Interventions for renal artery stenosis: Appraisal of novel physiological insights and procedural techniques to improve clinical outcome.

Randomized clinical trials failed to show additional benefit of renal artery stenting on top of medical therapy. Instead of writing an obituary on renal artery stenting, we try to explain these disappointing results. A transstenotic pressure gradient is needed to reduce renal perfusion and to activate the renin-angiotensin-aldosterone system. In only a minority of patients included in trials, a transstenotic pressure gradient is measured and reported. Like the coronary circulation, integration of physiological lesion assessment will allow to avoid stenting of non-significant lesions and select those patients that are most likely to benefit from renal artery stenting. Renal artery interventions are associated with peri-procedural complications. Contemporary techniques, including radial artery access, no-touch technique to engage the renal ostium and the use of embolic protection devices, will minimize procedural risk. Combining optimal patient selection and meticulous technique might lead to a netto clinical benefit when renal artery stenting is added to optimal medical therapy.

Renal Transplant Anastomotic Pseudoaneurysm and Stenosis at the Proximal Transplant Renal Artery and Worse Renal Blood Flow After Stent Placement.

ABSTRACT: A 60-year-old man with a history of end-stage renal disease received renal transplant and had decreasing renal function 4 months later. Nuclear medicine renal flow and functional study showed severely decreased blood flow and decreased function of the right renal allograft. There was focal increased radiotracer uptake at blood flow phase around the anastomosis of the renal allograft artery and the right external iliac artery. CT angiogram revealed right external iliac artery pseudoaneurysm. Interventional radiology angiography reconfirmed the pseudoaneurysm and revealed stenosis at the proximal transplant renal artery. After stent placement, however, there was worse renal allograft blood flow.

Double kiss mini-crush technique to treat complex recurrent renal artery in-stent restenosis.

The double-kiss mini-crush (DKMC) technique has been successfully deployed in the past for the treatment of complex coronary lesions even for left main lesions. Our case report consists of a proof-of-principle that the DKMC technique can be successfully translated as well to the field of complex renal artery lesions. Insightful thinking out-of-the "coronary" box in concert with skillful off-label application of coronary stenting procedures may open the gate for unprecedented opportunities for the treatment of difficult-to-tackle in-stent restenosis in the renal circulation.

Improving outcomes in atherosclerotic renovascular disease: importance of clinical presentation and multi-disciplinary review.

BACKGROUND AND OBJECTIVES: Atherosclerotic renal artery stenosis may cause hypertension, chronic kidney disease and heart failure, but large randomized control trials to date have shown no major additional benefit of renal revascularization over optimal medical management. However, these trials did not consider outcomes specifically in relation to clinical presentations. Given that atherosclerotic renal artery stenosis is a heterogenous condition, measures of success likely differ according to the clinical presentation. Our retrospective study objectives were to determine the effects of revascularization when applied to specific clinical presentations and after careful multi-disciplinary team review. METHODS: All patients presenting to our centre and its referring hospitals with radiological findings of at least one renal artery stenosis > 50% between January 2015 and January 2020 were reviewed at the renovascular multi-disciplinary team meeting with revascularization considered in accordance with international guidelines, notably for patients with anatomically significant renal artery stenosis, adequately sized kidney and presentations with any of; deteriorating kidney function, heart failure syndrome, or uncontrollable hypertension. Optimal medical management was recommended for all patients which included lipid lowering agents, anti-platelets and anti-hypertensives targeting blood pressure ≤ 130/80 mmHg. The effect of revascularization was assessed according to the clinical presentation; blood pressure and number of agents in those with renovascular hypertension, delta glomerular filtration rate in those with ischaemic nephropathy and heart failure re-admissions in those with heart failure syndromes. RESULTS: During this 5-year period, 127 patients with stenosis ≥ 50% were considered by the multidisciplinary team, with 57 undergoing revascularization (17 primarily for severe hypertension, 25 deteriorating kidney function, 6 heart failure syndrome and 9 for very severe anatomical stenosis). Seventy-nine percent of all revascularized patients had a positive outcome specific to their clinical presentation, with 82% of those with severe hypertension improving blood pressure control, 72% with progressive ischaemic nephropathy having attenuated GFR decline, and no further heart failure admissions in those with heart failure. Seventy-eight percent of patients revascularized for high grade stenosis alone had better blood pressure control with 55% also manifesting renal functional benefits. CONCLUSIONS: Multi-disciplinary team discussion successfully identified a group of patients more likely to benefit from revascularization based on 3 key factors: clinical presentation, severity of the renal artery lesion and the state of the kidney beyond the stenotic lesion. In this way, a large proportion of patients can clinically improve after revascularization if their outcomes are considered according to the nature of their clinical presentation.

