Prediction of Hypertension Improvement After Stenting of Renal Artery Stenosis

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.

Correlation of renal cortical blood perfusion and BP response after renal artery stenting

Background

This study aimed to observe the correlation between renal cortical blood perfusion (CBP) parameters and BP response in patients with severe renal artery stenosis (RAS) who underwent stenting.

Methods

This was a single-center retrospective cohort study. A total of 164 patients with unilateral severe RAS after successful percutaneous transluminal renal artery stenting in Beijing Hospital from October 2017 to December 2020 were included. According to the results of BP evaluated at 12 months, all patients were divided into the BP response group (n = 98) and BP nonresponse group (n = 66). The baseline clinical and imaging characteristics and follow-up data about 24 h ABPM and CBP were recorded and analyzed. Pearson correlation analysis was used to evaluate the relationship between CBP parameters and 24 h average SBP. Univariate and multivariate logistic regression analysis was used to evaluate the risk factors for BP response.

Results

Among 164 patients with severe RAS, there were 100 males (61.0%), aged 37–75 years, with an average of 56.8 ± 18.4 years, and average artery stenosis of 84.0 ± 12.5%. The BP nonresponse patients had a longer duration of hypertension, more current smoking subjects and diabetic patients, lower eGFR, increased number of hypertensive agents, and rate of insulin compared with the BP response group (P < 0.05). After PTRAS, patients in the BP response group were associated with significantly lower BP and improved CPB, characterized by increased levels of maximum intensity (IMAX), area under ascending curve (AUC1), area under the descending curve (AUC2), shortened rising time (RT), mean transit time (mTT), and prolonged time to peak intensity (TTP; P < 0.05). However, the BP nonresponse group was only associated with significantly reduced RT (P < 0.05) compared with baseline data. During an average follow-up of 11.5 ± 1.7 months, the BP response group was associated with significantly lower levels of SBP, DBP, 24 h average SBP, and 24 h average DBP compared with the nonresponse group (P < 0.05). Pearson correlation analysis showed that the the pre-operative CBP parameters, including IMAX (r = 0.317), RT (r = 0.249), AUC1 (r = 0.614), AUC2 (r = 0.558), and postoperative CBP parameters, including RT (r = 0.283), AUC1 (r = 0.659), and AUC2 (r = 0.674) were significantly positively correlated with the 24 h average SBP, while the postoperative TTP (r = −0.413) and mTT (r = −0.472) were negatively correlated with 24 h average SBP (P < 0.05). Multivariate Logistic regression analysis found that diabetes (OR = 1.294), NT-proBNP (OR = 1.395), number of antihypertensive agents (OR = 2.135), pre-operation IMAX (OR = 1.534), post-operation AUC2 (OR = 2.417), and baseline dDBP (OR = 2.038) were related factors for BP response (all P < 0.05).

Conclusion

Patients in the BP nonresponse group often have diabetes, a longer duration of hypertension, significantly reduced glomerular filtration rate, and heavier renal artery stenosis. CBP parameters are closely related to 24 h average SBP, and pre-operation IMAX and post-operation AUC2 are markers for a positive BP response.

Revascularization for Renovascular Disease: A Scientific Statement From the American Heart Association

Renovascular disease is a major causal factor for secondary hypertension and renal ischemic disease. However, several prospective, randomized trials for atherosclerotic disease failed to demonstrate that renal revascularization is more effective than medical therapy for most patients. These results have greatly reduced the generalized diagnostic workup and use of renal revascularization. Most guidelines and review articles emphasize the limited average improvement and fail to identify those clinical populations that do benefit from revascularization. On the basis of the clinical experience of hypertension centers, specialists have continued selective revascularization, albeit without a summary statement by a major, multidisciplinary, national organization that identifies specific populations that may benefit. In this scientific statement for health care professionals and the public-at-large, we review the strengths and weaknesses of randomized trials in revascularization and highlight (1) when referral for consideration of diagnostic workup and therapy may be warranted, (2) the evidence/rationale for these selective scenarios, (3) interventional and surgical techniques for effective revascularization, and (4) areas of research with unmet need.

Prediction of Split Renal Function Improvement After Renal Artery Stenting by Blood Oxygen Level–Dependent Magnetic Resonance Imaging

Background

The discrepancy between the high technical success rate and the relatively low clinical response rate of renal artery stenting (RAS) raises the importance to identify atherosclerotic renal artery stenosis (ARAS) patients who are most likely to benefit from RAS. This study aimed to investigate the feasibility and accuracy of blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) in predicting split renal function (SRF) improvement after RAS in patients with ARAS.

Methods

Thirty patients with severe ARAS who were treated with RAS were enrolled. Baseline cortical and medullary R2* values of each kidney were measured by BOLD-MRI, and each patient’s SRF was evaluated by nuclear renal dynamic imaging at baseline and 1-month follow-up.

