renal artery stenosis

What is renal artery stenosis, what is the cause? A: renal artery stenosis (RAS) refers to a variety of reasons caused by unilateral or bila


What is renal artery stenosis, what is the cause? A: renal artery stenosis (RAS) refers to a variety of reasons caused by unilateral or bilateral renal artery stenosis or main branch, which is one of the most common causes of secondary hypertension. The reason of renal artery stenosis complicated for congenital abnormal, can also be caused by large arteritis, atherosclerosis, arterial wall development. Before 1990s, arteritis was the first cause of renal artery stenosis in china. In recent years, atherosclerosis has replaced Takayasu's arteritis become the primary causes of RAS currently. Renal artery stenosis can occur in renal artery trunk or branch. Because of the stenosis of renal artery stenosis, before and after the blood pressure had obvious differences, resulting in renal ischemia, thus stimulating the human renin secretion, activation of the renin angiotensin aldosterone system, and cause hypertension.

Atherosclerosis occurs in elderly patients.  fibromuscular dysplasia: young people see more, western countries also see more.  arteritis - see more young women. Other rare causes include congenital renal artery dysplasia, renal artery aneurysm, renal artery embolization, renal arteriovenous fistula, renal artery injury caused by trauma or surgery. Usually, the sick children for congenital anomalies, young adults for renal arteritis or fibromuscular hyperplasia, the elderly is more for atherosclerotic renal artery.

What is the consequence of renal artery stenosis? A: (1) renovascular hypertension is the main clinical manifestation of renal artery stenosis, renal vascular hypertension is the secondary cause of hypertension of the second major causes. Is characterized by high blood pressure, ordinary antihypertensive drugs difficult to control. (2) renal atrophy is a direct consequence of renal artery stenosis. Patients with renal atrophy showed progressive renal insufficiency. (3) patients with end-stage renal disease (ESRD) were studied and analyzed in the last 20 years because of the final ESRD dialysis treatment in a total of 683 patients, of whom, 83 (12%) were diagnosed with RAS. However, according to the current data can not be fully defined the impact of RAS on ESRD. (4) recurrent pulmonary edema in patients with renal artery stenosis may occur or recurrent pulmonary edema. Patients with severe bilateral or unilateral RAS may manifest as volume overload. Patients with unilateral RAS may also have an increased left ventricular afterload because of angiotensin mediated vasoconstriction. (5) cardiovascular events in patients with RAS have a higher risk of cardiovascular events, which may be due to systemic atherosclerosis. In patients with severe RAS, because of the high level of angiotensin II in the body, leading to vasoconstriction of peripheral arteries, coronary artery ischemia can be induced. (6) patients with asymptomatic renal artery stenosis with renal artery stenosis can also be seen as having no clinical signs, but the presence of renal artery stenosis during coronary angiography and peripheral angiography. Compared with those without renal artery stenosis, the prognosis of patients with asymptomatic renal artery stenosis is poor. A study found that the accidental discovery of cardiac catheterization in asymptomatic and severe RAS (more than 75%) of the 4 year survival rate was 57%, and 89% patients with severe RAS.

Why renal artery stenosis can cause high blood pressure? A: because the kidney in our memory in a blood pressure regulation signal system -" renin angiotensin aldosterone system, " this system is to protect the kidney, in the body of a drop in blood pressure, decreased renal blood flow, the system will send a signal to elevated blood pressure, maintain renal blood flow. Angiotensin can make the body's Micro artery contraction, peripheral vascular resistance increases, so that blood pressure increases, while the increase in aldosterone induced increase in blood volume, but also increase blood pressure. When the renal artery stenosis, renal blood flow is reduced, the same regulation system that is due to decreased blood pressure caused by the same active, elevated blood pressure, leading to renal artery stenosis in patients with hypertension. The high blood pressure is intractable and difficult to use. This is due to renal artery stenosis caused by renal ischemia caused by high blood pressure, clinically known as renovascular hypertension. In the late stage of the disease, the level of plasma renin decreased, and the mechanism of hypertension was the decrease of glomerular filtration rate and the retention of sodium and water.

