Renal artery stenosis: diagnosis

Diagnosis of stenosis of the renal artery requires an objective search for atherosclerotic stenosis and depends on the characteristics of arterial hypertension, chronic renal failure, and signs of widespread atherosclerosis. In physical examination, peripheral edema, manifestations of chronic heart failure (hepatomegaly, bilateral crepitus or wet wheezing in the basal parts of the lungs), as well as noise over the aorta and large vessels, including kidneys, can be detected. The sensitivity and specificity of these symptoms is extremely low.

Changes in urine in atherosclerotic stenosis of renal arteries are limited to "trace" proteinuria, often transient; hematuria, leukocyturia are not characteristic (with the exception of embolism of the intrarenal arteries and arterioles with cholesterol crystals). In most patients with atherosclerotic Renovascular hypertension, when using the appropriate qualitative (test strip) or quantitative (immunoneferometry) methods, it is possible to detect microalbuminuria, nevertheless, pronounced changes in urine, including proteinuria exceeding 1 g / day, do not completely disprove the assumption of atherosclerotic stenosis of the renal arteries, because they may reflect the presence of a combination of chronic nephropathy (eg, diabetic or due to chronic glaucoma merulonefrita).

Ultrasonic examination of the kidneys often reveals their decrease (asymmetric or symmetrical), uneven contours and thinning of the cortical layer.

Ischemic kidney disease is confirmed by the results of visualization methods of examination. UZDG renal arteries are not sensitive enough and specific, but non-invasive and does not require the introduction of contrast agents, therefore it is preferable for use in the first stage of diagnosis, as well as in dynamic observation.

Multispiral computed tomography of the renal arteries, performed in the mode of angiocontrast, allows to reliably estimate the size of the kidneys and the thickness of their cortex, the degree of stenosis of the renal arteries and the state of atherosclerotic plaques in them and the adjacent abdominal aorta. For sensitivity and specificity, this method is close to contrast angiography, but is safer from the point of view of the risk of radiopaque nephropathy.

Magnetic resonance imaging requires the use of contrast substances containing gadolinium, which are practically safe for renal failure. High cost limits the widespread use of this method.

Contrast angiography with the greatest reliability allows us to identify atherosclerotic stenosis of the renal arteries. The use of this method is associated with a risk of aggravation of impaired renal function associated with the administration of contrast agents, as well as the danger of cholesterol embolism arising from the destruction of the fibrous plaque of atherosclerotic plaques localized in the abdominal aorta during catheter placement. However, in specialized centers where a large amount of angiography is performed, the frequency of this complication is extremely small.

The results of radioisotope scintigraphy of the kidneys (possibly an acute test with captopril) confirm the worsening of the function of one or both kidneys, but only indirectly indicate stenosing lesions of the renal arteries. In addition, even a single dose of a short-acting ACE inhibitor can be dangerous in severe hypercreatininaemia, as well as in elderly patients with unstable blood pressure.

All patients with atherosclerotic renovascular hypertension should be purposefully examined for cardiovascular risk factors (parameters characterizing the exchange of lipoproteins and glucose, homocysteine, waist circumference, and body mass index) and markers of high risk of cardiovascular complications (an increase in the serum level of the C-reactive protein , hyperfibrinogenemia). Automatic daily monitoring of blood pressure allows timely detection of violations of its circadian rhythm, including prognostically unfavorable.

Data obtained with echocardiography with greater reliability reflect the degree of hypertrophy and disturbance of systolic and / or diastolic function of the left ventricle, as well as changes in heart valves (mitral regurgitation and atherosclerotic aortic stenosis, sometimes associated with insufficiency). The detection of atherosclerotic lesions of carotid arteries in UZDG carotid arteries indirectly proves the atherosclerotic nature of stenosis of the renal arteries.

Evaluation of GFR in dynamics is carried out using conventional calculation methods (the Cockcroft-Gault formula, MDRD).

A common tactic for the diagnosis of cholesterol embolism of the intrarenal arteries and arterioles has not been developed. A kidney biopsy, as a rule, is not performed due to a very high probability of life-threatening complications. Detection of cholesterol emboli is possible with morphological examination of affected skin areas.

[1], [2], [3]

Differential diagnosis of atherosclerotic stenosis of the renal arteries

The main task of differential diagnostics of atherosclerotic stenosis of the renal arteries is as early as possible to separate it from similar in clinical manifestations of chronic nephropathies, which nevertheless require radically different tactics of management.

Symptoms of atherosclerotic stenosis of the renal arteries are often mistakenly regarded as signs of involuntary changes in renal tissue, which, however, are not characterized by a decrease in GFR and hypercreatininaemia, as well as high and / or uncontrolled hypertension.

For hypertensive nephroangiosclerosis, microalbuminuria is typical with normal or moderately reduced GFR, hypercreatininaemia is absent or mild. In contrast to atherosclerotic stenosis of the renal arteries, hypertensive kidney damage, their function in the appointment of RAAS blockers, as a rule, does not deteriorate.

Diabetic nephropathy is inherent in a succession of stages from microalbuminuria to increasing proteinuria: a decrease in GFR is recorded only when the protein is excreted in the urine, reaching a nephrotic (> 3 g / day) level. Hypercreatininaemia and the more hyperkalemia that occur with the use of ACE inhibitors or angiotensin II receptor blockers require the aim of excluding atherosclerotic stenosis of renal arteries in all patients suffering from type 2 diabetes.

Differences in atherosclerotic stenosis of the renal arteries from fibromuscular dysplasia of the renal arteries are usually obvious. The latter is more often observed in women under the age of 50; The main symptom is hypertension, while impairment of renal function is very rarely recorded. It is possible to combine a lesion of renal vessels with the involvement of cerebral arteries and visceral branches of the aorta. During angiography, the stenotic portion of the artery has a characteristic "rosary" appearance.

Renascous hypertension in Takayasu syndrome is usually combined with common signs of a systemic inflammatory response: fever, arthralgia, weight loss, acceleration of ESR. Often the coronary arteries, as well as the arteries of the intestine and upper limbs, are simultaneously affected (asymmetry of the pulse and arterial pressure is measured when measured on both hands). Takayasu's syndrome, as a rule, debuts at a younger age than atherosclerotic stenosis of the renal arteries.

It is necessary to emphasize once again the possibility of combining atherosclerotic stenosis of the renal arteries with virtually any chronic nephropathy. Identifying the symptoms of the latter does not in itself completely disprove the possibility of the simultaneous presence of the patient atherosclerotic stenosis of the renal arteries.

[4], [5], [6]