Chronic renal ischemia: implications for cardiovascular disease risk

Successful Depressor Effect Concomitant with Complete Normalization of High Renin and Aldosterone Profile by Percutaneous Transluminal Renal Angioplasty in a Patient with Acute Exacerbated Heart Failure with Preserved Ejection Fraction

Patient: Male, 59

Final Diagnosis: Renovascular hypertension

Symptoms: Dyspnea

Medication: —

Clinical Procedure: Percutaneous transluminal renal angioplasty

Specialty: Cardiology

Chronic renal ischemia in humans: can cell therapy repair the kidney in occlusive renovascular disease?

Occlusive renovascular disease caused by atherosclerotic renal artery stenosis (ARAS) elicits complex biological responses that eventually lead to loss of kidney function. Recent studies indicate a complex interplay of oxidative stress, endothelial dysfunction, and activation of fibrogenic and inflammatory cytokines as a result of atherosclerosis, hypoxia, and renal hypoperfusion in this disorder. Human studies emphasize the limits of the kidney adaptation to reduced blood flow, eventually leading to renal hypoxia with activation of inflammatory and fibrogenic pathways. Several randomized prospective clinical trials show that stent revascularization alone in patients with atherosclerotic renal artery stenosis provides little additional benefit to medical therapy once these processes have developed and solidified. Experimental data now support developing adjunctive cell-based measures to support angiogenesis and anti-inflammatory renal repair mechanisms. These data encourage the study of endothelial progenitor cells and/or mesenchymal stem/stromal cells for the repair of damaged kidney tissue.

The association between atherosclerotic renal artery stenosis and acute kidney injury in patients undergoing cardiac surgery

BACKGROUND

Atherosclerotic renal artery stenosis (ARAS) and coronary artery disease (CAD) commonly co-exist. Some patients with unidentified ARAS may undergo cardiac surgery. While acute kidney injury (AKI) is a frequent and serious complication of cardiac surgery, we aim to evaluate the influence of ARAS on the occurrence of postoperative AKI in patients with normal or near-normal baseline renal function following cardiac surgery.

METHODS

A total of 212 consecutive patients undergoing aortography after coronary angiography and cardiac surgery were retrospectively studied for their preoperative and intraoperative conditions. AKI was defined as an absolute increase in serum creatinine of more than or equal to 0.3 mg/dl (≥26.4 µmol/l) or a percentage increase in creatinine of more than or equal to 50% (1.5-fold from baseline) after cardiac surgery. A propensity score-adjusted logistic regression models was used in estimating the effect of ARAS on the risk of postoperative AKI.

RESULTS

ARAS (≥50%) was observed in 50 (23.6%) patients, and 83 (39.2%) developed AKI after cardiac surgery. A correlation existed between renal artery patency and preoperative-to-postoperative %ΔCr in patients with ARAS (r = 0.297, P<0.0001). The propensity score-adjusted regression model showed the occurrence of postoperative AKI in patients with ARAS was significantly higher than those without ARAS (OR 2.858, 95% CI 1.260-6.480, P = 0.011).

CONCLUSION

ARAS is associated with postoperative AKI in patients with normal or near-normal baseline renal function after cardiac surgery.

Low birth weight increases susceptibility to renal injury in a rat model of mild ischemia-reperfusion

Renal injury due to ischemia-reperfusion (I/R) is the major cause of acute kidney injury. Whether enhanced susceptibility to renal injury due to I/R can be programmed during fetal life is unknown. Epidemiological studies indicate that low birth weight (LBW) individuals are more susceptible to renal injury than normal birth weight (NBW) individuals. Thus, the aim of this study was to test the hypothesis that LBW is associated with an increased susceptibility to renal injury induced by mild renal I/R (15-min ischemia). Systemic and renal hemodynamic parameters were determined in NBW and LBW adult male rats after mild renal I/R; renal superoxide production and tubular injury were also assessed. A subgroup was pretreated with tempol, a superoxide dismutase mimetic, initiated 15 min before ischemia. Mild renal I/R did not alter renal hemodynamic parameters, induce tubular injury, or induce superoxide production in NBW rats. However, renal hemodynamic parameters declined, superoxide production increased, and histological indicators of tubular injury were present following mild renal I/R in LBW rats. Acute treatment with tempol prevented these alterations in LBW rats subjected to mild renal I/R. Thus, these findings suggest that adverse conditions during fetal life can compromise the renal response to subtle insults leading to an increased susceptibility to renal injury, suggesting that LBW individuals may be an "at risk" population for renal disease. Additionally, the outcome of tempol treatment proposes a possible mechanistic pathway involved in mediating enhanced susceptibility to renal injury programmed during fetal life.

