Renal hemodynamics and renal function after catheter-based renal sympathetic denervation in patients with resistant hypertension

Increased renal resistive index and urinary albumin excretion are markers of hypertensive end-organ damage and renal vasoconstriction involving increased sympathetic activity. Catheter-based sympathetic renal denervation (RD) offers a new approach to reduce renal sympathetic activity and blood pressure in resistant hypertension. The influence of RD on renal hemodynamics, renal function, and urinary albumin excretion has not been studied. One hundred consecutive patients with resistant hypertension were included in the study; 88 underwent interventional RD and 12 served as controls. Systolic, diastolic, and pulse pressure, as well renal resistive index in interlobar arteries, renal function, and urinary albumin excretion, were measured before and at 3 and 6 months of follow-up. RD reduced systolic, diastolic, and pulse pressure at 3 and 6 months by 22.7/26.6 mm Hg, 7.7/9.7 mm Hg, and 15.1/17.5 mm Hg (P for all <0.001), respectively, without significant changes in the control group. SBP reduction after 6 months correlated with SBP baseline values (r=-0.46; P<0.001). There were no renal artery stenoses, dissections, or aneurysms during 6 months of follow-up. Renal resistive index decreased from 0.691±0.01 at baseline to 0.674±0.01 and 0.670±0.01 (P=0.037/0.017) at 3- and 6-month follow-up. Mean cystatin C glomerular filtration rate and urinary albumin excretion remained unchanged after RD; however, the number of patients with microalbuminuria or macroalbuminuria decreased. RD reduced blood pressure, renal resistive index, and incidence of albuminuria without adversely affecting glomerular filtration rate or renal artery structure within 6 months and appears to be a safe and effective therapeutic approach to lower blood pressure in patients with resistant hypertension.     

Renal hemodynamics in patients with sustained essential hypertension and in patients with unilateral stenosis of the renal artery

Systemic and renal hemodynamics including split renal function tests were studied in 41 patients with renovascular hypertension (RVH) related to unilateral stenosis of main renal artery in comparison to 36 subjects with essential hypertension (EH). The two populations were matched for age, sex, body surface area, and systemic arterial pressure. Cardiac output and total peripheral resistances were similar in both groups, with total peripheral resistances increased in comparison to normal values (P less than .001). Patients with EH had a decreased blood volume (P less than .01) with a normal cardiopulmonary blood volume. Patients with RVH had a normal blood volume with an increase in cardiopulmonary blood volume (P less than .02). The para-amino hippurate clearance (CPAH) was decreased in EH. The decrease was similar in the right (160.3 +/- 56.9 mL/min/m2) and left kidneys (158.7 +/- 45 mL/min/m2). The inulin clearance (Cin) was similar in both kidneys (35.2 +/- 12.5 v 33.6 +/- 11.6 mL/min/m2). In addition, in EH, CPAH was negatively correlated with blood pressure (P less than .01). In patients with RVH, CPAH of the "stenotic" kidney was reduced (91.5 +/- 47.8 mL/min/m2) as well as Cin (22.9 +/- 9.3 mL/min/m2). In contrast a significant increase in CPAH (194.1 +/- 63.8 mL/min/m2) and Cin (47.6 +/- 12.6 mL/min/m2) was observed in the contralateral kidney. Kidney function (CPAH and Cin) was not correlated with blood pressure in the "stenotic" kidney. The CPAH and Cin of the nonstenotic kidney were positively and significantly correlated with systemic arterial pressure (P less than .001). The Cin was positively correlated with CPAH in all kidneys in RVH or in EH.(ABSTRACT TRUNCATED AT 250 WORDS)     

