PEI for allograft renal artery stenosis: a unique role and broad implications for renal artery stenosis treatment

Kidney transplant is the treatment of choice for patients with endstage renal disease. Post-transplant renal artery stenosis (TRAS) is a critical cause of graft loss and premature death among kidney recipients. It accounts for 5% of postrenal transplant hypertension and for ominous deterioration of renal function. Vascular complications of renal allografts fall into four categories: arterial stenoses, vascular occlusion, arteriovenous fistula, and pseudoaneurysm. The most common condition (about 10% of transplant patients) is arterial stenosis, which occurs within the first 3 years post transplantation and is heralded by allograft dysfunction manifested by abnormal increase of serum creatinine and refractory hypertension. Using the arterial anastomosis site as a reference point, a proximal stenosis can be caused by the recipient's atherosclerotic disease or surgical trauma while a short anastomotic lesion can result from surgical trauma to either recipient or donor vessels with subsequent fibrosis. A distal, long-segment stenosis (or stenoses) is a latter morphology that develops from several etiologies such as intimal hyperplasia, atherosclerosis, and mechanical forces, including scarring or immunological rejection. Percutaneous interventional procedures are the preferred method for revascularization of TRAS. In this issue, Ren and colleagues from the Union Hospital of the Tongji Medical College, Huazhong University of Science and Technology in Wuhan, China, meticulously report their evaluation of the efficacy and complications of PEI in the treatment of TRAS in 33 patients during a 7-year period, with a median time from transplantation to TRAS diagnosis of 7 months. All patients underwent angiography to identify the precise location and morphology of the target lesion and vessel. Noteworthy, literature indicates the usefulness and accuracy of Doppler imaging for the detection of allograft renal artery stenosis and concomitant quantification of flow velocity. Regarding TRAS, Doppler velocity imaging may be superior to angiography, Digital Subtraction Angiography, Magnetic Resonance Angiography (MRA), and Computerized Tomographic Angiography (CTA) because this simple technology is readily available, inexpensive, and devoid of nephrotoxic effects; it also enables efficient follow-up. Nevertheless, as recognized by Ren and colleagues, MRA and CTA may be required for preprocedure planning and selection of either femoral (most commonly) or brachial access site. The PEI by Ren and colleagues involved a nonrandomized, almost equal rate of selection between balloon or stenting as defined by criteria related to the vessel's contour and the target lesion location. Although the question of which modality is the best choice for PEI in TRAS (i.e., balloon only versus balloon coated, or BMS or DES stents) remains unanswered in the absence of prospective, randomized studies (which, realistically, will not occur), the selection criteria as set forth by Ren and associates are reasonable and applicable. Recognizing the technical challenge that unique vascular anatomic features impose on delivery of balloon/stent onto the stenosed artery and crossing the lesion, the investigators successfully applied a “Buddy wire” technique whereby a 0.035-in. wire supports a 0.014-in. guidewire. When compared with the pre-PEI levels, the systolic and diastolic blood pressure and renal function significantly improved with revascularization and the restenosis rate is low. The authors are to be commended for the excellent results, corresponding to 97% success rate, impressive low rate of complications, and longterm sequelae, all in demanding procedures. Received: 27 January 2020 Accepted: 29 January 2020