Prevalence of renal artery stenosis in subjects with type 2 diabetes and coexistent hypertension

Atherosclerotic renovascular disease - epidemiology, treatment and current challenges

The neutral results of recent large randomized controlled trials comparing renal revascularization with optimal medical therapy in patients with atherosclerotic renovascular disease (ARVD) have cast doubt on the role of revascularization in the management of unselected patients with this condition. However, these studies have strengthened the evidence base for the role of contemporary intensive medical vascular protection therapy and aggressive risk factor control in improving clinical outcomes in ARVD. Patients presenting with ‘high-risk’ clinical features such as uncontrolled hypertension, rapidly declining renal function or flash pulmonary oedema are underrepresented in these studies; hence these results may not be applicable to all patients with ARVD. In this ‘high-risk’ subgroup, conservative management may not be sufficient in preventing adverse events, and indeed, observational evidence suggests that this specific patient subgroup may gain benefit from timely renal revascularization. Current challenges include the development of novel diagnostic techniques to establish haemodynamic significance of a stenosis, patient risk stratification and prediction of post-revascularization outcomes to ultimately facilitate patient selection for revascularization. In this paper we describe the epidemiology of this condition and discuss treatment recommendations for this condition in light of the results of recent randomized controlled trials while highlighting important clinical unmet needs and challenges faced by clinicians managing this condition.

Cardiovascular manifestations of renovascular hypertension in diabetic mice

Purpose. Type 2 diabetes is the leading cause of end stage renal disease in the United States. Atherosclerotic renal artery stenosis is commonly observed in diabetic patients and impacts the rate of renal and cardiovascular disease progression. We sought to test the hypothesis that renovascular hypertension, induced by unilateral renal artery stenosis, exacerbates cardiac remodeling in leptin-deficient (db/db) mice, which serves as a model of human type II diabetes.

Methods. We employed a murine model of renovascular hypertension through placement of a polytetrafluoroethylene cuff on the right renal artery in db/db mice. We studied 109 wild-type (non-diabetic, WT) and 95 db/db mice subjected to renal artery stenosis (RAS) or sham surgery studied at 1, 2, 4, and 6+ weeks following surgery. Cardiac remodeling was assessed by quantitative analysis of the percent of myocardial surface area occupied by interstitial fibrosis tissue, as delineated by trichrome stained slides. Aortic pathology was assessed by histologic sampling of grossly apparent structural abnormalities or by section of ascending aorta of vessels without apparent abnormalities.

Results. We noted an increased mortality in db/db mice subjected to RAS. The mortality rate of db/db RAS mice was about 23.5%, whereas the mortality rate of WT RAS mice was only 1.5%. Over 60% of mortality in the db/db mice occurred in the first two weeks following RAS surgery. Necropsy showed massive intrathoracic hemorrhage associated with aortic dissection, predominantly in the ascending aorta and proximal descending aorta. Aortas from db/db RAS mice showed more smooth muscle dropout, loss of alpha smooth muscle actin expression, medial disruption, and hemorrhage than aortas from WT mice with RAS. Cardiac tissue from db/db RAS mice had more fibrosis than did cardiac tissue from WT RAS mice.

Conclusions. db/db mice subjected to RAS are prone to develop fatal aortic dissection, which is not observed in WT mice with RAS. The db/db RAS model provides the basis for future studies directed towards defining basic mechanisms underlying the interaction of hypertension and diabetes on the development of aortic lesions.

Prevalence and predictors of atherosclerotic renal artery stenosis in hypertensive patients undergoing simultaneous coronary and renal artery angiography; a cross-sectional study

Introduction: According to the non-specific presentation of atherosclerotic renal artery stenosis (ARAS), this disease is usually an under-diagnosed in clinical conditions.

Objectives: The aim of the presence study was to evaluate the prevalence of renal artery stenosis (RAS) and its related risk factors in hypertensive patients undergoing coronary angiography.

Patients and Methods: In a cross-sectional study, between March 2009 and October 2010, all of hypertensive patients candidate for diagnostic cardiac catheterization, underwent nonselective renal angiography before completion of their coronary angiography procedure. A standardized questionnaire was used to collect demographics, cardiac history, indications for cardiac catheterization and angiographic data. The degree of ARAS was estimated visually by skilled cardiologist. Narrowing greater than 50% of the arterial lumen considered as arterial stenosis. Data was analyzed by SPSS version 19, and by chi-square test and logistic regression model.