Results

In total, 35 severe stenotic renal arteries of the 30 patients were analyzed. At 1-month follow-up, 34 kidneys (97.1%) of severe ARAS had acquired SRF. SRF improved in 12 kidneys of 10 patients. The cortical R2* and medullary R2* values in the SRF improvement kidneys were higher than those in the non-improvement kidneys (P ≤ 0.001). The area under the curve of medullary R2* was 0.879 (95% confidence interval [CI] 0.736–1.000). A medullary R2* value ≥29.1 s^–1 was noted to provide good sensitivity (0.833, 95% CI 0.552–0.970) and specificity (0.864, 95% CI 0.667–0.953) in predicting SRF improvement. Medullary R2* value was the only independent predictor of SRF improvement in multivariable analysis (P = 0.034, OR 3.017, 95%CI 1.089–8.358).

Conclusion

This study showed that a BOLD-MRI medullary R2* value ≥29.1 s^–1 was an excellent predictor of SRF improvement in patients with severe ARAS who underwent renal artery stenting.

Case Report: Combination of Pressure Guidewire and Optical Coherence Tomography-Guided Drug-Coated Balloon Revascularization for Renal Artery Fibromuscular Dysplasia

Fibromuscular dysplasia (FMD) is the second common cause of renovascular hypertension. With the advent of endovascular therapy, angiography has become a diagnostic gold standard for FMD. Optical coherence tomography (OCT) by reflecting in vivo histology may improve diagnostic and classification accuracy. Renal fractional flow reserve (rFFR), measured by pressure guidewire, may distinguish the patients who may benefit from revascularization by identifying physiologically significant stenoses. However, the role of usage of both OCT and rFFR is not well-studied. We herein report a 17-year-old male with renovascular hypertension due to FMD. Angioplasty of drug-coated balloon (DCB) guided by OCT and FFR favorably achieved blood pressure (BP) control. In conclusion, the utility of both OCT and FFR may be useful for the appropriate selection of patients with renal FMD.

Renal interventions in the management of hypertension

PURPOSE OF REVIEW

In the present comprehensive review, we describe the pathophysiology, indications, and evidence for both renal artery stenting and renal artery denervation. We also discuss the procedural techniques, risks, benefits, and future directions of renal intervention in the management of hypertension (HTN).

RECENT FINDINGS

Hemodynamic confirmation of lesion severity in severe renal artery stenosis is a resting or hyperemic translesional systolic gradient >20, resting or hyperemic mean translesional gradient >10 and/or renal fractional flow reserve <0.8 are considered severe. Knowing that correct stent size was used is the best predictor of restenosis, intravascular ultrasound is effective and well tolerated for stent sizing. The main categories of renal denervation: radiofrequency ablation, ultrasound, chemical ablation, and brachytherapy have shown impressive outcomes in treating resistant HTN.

SUMMARY

Over the past decade, several studies have shown the safety and benefit of catheter-based renal interventions in managing HTN. Renal artery stenting and renal artery denervation are the leading alternative invasive treatment employed in managing HTN.

Use of percutaneous transluminal renal angioplasty in atherosclerotic renal artery stenosis: a systematic review and meta-analysis

OBJECTIVE

For patients with atherosclerotic renal artery stenosis (ARAS), the role of percutaneous transluminal renal angioplasty (PTRA) remains inconclusive. This study aimed to comparatively evaluate the benefits of best medical therapy (BMT) plus PTRA and BMT alone in treating ARAS.

METHODS

We performed a systematic review and meta-analysis, and searched for all randomized, controlled trials that reported patients with ARAS. The effectiveness and safety in the BMT plus PTRA and BMT alone groups were estimated, taking into account hypertension, stroke, renal events, cardiac events, and mortality.

RESULTS

Nine randomized, controlled trials involving 2309 patients were included. In the BMT plus PTRA group, the incidence of refractory hypertension was significantly lower compared with that in the BMT alone group (odds ratio 0.09; 95% confidence interval 0.01, 0.70). However, there were no significant differences in the rates of stroke, renal events, cardiac events, cardiac mortality, and all-cause mortality between the two groups.

CONCLUSIONS

PTRA plus BMT improves blood pressure in patients with ARAS, but there is insufficient evidence for this therapy in improving stroke, renal events, cardiac events, and cardiac and all-cause mortality.

Renal Artery Stenosis in the Patient with Hypertension: Prevalence, Impact and Management

Atherosclerosis is the primary cause of renal artery stenosis. Atherosclerotic renal artery stenosis (ARAS) is associated with three clinical problems: renovascular hypertension, ischemic nephropathy and cardiac destabilization syndrome which pose huge healthcare implications. There is a significant rate of natural disease progression with worsening severity of renal artery stenosis when renal revascularization is not pursued in a timely manner. Selective sub-groups of individuals with ARAS have had good outcomes after percutaneous renal artery stenting (PTRAS). For example, individuals that underwent PTRAS and had improved renal function were reported to have a 45% survival advantage compared to those without improvement in their renal function. Advances in the imaging tools have allowed for better anatomic and physiologic measurements of ARAS. Measuring translesional hemodynamic gradients has allowed for accurate assessment of ARAS severity. Renal revascularization with PTRAS provides a survival advantage in individuals with significant hemodynamic renal artery stenosis lesions. It is important that we screen, diagnosis, intervene with invasive and medical treatments appropriately in these high-risk patients.

When and How Should We Revascularize Patients With Atherosclerotic Renal Artery Stenosis?

