Renal Atherosclerotic Lesions Research Articles

Invited commentary

Invited commentary

Is Renal Artery Stenting the Correct Treatmentof Renal Artery Stenosis?

The case favoring renal artery stenting for individuals with renal artery hypertension is largely circumstantial. At best, the clinical evidence presented in this discussion is derived primarily from nonrandomized cohort studies. It would certainly be easier to argue that medical therapy is preferred for such individuals because there are 3 published randomized clinical trials that concluded just that and none that support renal artery intervention. Nonetheless, there is considerable evidence to support the role for revascularization in general, and stenting specifically, as an important adjunctive therapy to medical therapy in the care of patients with renal artery stenosis (RAS). The argument has 3 principal components: observations about the impact on cardiovascular physiology, end-organ effects, and natural history. Response by Dworkin and Jamerson p 270 RAS is associated with and is an important cause of secondary hypertension. RAS causes endocrine activation with release of renin from renal juxtaglomerular cells. Renin catalyzes the breakdown of angiotensinogen to angiotensin I. Angiotensin I is transformed by angiotensin-converting enzyme into angiotensin II, and angiotensin II promotes the release of aldosterone from the adrenal cortex.1 Angiotensin II is a potent vasoconstrictor,2 substantially more potent than epinephrine, and is implicated in end-organ damage in the heart3 and kidney.4 RAS is suggested to cause 2 types of hypertension. With unilateral RAS and a normally perfused and normally functioning contralateral kidney, blood pressure elevation is referred to as “renin dependent” and is characterized by increased peripheral resistance.5,6 In this circumstance, renin and angiotensin levels remain elevated, but volume expansion is limited by natriuresis of the contralateral normally functioning kidney.6 Importantly, although renin levels are elevated, the value of peripheral or even renal vein renin values is limited by substantial overlap with patients having essential hypertension.7,8 When stenoses are bilateral or when the …

Renovascular hypertension update

Hypertension detected in patients with renovascular disease poses a major clinical challenge. The rapid expansion of noninvasive imaging, effective antihypertensive drug therapy, and endovascular interventional procedures combine to make optimal management a moving target. Renal arterial disease accelerates the development of hypertension associated with activation of multiple pressor systems and accelerated target organ injury. Younger individuals with fibromuscular lesions often respond well to renal revascularization with minor associated risks. Care must be taken in cases of complex vascular anomalies, such as renal artery aneurysms. Atherosclerotic renal artery stenosis is detected more commonly than ever before and affects more than 85% of patients referred for revascularization. Most are older patients with long-standing hypertension, diabetes, and pre-existing complications of vascular disease. The benefits of extensive workup and intervention in this group of patients are controversial. Antihypertensive drug therapy is most effectively achieved with drugs that block the renin-angiotensin system, but most require multiple agents. Selection of patients for renal revascularization in this group is far more controversial than with fibromuscular disease. Several small trials failed to identify major benefits with renal artery angioplasty as compared to closely monitored drug therapy, although crossover rates from medical to interventional arms were high. The Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) seeks to randomly assign subjects with proven, high-grade renal artery lesions to optimal medical management with and without stenting. This important trial employs distal embolic protection to prevent deterioration of renal function. Understanding the optimal role for renal revascularization depends heavily upon the successful conduct of such trials.

Controversial Treatment of Atherosclerotic Renal Vascular Disease

Atherosclerotic renal artery stenosis (RAS) is a relatively common problem, affecting from 1% to 5% of patients with hypertension.1,2 Given the high prevalence of hypertension, it follows that there are from 2 million to 4 million individuals with RAS in the United States alone. Autopsy data demonstrate that the incidence of RAS increases with age affecting 18% of individuals between the ages 65 to 74 years and >40% of those more than age 75.3 RAS is also common in individuals with vascular disease in other beds and is present in ≤40% of those with overt coronary artery disease, aortoiliac disease, or peripheral vascular disease.4–6 At present, the best treatment for RAS is unknown, and, in particular, whether or not revascularization, typically accomplished by angioplasty and stenting, improves clinical outcomes for patients with RAS is unclear. Nevertheless, it is estimated that &40 000 renal artery angioplasties procedures are performed in the United States each year, which, depending on whether or not the procedure is beneficial, is either far too many or far too few. The purpose of this article is to review current knowledge about atherosclerotic RAS and to discuss the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial, which is examining the best treatment for this disease. The pathophysiology of hypertension is different in patients with unilateral and bilateral RAS. In both, a drop in perfusion pressure to a kidney distal to a stenosis induces an increase in the activity of the renin–angiotensin–aldosterone system (RAAS). Salt and water retention and vasoconstriction contribute to the initial rise in systemic blood pressure, which tends to raise perfusion pressure of the poststenotic kidney toward normal. In patients with unilateral disease, perfusion pressure also rises in the contralateral, nonstenotic kidney to supra normal levels, inducing a pressure natriuresis response. Salt and …

Atherosclerotic renal artery stenosis and renovascular hypertension: clinical diagnosis and indications for revascularization.

Atherosclerotic renal artery stenosis (RAS) is relatively common and often associated with reversible hypertension, progressive renal insufficiency, and/or coronary-independent pulmonary edema. Not all RAS is associated with renovascular hypertension. Historical and physical findings may suggest renovascular hypertension and warrant investigation for RAS. Noninvasive diagnostic imaging options include renal artery duplex ultrasonography, magnetic resonance angiography, computed tomographic angiography, and CO2 angiography, with each method having its own advantages and limitations. Functional tests of renal flow, which characterize RAS significance, include captopril-stimulated plasma renin activity and captopril renography. To date, no single approach has shown clear superiority either in diagnosis or identification of patients most likely to benefit from revascularization. Revascularization of RAS is recommended for severe/drug-refractory hypertension, preservation of renal function, recurrent flash pulmonary edema, or recurrent severe heart failure. Intervention response is variable, but the ongoing Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial, comparing medical therapy with and without stenting, should provide management guidance.