Determinants of renal function in patients with renal artery stenosis

Renal artery stenosis (RAS) is an important cause of renal failure; however, the factors associated with loss of kidney function in patients with RAS are poorly described, as are the predictors of an improvement in kidney function after stenting. One hundred patients at seven centers undergoing renal stenting were randomly assigned to an embolic protection device or double-blind use of a platelet glycoprotein IIb/IIIa inhibitor. The glomerular filtration rate (GFR) was measured using the creatinine-derived modified Modification of Diet in Renal Disease (MDRD) equation, cystatin C, and iohexol clearance. In univariate and multivariate models, baseline MDRD and cystatin C GFR were associated with congestive heart failure (CHF) (p = 0.01), lesion length (p = 0.01), and percent stenosis (-0.27, p = 0.01). In multivariate models, MDRD-estimated GFR 1 month after stenting was associated with bilateral stenosis (p < 0.05) and lesion length (p < 0.05), whereas with cystatin C the multivariate model included angiotensin receptor blocker (ARB) (p < 0.05) and minimal luminal diameter (MLD) (p < 0.05). The improvement in GFR from baseline to 1 month, measured as percent change, was related to baseline MDRD (p = 0.009) and cystatin C (p = 0.03) GFR. For MDRD GFR combined treatment with abciximab and Angioguard(?) embolic protection (p = 0.02) remained significant in multivariate analysis as did CHF, which was also significant with cystatin C (p = 0.05). In conclusion, CHF and lesion characteristics (MLD, percent stenosis and lesion length) are determinants of renal function in patients with RAS. In contrast, the acute improvement in renal function after revascularization is most strongly influenced by baseline GFR, and to a lesser degree CHF and combined procedural treatment with abciximab and embolic protection but not lesion characteristics. Clinical Trial Registration - URL:http://www.clinicaltrials.gov. Unique identifier: NCT00234585.     

Determination of urinary N-acetyl-beta-glucosaminidase in patients with hypertension and renal artery stenosis

Abstract. The purpose of the study was to measure the urinary excretion of N-acetyl-beta-glucosaminidase (U-NAG) in patients suspected of having renovascular hypertension and to compare the enzyme excretion before and after active intervention with operation or percutaneous transluminal renal angioplasty (PTRA). Eighty-one patients with severe, therapy-resistant hypertension were examined with regard to renal artery stenosis (RAS). At least one significant renal artery stenosis was found in 61 patients, whilst the remaining 20 patients were classified as having essential hypertension. Enzyme levels were found to be significantly higher in RAS patients as compared with patients with severe hypertension lacking significant renal artery stenosis, 0.66 (0.41–0.91, median value, 1st and 3rd quartiles) versus 0.35 (0.27–0.54); P < 0.01. Both groups of patients had significantly higher U-NAG values than a healthy reference population (0.2, 0.13–0.27; P < 0.01). Forty of the RAS patients were randomized to surgery or PTRA and followed prospectively for 2 years. After either renal vascular surgery or PTRA a significant rise in U-NAG excretion was observed 7–10 days after treatment. Urinary NAG excretion remained elevated during long-term follow-up. It is suggested that U-NAG should be determined in patients with therapy-resistant hypertension with suspicion of renal artery stenosis.     

Orthostatic function after renal sympathetic denervation in patients with resistant hypertension

Introduction

Catheter-based renal denervation (RDN) reduces local and whole-body sympathetic activity and blood pressure (BP) in patients with resistant hypertension. However, safety concerns exist concerning the development of orthostatic dysfunction after RDN.

Methods and results

In 36 patients (65 ± 7.6 years, 75% male) with resistant hypertension (office BP 162 ± 24/91 ± 14 mm Hg) treated with 4.8 ± 1.7 antihypertensive drugs, tilt table testing (TTT) was performed before and three months after RDN. Response to RDN was defined as a reduction in office systolic BP (SBP) ≥ 10 mm Hg three months after RDN. Responders (n = 26; 72.2%) and non-responders (n = 10; 27.8%) were evaluated separately. After RDN, office SBP and diastolic BP (DBP) were reduced by 29 ± 6.2/14 ± 3.6 mm Hg (p < 0.0001; p = 0.0002) only in responders. During TTT, SBP and DBP in supine position were only reduced in responders. Resting heart rate (HR) decreased in responders but not in non-responders by 5.9 ± 1.7 beats/min (p = 0.0016). Mean and minimal SBP were not altered during passive tilting. In the responder group, ?SBP was reduced in the initial phase of tilting. The adaptive increase of HR was preserved in both groups after RDN, while only in responders mean and minimal HR were reduced after passive tilting. Following drug provocation, mean and minimal SBP during all phases of passive tilting remained unchanged. ?SBP, ?HR and total number of (pre-)syncopes were neither influenced by RDN nor differing between responders and non-responders.

Conclusions

In patients with resistant hypertension, RDN reduced office BP, supine BP and HR during TTT without causing orthostatic dysfunction or (pre-)syncopes three months after treatment.     