Atherosclerotic renal artery stenosis is the leading cause of secondary hypertension and may lead to resistant (refractory) hypertension, progressive decline in renal function, and cardiac destabilization syndromes (pulmonary edema, recurrent heart failure, or acute coronary syndromes) despite guideline-directed medical therapy. Although randomized controlled trials comparing medical therapy with medical therapy and renal artery stenting have failed to show a benefit for renal artery stenting, according to comparative effectiveness reviews by the Agency for Healthcare Research and Quality, the trials may not have enrolled patients with the most severe atherosclerotic renal artery stenosis, who would be more likely to benefit from renal stenting. Because of limitations of conventional angiography, it is critical that the hemodynamic severity of moderately severe (50% to 70%) atherosclerotic renal artery stenosis lesions be confirmed on hemodynamic measurement. The authors review techniques to optimize patient selection, to minimize procedural complications, and to facilitate durable patency of renal stenting. The authors also review the current American College of Cardiology and American Heart Association guidelines and the Society for Cardiovascular Angiography and Interventions appropriate use criteria as they relate to renal stenting.

Selection of Patients for Angioplasty for Treatment of Atherosclerotic Renovascular Disease: Predicting Responsive Patients

Atherosclerotic renal artery stenosis (ARAS) can cause secondary hypertension, progressive decline in renal function, and cardiac complications. Recent randomized controlled trials including the Cardiovascular Outcomes in Renal Atherosclerotic Lesions study have not reported the benefit of renal artery stenting compared with medical therapy alone to improve renal function or reduce cardiovascular and renal events in the enrolled patients with ARAS. However, observational evidence indicating the benefits of angioplasty in the selected high-risk patients with ARAS has been increasing. Thus, the timely correction of stenosis through angioplasty may have a beneficial effect in selected patients. However, optimal patient selection for angioplasty has been debated and can be challenging at times. Clinicians must identify the responsive patients who would benefit from angioplasty through risk stratification and the prediction of outcomes. Efforts have been made for the determination of predictors that can identify the subgroups of patients who would benefit from angioplasty. Lower age, more severe stenosis, preserved renal perfusion, and absence of diabetes or generalized atherosclerosis have been reported as the predictors for the improvement of hypertension after angioplasty. Global renal ischemia, rapidly declining renal function over 6-12 months, progressive shrinkage of the affected kidney, lower resistive index, and lower levels of albuminuria have been reported as predictors of improved or preserved renal function after angioplasty. This review discusses the identification of ARAS patients who will potentially respond well to angioplasty.

Atherosclerotic-nephropathy: an updated narrative review

The increased prevalence of chronic kidney disease (CKD) in elderly patients recognizes, as main cause, the long-term exposure to atherosclerosis and hypertension. Chronic ischemic damage due to critical renal arterial stenosis induces oxidative stress and intra-renal inflammation, resulting in fibrosis and microvascular remodelling, that is the histological picture of atherosclerotic renal vascular disease (ARVD). The concomitant presence of a long history of hypertension may generate intimal thickening and luminal narrowing of renal arteries and arterioles, glomerulosclerosis, interstitial fibrosis and tubular atrophy, more typically expression of hypertensive nephropathy. These complex mechanisms contribute to the development of CKD and the progression to End Stage Kidney Disease. In elderly CKD patients, the distinction among these nephropathies may be problematic; therefore, ischemic and hypertensive nephropathies can be joined in a unique clinical syndrome defined as atherosclerotic nephropathy. The availability of novel diagnostic procedures, such as intra-vascular ultrasound and BOLD-MRI, in addition to traditional imaging, have opened new scenarios, because these tools allow to identify ischemic lesions responsive to renal revascularization. Indeed, although trials have deflated the role of renal revascularization on the renal outcomes, it should be still used to avoid dialysis initiation and/or to reduce blood pressure in selected elderly patients at high risk. Nonetheless, lifestyle modifications (smoking cessation, increased physical activity), statins and antiplatelet use, as well as cautious use of renin-angiotensin system inhibitors, remain the main therapeutic approach aimed at slowing the renal damage progression. Mesenchymal stem cells and Micro-RNA are promising target of anti-fibrotic therapy, which might provide potential benefit in ARVD patients, though safety and efficacy profile in humans is unknown too.

Effects of percutaneous angioplasty on kidney function and blood pressure in patients with atherosclerotic renal artery stenosis

Background

Previous randomized controlled trials of revascularization for atherosclerotic renal artery stenosis (ARAS) were not successful. We investigated the effects of percutaneous transluminal angioplasty with stent insertion (PTA/S) on kidney function and blood pressure (BP) control in patients with ARAS.

Methods

From 2000 to 2017, 47 subjects who underwent PTA/S for ARAS were identified. A high-risk group was defined, composed of patients having one or more of the following clinical presentations: pulmonary edema, refractory hypertension, and rapid deterioration of kidney function. Subjects who met the criteria of 'kidney function improvement' or 'hypertension improvement' after PTA/S were classified as responders.