Results: In overall 274 patients with mean age of 60.75 ± 10.92 years 108 (39.4%) were male and 166 (60.61%) were female. The prevalence of ARAS calculated 18.2%. According to the present study, heart failure and smoking were predictors of ARAS. However, old age, gender, diabetes mellitus, hyperlipidemia and family history of cardiovascular disease were not clinical predictors of significant ARAS in hypertensive patients, candidate for coronary angiography.

Conclusion: According to present data, we suggest to consider renal artery angiography in combination with coronary artery angiography especially in hypertensive patients who are smoker or individuals who have heart failure.

Hypertensive Urgencies and Emergencies in the Hospital Setting

The prevalence of hypertension in the general population has steadily climbed over the past several decades and hypertension is a primary or secondary diagnosis in nearly a fourth of hospitalized adults. Hospitalization is often a time of pertubation in a patient's usual blood pressure control, with pain, anxiety and missed medications all risk factors for severe hypertension. Hospitalists are often faced with severe hypertension in a patient not previously known to them and this presents a challenge of how best to assess the clinical importance of blood pressure elevation. An additional challenge is the lack of literature to guide the optimal management of hypertension in inpatients. This review aims to describe the scope of the problem, to describe the near and long-term risks of overzealous blood pressure management, and to identify areas for future study.

Atherosclerotic Renal Artery Stenosis Prevalence and Correlations in Acute Myocardial Infarction Patients Undergoing Primary Percutaneous Coronary Interventions: Data From Nonrandomized Single-Center Study (REN-ACS)—A Single Center, Prospective, Observational Study

Background

We are the first to evaluate the prevalence of renal artery stenosis (RAS) in consecutive patients with acute myocardial infarction (AMI) referred for primary percutaneous coronary intervention from a single tertiary center. As a novelty, we assessed hydration and metabolic status and measured arterial stiffness. We elaborated a predicting model for RAS in AMI.

Methods and Results

One hundred and eighty‐one patients with AMI underwent concomitantly primary percutaneous coronary intervention and renal angiography. We obtained data on demographics, medical history, cardiovascular risk factors, echocardiography, Killip class, and blood tests. In the first 24 hours post–primary percutaneous coronary intervention, we assessed bioimpedance through Body Composition Monitoring^® and arterial stiffness through pulsed‐wave velocity, SphygmoCor^®. Significant RAS (>50% lumen narrowing, RAS+) was present in 16.6% patients. In the RAS+ group we recorded significantly higher stiffness, CRUSADE score and dehydration, and more women with higher prevalence of multivascular coronary artery disease and heart failure. In our multivariate models, variables independently associated with RAS+ were previous percutaneous coronary intervention, low estimated glomerular filtration rate, multivascular coronary artery disease, and total/extracellular body water. These models had good specificity and low sensitivity.

Conclusions

We observed that RAS+ AMI patients have a particular hydration, metabolic, and endothelial profile that could generate more future major adverse cardiac events. Hence, renal angiography in AMI should be considered in specific subsets of patients.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02388139.

Risk factors associated with end-stage renal disease (ESRD) in patients with atherosclerotic renal artery stenosis: a nationwide population-based analysis

The aim of this study was to investigate the risk factors associated with end-stage renal disease (ESRD) in patients with atherosclerotic renal artery stenosis (ARAS). Information about the study participants was extracted from the National Health Insurance Research Database of Taiwan for the years 1999 through 2011. We conducted this retrospective cohort study of patients with ARAS to identify the potential risk factors associated with long-term renal outcomes. A total of 2184 patients with ARAS were enrolled, of whom 840 had ESRD and were classified as the study group, and 1344 patients who were without ESRD were included in the comparison cohort. After adjusting for related variables, univariable, and multivariable logistic regression analysis showed that ESRD was associated with higher Charlson-comorbidity index (CCI) score (adjusted odds ratio [OR] = 6.78, 95% CI = 4.59-10.0 for CCI = 2; adjusted OR = 20.0, 95% CI = 13.7-29.2 for CCI ≥3), diabetes (adjusted OR = 1.55, 95% CI = 1.24-1.93), hypertension (adjusted OR = 3.66, 95% CI = 2.36-5.66), and age 20 to 49-years old (adjusted OR = 2.14, 95% CI = 1.51-3.03). Moreover, our data showed that renal artery revascularization (RAR) was significantly associated with a lower risk of ESRD in ARAS patients (crude OR = 0.64, 95% CI = 0.50-0.84). Our study is the first to disclose that CCI score was significantly associated with the risk of ESRD in ARAS patients, and comorbid diseases including diabetes mellitus and hypertension significantly affect renal outcomes in patients with ARAS. Of note, our data showed that renal artery revascularization was associated with a lower risk of ESRD in ARAS patients in long-term follow-up.