Why do some patients before renal artery stenosis and found no obvious hypertension? Answer: as we have said before, the clinical manifestations of patients with renal artery stenosis can be no specific, some due to renal atherosclerotic renal artery stenosis in patients with high blood pressure can not occur, and showed ischemic renal disease, gradually lead to glomerular sclerosis and renal renal tubular atrophy and interstitial fibrosis. The clinical manifestations of renal function loss (renal tubule dysfunction occurs early, patients with nocturia, urine specific gravity and osmotic pressure decreased; and impaired glomerular function, creatinine clearance decreased, serum creatinine increased), mild urinary abnormalities (mild proteinuria, a small amount of red blood cells and kidney and tube type) the volume of progressive narrowing (two renal size often asymmetric) etc..

How to diagnose renal artery stenosis? What is the possibility of renal artery stenosis? A: renal artery stenosis is generally the incidence of insidious, but there is a tendency to gradually increase, once the symptoms often have reached the late stage, it must be in the occurrence of irreversible renal damage before the diagnosis. Due to renal artery stenosis caused by hypertension and essential hypertension clinical symptoms no difference, the diagnosis depends on a high degree of vigilance. So when it was discovered that some clinical clues should be thought that there is the possibility of this disease may appear the following situations that RAS (1) following hypertension: hypertension appear before the age of 30, or 55 years after the onset of severe hypertension; the primary hypertension (previous controlled hypertension suddenly appeared continuous deterioration); the refractory hypertension (3 antihypertensive drugs included diuretics when combined with enough, still difficult to reach the target blood pressure); the malignant hypertension (with acute hypertension target organ damage, such as acute renal failure, acute heart failure or new onset of optic nerve or other brain lesions and III~IV retinopathy etc.); (2) when the application of angiotensin converting enzyme (ACEI) inhibitors or angiotensin receptor antagonist (ARB) the emergence of new drugs Azotemia or deterioration of renal function (serum creatinine of greater than 50%), or the elderly renal function is not easy to explain the decline; (3) there are unexplained renal atrophy; (4) the sudden appearance of pulmonary edema; (5) abdominal vascular murmur could be heard; (6) ultrasound examination found double kidney size obvious asymmetry; (7) associated with other vascular diseases, such as coronary heart disease, carotid artery stenosis or lower extremity artery stenosis.

What are the clinical manifestations of renal artery stenosis? A: 1, renal vascular hypertension patients with renal artery stenosis, most of them do not have a family history of hypertension, which is characterized by rapid progress in hypertension, and blood pressure is not easy to control. Diastolic blood pressure increased significantly (often more than 110 120mmHg), can be expressed as malignant hypertension (blood pressure significantly increased diastolic blood pressure, lasting more than 130 mmHg, and a headache, blurred vision, retinal hemorrhage, exudation and papillary edema and even sudden blindness, epilepsy seizures, persistent proteinuria, hematuria and cylindruria). 2, abdomen, waist, about 50% of patients can be around the umbilical 2~7cm, around the 2.5cm systolic murmurs heard. 3, the primary disease manifestations caused by atherosclerosis or Takayasu's arteritis, often Youyuan onset, the former occurred in the elderly, can appear stroke, coronary heart disease, peripheral arterial sclerosis and fundus changes; the latter is a young female, fever, arthralgia, veinless etc.. 4, other: some patients with high blood pressure (caused by hypokalemia), mild urinary abnormalities, impaired renal function (ischemic kidney disease).

What examinations are needed for patients with suspected renal artery stenosis? Answer: Patients with renal artery stenosis often need to do the following checks: 1, routine examination including blood routine, urine routine, stool routine and blood biochemical examination. Anemia is often a manifestation of renal insufficiency, to think of the possibility of renal artery stenosis, serum creatinine, creatinine clearance is the most commonly used to determine the index of renal function. Hypokalemia is a manifestation of secondary aldosteronism. 2 imaging examination (1) double renal artery ultrasound: B ultrasound found that the difference between the length of the kidney of more than 1.5cm of two or more often can be explained on the side of the small renal artery stenosis. The changes of renal artery and renal blood flow were observed by color Doppler ultrasonography. Compared with the contrast, the sensitivity was as high as 84%~98%, the specificity of 92%~99%. It can also be used to measure the resistance index of renal artery. It can also be used to determine the effect of renal artery revascularization. (2) () plasma renin angiotensin system test and renin challenge test are not necessary for the diagnosis of renal artery stenosis, but some endocrine tests are sometimes useful in some cases. (4) renal artery CT and / or nuclear magnetic resonance: CT, MRI examination of renal artery can be found in the degree and extent of stenosis. (5) renal arteriography: the most diagnostic value (gold). Can clearly demonstrate the location, scope, extent and formation of collateral circulation, and angiography were treated at the same time. Atherosclerotic lesions in the renal artery and abdominal aorta. Aortitis lesions in the descending aorta and renal artery proximal 1/3 segment. Fibromuscular dysplasia lesions in the distal renal artery 1/3 segment and primary branch.