双侧肾动脉狭窄致难治性高血压2例并文献复习

难治性高血压的发病机制及病因复杂,其心血管风险及预后不良的概率增加,因此对难治性高血压的诊断及治疗十分重要.本文通过两个病例,并结合相关文献,对难治性高血压的诊断及治疗进展进行了简要的梳理.     

Outcome of blood pressure and renal function in patients with renal artery stenosis after stenting

OBJECTIVE

To study the response of systolic and diastolic blood pressure (BP) and renal function after renal artery stenting at three months, six months, one year and last follow-up.

METHODS

Patients with significant renal artery stenosis who underwent angioplasty with stenting from January 1999 to September 2006 were analyzed. The BP and serum creatinine levels were recorded at baseline, three months, six months, one year and at last follow-up. Generalized estimating equations were applied to analyze the changes in blood pressure and serum creatinine over time.

RESULTS

There were 32 patients – 21 Chinese, six Malay and five Indian. The male to female ratio was 1.3:1. The mean age (± SD) was 69.4±8.8 years. The mean follow-up time was 1.8±1.6 years (range 0.5 to six years). When compared with the baseline BP, there was significant improvement at three months, six months, one year and at last follow-up. In the diabetes mellitus (DM) group, there was deterioration in serum creatinine. In the non-DM group, there was stabilization of serum creatinine with improvement at one year.

CONCLUSION

Significant improvement in BP occurs in renal artery stenosis patients after stenting. In patients without DM, renal function remains stable or improves. However, in DM patients, especially those with proteinuria, there is deterioration in renal function.     

Predictors of renal artery stenosis in patients with normal renal function undergoing coronary angiography

AIM: A number of patients with normal renal function undergoing coronary angiography have shown a renal artery stenosis (RAS). Detection of unknown RAS may influence therapeutic strategy in patients with coronary artery disease (CAD) candidate to coronary revascularization. Prevalence of RAS in patients with normal renal function has not been yet fully investigated. We retrospectively evaluated the prevalence of RAS in patients with normal renal function undergoing coronary angiography and candidate to coronary revascularization. METHODS: Medical records of consecutive patients underwent coronary angiography at a single public institutions over a twelve-month period were evaluated. Patients with normal renal function undergoing coincident diagnostic renal angiography to evaluate renal vessels on the basis of clinical criteria and at least one-vessel CAD were analyzed. Moderate to severe arterial stenosis (>50% stenosis), vessel occlusion were noted as significant angiographic findings. RESULTS: Angiographically significant RAS were reported in 35 (17%) of 205 consecutive patients (mean age 67.1+/-12.8 years, mean serum creatinine 0.8+/-0.5 mg/dL, mean glomerular filtration rate 112+/-13 mL/min). Twenty patients (9.8% of total) underwent renal angioplasty and stenting before successful coronary revascularization. Multivariate logistic regression analyses revealed three-vessel CAD (odds ratio[OR] 8.71; 95% confidence interval [CI] 2.24-40.8; P=0.002), hypertension (OR 2.34 CI 95% 0.96-6.9; P=0.048), and hypercholesterolemia (OR 2.851; CI 95% 1.03 to 7.9; P=0.044) as independent predictors of RAS. CONCLUSIONS: The association of significant RAS with CAD is relatively high in patients with normal renal function. Renal semi-selective or selective angiography may contribute to detect unknown significant RAS in patients undergoing coronary angiography: our small series suggests that this strategy may be useful also in patients with normal renal function in presence of three- or four-vessel CAD and multiple risk factors.     

Splanchnic blood flow in essential hypertension and in hypertensive patients with renal artery stenosis.

Splanchnic blood flow (SBF) was measured simultaneously with cardiac output (dye dilution) and intrarterial blood pressure by constant infusion of indocyanine green in 11 control subjects, 13 patients with essential hypertension (EH) and seven hypertensive patients with renal artery stenosis (RAS). The cardiac index (CI) was lower (P less than 0.05) in patients with EH (3.17 plus or minus 0.07 L/min/m-2) (mean plus or minus SEM) than in control subjects (3.43 plus or minus 0.09). Associated with the lower CI was a significantly (P less than 0.01) lower SBF (0.797 plus or minus 0.02 L/min/m-2 vs 0.889 plus or minus 0.04). Patients with RAS presented with higher (P less than 0.01 vs EH, nonsignificant vs control subjects) cardiac index (3.66 plus or minus 0.17) and even lower SBF (0.749 PLUS OR MINUS 0.02). Furthermore, there was a negative correlation (r = - 0.652) between the mean arterial pressure and the SBF when results for all patients were considered. The correlation remained (r = - 0.568) in the EH group and the slope of regression line was not different from that for all subjects. The CI and SBF were weakly correlated (r = 0.423) in control subjects and patients with EH, whereas in patients with RAS, a negative correlation was found (r = - 0.778). This study indicates that the SBF, although significantly decreased in patients with EH, remains proportional to the CI in control subjects and in essential hypertensive patients. No redistribution of CI in regard to the splanchnic circulation occurs in EH. In contrast, in patients with RAS a dissociation of CI and SBF occurs and the fraction of the CI which passes through the splanchnic vascular bed is markedly reduced. The close correlation between mean arterial pressure and SBF suggests that both parameters are influenced by a common pathophysiological factor.     