Management of renal artery stenosis: What does the experimental evidence tell us?

Optimal management of patients with renal artery stenosis (RAS) is a subject of considerable controversy. There is incontrovertible evidence that renal artery stenosis has profound effects on the heart and cardiovascular system in addition to the kidney. Recent evidence indicates that restoration of blood flow alone does not improve renal or cardiovascular outcomes in patients with renal artery stenosis. A number of human and experimental studies have documented the clinical, hemodynamic, and histopathologic features in renal artery stenosis. New approaches to the treatment of renovascular hypertension due to RAS depend on better understanding of basic mechanisms underlying the development of chronic renal disease in these patients. Several groups have employed the two kidney one clip model of renovascular hypertension to define basic signaling mechanisms responsible for the development of chronic renal disease. Recent studies have underscored the importance of inflammation in the development and progression of renal damage in renal artery stenosis. In particular, interactions between the renin-angiotensin system, oxidative stress, and inflammation appear to play a critical role in this process. In this overview, results of recent studies to define basic pathways responsible for renal disease progression will be highlighted. These studies may provide the rationale for novel therapeutic approaches to treat patients with renovascular hypertension.

Combined effect of hyperfiltration and renin angiotensin system activation on development of chronic kidney disease in diabetic db/db mice

Background

Hypertension is a major risk factor for renal disease progression. However, the mechanisms by which hypertension aggravates the effects of diabetes on the kidney are incompletely understood. We tested the hypothesis that renovascular hypertension accelerates angiotensin-II-dependent kidney damage and inflammation in the db/db mouse, a model of type II diabetes.

Methods

Renovascular hypertension was established in db/db and wild-type control mice through unilateral renal artery stenosis (RAS); the non-stenotic contralateral kidneys evaluated 2, 4 and 6 weeks later. Angiotensin-II infusion (1000 ng/kg/min), unilateral nephrectomy, or both were also performed in db/db mice to discern the contributions of hypertension versus hyperfiltration to development of chronic renal injury in db/db mice with RAS. The effect of blood pressure reduction in db/db mice with RAS was assessed using angiotensin-receptor-blocker (ARB) or hydralazine treatment.

Results

Db/db mice with renovascular hypertension developed greater and more prolonged elevation of renin activity than all other groups studied. Stenotic kidneys of db/db mice developed progressive interstitial fibrosis, tubular atrophy, and interstitial inflammation. Contralateral kidneys of wild type mice with RAS showed minimal histopathologic abnormalities, whereas db/db mice with RAS developed severe diffuse mesangial sclerosis, interstitial fibrosis, tubular atrophy, and interstitial inflammation. Db/db mice with Angiotensin II-induced hypertension developed interstitial lesions and albuminuria but not mesangial matrix expansion, while nephrectomized db/db mice exhibited modest mesangial expansion and interstitial fibrosis, but not significant albuminuria. The combination of unilateral nephrectomy and angiotensin II infusion reproduced all the features of the injury albeit in a less severe manner. ARB and hydralazine were equally effective in attenuating the development of mesangial expansion in the contralateral kidneys of db/db mice with RAS. However, only ARB prevented elevation of urinary albumin/creatinine in db/db mice with RAS.

Conclusion

Renovascular hypertension superimposed on diabetes exacerbates development of chronic renal disease in db/db mice at least in part through interaction with the renin-angiotensin system. Both ARB and hydralazine were equally effective in reducing systolic blood pressure and in preventing renal injury in the contralateral kidney of db/db mice with renal artery stenosis. ARB but not hydralazine prevented elevation of urinary albumin/creatinine in the db/db RAS model.