Results

Twenty-one (44.7%) subjects were classified into the high-risk group. Two subjects (8.0%) in the low-risk group (n = 25) and 5 subjects (27.8%) in the high-risk group (n = 18) showed improvement in kidney function after PTA/S (P = 0.110). In patients with rapid decline of kidney function, estimated glomerular filtration rate improved from 28 (interquartile range [IQR], 10-45) mL/min/1.73 m² to 41 (IQR, 16-67) mL/min/1.73 m² at 4 months after PTA/S, although the difference was not significant (P = 0.084). Regarding BP control, 9 (36.0%) and 14 (77.8%) subjects showed improvement after PTA/S in the low- (n = 25) and high-risk (n = 18) groups, respectively (P = 0.007). In patients with refractory hypertension, the systolic BP dropped from 157 (IQR, 150-164) mmHg to 140 (IQR, 131-148) mmHg at 4 months after PTA/S (P = 0.005). Twenty-five subjects were defined as responders and comprised a significant proportion of the high-risk group (P = 0.004).

Conclusion

PTA/S might improve BP control and kidney function in patients with ARAS presenting with high-risk clinical features. The optimal application of PTA/S should be based on individual assessment of the clinical significance of renal artery stenosis.

Endovascular treatment of transplant renal artery stenosis based on hemodynamic assessment using a pressure wire: a case report

Background

Transplant renal artery stenosis (TRAS) is a serious complication after renal transplantation, leading to hypertension, deterioration in renal function, and/or graft loss. The incidence of TRAS reportedly varies from 1 to 23%, depending on its definition or diagnostic tools. The hemodynamic definition or therapeutic indication of TRAS is unclear.

Case presentation

A 66-year-old man with a history of diabetes, chronic kidney disease, and angina presented with a 2-week history of dyspnea and leg edema. He had undergone living-donor kidney transplantation for end-stage renal disease secondary to diabetic nephropathy 7 years earlier. He developed acute deterioration in renal function after the administration of an angiotensin II receptor blocker and required emergency hospitalization owing to acute congestive heart failure with pulmonary edema. A vasodilator and loop diuretics were administered following his admission, and the patient’s symptoms resolved quickly. Further investigation, including magnetic resonance angiography and ultrasonography, revealed severe stenosis of the transplant renal artery. Renal arteriography and pressure gradient measurement using a 0.014-inch pressure wire were performed. The systolic pressure gradient was 40 mmHg, and the resting Pd/Pa ratio (ratio of mean distal to lesion and mean proximal pressures) was 0.90 without hyperemia. Hemodynamically significant stenosis was suspected. Intravascular ultrasonography revealed vessel shrinkage in the stenotic area, suggestive of the end-to-end anastomosis site. Pre-dilation using a 4-mm balloon, implantation of a 6-mm self-expandable stent, and post-dilatation using a 5-mm balloon were performed. Although the moderate stenosis persisted angiographically, the systolic pressure gradient dropped to 20 mmHg with the mean systolic pressure ratio increased to 0.95, which was considered an acceptable result. One month after the procedure, the patient’s renal function and blood pressure control had significantly improved.

Conclusions

Hemodynamic assessment using a pressure wire is useful in determining the appropriate therapeutic indication and endpoint of endovascular treatment of TRAS.

Is there still a role for renal artery stenting in the management of renovascular hypertension - A single-center experience and where do we stand?

BACKGROUND

Renal artery (RA) stenosis has been implicated in the pathophysiological mechanism for resistant hypertension. Despite the increasingly diagnosed frequency of hemodynamically significant lesions, the value of RA revascularization remains controversial. Our group had previously demonstrated significant blood pressure (BP) reduction in a retrospective cohort of appropriately selected patients undergoing RA stenting up to 18-months of follow-up. We herein present long-term clinical outcomes data 5-years post revascularization on 26 subjects who continued follow-up at our institution.

METHODS

Retrospective analysis was performed on subjects who underwent RA stenting at our institution for hemodynamically significant (≥70%) RA stenosis and systolic hypertension on ≥3 antihypertensive agents. Clinical outcome data for systolic blood pressure (SBP), diastolic blood pressure (DBP), creatinine level and number of antihypertensive drugs was assessed prior to and then later at 6-12 months and 3-5 years post RA stenting.

RESULTS

Mean age was 69 ± 9 years; 27% (7/26) were male. Median follow-up was 5.1 years. Blood pressure reduction was sustained at long-term follow-up (135/70 ± 18/11 mmHg) compared to initial reduction noted at 6-months (136/69 ± 16/8 mmHg; p ≤0.01 for both) and from baseline (162/80 ± 24/18 mmHg; p ≤0.001 for both). The number of antihypertensive agents also decreased from 4.1 ± 1.0 to 2.7 ± 2.1 (p = 0.002) at 6-months and was sustained at long-term follow-up, 3.4 ± 1.2 (p = 0.03) with no difference in renal function between short- and long-term follow-up compared to baseline.

CONCLUSIONS

This study shows sustained benefit of RA stenting in BP reduction in an appropriately selected cohort with significant stenosis ≥70% and uncontrolled hypertension on multiple medications on long-term follow-up.

Atherosclerotic Renal Artery Stenosis: Should we Intervene Earlier?

