CT-based radiomics: predicting early outcomes after percutaneous transluminal renal angioplasty in patients with severe atherosclerotic renal artery stenosis

This study aimed to comprehensively evaluate non-contrast computed tomography (CT)-based radiomics for predicting early outcomes in patients with severe atherosclerotic renal artery stenosis (ARAS) after percutaneous transluminal renal angioplasty (PTRA). A total of 52 patients were retrospectively recruited, and their clinical characteristics and pretreatment CT images were collected. During a median follow-up period of 3.7 mo, 18 patients were confirmed to have benefited from the treatment, defined as a 20% improvement from baseline in the estimated glomerular filtration rate. A deep learning network trained via self-supervised learning was used to enhance the imaging phenotype characteristics. Radiomics features, comprising 116 handcrafted features and 78 deep learning features, were extracted from the affected renal and perirenal adipose regions. More features from the latter were correlated with early outcomes, as determined by univariate analysis, and were visually represented in radiomics heatmaps and volcano plots. After using consensus clustering and the least absolute shrinkage and selection operator method for feature selection, five machine learning models were evaluated. Logistic regression yielded the highest leave-one-out cross-validation accuracy of 0.780 (95%CI: 0.660-0.880) for the renal signature, while the support vector machine achieved 0.865 (95%CI: 0.769-0.942) for the perirenal adipose signature. SHapley Additive exPlanations was used to visually interpret the prediction mechanism, and a histogram feature and a deep learning feature were identified as the most influential factors for the renal signature and perirenal adipose signature, respectively. Multivariate analysis revealed that both signatures served as independent predictive factors. When combined, they achieved an area under the receiver operating characteristic curve of 0.888 (95%CI: 0.784-0.992), indicating that the imaging phenotypes from both regions complemented each other. In conclusion, non-contrast CT-based radiomics can be leveraged to predict the early outcomes of PTRA, thereby assisting in identifying patients with ARAS suitable for this treatment, with perirenal adipose tissue providing added predictive value.

Renal Stem Cells, Renal Resistive Index, and Neutrophil Gelatinase Associated Lipocalin Changes After Revascularization in Patients With Renovascular Hypertension and Ischemic Nephropathy

BACKGROUND

Percutaneous transluminal renal angioplasty (PTRA) with or without stenting is the gold standard therapy in patients with atherosclerotic renal artery stenosis (aRAS). However, therapeutic success depends on the correct timing of revascularization and the reversibility of the renal damage.

MATERIALS AND METHODS

We report a case series of patients treated with PTRA for renovascular hypertension and ischemic nephropathy. We measured bilateral renal resistive index (RRI), circulating renal stem cells (RSC), and Neutrophil Gelatinase Associated Lipocalin (NGAL) at baseline and after PTRA at different time points to understand their changes in post-revascularization.

RESULTS

At baseline, the studied patients (n = 5) had different RSC levels. After PTRAs, all patients showed an improvement in blood pressure, while renal function varied differently within the studied subjects. RRI > 0.75 at baseline and the absence of NGAL decrease after PTRAs were associated with post-PTRA renal function worsening, despite an increase of RSC in all patients.

CONCLUSION

Although limited to a few patients, our observation allowed the exploration of the behaviour of the studied parameters in different degrees of renal ischemia. This revealed different disease models suggesting the importance of further investigations in larger and homogeneous cohorts to confirm that a greater basal RSC percentage, low RRI values before PTRA, and a post-revascularization NGAL reduction could be related to better renal outcomes in aRAS patients.

Mid-term outcome of angioplasty for pediatric renovascular hypertension

PURPOSE

To evaluate the mid-term outcome of percutaneous transluminal renal angioplasty (PTRA) for pediatric renovascular hypertension (RVH).

MATERIALS AND METHODS

The clinical data of patients who underwent PTRA for RVH in our hospital from 2012 to 2019 were analyzed retrospectively. Post-procedural blood pressure, glomerular filtration rate (GFR) of the affected kidney, restenosis and complications were closely followed up.