Patterns of cortical oxygenation may predict the response to stenting in subjects with renal artery stenosis: A radiomics-based model.

BACKGROUND: Percutaneous-transluminal renal angioplasty (PTRA) and stenting aim to halt the progression of kidney disease in patients with renal artery stenosis (RAS), but its outcome is often suboptimal. We hypothesized that a model incorporating markers of renal function and oxygenation extracted using radiomics analysis of blood oxygenation-level dependent (BOLD)-MRI images may predict renal response to PTRA in swine RAS. MATERIALS AND METHODS: Twenty domestic pigs with RAS were scanned with CT and BOLD MRI before and 4 weeks after PTRA. Stenotic (STK) and contralateral (CLK) kidney volume, blood flow (RBF), and glomerular filtration rate (GFR) were determined, and BOLD-MRI R2 * maps were generated before and after administration of furosemide, a tubular reabsorption inhibitor. Radiomics features were extracted from pre-PTRA BOLD maps and Robust features were determined by Intraclass correlation coefficients (ICC). Prognostic models were developed to predict post-PTRA renal function based on the baseline functional and BOLD-radiomics features, using Lasso-regression for training, and testing with resampling. RESULTS: Twenty-six radiomics features passed the robustness test. STK oxygenation distribution pattern did not respond to furosemide, whereas in the CLK radiomics features sensitive to oxygenation heterogeneity declined. Radiomics-based model predictions of post-PTRA GFR (r = 0.58, p = 0.007) and RBF (r = 0.68; p = 0.001) correlated with actual measurements with sensitivity and specificity of 92% and 67%, respectively. Models were unsuccessful in predicting post-PTRA systemic measures of renal function. CONCLUSIONS: Several radiomics features are sensitive to cortical oxygenation patterns and permit estimation of post-PTRA renal function, thereby distinguishing subjects likely to respond to PTRA and stenting.

Índice de resistividade renal como preditor da revascularização renal para hipertensão renovascular / Renal resistance index predicting outcome of renal revascularization for renovascular hypertension

FUNDAMENTO: A estenose arterial renal (EAR) é uma causa potencialmente reversível de hipertensão arterial sistêmica (HAS) e nefropatia isquêmica. Apesar da revascularização bem sucedida, nem todos os pacientes (pt) apresentam melhora clínica e alguns podem piorar. OBJETIVO: O presente estudo se destina a avaliar o valor do índice de resistividade renal (IR) como preditor dos efeitos da revascularização renal. MÉTODOS: Entre janeiro de 1998 e fevereiro de 2001, 2.933 pacientes foram submetidos ao duplex ultrassom renal. 106 desses pacientes apresentaram EAR significativa e foram submetidos a angiografia e revascularização renal. A pressão arterial (PA) foi medida antes e depois da intervenção, em intervalos de até 2 anos e as medicações prescritas foram registradas. Antes da revascularização, o IR foi medido em 3 locais do rim, sendo obtida uma média dessas medições. RESULTADOS: Dos 106 pacientes, 81 tiveram IR<80 e 25 RI>80. A EAR foi corrigida somente por angioplastia (PTA) em 25 pts, PTA + stent em 56 pts e cirurgicamente em 25 pts. Dos pacientes que se beneficiaram da revascularização renal; 57 dos 81 pacientes com IR <80 apresentaram melhora em comparação a 5 de 25 com IR > 80. Usando um modelo de regressão logística múltipla, o IR esteve significativamente associado à evolução da PA (p = 0,001), ajustado de acordo com os efeitos da idade, sexo, PAS, PAD, duração da hipertensão, o tipo de revascularização, número de fármacos em uso, nível de creatinina, presença de diabete melito, hipercolesterolemia, volume sistólico, doença arterial periférica e coronariana e tamanho renal (OR 99,6-95 por centoCI para OR 6,1-1.621,2). CONCLUSÃO: A resistividade intrarrenal arterial, medida por duplex ultrassom, desempenha um papel importante na predição dos efeitos pós revascularização renal para EAR.