Novel pharmacological approaches to the treatment of renal ischemia-reperfusion injury: a comprehensive review

Renal ischemia-reperfusion (I-R) contributes to the development of ischemic acute renal failure (ARF). Multi-factorial processes are involved in the development and progression of renal I-R injury with the generation of reactive oxygen species, nitric oxide and peroxynitrite, and the decline of antioxidant protection playing major roles, leading to dysfunction, injury, and death of the cells of the kidney. Renal inflammation, involving cytokine/adhesion molecule cascades with recruitment, activation, and diapedesis of circulating leukocytes is also implicated. Clinically, renal I-R occurs in a variety of medical and surgical settings and is responsible for the development of acute tubular necrosis (a characteristic feature of ischemic ARF), e.g., in renal transplantation where I-R of the kidney directly influences graft and patient survival. The cellular mechanisms involved in the development of renal I-R injury have been targeted by several pharmacological interventions. However, although showing promise in experimental models of renal I-R injury and ischemic ARF, they have not proved successful in the clinical setting (e.g., atrial natriuretic peptide, low-dose dopamine). This review highlights recent pharmacological developments, which have shown particular promise against experimental renal I-R injury and ischemic ARF, including novel antioxidants and antioxidant enzyme mimetics, nitric oxide and nitric oxide synthase inhibitors, erythropoietin, peroxisome-proliferator-activated receptor agonists, inhibitors of poly(ADP-ribose) polymerase, carbon monoxide-releasing molecules, statins, and adenosine. Novel approaches such as recent research involving combination therapies and the potential of non-pharmacological strategies are also considered.

Peripheral vascular disease endovascular management in patients scheduled for cardiac surgery: a clinical-angiographic approach

BACKGROUND

Endovascular management of peripheral vascular disease before cardiac surgery is still debated. We sought to present our preliminary experience of endovascular stent placement in patients scheduled for urgent cardiac surgery.

METHODS

Between November 2003 and August 2005, 20 patients scheduled for urgent coronary surgery (13 males, mean age 72.5+/-5.3 years) underwent endovascular repair of PVD on the basis of clinical and angiographic indications. Aspirin (100 mg/day) plus low molecular weight heparin (nadroparin calcium) 100 IU/kg/12 h for urgent coronary surgical revascularization was administered after the procedure.

RESULTS

Endovascular stenting has been performed in four clinical settings: renal artery stenting prior to coronary surgery (nine patients) to decrease the impact of extracorporeal circulation on an impaired renal function, iliac artery artery angioplasty and stenting (eight patients) in order to facilitate aortic balloon pump insertion after surgery, subclavian artery angioplasty and stenting propedeutical to arterial conduits bypass surgery (one patient), carotid artery stenting before coronary surgery (two patients). All patients underwent successful endovascular repair followed by cardiac surgery. At a mean follow-up of 12+/-4.6 months all patients are alive and without evident thrombosis or restenosis of the implanted vascular stents.

CONCLUSIONS

Endovascular treatment of PVD in patients scheduled for urgent coronary surgery may be effective, relatively safe and lasting in spite of low dose antiplatelet regimen.

Atherosclerotic renovascular disease in chronic heart failure: should we intervene?

Renal artery stenosis (RAS) is most commonly caused by atherosclerosis, which is also the most common cause of chronic heart failure (CHF). One-third of patients with CHF are reported to have significant renovascular disease. The presence of RAS confers a worse outcome in studies of hypertension and coronary disease, though data are lacking for patients with CHF. As the kidney is intricately involved in the fluid retention that occurs in CHF, an adverse effect of RAS on outcome would be expected. Presentations of RAS in CHF include flash pulmonary oedema, hypertension, worsening of CHF, and worsening renal function. RAS commonly progresses and may cause worsening of renal function in patients with CHF and previously stable renal function. A variety of investigations that can safely and accurately identify RAS in CHF are available, although none is recommended in current guidelines for the management of CHF. Treatment for RAS, whether for hypertension, for renal dysfunction, or for pulmonary oedema, is at the discretion of the physician due to the lack of adequate randomized controlled trials demonstrating the efficacy and safety of intervention. As it is not clear how RAS should be managed in CHF, screening cannot be advocated. Currently, a multicentre randomized outcome trial, which includes a cohort of patients with RAS and CHF, is in progress to provide answers in this area of uncertainty.

