Atheroembolism

Acute Kidney Injury Following Percutaneous Coronary Intervention for Acute Coronary Syndrome: Incidence, Aetiology, Risk Factors and Outcomes

We investigated the predictors, aetiology and long-term outcomes of acute kidney injury (AKI) following urgent percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS). Acute kidney injury occurred in 198 (7.2%) of 2917 patients: 14.1% of AKI cases were attributed to cardiogenic shock and 5.1% were classified as atheroembolic renal disease (AERD). Significant risk factors for AKI included age (odds ratio [OR] 1.05, 95% confidence limits [CI] 1.03-1.06), diabetes (OR 1.73, 95% CI 1.20-2.47), hypertension (OR 1.43, 95% CI 1.03-2.00), heart failure (OR 3.01, 95% CI 1.58-5.57), femoral access (OR 1.50, 95% CI 1.03-2.15), cardiogenic shock (OR 2.03, 95% CI 1.19-3.37) and ST-elevation myocardial infarction (STEMI) (OR 3.89, 95% CI 2.80-5.47). One-year mortality after AERD was 44.4% and renal replacement therapy (RRT) requirement 22.2% (compared with mortality 33.3% and RRT requirement 7.4%, respectively, in all other AKI patients). Mortality at 1 year was associated with AKI (OR 4.33, 95% CI 2.89-6.43), age (OR 1.08, 95% CI 1.06-1.09), heart failure (OR 1.92, 95% CI 1.05-3.44), femoral access (OR 2.05, 95% CI 1.41-2.95) and cardiogenic shock (OR 3.63, 95% CI 2.26-5.77). Acute kidney injury after urgent PCI is strongly associated with worse outcomes. Atheroembolic renal disease has a poor outcome and a high likelihood of long-term RRT requirement.

Ultrasound and color Doppler applications in chronic kidney disease

Chronic kidney disease (CKD) includes all clinical features and complications during the progression of various kidney conditions towards end-stage renal disease (ESRD). These conditions include immune and inflammatory disease such as: primary and hepatitis C virus (HCV)-related glomerulonephritis; infectious disease such as pyelonephritis with or without reflux and tuberculosis; vascular disease such as chronic ischemic nephropathy; hereditary and congenital disease such as polycystic disease and congenital cystic dysplasia; metabolic disease including diabetes and hyperuricemia; and systemic disease (collagen disease, vasculitis, myeloma). During the progression of CKD, ultrasound imaging and color Doppler imaging (US-CDI) can differentiate the etiology of the renal damage in only 50-70% of cases. Indeed, the end-stage kidney appears shrunken, reduced in volume (Ø < 9 cm), unstructured, amorphous, and with acquired cystic degeneration (small and multiple cysts involving the cortex and medulla) or nephrocalcinosis, but there are rare exceptions, such as polycystic kidney disease, diabetic nephropathy, and secondary inflammatory nephropathies. The main difficulties in the differential diagnosis are encountered in multifactorial CKD, which is commonly presented to the nephrologist at stage 4-5, when the kidney is shrunken, unstructured and amorphous. As in acute renal injury and despite the lack of sensitivity, US-CDI is essential for assessing the progression of renal damage and related complications, and for evaluating all conditions that increase the risk of CKD, such as lithiasis, recurrent urinary tract infections, vesicoureteral reflux, polycystic kidney disease and obstructive nephropathy. The timing and frequency of ultrasound scans in CKD patients should be evaluated case by case. In this review, we will consider the morpho-functional features of the kidney in all nephropathies that may lead to progressive CKD.

Atheroembolic renal disease

Atheroembolic renal disease develops when atheromatous aortic plaques rupture, releasing cholesterol crystals into the small renal arteries. Embolisation often affects other organs, such as the skin, gastrointestinal system, and brain. Although the disease can develop spontaneously, it usually develops after vascular surgery, catheterisation, or anticoagulation. The systemic nature of atheroembolism makes diagnosis difficult. The classic triad of a precipitating event, acute or subacute renal failure, and skin lesions, are strongly suggestive of the disorder. Eosinophilia further supports the diagnosis, usually confirmed by biopsy of an affected organ or by the fundoscopic finding of cholesterol crystals in the retinal circulation. Renal and patient prognosis are poor. Treatment is mostly preventive, based on avoidance of further precipitating factors, and symptomatic, aimed to the optimum treatment of hypertension and cardiac and renal failure. Statins, which stabilise atherosclerotic plaques, should be offered to all patients. Steroids might have a role in acute or subacute progressive forms with systemic inflammation.

Color Doppler sonography in the study of chronic ischemic nephropathy

In western countries, the risk of cardiovascular disease has increased considerably in recent decades. This trend has been paralleled by an increase in cases of atherosclerotic renal disease, which is related to the improved prognosis of cardiovascular diseases, aging, and the increasing mean age of the general population. It is reasonable to expect that in the near future, there will be a sharp increase in the number of elderly patients with atherosclerotic vascular disease in chronic dialysis programs. The result will be a dramatic rise in the social and economic costs of dialysis that could constitute a true clinical emergency. In this epidemiologic scenario, one of the most important targets of 21st century nephrology will be the early diagnosis of chronic ischemic nephropathy and the development of new and more effective strategies for its treatment.Color Doppler (CD) ultrasonography has displayed high sensitivity, specificity, and positive and negative predictive values in the diagnosis of this disease in selected population, making it an ideal tool for use in screening programs. Eligibility for screening should be based on clinical criteria. For the most part, it will be aimed at adults (especially those who are elderly) with atherosclerotic vascular disease involving multiple districts and chronic kidney disease (CKD), stage 2-3, in the absence of a documented history of renal disease. In these patients, hypertension may be a secondary manifestation or a symptom of the ischemic nephropathy itself. The objectives of sonographic screening should be (1) to identify subjects in the population at risk who are affected by stenosis of the main renal artery (RAS); (2) to identify and characterize patients without RAS who have chronic ischemic nephropathy caused by nephroangiosclerosis and/or atheroembolic disease. The former group will require second-level diagnostic studies or angioplasty with stenting; the latter can be managed conservatively. The most important CD parameters in the workup of suspected RAS are those that are direct signs, i.e., increases in peak systolic velocity (PSV) and diastolic velocity (DV), spectral broadening, and an altered renal:aortic ratio (RAR). Their assessment requires full-length sampling of the renal artery and is associated with greater practical/technical difficulties. Measurement in triplicate of the PSV in the ostial, medial, and hilar segments of both arteries and bilateral measurement of parenchymal resistance indices are usually sufficient to detect the presence of stenosis and refer the patient for second-level studies. Important parameters for estimating the severity of a stenosis include the renal:aortic ratio (>3.5), disappearance of the early systolic peak in segmental vessels, lateralization of the resistance index (ΔRI > 0.05), and the evaluation of the acceleration index (AI) and acceleration time (AT). Second-level imaging studies (CT angiography, MR angiography) are still indispensable for precise definition of the location and extension of the stenosis and the therapeutic approach during digital subtraction angiography (DSA). In the absence of direct or indirect signs of RAS, increases in the intraparenchymal resistance indices (RI > 0.75-0.80; PI > 1.50) associated with systemic atherosclerotic disease are indicative of microcirculatory damage related to nephroangiosclerosis or atheroembolic disease.