BACKGROUND: Renal artery stenosis (RAS) is a potentially correctable cause of hypertension and ischemic nephropathy. Despite successful renal revascularization, not all patients (pt) overcome it and some get worse. OBJECTIVE: This study was designed to assess the value of renal resistance index (RI) in predicting the outcome of renal revascularization. METHODS: Between Jan 1998 and Feb 2001, 2,933 pts were referred to renal duplex ultrasound. 106 out of these had significant RAS and underwent angiography and renal revascularization. Arterial blood pressure (BP) was measured before and after the intervention, at intervals of up to 2 years and medications recorded. Prior to revascularization, RI was measured at 3 sites of each kidney and averaged. RESULTS: Out of the 106 patients, 81 had RI<80 and 25 RI>80. RAS was corrected with angioplasty (PTA) alone in 25 pts, PTA + stent in 56 pts and corrected by surgery in 25 pts. Of patients who benefited from renal revascularization; 57 of the 81 patients with RI <80 improved as compared to 5 of 25 with RI>80. Using a multiple logistic regression model, RI was significantly associated with BP outcome (p=0.001), adjusted for the effects of age, sex, SBP, DBP, duration of hypertension, type of revascularization, number of medication in use, creatinine level, presence of diabetes mellitus, hypercholesterolemia, stroke, peripheral and coronary artery disease and kidney size (OR 99.6 - 95 percentCI for OR 6.1 to 1,621.2). CONCLUSION: Intrarenal arterial resistance measured by duplex ultrasound plays an important role in predicting BP outcome after renal revascularization for RAS.

Glomerular filtration rate measured by 51Cr-EDTA clearance: evaluation of captopril-induced changes in hypertensive patients with and without renal artery stenosis

INTRODUCTION: Renal artery stenosis can lead to renovascular hypertension; however, the detection of stenosis alone does not guarantee the presence of renovascular hypertension. Renovascular hypertension depends on activation of the renin-angiotensin system, which can be detected by functional tests such as captopril renal scintigraphy. A method that allows direct measurement of the baseline and post-captopril glomerular filtration rate using chromium-51 labeled ethylenediamine tetraacetic acid (51Cr-EDTA) could add valuable information to the investigation of hypertensive patients with renal artery stenosis. The purposes of this study were to create a protocol to measure the baseline and post-captopril glomerular filtration rate using 51Cr-EDTA, and to verify whether changes in the glomerular filtration rate permit differentiation between hypertensive patients with and without renal artery stenosis. METHODS: This prospective study included 41 consecutive patients with poorly controlled severe hypertension. All patients had undergone a radiological investigation of renal artery stenosis within the month prior to their inclusion. The patients were divided into two groups: patients with (n=21) and without renal artery stenosis, (n=20). In vitro glomerular filtration rate analysis (51Cr-EDTA) and 99mTc-DMSA scintigraphy were performed before and after captopril administration in all patients. RESULTS: The mean baseline glomerular filtration rate was 48.6±21.8 ml/kg/1.73 m² in the group wuth renal artery stenosis, which was significantly lower than the GFR of 65.1±28.7 ml/kg/1.73m² in the group without renal artery stenosis (p=0.04). Captopril induced a significant reduction of the glomerular filtration rate in the group with renal artery stenosis (to 32.6±14.8 ml/kg/1.73m², p=0.001) and an insignificant change in the group without RAS (to 62.2±23.6 ml/kg/1.73m², p=0.68). Scintigraphy with technetium-99m dimercapto-succinic acid (DMSA) did...