The Cardiovascular Outcomes with Renal Atherosclerotic Lesions (CORAL) Study: Rationale and Methods

The Cardiovascular Outcomes with Renal Atherosclerotic Lesions (CORAL) Study: Rationale and Methods

The heart in Anderson Fabry disease

Anderson Fabry disease is a life threatening, X-linked inborn metabolic defect of the lysosomal enzyme áalpha-galactosidase A. The deficiency of alpha-galactosidase A leads to a progressive accumulation of globotriaosylceramide (Gb(3)), the major glycosphingolipid substrate of the enzyme, within vulnerable cells, tissues, and organs, including the cardiovascular system. Cardiac involvement is frequent and patients with cardiac affection develop progressive hypertrophic infiltrative cardiomyopathy, valvular abnormalities, arrhythmias, and conduction abnormalities and may develop coronary heart disease. Hemizygous male patients have no detectable alpha-galactosidase A activity, while affected heterozygous females may have normal level of alpha-galactosidase A activity. Death occurs in male patients at 45 to 50 years, about 15 to 20 years earlier than in female patients due to a vicious circle from chronic renal insufficiency, arterial hypertension, atherosclerotic lesions and cerebrovascular hemorrhage or insults, and cardiomyopathy. Cardiac involvement in hetero- and hemizygotes will be discussed as well as the influence of enzyme replacement of alpha-galactosidase A.

The transitional zone in the tunica media of renal arteries has a maximal length of 10 millimetres.

The goal of our study was to demonstrate and to determine the length of the transitional zone in the tunica media in renal arteries. The majority of renal artery atherosclerotic stenotic lesions occurs in this segment. Anatomical and histological studies were performed on 26 renal arteries from 13 adults at autopsy (mean age 61.6 years, range 33 to 87 years). In the macroscopical examination the right renal arteries (RRA) were longer with a median 53.8 mm (range 38 to 65 mm) than the left renal arteries (LRA) with a median 47.6 mm (range 35 to 63 mm), the circumferences were nearly the same: RRA 10.9 mm (range 5 mm to 15 mm) and LRA 11 mm (range 5 mm to 15 mm). Probes for histological examinations were taken from three different regions of each renal artery (origin, 5 mm and 10 mm distal to the origin). We observed a typical elastic arterial structure at the origin and muscular types at the distal 10 mm region. At the distal 5 mm region variable ratios of elastic tissue (ET) and smooth muscle cells (SMC) were found as follows: 15 arteries presented an equal ratio of EM:SMC, 7 arteries presented ET > SMC and 4 arteries presented ET < SMC ratios. In this study we confirmed that in renal arteries, a transitional zone (TZ) that is an arterial segment with transition from elastic to muscular type, does exist, involving the maximal length of 10 mm. Further studies on the impact of the biomechanical properties of the transitional zone as a potential localizing factor in renal atherosclerotic disease are justified. In addition, the complex biomechanical behavior of the TZ of the arterial wall should be taken into consideration when interventional procedures are planned.

Chronic Renal Artery Occlusion: Nephrectomy Versus Revascularization

Renal artery occlusion (RA-OCC) represents the final expression of anatomically progressive atherosclerotic renovascular occlusive disease. When a highgrade stenosis progresses to occlusion, the event may be clinically silent or previously controlled hypertension may worsen and serum creatinine levels may elevate.1 Given that as much as 35% of mild contralateral renal artery atherosclerotic lesions progress to sigChronic renal artery occlusion: Nephrectomy versus revascularization

Renal Failure and Advanced Atherosclerotic Lesions: Salvage by Vascular Reconstruction

• Occlusive renal artery lesions and progressive renal failure have a dismal prognosis if not treated. We analyzed our results to determine if the risks of renal vascularization were justified based on the final outcome in such patients. Inclusion criteria were a creatinine concentration of at least 160 μmol/L (1.8 mg/dL) and one of the following angiographic findings: (1) severe (≥75%) bilateral occlusions, (2) total occlusion with severe (≥75%) contralateral occlusion, or (3) solitary kidney with severe (≥75%) occlusion. Thirty patients met these criteria and underwent revascularization. Six required simultaneous aortic reconstruction. The average creatinine concentration on admission was 310 μmol/L (3.55 mg/dL); this had a statistically significant improvement to 210 μmol/L (2.41 mg/dL) at discharge. There was one perioperative death (3.3%). Initially, 22 patients had improved function (creatinine concentrations 20% lower), and seven patients had stable creatinine values. Eight patients ultimately required long-term dialysis. In the remaining 21 patients, with an average follow-up of 32 months, the average creatinine concentration was 220 μmol/L (2.51 mg/dL), still a significant improvement. Thus, we have demonstrated the relative safety and benefit of operating on these high-risk patients. ( Arch Surg 1988;123:610-613)

Percutaneous Transluminal Angioplasty of the Renal Arteries

Percutaneous transluminal angioplasty (PTA) of renal artery stenosis has proved highly efficacious, particularly in patients with lateralizing renal vein renin ratios, fibromuscular dysplasia, and atherosclerotic lesions confined to one renal artery without involvement of the aortic wall surrounding the renal ostium. In some series, a moderate recurrence rate has been reported, but these recurrences usually respond well to redilatation. Complications are relatively rare and generally not serious. Early results compare favorably with those of large surgical series. Some of the disparities in published results of renal PTA may be accounted for by differences in technique. Important advances in both equipment and PTA technique have occurred since the procedure was introduced in 1978; these may prove to favorably affect the long-term results.