RESULTS

The procedure of PTRA was performed in total of 30 children (20 males and 10 females), with a mean age of 7.32±0.74 years (40 days ∼13.92 years) and a mean weight of 24.99±2.26 kg (3.4 ∼ 53kg). The median follow-up period was 26.5 months (1 month ∼7.5 years). Technical success was achieved in 26 of 30 patients (86.7%). Three patients (10.0%) developed restenosis. Only 1 patient underwent stent implantation, and the stent fractured 8 months later, requiring further intervention. No other complication was found. In terms of clinical benefit of blood pressure control after the initial PTRA procedure, 15 patients (50%) were cured and 7 (23.3%) improved. There was no significant difference in etiology, lesion location and length between patients with clinical benefit and failure (p=0.06, 0.202 and 0.06). The GFR of the affected kidney was significantly improved from 19.85±11.24 (ml/min) to 38.09±11.88 (ml/min) at 6 months follow-up after PTRA (p<0.001).

CONCLUSION

The overall results of PTRA for pediatric RVH caused by different etiologies are promising. Not only does it provide clinical benefit of blood pressure control in 73.3% of patients, it also significantly improves the function of the affected kidney.

Renovascular hypertension in pediatric patients: update on diagnosis and management

Renovascular hypertension (RVH) is defined as an elevated blood pressure caused by kidney hypoperfusion, generally as a result of anatomic stenosis of the renal artery with consequent activation of the Renin Angiotensin-Aldosterone System. The main causes include genetic and inflammatory disorders, extrinsic compression, and idiopathic alterations. RVH is often asymptomatic and should be suspected in any child with refractory hypertension, especially if other suggestive findings are present, including those with severe hypertension, abdominal bruit, and abrupt fall of glomerular filtration rate after administration of angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers. There is a consensus that digital subtraction angiography is the gold standard method for the diagnosis of RVH. Nevertheless, the role of non-invasive imaging studies such as Doppler ultrasound, magnetic resonance angiography, or computed tomographic angiography remains controversial, especially due to limited pediatric evidence. The therapeutic approach should be individualized, and management options include non-surgical pharmacological therapy and revascularization with percutaneous transluminal renal angioplasty (PTRA) or surgery. The prognosis is related to the procedure performed, and PTRA has a higher restenosis rate compared to surgery, although a decreased risk of complications. This review summarizes the causes, physiopathology, diagnosis, treatment, and prognosis of RVH in pediatric patients. Further studies are required to define the best approach for RVH in children.

PTRA is useful for renal artery angina by atherosclerotic plaque rupture with unilateral functioning kidney

We report a case of acute ischemic nephropathy in a patient with severe renal artery stenosis and bradycardia due to sick sinus syndrome. An 83-year-old Japanese woman with a history of hypertension was diagnosed with sick sinus syndrome and scheduled for pacemaker implantation. Four days prior to admission for the procedure, she experienced sudden-onset severe right flank pain that persisted for 1 day. On the day of admission, her serum creatinine level increased from 1.35 mg/dL, measured 2 weeks earlier, to 7.04 mg/dL. Laboratory examinations showed elevated C-reactive protein and lactate dehydrogenase levels. A computed tomography scan showed a severely atrophied left kidney, suggesting that it was non-functioning. Doppler ultrasonography of the right renal artery showed an extended acceleration time, suggesting proximal stenosis. Magnetic resonance imaging showed no enhancement in the proximal portions of the right renal artery, consistent with severe stenosis or occlusion. The patient developed severe bradycardia with lightheadedness; as a result, pacemaker implantation was performed on post-admission day 7. On day 10, digital subtraction angiography revealed diffuse severe stenosis of the right renal artery; intravascular ultrasonography suggested plaque rupture. Percutaneous transluminal renal angioplasty (PTRA) was performed and a drug-eluting stent was placed. On day 11, hemodialysis was performed owing to deteriorating renal function. The patient's renal function dramatically improved shortly thereafter. This case highlights the importance of PTRA for select patients, as it can potentially save some patients from chronic dialysis, and outlines the possible implications of bradycardia in the pathogenesis of ischemic nephropathy.