Quantitative imaging biomarkers for the evaluation of cardiovascular complications in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a prevalent condition in aged populations. Cardiovascular diseases are leading causes of death and disability in patients with T2DM. Traditional strategies for controlling the cardiovascular complications of diabetes primarily target a cluster of well-defined risk factors, such as hyperglycemia, lipid disorders and hypertension. However, there is controversy over some recent clinical trials aimed at evaluating efficacy of intensive treatments for T2DM. As a powerful tool for quantitative cardiovascular risk estimation, multi-disciplinary cardiovascular imaging have been applied to detect and quantify morphological and functional abnormalities in the cardiovascular system. Quantitative imaging biomarkers acquired with advanced imaging procedures are expected to provide new insights to stratify absolute cardiovascular risks and reduce the overall costs of health care for people with T2DM by facilitating the selection of optimal therapies. This review discusses principles of state-of-the-art cardiovascular imaging techniques and compares applications of those techniques in various clinical circumstances. Individuals measurements of cardiovascular disease burdens from multiple aspects, which are closely related to existing biomarkers and clinical outcomes, are recommended as promising candidates for quantitative imaging biomarkers to assess the responses of the cardiovascular system during diabetic regimens.

The prevalence of renal artery stenosis among patients with diabetes mellitus

BACKGROUND

Patients with diabetes mellitus (DM) have a high prevalence of atherosclerotic vascular lesions. It is therefore reasonable to assume that also the rate of renal artery stenosis (RAS) is higher. The presence of a RAS can have implications for the treatment of patients with diabetes mellitus and hypertension and renal impairment. Therefore it is important to be informed about the chance that a RAS is present among such patients.

METHODS

We prospectively studied the prevalence of atherosclerotic renal artery stenosis (RAS) among patients with diabetes mellitus. Patients were included if they were diagnosed with DM and hypertension with or without impairment of renal function. If causes of renal disease other than DM or hypertension were more probable on the basis of biochemical data, then such patients were excluded. A magnetic resonance angiography (MRA) of the renal arteries was made in 54 included successive patients.

PATIENT CHARACTERISTICS

mean age 59 ± 8.5 years (range 35 to 80). Eight patients had DM 1 and 46 DM 2. Mean BMI was 31.4 ± 5.6 kg/m(2). A RAS was present in 18 of the 54 (33%) patients, 3 patients had bilateral stenoses. Factors related to the presence of RAS were diastolic blood pressure, glomerular filtration rate and dyslipidaemia.

CONCLUSION

In this group of diabetic patients with hypertension and or renal impairment the prevalence of RAS was 33%.

The prevalence of atherosclerotic renal artery stenosis in risk groups: a systematic literature review

OBJECTIVE

We performed a literature review and analysis to improve the insight in the prevalence of renal artery stenosis (RAS) in risk groups.

METHODS

Relevant studies were identified by a MEDLINE and EMBASE database search (1966 to December 2007), complemented by hand searching of reference lists. Review was restricted to English language studies, using any form of angiography as diagnostic method. Studies were grouped in risk group categories sharing similar clinical characteristics, and pooled prevalence rates were calculated for each category.

RESULTS

Forty studies, involving a total number of 15 879 patients, were identified. The following pooled prevalence rates (95% confidence interval; sample size risk group) of RAS were found: suspected renovascular hypertension, 14.1% (12.7-15.8%; n = 1931); hypertension and diabetes mellitus, 20% (14.9-25.1%; n = 240); coronary angiography (CAG) in consecutive patients, 10.5% (9.8-11.2%; n = 8011); CAG in hypertensive patients, 17.8% (15.4-20.6%; n = 836); CAG and suspected renovascular disease, 16.6% (14.8-18.5%; n = 1576); congestive heart failure, 54.1% (45.7-62.3%; n = 135); peripheral vascular disease, 25.3% (23.6-27.0%; n = 2632); abdominal aortic aneurysm, 33.1% (27.4-39.2%; n = 239) and end-stage renal failure, 40.8% (27-55.8%; n = 49.) In patients with an incidentally discovered RAS, hypertension and renal failure were present in 65.5 and 27.5%, respectively.

CONCLUSION

RAS has a high prevalence in risk groups, especially in those with extrarenal atherosclerosis, end-stage renal failure and heart failure. These findings are important when screening for RAS or prescription of an angiotensin converting enzyme inhibitor or angiotensin-II receptor blocker is considered.