Hipertensión arterial renovascular: rol del cintigrama renal en su detección y en la predicción de la respuesta clínica a la revascularización / Renovascular arterial hypertension: role of renal scintigraphy on it detection and on the prediction of clinical response to revascularization

The most frequently used non invasive tests in the diagnosis of renovascular hypertension are the measurement of peripheral blood renin before and after captopril administration, intravenous pyelogram, renal Doppler examination and radionuclide renography without and with angiotensin converting enzyme inhibitor administration. Measurement of renal vein renin levels and renal angiography are invasive tests commonly used. The latter allows an anatomical disgnosis of renal veins stenosis but does not give information about pressure to revascularization. Radionuclide renography has become the most useful non invasive diagnostic test, with a sensitivity and specificity of 83-94 and 85-97 percent respectively. It also predicts clinical response to revascularization and is useful for follow up after surgery or angioplasty. It also had good results in patients with renal failure, bilateral stenosis or stenosis in a solitary kidney and in transplantated patients

Recuperación de la insuficiencia renal crónica grave luego de la revascularización renal / Impairment or renal failure after flow renal restored with saphenous vein grafts

Se revascularizaron 4 enfermos con insuficiencia renal severa causada por arteriosclerosis en 3 y por una disección aórtica aguda en el último. En el preoperatorio, 3 requerían hemodiálisis permanente durante días y meses y el tercero peritoneal transitoria. En todos la reconstrucción arterial se efctuó con vena safena autóloga; 2 puentes aorto renales, 1 ilíaco renal y un "by pass" aortobifemoral con reimplante de la renal derecha. La diuresis se recuperó rápidamente sin requerir diálisis en ninguno. Dos reoperaciones fueron necesarias a los 12 y 40 meses por hipertensión y deterioro de la función renal causado por estenosis del injerto con buena evolución posterior. No se contraindicó el intento de revascularización por ausencia de lecho distal en la arteriografía (n = 2), tiempo de diálisis pre-operatoria ni el tamaño renal (6,4 cm el más pequeño)

Estenosis de arteria renal: características angiográficas en 210 casos / Stenosis or the renal artery: angiographic characteristics in 210 cases

Se presentan 210 casos de enfermos portadores de lesiones estenosantes de arteria renal, estudiados en el Departamento de Angiología del Hospital de Especialidades del Centro Médico Nacional, durante un periodo de 29 años (1963-1992), documentados angiográficamente. La indicación del estudio fue la hipertensión arterial severa y las manifestaciones de insuficiencia arterial crónica de miembros inferiores, así como enfermedad aortoiliaca. De estos casos, 92 correspondieron al sexo femenino y 118 al masculino. La edad varió de 9 a 76 años. En cuanto a la localización de la lesión de la arteria renal, en 58 casos, fue en el ostium y/o en el tercio proximal y, en 50 de ellos, la lesión fue bilateral y estaba asociada a otras lesiones del territorio aórtico y correspondieron a mujeres jóvenes los cuales se consideraron de etiología inflamatoria (artritis). En otros 75 casos, la lesión se localizó en el tercio medio con estenosis única o múltiple, y extensión al tercio distal, en la mayoría fue unilateral y solamente en 15 casos, la lesión estaba presente en forma bilateral. Estos casos predominaron en el sexo masculino, entre la tercera y cuarta década de la vida y correspondieron a discplasia fibromuscular. En cambio en los 65 casos restantes, la lesión estenosante se presentó en personas de la sexta década de la vida predominando también en el sexo masculino, donde la angiografía mostró lesiones muy importantes del eje aortoiliaco y se consideraron de origen ateroscleroso. En 12 casos, la estenosis estuvo en relación a otras patologías. Algunos de estos casos fueron sometidos a procedimientos quirúrgicos, del tipo de las derivaciones arteriales, angioplastia transluminal y en los últimos años al autotrasplante renal (descenso renal), con excelentes resultados