Programming blood pressure in adult SHR by shifting perinatal balance of NO and reactive oxygen species toward NO: the inverted Barker phenomenon

The “programming hypothesis” proposes that an adverse perinatal milieu leads to adaptation that translates into cardiovascular disease in adulthood. The balance between nitric oxide (NO) and reactive oxygen species (ROS) is disturbed in cardiovascular diseases, including hypertension. Conceivably, this balance is also disturbed in pregnancy, altering the fetal environment; however, effects of perinatal manipulation of NO and ROS on adult blood pressure (BP) are unknown. In spontaneously hypertensive rats (SHR), NO availability is decreased and ROS are increased compared with normotensive Wistar-Kyoto rats, and, despite the genetic predisposition, the perinatal environment can modulate adult BP. Our hypothesis is that a disturbed NO-ROS balance in the SHR dam persistently affects BP in her offspring. Dietary supplements, which support NO formation and scavenge ROS, administered during pregnancy and lactation resulted in persistently lower BP for up to 48 wk in SHR offspring. The NO donor molsidomine and the superoxide dismutase mimic tempol-induced comparable effects. Specific inhibition of inducible nitric oxide synthase (NOS) reduces BP in adult SHR, suggesting that inducible NOS is predominantly a source of ROS in SHR. Indeed, inducible NOS inhibition in SHR dams persistently reduced BP in adult offspring. Persistent reductions in BP were accompanied by prevention of proteinuria in aged SHR. We propose that in SHR the known increase in ANG II type 1 receptor density during development leads to superoxide production, which enhances inducible NOS activity. The relative shortage of substrate and cofactors leads to uncoupling of inducible NOS, resulting in superoxide production, activating transcription factors that subsequently again increase inducible NOS expression. This vicious circle probably is perpetuated into adult life.

Angiographic characteristics of renal arterial disease over the spectrum of coronary artery disease

BACKGROUND/AIM

The angiographic characteristics of renal artery stenoses (RAS) in patients with coronary artery disease (CAD) have not been yet fully investigated. We sought to evaluate the angiographic characteristics of RAS in patients with CAD.

METHODS

The medical records of consecutive patients who underwent coronary angiography in a single public institution over a 12-month period were evaluated. The patients who underwent coincident diagnostic renal angiography to evaluate renal vessels on the basis of clinical criteria and who had at least one-vessel CAD were analyzed. Moderate (50-70%) to severe (70-100%) arterial stenoses were noted as significant angiographic findings. The types of stenosis (ostial, true renal, mixed) and presence and location of calcium were recorded.

RESULTS

Angiographically significant RAS were reported in 40 (19.5%) of 205 consecutive patients (mean age 67.1 +/- 12.8 years, mean serum creatinine concentration 2.1 +/- 0.5 mg/dl, mean glomerular filtration rate 52 +/- 13 ml/min) for a total of 55 lesions. The RAS severity was moderate in 30.9% (17/55), severe in 69.1% (38/55), ostial in 27.2% (15/55), true renal in 10.9% (6/55), and mixed in 61.8% (34/55) of the patients. The mean lesion length was 16 +/- 1.8 mm. Patients with > or = 3-vessel CAD had a statistically significantly higher prevalence of mixed calcified RAS (18/24, 75%). Logistic regression analyses revealed > or = 3-vessel CAD (odds ratio 9.917, p = 0.002), age > 65 years (odds ratio 3.817, p = 0.036), and > or = 3 risk factors (odds ratio 2.8, p = 0.048) as independent predictors of RAS.

CONCLUSION

RAS in multivessel CAD patients seems to have a peculiar angiographic pattern, such as a higher prevalence of mixed calcified lesions and poststenotic enlargement, that should be taken in account when dealing with RAS.