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Abstract Background Transcatheter aortic valve implantation (TAVI) has evolved to be a treatment of choice in high-risk patients with aortic stenosis (AS). However, it is not known whether TAVI is safe and beneficial for the creation of arteriovenous fistula for maintenance hemodialysis in high-risk patients with severe AS. Case presentation A 91-year-old woman was referred to our hospital due to oligoanuria and progressive renal dysfunction. She was diagnosed with anti-glomerular basement membrane (GBM) disease. She had hypertension, chronic kidney disease stage G3b, and AS. We chose not to perform immunosuppressive therapy and plasmapheresis for anti-GBM disease because the risk of death outweighed the benefit of treatment. Hemodialysis with a venous catheter was initiated for the renal indication. As she showed severe AS, she had a risk of cardiac decompensation after arteriovenous fistula creation for dialysis. Following the clinical decision-making process, she underwent TAVI. Although she required the implantation of a cardiac pacemaker for an advanced atrioventricular block that occurred 11 days after TAVI, arteriovenous fistula was successfully created thereafter. She could undergo maintenance hemodialysis using arteriovenous fistula. Conclusions TAVI is safe and beneficial for the creation of arteriovenous fistula shortly after initiating acute hemodialysis using a catheter in a very old patient with anti-GBM disease.

Homozygous mutations in SLC4A4, which encodes the electrogenic Na+/HCO-3 cotransporter (NBCe1), cause proximal renal tubular acidosis associated with extrarenal symptoms. Although 17' mutated sites in SLC4A4 have thus far been identified among patients with proximal renal tubular acidosis, the physiological significance of other nonsynonymous single-nucleotide variants (SNVs) remains largely undetermined. Here, we investigated the functional properties of SNVs in NBCe1. From the National Center for Biotechnology Information dbSNP database, we identified 13 SNVs that have not previously been characterized in the highly conserved, transmembrane domains of NBCe1-A. Immunocytochemical analysis revealed that the I551F variant was present predominantly in the cytoplasm in human embryonic kidney (HEK)-293 cells, whereas all other SNVs did not show as dramatic a change in subcellular distribution. Western blot analysis in HEK-293 cells demonstrated that the I551F variant showed impaired glycosylation and a 69% reduction in cell surface levels. To determine the role of I551 in more detail, we examined the significance of various artificial mutants in both nonpolarized HEK-293 cells and polarized Madin-Darby canine kidney cells, which indicated that only I551F substitution resulted in cytoplasmic retention. Moreover, functional analysis using Xenopus oocytes demonstrated that the I551F variant had a significantly reduced activity corresponding to 39% of that of the wild-type, whereas any other SNVs and artificial I551 mutants did not show significant changes in activity. Finally, immunofluorescence experiments in HEK-293 cells indicated that the I551F variant retained wild-type NBCe1-A in the cytoplasm. These data demonstrate that the I551F variant of NBCe1-A shows impaired transport activity predominantly through cytoplasmic retention and suggest that the variant can have a dominant negative effect by forming complexes with wild-type NBCe1-A. [ABSTRACT FROM AUTHOR]