Purpose of Review

Randomized trials have failed to show clinical benefit in patients with atherosclerotic renal artery stenosis who were treated with angioplasty with or without stenting. However, these studies were done in patients with a high-grade stenosis. This paper examines whether there are arguments to consider patients with low-grade stenosis for angioplasty.

Recent Findings

Patients with low-grade (< 50%) atherosclerotic renal artery stenosis have an excess risk for cardiovascular and renal complications. This could be related to inflammatory factors being generated by the stenotic kidney. Moreover, even a kidney with low-grade stenosis clears less or produces more of the natural nitric oxide inhibitor ADMA.

Summary

Patients with low-grade atherosclerotic renal artery stenosis have an increased risk for a variety of complications. In addition, the abnormality is progressive. There is a case for setting up a prospective trial to examine whether angioplasty confers benefit in patients with low-grade renal artery stenosis.

Predictors of cardiac benefits of renal artery stenting from a multicentre retrospective registry

OBJECTIVES

There have been limited data regarding the prediction of cardiac benefits after renal artery stenting for patients with atherosclerotic renal artery disease (ARAD). The aim of this multicentre retrospective study was to identify clinical or echocardiographic factors associated with improvements of cardiac symptoms after renal artery stenting.

METHODS

We enrolled 58 patients with de novo ARAD undergoing successful renal artery stenting for heart failure, angina or both between January 2000 and August 2015 at 13 hospitals.

RESULTS

Improvement of cardiac symptoms was observed in 86.2% of patients during a mean follow-up of 6.0±2.7 months. Responders demonstrated significantly lower New York Heart Association functional class, higher estimated glomerular filtration rate, lower serum creatinine and lower interventricular septal wall thickness (IVS), lower left ventricular mass index, lower left atrial dimension and lower E-velocity than non-responders. Backward stepwise multivariate analysis identified IVS as an independent predictor of improvement of cardiac symptoms (OR 0.451, 95% CI 0.209 to 0.976; p=0.043). According to receiver operating characteristic curve analysis, an IVS cut-off of 11.9 mm provided the best predictive value, with sensitivity of 71.4%, specificity of 75.5% and accuracy of 73.5%. The positive predictive value was 74.5% and the negative predictive value was 72.5%.

CONCLUSIONS

This multicentre retrospective study shows that the echocardiographic index of IVS is an independent predictor for improvement of cardiac symptoms after renal artery stenting.

Renal artery stenting for atherosclerotic renal artery stenosis identified in patients with coronary artery disease: Does captopril renal scintigraphy predict outcomes?

The authors evaluated the effectiveness of percutaneous renal revascularization (PRR) with stenting for the treatment of atherosclerotic renal artery stenosis (ARAS) in patients with coronary artery disease and the usefulness of captopril renal scintigraphy for predicting clinical outcomes after PRR. Sixty-four consecutive patients, referred for evaluation of suspected ARAS, after coronary angiography, underwent baseline captopril renal scintigraphy followed by renal angiography. Forty-four patients (68.7%) were diagnosed with a significant ARAS≥ 60% and were treated with PRR plus medical therapy. Twenty-four months after PRR, 86.4% and 73.3% of patients showed a hypertension and renal benefit, respectively. Captopril renal scintigraphy positivity had moderate sensitivity and high specificity in predicting a hypertension and renal benefit. In patients with ARAS≥ 70%, the sensitivity and specificity were 100% for both a hypertension and renal benefit.PRR for ARAS conferred a substantial benefit in patients with a high coronary artery disease burden. Captopril renal scintigraphy was highly accurate in predicting clinical outcomes.

Hemodynamic Measurements for the Selection of Patients With Renal Artery Stenosis: A Systematic Review

Interventions targeting renal artery stenoses have been shown to lower blood pressure and preserve renal function. In recent studies, the efficacy of catheter-based percutaneous transluminal renal angioplasty with stent placement has been called into question. In the identification of functional coronary lesions, hyperemic measurements have earned a place in daily practice for clinical decision making, allowing discrimination between solitary coronary lesions and diffuse microvascular disease. Next to differences in clinical characteristics, the selection of renal arteries suitable for intervention is currently on the basis of anatomic grading of the stenosis by angiography rather than functional assessment under hyperemia. It is conceivable that, like the coronary circulation, functional measurements may better predict therapeutic efficacy of percutaneous transluminal renal angioplasty with stent placement. In this systematic review, the authors evaluate the available clinical evidence on the optimal hyperemic agents to induce intrarenal hyperemia, their association with anatomic grading, and their predictive value for treatment effects. In addition, the potential value of combined pressure and flow measurements to discriminate macrovascular from microvascular disease is discussed.

Renal Artery Stenosis: When to Revascularize in 2017

Atherosclerotic renal artery stenosis is the leading cause of secondary hypertension; it can also cause progressive renal insufficiency and cardiovascular complications such as refractory heart failure and flash pulmonary edema. Medical therapy including risk factor modification, renin-angiotensin-aldosterone system antagonists, lipid lowering agents, and antiplatelet therapy is the first line of treatment in all patients. Patients with uncontrolled renovascular hypertension despite optimal medical therapy, ischemic nephropathy, and cardiac destabilization syndromes who have severe renal artery stenosis are likely to benefit from renal artery revascularization. Screening for renal artery stenosis can be done with Doppler ultrasonography, computed tomographic angiography and magnetic resonance angiography. Invasive physiologic measurements are useful to confirm the severity of renal hypoperfusion and therefore improve the selection patients likely to respond to renal artery revascularization. Primary patency exceeds 80% at 5 years and surveillance for in-stent restenosis can be done with periodic clinical, laboratory, and imaging follow-up.