How should we define appropriate patients for percutaneous transluminal renal angioplasty treatment?

Renovascular hypertension (RVH) is one of the most common causes of secondary hypertension and can result in resistant hypertension. RVH is associated with an increased risk for progressive decline in renal function, cardiac destabilization syndromes including "flash" pulmonary edema, recurrent congestive heart failure, and cerebrocardiovascular disease. The most common cause of renal artery stenosis (RAS) is atherosclerotic lesions, followed by fibromuscular dysplasia. The endovascular technique of percutaneous transluminal renal angioplasty (PTRA) with or without stenting is one of the standard treatments for RAS. Randomized controlled trials comparing medical therapy with PTRA to medical therapy alone have failed to show a benefit of PTRA; however, the subjects of these randomized clinical trials were limited to atherosclerotic RAS patients, and patients with the most severe RAS, who would be more likely to benefit from PTRA, might not have been enrolled in these trials. This review compares international guidelines related to PTRA, reevaluates the effects of PTRA treatment on blood pressure and renal and cardiac function, discusses strategies for the management of RVH patients, and identifies factors that may predict which patients are most likely to benefit from PTRA.

Percutaneous transluminal renal angioplasty of global kidney ischemia improves renal function and blood pressure

Background

Renal artery stenosis (RAS) can lead to hypertension and renal failure. Nevertheless, its treatment by percutaneous transluminal renal angioplasty (PTRA) remains controversial. It is unknown, whether patients with global kidney ischemia (GKI), that means patients with bilateral RAS or RAS with a single functioning kidney, may benefit from PTRA or not.

Methods

We retrospectively analyzed 93 patients with RAS (25 bilateral or single functioning kidney) undergoing PTRA. Patients had refractory hypertension (≥3 medications). Blood pressure, antihypertensive drugs and serum-creatinine were compared pre-/post-intervention and at 1 year’s follow-up.

Results

At 1 year after PTRA of patients with GKI, systolic and diastolic blood pressure were significantly reduced compared to patients with unilateral PTRA (systolic: −19.1 ± 10.5 [bilateral] vs. −11.4 ± 12.1 mmHg [unilateral], P < 0.01; diastolic: −10.1 ± 6.8 mmHg vs. −6.3 ± 6.6 mmHg, P < 0.05). The number of antihypertensive drugs was reduced by −0.8 ± 3.0 at 1 year in patients with GKI, while it increased by +0.1 ± 3.5 in the unilateral RAS group (P < 0.001). Furthermore, post-interventional serum-creatinine decreased by −34.6 ± 31.4 μmol/I after of patients with GKI (P < 0.001 vs. baseline). In patients with unilateral PTRA, a non-significant increase in serum-creatinine was observed (+8.3 ± 2 μmol/l).

Conclusion

PTRA in patients with GKI led to improved blood pressure and renal function. A large, well-designed, randomized clinical trial targeting this population is still needed. The benefit of PTRA should be measured with the risks in each patient individually.

Successful endovascular treatment of chronic renal artery occlusion: a preliminary retrospective case series including 15 patients

PURPOSE

To evaluate in a retrospective, single-center, case series if percutaneous transluminal renal angioplasty/stenting of chronic renal artery occlusion is beneficial to renal function and blood pressure control, which remains controversial.

METHODS

Data from 15 consecutive patients with renal artery stump who underwent successful percutaneous transluminal renal angioplasty/stenting only for unilateral chronic renal artery occlusion at our center from January 2007 to February 2018 and completed follow-up were retrospectively evaluated. Of the 15 patients, 14 (93.3%) were treated with stenting and 1 with only balloon angioplasty. Estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet in Renal Disease (MDRD) formula corrected for Chinese, and changes in blood pressure and need for antihypertensive medications were recorded.