Evaluation and approach to treatment of renal artery stenosis in patients with diabetic nephropathy

Patients with diabetes mellitus are at increased risk for developing peripheral vascular disease and renal artery stenosis (RAS). Furthermore, in diabetic patients the progression of renal atherosclerotic disease toward critical stenosis or occlusion occurs more frequently than in their nondiabetic counterparts. Consequently, clinicians must carry a high level of suspicion for detecting RAS in diabetic patients, particularly those with established coronary and/or peripheral atherosclerotic disease and compromised renal function. In this group of patients early detection of this condition, preferably with a noninvasive diagnostic test, is very important to plan revascularization therapy. In nondiabetic patients, several studies have demonstrated that catheter-based revascularization therapy may arrest or revert renal dysfunction in patients with RAS. Although still the subject of debate, a recent study has shown that in diabetic patients with RAS and impaired renal function, revascularization therapy with endovascular stents has a positive impact in the progression of renal dysfunction.

Positron-Emission Tomography Imaging of the Angiotensin II Subtype 1 Receptor in Swine Renal Artery Stenosis

The angiotensin II subtype 1 receptor (AT 1 R) has been linked to the development and progression of renovascular hypertension. In this study we applied a pig model of renovascular hypertension to investigate the AT 1 R in vivo with positron-emission tomography (PET) and in vitro with quantitative autoradiography. AT 1 R PET measurements were performed with the radioligand [ 11 C]KR31173 in 11 control pigs and in 13 pigs with hemodynamically significant renal artery stenosis; 4 were treated with lisinopril for 2 weeks before PET imaging. The radioligand impulse response function was calculated by deconvolution analysis of the renal time-activity curves. Radioligand binding was quantified by the 80-minute retention of the impulse response function. Median values and interquartile ranges were used to illustrate group statistics. Radioligand retention was significantly increased ( P =0.044) in hypoperfused kidneys of untreated (0.225; range: 0.150 to 0.373) and lisinopril-treated (0.237; range:0.224 to 0.272) animals compared with controls (0.142; range:0.096 to 0.156). Increased binding of [ 11 C]KR31173 documented by PET in vivo was confirmed by in vitro autoradiography. Both in vivo and in vitro binding measurements showed that the effect of renal artery stenosis on the AT 1 R was not abolished by lisinopril treatment. These studies provide insight into kidney biology as the first in vivo/in vitro experimental evidence about AT 1 R regulation in response to reduced perfusion of the kidney. The findings support the concept of introducing AT 1 R PET as a diagnostic biomarker of renovascular disease.

Nefropatia diabética e doença cardíaca

Pacientes em diferentes estágios de nefropatia diabética (ND) apresentam freqüentemente comprometimento cardíaco expresso por isquemia miocárdica e/ou cardiomiopatia diabética. Estas alterações já estão presentes em estágios iniciais da ND e provavelmente mesmo antes de a excreção urinária de albumina (EUA) atingir níveis tradicionalmente diagnósticos de microalbuminúria. As alterações cardíacas são responsáveis por uma proporção significativa de mortes nos pacientes com ND e podem ser reduzidas através de intervenção nos múltiplos fatores de risco cardiovascular encontrados nesses pacientes. A avaliação de doença cardíaca deve idealmente ser realizada em todos os pacientes com qualquer grau de ND através de métodos específicos para detectar isquemia e disfunção miocárdica, além do emprego rotineiro da monitorização ambulatorial da pressão arterial em 24 h. Em pacientes com aterosclerose avançada também devem ser avaliadas outras artérias (carótidas, aorta, renais). O tratamento rigoroso da hipertensão arterial, o uso de fármacos cardioprotetores, o tratamento da dislipidemia e da anemia, assim como o emprego de medicamentos anti-plaquetários, poderão reduzir a elevada mortalidade cardiovascular na ND.

Renal artery stenosis and accelerated atherosclerosis: which comes first?