What is the treatment of renal artery stenosis? A: the treatment of renal artery stenosis for the purpose of reducing blood pressure, more important is to preserve renal function. Including: 1, medical treatment: can not improve the incidence of renal ischemia, can only help control hypertension. However, hypertension can prevent complications caused by high blood pressure, such as cerebral hemorrhage, hypertensive encephalopathy, acute renal failure, aortic dissection, etc.. In this case it is very important to quickly buck. The usual treatment of hypertension can not be ignored, ACEI drugs and calcium antagonists can effectively control RAS patients with hypertension, and delay the progression of kidney disease. ACE inhibitors and ARB may be effective in the treatment of hypertension induced by unilateral RAS. Beta blockers are effective drugs for treatment of hypertension induced by RAS. Diuretics can also reduce blood pressure to target levels in RAS patients. 2. Revascularization treatment: surgical treatment of renal artery stenosis can be divided into two categories, namely, the reconstruction of abdominal renal artery and percutaneous transluminal renal angioplasty. No matter what kind of treatment, the purpose is to make the stenosis of renal artery patency changed, the renal blood flow restored to normal levels, the kidney blood pressure regulation system no longer releases the elevated blood pressure signal, thereby reducing the patient's blood pressure. (1) percutaneous transluminal renal angioplasty. Through the femoral artery in the thigh, a catheter with a balloon inserted into the renal artery stenosis, and then use the contrast agent inflated balloon, from the inside of the expansion of renal artery stenosis to normal caliber, this method is especially suitable for patients with fibromuscular dysplasia. Because patients with Takayasu's arteritis occurs in atherosclerosis and restenosis after expansion of treatment failure, so these patients can be placed stent after dilation, to prevent postoperative stenosis. This kind of surgery was invented by a Swedish doctor in 1978. It has the advantages of small trauma, high safety and rapid postoperative recovery. It has been widely used in the world. It has become the first choice for the treatment of renal artery stenosis. Endovascular treatment indications of endovascular treatment for the abnormal hemodynamics, significantly in the following circumstances: RAS patients with primary hypertension, hypertension, malignant hypertension, with unexplained renal hypertension and reduce intolerance of drug treatment of hypertension; the progression of chronic kidney disease complicated with bilateral RAS or solitary kidney RAS patients; patients with sudden pulmonary edema to have significant hemodynamic significance in patients with RAS and RAS, with unexplained recurrent congestive heart failure or unexplained; the patients with unstable angina pectoris and significant hemodynamics in patients with RAS. Percutaneous transluminal renal angioplasty has some defects, such as high rate of recurrence is low, narrow the success rate of operation, there are some patients because of contrast agent allergy, iliac artery distortions and other reasons will not do the surgery, then you have to resort to the traditional transabdominal renal artery reconstruction surgery, including: abdominal aorta renal artery bypass, renal artery endarterectomy, renal artery stenosis, segmental resection of the disease of kidney renal transplantation end anastomosis, obtain blood supply, can not be the treatment can be considered when the kidney was. Abdominal aorta and renal artery bypass, or renal artery " we usually said; bypass " surgery, the surgical method is a section of the great saphenous vein from the patient's thigh, and one end of patients with abdominal aortic anastomosis stenosis, the other end to bypass the renal artery anastomosis in patients with renal artery, so the abdominal aorta bypass into the kidney solved the patients with renal ischemia. The disadvantage of this approach is that the trauma is relatively large, but the treatment effect is very reliable, but also can be used to treat patients who are not suitable for percutaneous transluminal renal angioplasty.

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