Ischemic nephropathy

Ischemic nephropathy

Ischemic nephropathy is significant reduction in glomerular filtration rate in patients with hemodynamically significant renovascular occlusive disease affecting the functional renal parenchyma. Other terminologies which have been used to describe ischemic nephropathy are ischemic renal disease, chronic renal ischemic disease, azotemic renovascular disease, atherosclerotic renovascular disease and renal insufficiency of renovascular hypertension. End-stage renal disease can occur in case of progressive bilateral renal artery stenosis or renal artery stenosis of a single kidney. In some studies, ischemic nephropathy has been reported to be the primary cause of end-stage renal disease in persons older than 65 years [1].

Spanish Group of Ischaemic Nephrology carried out an observational multicentre study in 20 Spanish hospitals with a 14 month follow up and 156 patients [2]. They included persons with bilateral renal artery stenosis of more than 50% and serum creatinine levels of 1.5 mg/dl or more. Diagnosis was made by arterial digital angiography. 78.5% of the patients were male and mean age was 68.7 years. Mean serum creatinine was 2.9 mg/dl. Hypertension was present in 97.4% with a mean duration of 12 years. Smoking was noted in 69.8% and cholesterol levels of 240 mg/dl or more in 62.9%. 32.1% were diabetic.

This study showed a close association between ischemic nephropathy and cardiovascular disease. About two third had peripheral arterial disease, nearly half had ischemic heart disease and a little over one fourth had stroke. 94.4% had bilateral renal artery stenosis and 23% had total obstruction. Only 8% had a body mass index of 30 Kg per square meter or more, indicating that this problem is seen mainly in elderly non-obese males.

In a review of ischemic nephropathy by Alcazar et al, presentation of ischemic nephropathy as acute renal failure was noted in 29.5%. More than half of these were secondary to administration of angiotensin converting enzyme inhibitor. Just over a quarter were due to renal artery occlusion by  renal artery thrombosis. They noted that surgical revascularization may stabilize or improve renal function even in patients with nonfunctioning kidneys. Results of renal angioplasty was worse with high percentage of restenosis. They suggested stenting when the lesions affected the ostium or proximal third of that of the artery. This was a review published in the year 2000 [3].

Another review in 2012 found that the prevalence of ischemic nephropathy is increasing especially in older individuals. They opined that pathogenesis of the disease is more complex than just narrowing of renal arteries due to atherosclerosis. Factors like renin-angiotensin system, growth factors, cytokines and chemokines were implicated in the pathogenesis of ischemic nephropathy. Optimal medical management in majority and revascularization in selected patients were considered the best options [4].

A 2021 review on renal artery stenosis mentioned that it is the most common cause of secondary hypertension, predominantly caused by atherosclerosis. Preferred non-invasive investigation is duplex ultrasound. Asymptomatic incidentally detected renal artery stenosis does not require revascularization according to the authors [5].

Renal artery stenting was the preferred method of revascularization in symptomatic renal artery stenosis. Multi-disciplinary team approach for selecting appropriate patients for revascularization considering lesion severity and optimization was suggested. Guideline directed medical therapy for all patients would include control of hypertension and diabetes if present, statins, anti-platelet therapy, smoking cessation and encouragement of activity.

References

1. García-Donaire JA, Alcázar JM. Ischemic nephropathy: detection and therapeutic intervention. Kidney Int Suppl. 2005 Dec;(99):S131-6. doi: 10.1111/j.1523-1755.2005.09924.x. PMID: 16336566.
2. Alcázar JM, Marín R, Gómez-Campderá F, Orte L, Rodríguez-Jornet A, Mora-Macía J; Spanish Group of Ischaemic Nephrology (GEDENI). Clinical characteristics of ischaemic renal disease. Nephrol Dial Transplant. 2001;16 Suppl 1:74-7. doi: 10.1093/ndt/16.suppl_1.74. PMID: 11369827.
3. Alcazar JM, Rodicio JL. Ischemic nephropathy: clinical characteristics and treatment. Am J Kidney Dis. 2000 Nov;36(5):883-93. doi: 10.1053/ajkd.2000.19077. PMID: 11054344.
4. Adamczak M, Wiecek A. Ischemic nephropathy – pathogenesis and treatment. Nefrologia. 2012 Jul 17;32(4):432-8. doi: 10.3265/Nefrologia.pre2012.Apr.11472. PMID: 22806277.
5. Safian RD. Renal artery stenosis. Prog Cardiovasc Dis. 2021 Mar-Apr;65:60-70. doi: 10.1016/j.pcad.2021.03.003. Epub 2021 Mar 18. PMID: 33745915.