Renal artery stenosis (RAS) is usually observed in hypertensive patients with extensive atherosclerosis. There is some evidence that in these patients the atherosclerotic process and the consequent target-organ damage is more severe than in hypertensive patients without RAS. In this review we will entertain the hypothesis that some of the humoral factors that are activated by RAS may contribute to accelerate the progression of atherosclerosis. Several studies identified RAS as a predictor of cardiovascular events in high-risk patients, although in most cases the contribution of blood pressure per se to the progression of vascular lesions could not be determined. As a result of experimental RAS, hypertension and increased oxidative stress are stimuli for atherosclerosis as well as cardiac and renal damage. In the presence of RAS, the renin-angiotensin system is stimulated, and it has been shown that angiotensin II exerts proinflammatory, pro-oxidant and procoagulant activities in experimental models and humans. The potential contribution of reactive oxygen species to the prohypertensive and proatherosclerotic effects of RAS is supported by evidence that nicotinamide adenine dinucleotide phosphate, reduced form oxidase is specifically stimulated by angiotensin II, an activity not shared by epinephrine. Moreover, angiotensin II triggers the release of aldosterone, endothelin 1, thromboxane A2 and other derivatives of the arachidonic acid metabolism, all of which can further and independently aggravate cardiovascular damage. Epidemiological and experimental evidence so far available suggests that accelerated atherosclerosis can be both the cause and the consequence of RAS.

Diabetes mellitus does not preclude stabilization or improvement of renal function after stent revascularization in patients with kidney insufficiency and renal artery stenosis

OBJECTIVE

To assess the impact of stent revascularization on the renal function of diabetic and nondiabetic patients with renal insufficiency.

BACKGROUND

Renal artery revascularization has been shown to stabilize or improve renal function in patients with significant renal artery stenosis and impaired renal function. However, some studies have suggested negligible or no benefit of renal function in diabetic patients with the same condition.

METHODS

We retrospectively compared data from 50 consecutive patients undergoing renal artery stent placement with renal insufficiency (serum creatinine > or = 1.5-4.0 mg/dl) and global ischemia (bilateral or solitary [single] kidney renal artery stenosis) There were 17 diabetic (DM) and 33 nondiabetic (NDM) patients. The endpoints included the follow-up measurements of renal function, blood pressure, and number of antihypertensive medications.

RESULTS

After stent placement, at a mean follow-up of 42 +/- 18 months (range: 6-62 months), 79% NDM (N = 26), and 76% DM patients (N = 13) (P = NS) had improvement in the slope of the reciprocal of creatinine (1/SCr), indicating a beneficial effect in renal function in many patients.

CONCLUSION

Renal artery stent placement appears to be equally beneficial in preserving renal function in DM and NDM patients with ischemic nephropathy and global renal ischemia.

Matrix metalloproteinases and diabetic vascular complications

Diabetes mellitus (DM) is associated with an increased incidence of cardiovascular events and microvascular complications. These complications contribute to the morbidity and mortality associated with DM. There is increasing evidence supporting a role for matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of matrix metalloproteinases - TIMPs) in the atherosclerotic process. However, the relationship between MMPs/TIMPs and diabetic angiopathy is less well defined. Hyperglycemia directly or indirectly (eg, via oxidative stress or advanced glycation products) increases MMP expression and activity. These changes are associated with histologic alterations in large vessels. On the other hand, low proteolytic activity of MMPs contributes to diabetic nephropathy. Within atherosclerotic plaques an imbalance between MMPs and TIMPs may induce matrix degradation, resulting in an increased risk of plaque rupture. Furthermore, because MMPs enhance blood coagulability, MMPs and TIMPs may play a role in acute thrombotic occlusion of vessels and consequent cardiovascular events. Some drugs can inhibit MMP activity. However, the precise mechanisms involved are still not defined. Further research is required to demonstrate the causative relationship between MMPs/TIMPs and diabetic atherosclerosis. It also remains to be established if the long-term administration of MMP inhibitors can prevent acute cardiovascular events.