Efficacy of 24-Hour Blood Pressure Monitoring in Evaluating Response to Percutaneous Transluminal Renal Angioplasty

BACKGROUND

Percutaneous transluminal renal angioplasty (PTRA) improves patency in atherosclerotic renal artery stenosis (ARAS), but improvement in clinic blood pressure (BP) is seen in only 20-40% of patients who undergo PTRA. This study investigated the effects of PTRA on BP lowering, assessed on 24-h ambulatory BP monitoring (ABPM), and identified preoperative features predictive of satisfactory BP improvement after PTRA.

METHODS AND RESULTS

Of 1,753 consecutive patients undergoing coronary angiography, 31 patients with angiographically significant ARAS and translesional pressure gradient (TLPG) >20 mmHg underwent PTRA. ABPM was performed before, at 1 month and at 1 year after PTRA; patients with average systolic ABPM-BP decrease >10 mmHg at 1 month from baseline were categorized as responders. There was no obvious relationship between clinic BP and ABPM-BP at baseline. ABPM-BP was significantly higher in responders at baseline (SBP: 148 vs. 126 mmHg, P<0.01) and was improved 1 month after PTRA. This difference persisted until 1 year after PTRA. Night-time BP improved more than daytime BP in responders. Patients with higher baseline ABPM-BP achieved a larger decrease in ABPM-BP, but the severity of stenosis reflected by TLPG; renal duplex findings; and neurohumoral parameters other than baseline renal function, did not differ between the groups.

CONCLUSIONS

Clinic BP does not represent daily hemodynamic status, whereas high ABPM-BP is a potent predictor of satisfactory BP response to PTRA. (Circ J 2016; 80: 1922-1930).

Renal Artery Stenosis: Optimal Therapy and Indications for Revascularization

Atherosclerotic renal artery stenosis (ARAS) is associated with increased cardiovascular risk and overall mortality. Manifestations of ARAS include resistant or malignant hypertension, progressive deterioration of renal function, and cardiac dysfunction syndromes of flash pulmonary edema and angina. Diagnosis rests upon non-invasive studies such as duplex ultrasonography and is confirmed using invasive renal arteriography. Regardless of the severity of ARAS, management of this entity has been a topic of contentious debate. For over two decades, the use of percutaneous revascularization to treat ARAS has been studied with various clinical trials. Though case series seem to demonstrate favorable clinical response to revascularization, the overwhelming majority of randomized clinical trials have not mirrored a robust outcome. In these trials, poor correlation is noted between the reduction of stenosis and the improvement of renovascular hypertension and glomerular filtration rate, and decrease in cardiovascular outcomes and mortality. With dichotomizing results, the explanation for these discrepant findings has been attributed to improper trial design and inappropriate patient selection. An overview of the treatment options available will be provided, with a focus on the methodology and design of clinical trials investigating the efficacy of percutaneous revascularization. Emphasis is placed on appropriate patient selection criteria, which may necessitate the use of hemodynamic lesion assessment and clinical correlation based on individualized care. When clinical equipoise exists between optimal medical therapy and revascularization, the current paradigm supports ongoing medical therapy as the treatment of choice. However, renal artery stenting remains a viable therapeutic option for those who continue to have clinical syndromes consistent with renal hypoperfusion while adequately treated with optimal medical therapy. Despite observational studies suggesting clinical benefit for this specific patient population, there remains a paucity of randomized clinical trial data. Further trials targeting the patients who are inadequately treated with optimal medical therapy need to be undertaken to confirm the efficacy of revascularization.

Renovascular heart failure: heart failure in patients with atherosclerotic renal artery disease

Atherosclerotic renal artery disease presents with a broad spectrum of clinical features, including heart failure as well as hypertension, and renal failure. Although recent randomized controlled trials failed to demonstrate renal artery stenting can reduce blood pressure or the number of cardiovascular or renal events more so than medical therapy, increasing attention has been paid to flash pulmonary edema and congestive heart failure associated with atherosclerotic renal artery disease. This clinical entity "renovascular heart failure" is diagnosed retrospectively. Given the increasing global burden of heart failure, this review highlights the background and catheter-based therapeutic aspects for renovascular heart failure.

Kidney microcirculation response to adenosine stimulation in renal artery stenosis

The purpose of this study was to assess the vasoconstrictive effects of adenosine in the kidney microcirculation in hypertensive patients with renal artery stenosis (RAS). Twelve patients with resistant hypertension and moderate RAS were selected for the study. In all patients, systolic, diastolic and mean translesional pressure gradients, distal pressure (Pd), aortic pressure (Pa) and Pd/Pa ratio were measured using a pressure guidewire at baseline and after intrarenal bolus administration of 400 μg adenosine. We observed significant changes in mean translesional pressure gradient and systolic Pd after pharmacological stimulation. The results suggest that in hypertensive patients with RAS, vasomotor activity of the kidney microcirculation may be preserved.