Changes in circadian sodium excretion in patients with essential hypertension and with renal artery stenosis.

In groups of healthy volunteers (C), patients with essential hypertension (EH), and patients with renal arterial stenosis (S), the following indicators were followed during 12-hour daytime (d) and nighttime (n) intervals: mean BP, endogenous creatinine clearance Ccr (GF), excretion of sodium (UNaV) and potassium (UKV), and their excretion fractions (CNa/GF and CK/GF). The d/n ratios of both UNaV and CNa/GF were significantly lowered in both groups of hypertensive persons as against the controls (1.5): in the EH, to 1.1, and in the S, to 0.8 on the average. Positively correlated with the value of the d/n ratio of the sodium excretion are the changes in the d/n ratios of water and solute excretions. The daytime potassium excretion exceeded the nighttime values in both groups of hypertensive persons. The d/n ratios of UKV and CK/GF were, however, significantly lowered as compared to the control values. These signs of disturbances of the circadian excretion of Na and K in EH and S exhibited no correlations with the values, or rhythms, of the mean BP, GF, or dietary uptake of sodium. The results do not indicate that the antihypertensive drugs used (alpha-methyldopa, dihydralazine, reserpine) would influence the circadian rhythm of Na excretion. The factors responsible for the disturbances of the circadian rhythms of Na and K excretion in hypertensive subjects have not yet been revealed.     

Transplant renal artery stenosis: hypertension and graft function before and after angioplasty

We present a case, who after 15 years of renal transplantation developed severe deterioration of her hypertension without alteration in renal function. Colour Doppler sonography revealed a 90% stenosis near the anastomosis of the graft artery to iliac artery, which was successfully and uneventfully corrected by percutaneous balloon angioplasty. Following the procedure the blood pressure control dramatically improved and her antihypertensive regimen returned and remained at baseline for the subsequent year of observation. Renal function remained normal and stable before and after angioplasty.     

Prevalence and risk factors for atherosclerotic renal artery stenosis in elderly patients with refractory hypertension

正Objective To investigate the prevalence and risk factors for atherosclerotic renal artery stenosis(ARAS)in elderly patients with refractory hypertension.Methods Two hundred and eight elderly patients with a mean age of(68.3±4.9)years(53.8%in men)diagnosed with refractory hypertension were recruited in this retrospective study from January 2010 to January 2017 in Beijing     

老年动脉粥样硬化性肾动脉狭窄患者支架置入术后肾功能的变化

目的探讨经皮腔内肾动脉支架置入术(PTRAS)治疗动脉粥样硬化性肾动脉狭窄(ARAS)对肾功能的影响。方法经肾动脉造影确诊的ARAS并施行PTRAS患者50例,术后随访3～48(16.3±14.8)个月,回顾性分析PTRAS后患者血清肌酐和再狭窄发生率。结果 50例PTRAS全部成功。与PTRAS前比较,20例(40%)症状改善和26例(52%)症状稳定患者血清肌酐水平明显下降[(151.47±54.86)μmol/L vs(182.50±68.87)μmol/L,P<0.01;(95.56±1 2.87)μmol/L vs(101.37±1 5.53)μmol/L,P<0.05],4例(8%)症状恶化患者血清肌酐水平明显升高(P<0.05)。随访期间再狭窄6例(12%)。结论 PTRAS能够改善老年人肾动脉粥样硬化所致肾功能改变,并使肾功能长期保持稳定。加强对军队老干部PTRAS后的健康教育,可部分提高患者对相关危险因素的控制,减少术后并发症的发生,提高生活质量。