Diabetic nephropathy: diagnosis, prevention, and treatment

Diabetic nephropathy is the leading cause of kidney disease in patients starting renal replacement therapy and affects approximately 40% of type 1 and type 2 diabetic patients. It increases the risk of death, mainly from cardiovascular causes, and is defined by increased urinary albumin excretion (UAE) in the absence of other renal diseases. Diabetic nephropathy is categorized into stages: microalbuminuria (UAE >20 microg/min and < or =199 microg/min) and macroalbuminuria (UAE > or =200 microg/min). Hyperglycemia, increased blood pressure levels, and genetic predisposition are the main risk factors for the development of diabetic nephropathy. Elevated serum lipids, smoking habits, and the amount and origin of dietary protein also seem to play a role as risk factors. Screening for microalbuminuria should be performed yearly, starting 5 years after diagnosis in type 1 diabetes or earlier in the presence of puberty or poor metabolic control. In patients with type 2 diabetes, screening should be performed at diagnosis and yearly thereafter. Patients with micro- and macroalbuminuria should undergo an evaluation regarding the presence of comorbid associations, especially retinopathy and macrovascular disease. Achieving the best metabolic control (A1c <7%), treating hypertension (<130/80 mmHg or <125/75 mmHg if proteinuria >1.0 g/24 h and increased serum creatinine), using drugs with blockade effect on the renin-angiotensin-aldosterone system, and treating dyslipidemia (LDL cholesterol <100 mg/dl) are effective strategies for preventing the development of microalbuminuria, in delaying the progression to more advanced stages of nephropathy and in reducing cardiovascular mortality in patients with type 1 and type 2 diabetes.

Magnetic resonance imaging of the peripheral vasculature

BACKGROUND

Atherosclerotic disease of the peripheral vasculature is a prevalent condition for which catheter-based techniques have been considered to be the gold standard for diagnosis. However, because of their invasive nature, these techniques inherently have the potential for complications. Non-invasive diagnostic techniques have historically been limited by low accuracy and high operator dependence. Magnetic resonance angiography (MRA) is a new approach that has diagnostic accuracy comparable with invasive angiography.

METHODS

The literature on MRA for evaluation of carotid, mesenteric, renal, and lower-extremity arterial disease was extensively reviewed. Helpful diagnostic algorithms on the basis of the literature are also provided.

RESULTS

MRA is both sensitive and specific when compared with invasive angiography for the evaluation of peripheral arterial disease and avoids the potential for complications resulting from arterial puncture and use of iodinated contrast.

CONCLUSION

Current MRA techniques are diagnostically robust and have proven to be a highly accurate, safe, and convenient means of diagnosing atherosclerotic disease of the peripheral vascular system.

Managing renal arterial disease and hypertension

Treating patients with renovascular disease is complex, particularly as imaging and medical techniques become more effective. Atherosclerotic renal artery disease is present in 7% of the general population above age 65 and in 20 to 45% of patients with coronary disease or aortoiliac disease. Most patients are treated medically, but when progressive hypertension, renal insufficiency, or circulatory congestion develops, revascularization should be considered. Endovascular procedures with arterial stents are now widely employed. These procedures sometimes offer major benefits in blood pressure control and stabilization of renal function. Stent procedures continue to entail hazards, including atheroemboli, arterial dissections, and thrombosis, in addition to restenosis rates of 14 to 20%. Small, randomized trials to date demonstrate no survival benefit to either endovascular or surgical revascularization as compared with medical management. Recognizing renal artery disease and directing revascularization procedures to those with the most benefit remains a premier challenge for the clinician.

Trends in the prevalence of diabetic nephropathy in type 1 and type 2 diabetes

PURPOSE OF REVIEW

To summarize recent trends in the prevalence of nephropathy due to diabetes and to assess the causes of these changes. Such analysis may influence our strategy to reduce the increasing numbers of cases.

RECENT FINDINGS

Registry data show a progressive increase in the number of cases of nephropathy due to type 2 diabetes such that diabetes is now the leading cause of end-stage renal failure. Despite the increasing incidence of type 1 diabetes, European data indicate the numbers of type 1 patients going on to dialysis are stable. The increase in the prevalence of type 2 diabetes, which in itself is related to increasing levels of obesity, is a major factor but the increase in end-stage renal failure is disproportionately greater. Other factors are therefore important such as earlier development of diabetes and better prevention of coronary events. Similar changes are occurring worldwide. Clinical predictors and genetic markers are being studied.

SUMMARY

More active management of proteinuric type 2 diabetic patients is required to achieve the demanding targets recommended on the basis of clinical trial data. However, the figures suggest that only widespread application of public health measures aimed at the epidemic of type 2 diabetes itself will prevent further rapid escalation of the numbers of type 2 patients reaching end-stage renal failure.

