aldosterone increased, similar to renal vascular hypertension, but the former plasma renin activity decreased, and blood aldosterone increased Can not be inhibited for salt load test, can be identified.

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