Clinical outcome of renal artery stenting for hypertension and chronic kidney disease up to 12 months in the J-RAS Study – prospective, single-arm, multicenter clinical study

BACKGROUND

Atherosclerotic renal artery stenosis (ARAS) causes renovascular hypertension (HTN) and impairs renal function, leading to chronic kidney disease (CKD). The J-RAS study was a prospective, multicenter study to assess the clinical outcome of renal artery stenting for up to 1 year in Japanese patients with ARAS.

METHODS AND RESULTS

One hundred and forty-nine patients were enrolled between November 2010 and January 2013. The patients were classified into an HTN (n=121) group and a CKD (n=108) group in the primary analysis. The primary efficacy endpoints were change in blood pressure for the HTN group and change in estimated glomerular filtration rate (eGFR) for the CKD group at 1 months. The primary safety endpoint was freedom from major cardiovascular or renal events at 12 months. In the HTN group, the mean systolic blood pressure (SBP) significantly decreased from 161.6 ± 21 mmHg at baseline to 137.0 ± 21 mmHg (P<0.0001). In the CKD group, there was no significant difference in eGFR from 40.7 ± 10 ml·min(-1)·1.73 m(-2)at baseline to 40.8 ± 13 ml·min(-1)·1.73 m(-2)(P=0.32). The primary safety endpoint was 89.4% at 12 months.

CONCLUSIONS

In the J-RAS trial, significant SBP reduction was seen in the HTN group, and stabilization of renal function in the CKD group. Renal artery stenting for ARAS is safe and effective in Japanese patients.

[Atherosclerotic renal artery stenosis]

Atherosclerotic renal artery stenosis can cause ischaemic nephropathy and arterial hypertension. Renal artery stenosis (RAS) continues to be a problem for clinicians, with no clear consensus on how to investigate and assess the clinical significance of stenotic lesions and manage the findings. RAS caused by fibromuscular dysplasia is probably commoner than previously appreciated, should be actively looked for in younger hypertensive patients and can be managed successfully with angioplasty. Atheromatous RAS is associated with increased incidence of cardiovascular events and increased cardiovascular mortality, and is likely to be seen with increasing frequency. Many patients with RAS may be managed effectively with medical therapy for several years without endovascular stenting, as demonstrated by randomized, prospective trials including the cardiovascular outcomes in Renal Atherosclerotic Lesions (CORAL) trial, the Angioplasty and Stenting for Renal Artery Lesions (ASTRAL) trial. These trials share the limitation of excluding subsets of patients with high-risk clinical presentations, including episodic pulmonary edema and rapidly progressing renal failure and hypertension. Blood pressure control and medication adjustment may become more difficult with declining renal function and may prevent the use of angiotensin receptor blocker and angiotensin-converting enzyme inhibitors. The objective of this review is to evaluate the current management of RAS for cardiologists in the context of recent randomized clinical trials. There is now interest in looking more closely at patient selection for intervention, with focus on intervening only in patients with the highest-risk presentations such as flash pulmonary edema, rapidly declining renal function and severe resistant hypertension.

Atherosclerotic renal artery stenosis and revascularization

Atherosclerotic renovascular disease is the most common cause of secondary hypertension. The patients with renovascular disease are at increased risk for adverse cardiac outcomes. Recent trials comparing medical therapy alone to medical therapy with stenting are flawed, but lay to rest any existing debate that unselected revascularization is unwarranted; however, revascularization may be appropriate in high-risk populations. Defining an appropriate population for revascularization is an area of ongoing study. Furthermore, delivery of optimal medical therapy in this population is inadequate. This review describes recent developments in renal artery revascularization.

Where and when device therapy may be useful in the management of drug-resistant hypertension

Device therapy for the treatment of uncontrolled and resistant hypertension has evolved significantly over the past several decades. Both renal artery disease and sympathetic hyperactivity have been linked to resistant hypertension. This manuscript will review the current evidence base supporting device therapy (e.g., renal artery revascularization, sympathetic nervous system modulation) for resistant hypertension.

Technical discussion of diagnostic angiography and intervention of atherosclerotic renal artery stenosis

Renal artery stenting remains an important adjuvant treatment for true-resistant hypertension, although recent disappointing randomized trials highlight the importance of careful patient selection. Safe and successful renal interventions begin with critical core knowledge regarding renal artery anatomy and understanding the often hostile nature of the parent vessel (pararenal aorta). Armed with fundamental knowledge about anatomy and renal ostial disease pathology, it becomes easier to understand the advantages of less traumatic access techniques and how low-profile contemporary flexible stents have enhanced outcomes. In addition to suggested techniques based on detailed understanding of the vessel architecture and pathology, we will review the current available US Food and Drug Administration-approved balloon-expandable on-label renal stents and discuss the role of intravascular ultrasound for definition of lesion severity, stent sizing, and stent apposition. The durability of renal stenting will also be discussed, as will the velocity criteria for duplex surveillance. Lastly, the current empirical data related to renal embolic protection is provided, along with insight into technical issues in this domain.