Prevalence of renal artery stenosis requiring revascularization in patients initially referred for coronary angiography

To evaluate the prevalence of clinically significant renal artery stenosis (RAS) in patients referred for coronary angiography, we analyzed data on 2,439 consecutive patients. Patients underwent selective renal angiography in conjunction with coronary angiography if refractory hypertension (blood pressure > 140/90 on two drugs) or flash pulmonary edema was present. A total of 1,089 renal arteries of 534 patients were evaluated. Twelve percent (137/1,089) of the renal arteries in 19% (101/534) of patients had > 70% diameter stenosis in at least one vessel. Bilateral renal artery stenosis was present in 26% (26/101) of patients. One hundred and thirty-two of the 137 vessels underwent stent revascularization due to clinical renovascular hypertension. Acute clinical success (< 20% diameter stenosis without death or urgent surgery) was 98% (99/101). Due to high prevalence and effective available treatment, we recommend routine screening for RAS in all patients with refractory hypertension referred for coronary angiography.

The impact of atherosclerotic renovascular disease on diabetic renal failure

Atherosclerotic renovascular disease (ARVD) is common in the general population, and its prevalence increases with age. Parallel studies show it is also common in patients with diabetes. The widespread use of angiotensin converting enzyme inhibitors and angiotensin receptor antagonists for heart and kidney disease might therefore expose arteriopathic diabetic patients to potential harm if they had critical renal artery stenosis. This review looks at the natural history of ARVD in the diabetic and non-diabetic populations: while it is common, it only rarely leads to renal failure. Hence intervention to revascularize ischaemic kidney son the basis of radiological appearances alone may subject some patients to unnecessary therapy. Although untested by randomized trial, a policy of watchful waiting may be the simplest strategy for most diabetic patients with suspected ARVD, reserving angiography and angioplasty (usually backed up by a stent) for those with an abrupt decline in renal function and no other cause for renal deterioration. Future clinical trials may better define subgroups of patients who will truly benefit from renal revascularization.

Usefulness of captopril renography to predict the benefits of renal artery revascularization or captopril treatment in hypertensive patients with diabetic nephropathy

This retrospective study aimed to use captopril renography (CR) for predicting the benefits of captopril treatment in hypertensive patients with diabetic nephropathy. CR was utilized in 60 hypertensive patients with diabetic nephropathy for detecting the probability of renovascular hypertension (RVH) and predicting the benefits of renal artery revascularization or captopril treatment. Ten of the 60 patients showed a high probability of RVH with marked changes of the renogram curve after an oral intake of 50-mg captopril compared to baseline findings. All of the 10 patients confirmed significant main renal artery stenosis in all of them, bilaterally in four patients and unilaterally in the remaining six patients by renal angiographic findings. After successful revascularization, blood pressure was well controlled and renal function was preserved in all of the 10 patients. The other 50 patients showed a low or intermediate probability of RVH with normal findings or unchanged on CR after 50-mg captopril. Then, captopril alone or combination treatment started and continued on 50 patients. After monitoring for at least 6 months, blood pressure was well controlled and renal function was preserved in all the 50 patients on captopril treatment. We conclude that CR should be considered as the standard diagnostic criteria of RVH and may be helpful in predicting the beneficial impact of captopril treatment in hypertensive patients with diabetic nephropathy.

Diabetes mellitus and cardiovascular disease

Diabetes is associated with a high incidence and poor prognosis of cardiovascular disease, and with high short- and long-term mortality. Adequate treatment of cardiovascular disorders and aggressive management of coexisting risk factors have proved to be at least as effective in diabetic as in nondiabetic patients in randomized, controlled studies. Indeed, treating diabetic patients with cardiovascular disease results in a larger absolute risk reduction than in nondiabetic subjects. Nevertheless, diabetic patients often receive inadequate therapy, which may, to a certain extent, explain their poor prognosis. Recommendations for the treatment of diabetic patients with acute myocardial infarction should include beta-blockers, aspirin, and ACE-inhibitors in all patients in whom no specific contraindications exist. Fibrinolysis should be administered when indicated, and the benefits of improving glycemic control should not be forgotten either. In patients with multi-vessel disease who need revascularization, when selecting the type of procedure, the superiority of surgical revascularization over angioplasty should be borne in mind. Even heart transplantation should be included as a therapeutic option since there are no data to support the exclusion of patients on account of their diabetes. Finally, coexisting risk factors should be intensively treated through lifestyle intervention, with or without drug therapy, in order to achieve secondary prevention goals.