RESULTS

At median 1.5-year (interquartile range 0.5-5.0) follow-up, restenosis rate was 20.0%. Renal function improved or remained stable in 26.7% and 53.3% of patients, respectively, and blood pressure normalized or improved in 13.3% and 40.0% of patients, respectively. Young patients with Takayasu's arteritis or fibromuscular dysplasia appeared to benefit the most from revascularization.

CONCLUSIONS

In this preliminary retrospective series of select patients with renal artery stump, endovascular treatment of chronic renal artery occlusion appeared to preserve renal function and improve blood pressure.

A refractory hypertensive patient with fibromuscular dysplasia and multicystic dysplastic kidney

The case of a 16-year-old male patient with left renal artery stenosis due to fibromuscular dysplasia (FMD) and an atrophic kidney due to a right multicystic dysplastic kidney (MCDK) who presented with refractory hypertension is reported. On continuous Doppler imaging, the peak systolic velocity (PSV) at the stenotic site of the left renal artery was 404 cm/s. The FMD formed a "string-of-beads" appearance on computed tomographic angiography (CTA) and renal artery angiography. Percutaneous transluminal renal angioplasty (PTRA) with a balloon catheter was performed, after which the left renal artery returned to near normal, and his blood pressure decreased to within the normal range. In this case, the main cause of refractory hypertension was considered to have been renal artery stenosis due to left FMD.

Clinical characteristics and treatment of renal artery fibromuscular dysplasia with percutaneous transluminal angioplasty: a long-term follow-up study

BACKGROUND

Renal artery fibromuscular dysplasia (RAFMD) is a non-atherosclerotic cause of renal artery stenosis often affecting the young. Percutaneous transluminal renal angioplasty (PTRA) is the treatment of choice but there are few studies of the outcome of the procedure.

METHODS

This retrospective analysis included 64 patients (56.2 % female; mean age at diagnosis, 28.0 years) with RAFMD who underwent PTRA between November 2003 and August 2015. Technical and clinical success rates and restenosis rates were evaluated.

RESULTS

Seventy-six procedures were performed on 64 RAFMD patients. Technical success was 96.9 %, as defined by <30 % residual stenosis, with stent placement required in 11 patients (17.2 %). In the short term (1 month), the majority (79.7 %) had an immediate clinical benefit, with cure of hypertension in 35.9 %, and improvement in hypertension and a lower requirement for antihypertensive medications in 43.8 %. In the long term (mean, 47.5 months; range, 5-141 months), the survival rate was 96.9 %, freedom from restenosis was 84.4 %, and 76.6 % of patients showed a sustained clinical benefit (cure rate 40.6 %, improvement rate 35.9 %). Eight patients were treated with a second procedure and two had a third procedure, with half of these patients showing an improvement in hypertension.

CONCLUSION

PTRA for symptomatic RAFMD is safe and clinically successful. More than half of patients experience an immediate clinical benefit with sustained long-term effects. For patients with restenosis, there was a good response to a second PTRA.

Intravascular findings of fibromuscular dysplasia on optical coherence tomography

We present the case of a 29-year-old woman with right renal artery stenosis caused by fibromuscular dysplasia (FMD) who underwent optical coherence tomography (OCT)-guided percutaneous transluminal renal angioplasty. Using OCT, we could clearly observe intimal fibroplasia and medial hyperplasia that was indicative of FMD. Based on diagnosis of FMD by OCT, this patient was treated with plain old balloon angioplasty that resulted in adequate luminal opening without intimal dissection confirmed on final angiography and OCT. <Learning objective: Fibromuscular dysplasia (FMD) is most often diagnosed based on its characteristic appearance on angiography but it is insufficient. Although pathological examination is needed for definite diagnosis, it is not realistic. Therefore, it is important to assess the detailed intravascular findings of culprit and non-culprit lesions in FMD with optical coherence tomography.>.