Ischemic Nephropathy Caused By Atherosclerosis, How To Choose Drugs And Interventional Therapy?

Uncle Wang, who is 82 years old this year, has a history of type 2 diabetes and hypertension for many years. He usually has poor control of blood sugar and blood pressure. During the physical examination this year, he found abnormal kidney function, and his blood creatinine was 172 μmol/L. I heard from a neighbor that the high creatinine was probably due to uremia, and he might have to rely on hemodialysis for the rest of his life, so he was so frightened that he was rushed to the nephrology department of the hospital.

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During the complete examination, it was found that the left side of Uncle Wang’s kidney was slightly smaller than the right side, and the blood in the left renal artery was also abnormal. The blood vessels in other parts, such as the lower extremity artery, carotid artery, and abdominal aorta, had different degrees of atherosclerosis and plaque formation. After obtaining the consent of the patient and his family, CT reconstruction of both kidneys and renal arteries was carried out. The results indicated that Uncle Wang’s left renal artery was severely stenotic. kidney disease.

What is ischemic kidney disease?

Ischemic nephropathy refers specifically to hemodynamic changes caused by renal artery stenosis (RAS), which leads to decreased glomerular filtration rate [1].

Common causes of renal artery stenosis include muscle fiber dysplasia, Takayasu arteritis, and atherosclerosis. Among patients >40 years old, atherosclerotic renal artery stenosis (ARAS) accounts for as high as 94.7%, which is closely related to the changes in people's living and dietary patterns and population aging in recent years, especially closely related to the following factors: advanced age, smoking history, hyperlipidemia, diabetes, decreased renal function, etc., while muscle fiber dysplasia, multiple large arteries Inflammation is the main cause of disease in people under the age of 40 [1, 2].

Clinical Manifestations of Ischemic Nephropathy

The main clinical manifestation of ARAS is hypertension, which can be manifested as new hypertension, exacerbation of existing hypertension, or even malignant hypertension. The main manifestation of the kidney is chronic renal insufficiency. Some patients may have proteinuria, but generally, it does not exceed 1g/d. If hypertension progresses rapidly, the amount of proteinuria may increase significantly, and even proteinuria in the range of nephropathy may appear. With the control of blood pressure, the amount of proteinuria will also decrease.

How to Diagnose Ischemic Nephropathy

digital subtraction angiography      

It is currently the gold standard for the diagnosis of renal artery stenosis. It can display the anatomical structure of the renal artery and reflect the location, degree, and scope of the lesion. However, the examination is expensive and traumatic, and the injection of contrast medium may cause contrast-induced nephropathy and aggravate renal ischemia.

renal artery ultrasound  

It is a common first-line screening that can assess the degree and location of stenosis. It has the advantages of being non-invasive, safe, and convenient, but it is easily affected by many factors such as breathing, obesity, intestinal gas, degree of stenosis, equipment quality, and operator experience. Duplex ultrasound can not only evaluate the anatomical structure of the renal artery, but also display changes in blood flow, and its sensitivity to RAS detection is significantly higher than that of renal artery ultrasound.

Renal artery tomography (CTA)   

The sensitivity and specificity of this method are >90%, and the renal artery and accessory renal artery can be displayed, and the reconstructed image can be displayed in three dimensions, which has been widely used in the clinic. However, CTA requires the use of iodine-containing contrast agents. When the creatinine clearance rate (eGFR) is <60ml/min, preparations should be made to prevent contrast nephropathy. This method should be used with caution if the eGFR<30ml/min. Pay attention to severe hyperthyroidism and iodine contrast agents Patients with allergies are prohibited.

In addition, there is magnetic resonance angiography (MRA), lateral renal vein renin activity assay (RVRR), and lateral renal vein renin activity assay (RVRR), each of which has its imaging characteristics, advantages, and disadvantages, and can be used to diagnose RAS. [3].

Treatment of ischemic kidney disease

The treatment of ARAS is divided into drug therapy and renal revascularization therapy, that is, interventional therapy (including percutaneous renal angioplasty and stenting).

Clinical evidence indicates that for any degree of ARAS, treatment should be based on drug therapy, including antihypertensive, dyslipidemia control, and platelet inhibition. Angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB) are still the most advocated drugs for ARAS.

However, in patients with bilateral renal ischemia, ACEI/ARB may cause acute renal insufficiency, if significant renal dysfunction occurs after the drug, such as a rapid increase in serum creatinine exceeding 0.5 mg/dl or a decrease in eGFR exceeding 30% of the baseline value, the drug should be suspended.

In addition, β-receptor blockers can inhibit the release of renin and can be used; diuretics activate renin release, which is generally not recommended for renovascular hypertension, but if combined with essential hypertension, pulmonary edema, or heart failure, Still available.

A large number of Meta-analyses have proved that there is no statistically significant difference between the renal artery stent revascularization group and drug treatment in terms of blood pressure improvement or renal function decline.

Indications for Interventional Therapy

What kind of patients in the clinic can consider interventional therapy?

In conclusion, before making a treatment decision for renal artery stenosis revascularization, the patient's comorbidities, blood pressure control status, and renal function level should be fully clarified.

For those who are elderly, have basic medical diseases such as diabetes, hypertension, coronary heart disease, and have severe systemic vascular arteriosclerosis, conservative treatment with drugs is recommended, because these patients have a higher risk of stent implantation, and the blood vessels at the unstented site are vulnerable. Stenosis occurs again, and the effect of the stent is poor.

Given the above-mentioned understanding of various aspects of ARAS, combined with Uncle Wang's situation, and no history of repeated heart failure attacks in the past, it is recommended that the patient be treated conservatively with drugs. After continuous adjustment of the drug, the patient's blood sugar and blood pressure were controlled close to the target level, and the serum creatinine dropped and remained at 140-150 μmol/d stably. The patient and his family were very satisfied with the treatment effect.

References:

[1] Guo Hui, Ye Zhibin. Advances in therapeutics of atherosclerotic renal artery stenosis [J]. Fudan Journal (Medical Edition), 2018, 45(03): 418-422.

[2] Wan Jianxin. New progress in the diagnosis and treatment of senile ischemic nephropathy [J]. Chinese Journal of Integrated Traditional Chinese and Western Medicine Nephrology, 2017,18(12):1035-1037.

[3] Zou Yubao, Song Lei, Jiang Xiongjing. Diagnosis and treatment of renovascular hypertension [J]. Chinese Journal of Molecular Cardiology, 2017, 17(03): 2132-2136. DOI: 10.16563/j.cnki.1671 -6272.2017.06.017.