Renal artery stenosis

Introduction to renal artery stenosis The severity of renal artery stenosis varies from obvious renal artery stenosis to small renal artery lesions that are not clinically detectable. Severe stenosis can cause renal perfusion damage, decreased glomerular filtration rate (GFR), resulting in sodium retention, increased extracellular fluid volume, hypertension and renal failure. basic knowledge The proportion of illness: 0.002% Susceptible people: no special people Mode of infection: non-infectious Complications: Hypertension Retinopathy Cerebral thrombosis Heart failure Myocardial infarction

Cause of renal artery stenosis

(1) Causes of the disease

Common causes of renal artery stenosis are atherosclerosis, fibromuscular dysplasia and aortitis, chronic arteritis and chronic non-specific inflammation of the main branches, involving renal artery stenosis and renal ischemia, occurring at 30 years old The following women, renal artery muscle fiber structure is poor, lesions are located in the distal 2 / 3 of the renal artery and its branches, more common in young and middle-aged women, can be divided into intimal fibrosis, mesenteric fibromuscular dysplasia and adventitia or external Subtypes of fibrosis around the membrane, intimal fibrosis often with dissection thrombosis, mesenteric lesions often present a bead-like appearance, renal atherosclerosis, more common in men than middle-aged, lesions occur mostly in the main renal artery opening or near Within 1/3.

(two) pathogenesis

The pathophysiological mechanism of renal artery stenosis is divided into two groups, which are different on both sides.

The pathogenesis of renal artery stenosis can be divided into two phases: the main mechanism of maintaining hypertension in the first phase is increased renin release, increased systemic and intrarenal AngI production, and ACE under the action of endothelial cells in tissues, especially lung tissue. AngI is rapidly converted into AngII, AngII makes systemic vasoconstriction, increases aldosterone production, these AngII, aldosterone increase, the purpose is to increase renal perfusion pressure at the distal end of renal artery stenosis, thereby reducing renin release, the second phase to maintain hypertension The main mechanism is water, sodium retention, water, sodium retention for two reasons:

1 The perfusion pressure of the renal parenchyma is low, and the pressure-dependent sodium is weakened;

2 renal perfusion low pressure, increase renal renin activity, local Ang II increased, Ang II in addition to causing intrarenal vasoconstriction, but also stimulate renal tubular reabsorption, coupled with stimulation of aldosterone release, also increased sodium reabsorption, blood pressure Raise.

Unilateral renal artery stenosis: the pathogenesis of unilateral renal artery stenosis is relatively simple, unilateral renal perfusion pressure decreases, renin increases, Ang II increases, systemic blood pressure rises, hypertension acts on non-stenotic kidneys, and through pressure-diuresis Increased sodium excretion, but increased systemic AngII and aldosterone, AngII vasoconstriction reduces contralateral non-stenosis renal blood flow, reduces GFR, AngII on adrenal cortex, promotes aldosterone production, and promotes water and sodium recovery. It counteracts the pressure-diuretic effect of the contralateral non-stenosis kidney. The water and sodium balance can only be maintained by the pressure-diuretic effect caused by the increase of systemic blood pressure. The contralateral kidney is chronically hypertensive, and the effect of high AngII will slowly occur. Damage, in addition, vascular remodeling also plays an important role in the maintenance of chronic hypertension in renal vascular hypertension.

Prevention of renal artery stenosis

The key to prevention is to vigorously prevent and actively treat the primary disease causing renal vascular hypertension, such as multiple arteritis; atherosclerosis.

Renal artery stenosis complications Complications Hypertensive retinopathy Cerebral thrombosis Heart failure Myocardial infarction

There may be hypertension, severe retinopathy, cerebral thrombosis, heart failure, myocardial infarction, renal failure and other complications.

Renal artery stenosis symptoms common symptoms abdominal vascular murmur hypertension atherosclerosis

There is persistent high blood pressure, sometimes the upper limb can be touched without pulse, and the blood pressure of the upper and lower limbs can sometimes be significantly different. Physical examination often shows murmurs in the renal artery area, and the determination of the amount of urine can be significantly reduced on the affected side.

Sign

(1) Hypertension: The blood pressure is often greater than 200/120 mmHg, and the diastolic blood pressure is more obvious.

(2) Asymmetry of blood pressure in the extremities.