SCAI expert consensus statement for renal artery stenting appropriate use

The pathophysiology of atherosclerotic renal artery stenosis (RAS) includes activation of the renin-angiotensin-aldosterone axis with resultant renovascular hypertension. Renal artery stenting has emerged as the primary revascularization strategy in most patients with hemodynamically significant atherosclerotic RAS. Despite the frequency with which hemodynamically significant RAS is observed and high rates of technical success of renal artery stenting, there remains considerable debate among experts regarding the role of medical therapy versus revascularization for renovascular hypertension. Modern, prospective, multicenter registries continue to demonstrate improvement in systolic and diastolic blood pressure with excellent safety profiles in patients with RAS. Modern randomized, controlled clinical trials of optimal medical therapy versus renal stenting particularly designed to demonstrate preservation in renal function after renal artery stenting have demonstrated limited benefit. However, these trials frequently excluded patients that may benefit from renal artery stenting. This document was developed to guide physicians in the modern practical application of renal stenting, to highlight the current limitations in the peer-reviewed literature, to suggest best-practices in the performance of renal stenting and to identify opportunities to advance the field.

Management of Renal Arterial Disease

Severe atherosclerotic renal artery stenosis can manifest as treatment-resistant hypertension, ischemic nephropathy and/or cardiac disturbance syndromes of recurrent flash pulmonary edema and refractory angina. Renal artery revascularization can dramatically impact patient outcome. However, patient selection for revascularization can be challenging. Renal artery stenting is most commonly used for renal revascularization and is a safe procedure when performed in carefully selected patients. This review addresses the pathophysiology of renal artery stenosis and the data supporting revascularization in such patients.

Median arcuate ligament syndrome: Use of fractional flow reserve in documentation of chronic mesenteric ischemia

Median arcuate ligament syndrome (MALS) is a rare clinical entity. This condition typically affects women between the ages of 20 and 40 years and causes symptoms of abdominal pain, primarily post-prandial, as well as nausea, vomiting and weight loss. MALS is considered a diagnosis of exclusion. Typically, mesenteric arterial duplex ultrasonography, computed tomography (CT), and magnetic resonance (MR) are highly suggestive, and conventional contrast angiography confirmatory. We explore the role of fractional flow reserve and intravascular ultrasound in the evaluation of MALS. In order to illustrate the utility of these tools, we present the case of a 47-year-old symptomatic woman who underwent angiography, complemented by assessment of fractional flow reserve and intravascular ultrasound. These data convincingly demonstrated the dynamic nature of the obstructive characteristic of MALS.

Use of fractional flow reserve in the assessment of chronic mesenteric ischemia

Chronic mesenteric ischemia (CMI) is a rare condition that is usually the result of atherosclerotic obstructive disease affecting the mesenteric arteries. The classic triad of post-prandial pain, food aversion and weight loss is not always present, often leading to low clinical suspicion for CMI and underdiagnosis. Non-invasive evaluation for CMI usually starts with mesenteric arterial duplex scanning, followed by computed tomography angiography, magnetic resonance angiography or conventional angiography, the latter being the gold standard for establishing its diagnosis. However, angiography alone has been demonstrated in coronary and other vascular beds to be inaccurate in predicting the physiologic and hemodynamic significance of a certain subset of atherosclerotic stenoses. We present the case of a patient with risk factors and symptoms suggestive of CMI who underwent angiography. However, angiography was equivocal and invasive physiologic testing was required to confirm the diagnosis and guide revascularization.

Predictive role of renal resistive index for clinical outcome after revascularization in hypertensive patients with atherosclerotic renal artery stenosis: a monocentric observational study

Background

The present study evaluated the predictive value of renal resistive index (RI) for renal function and blood pressure (BP) outcome in hypertensive patients with unilateral atherosclerotic renal artery stenosis submitted to successful revascularization.

Methods

In 158 hypertensive patients with atherosclerotic renal artery stenosis RI was acquired. Twelve months after revascularization, they were classified on the basis of renal function and BP outcome as benefit (BP < 140/90 mmHg or diastolic BP reduction > 15 mmHg with the same of reduced drugs; decrease in glomerular filtration rate > 20%), or failure.

Results

Regarding renal function outcome, RI in the stenotic and in the contralateral kidney were significantly higher in patients with failure (n = 20) than in those with benefit (0.72 ± 0.11 vs 0.61 ± 0.11 and 0.76 ± 0.08 vs 0.66 ± 0.09, p < 0.05). Among different cutpoints generated, RI in the contralateral kidney >0.73 provided the largest area under the curve (0.77), and the highest sensitivity (80%) and specificity (72%). In the multivariate logistic regression analysis, RI in the contralateral kidney >0.73 was an independent predictor of a failure in renal function outcome.

Regarding BP outcome, patients with no benefit from revascularization (n = 60) had similar RI in the stenotic and contralateral kidney (p = ns), but presented higher pulse pressure, albuminuria and hypertension duration in comparison to patients with improved BP control.

Conclusions

RI in the contralateral kidney is an independent predictor of renal function outcome after successful revascularization in hypertensive patients with unilateral atherosclerotic renal artery stenosis, whereas it is not able to predict blood pressure outcome.