(3) Abdominal vascular murmur.

Examination of renal artery stenosis

Some patients may have abnormalities in laboratory tests such as hyperlipidemia and hyperglycemia.

In recent years, people have explored the use of new non-invasive imaging techniques to examine renal vascular disease. The new technologies currently used are:

1. Captopril-renin challenge test:

Under normal circumstances, after taking the conversion enzyme inhibitor captopril, the body's high renin response can be enhanced by inhibiting the negative feedback of angiotensin II. This reaction is particularly prominent in patients with renal artery stenosis. After 1 hour, the plasma renin increase was significantly greater than that of essential hypertension. The sensitivity and specificity of the test were 93%-100% and 80%-95%, respectively.

2. Captopril - radionuclide kidney map:

Renal artery-angiotensin system activity is stimulated by renal artery stenosis, and contraction of angiotensin II to the small arterioles helps maintain glomerular pressure and glomerular filtration rate, using a conversion enzyme inhibitor ( Inhibition of angiotensin II production, such as captopril, can reduce glomerular internal pressure and glomerular filtration rate, and can be more ideally detected by radionuclide technology before and after taking captopril. The ischemic condition of the unilateral kidney has a sensitivity and specificity of more than 90%.

3. Doppler ultrasound technology:

The combination of direct examination of the renal artery with abdominal ultrasonography and Doppler renal blood flow technique is currently the most commonly used screening method for the diagnosis of renal artery stenosis. Statistics show that the positive and negative predictive value of this technique for the diagnosis of renal artery stenosis are above 90%. Of course, the operator's experience is very important for accurate diagnosis. The development of renal artery during examination is often affected by gastro-intestinal gas, obesity, recent surgery and other nearby renal blood vessels. Sometimes the abdominal B-ultrasound knows whether the kidney has atrophy or morphological changes. Can also be used as a screening check.

4. Magnetic resonance imaging (MRI) and CT scans:

In recent years, magnetic resonance imaging and tomography have also been used for the diagnosis of renal artery stenosis. The specificity of MRI diagnosis can reach 92% to 97%. Recently, reports have shown that CT scanning is the most sensitive imaging examination for diagnosis of renal artery stenosis. Its sensitivity and specificity can reach 98% and 94%, respectively.

Diagnosis and diagnosis of renal artery stenosis

diagnosis

Screening check

In recent years, people have explored the use of new non-invasive imaging techniques to examine renal vascular disease. The new technologies currently used are:

(1) Captopril-renin challenge test: The sensitivity and specificity of the test can reach 93% to 100% and 80% to 95%, respectively.

(2) Captopril-radio-nuclear kidney map: its sensitivity and specificity can reach more than 90%.

(3) Doppler ultrasound: the combination of direct examination of renal artery with abdominal ultrasound and Doppler renal blood flow technique is currently the most commonly used screening method for the diagnosis of renal artery stenosis. Sometimes abdominal B ultrasound understands whether the kidney has atrophy or morphology. Changes can also be used as screening checks.

(4) Magnetic resonance imaging (MRI) and CT scan: In recent years, magnetic resonance imaging and tomography have also been used for the diagnosis of renal artery stenosis. The specificity of MRI diagnosis can reach 92% to 97%, and recent reports show that CT scan is the most sensitive imaging examination for the diagnosis of renal artery stenosis.

2. Confirmation examination

Screening test positive or negative, but clinically highly suspected, can do percutaneous renal angiography, renal angiography is the most valuable diagnosis of renal artery stenosis, is a "golden index" for the diagnosis of renal vascular disease, can reflect renal artery stenosis The location, extent, extent, nature of the lesion, distal branch and collateral circulation, and observation of changes in kidney morphology and function and judgment of vasodilation or surgical indications.

The incidence of this disease is relatively low, so the clinical screening of renal vascular stenosis in all hypertensive patients is generally not recommended, but there is currently no non-invasive examination whose sensitivity is high enough to exclude all renal arteries. Stenosis, so it is often seen in clinical practice that some hypertensive patients are difficult to determine whether it is renal vascular hypertension. The following are clinical indications and diagnostic flowcharts for screening renal vascular stenosis and determining renal angiography.

Differential diagnosis

Mainly differentiated from essential hypertension and various types of secondary hypertension.

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