Noninvasive imaging of the renal arteries

When Bodybuilding Goes Wrong—Bilateral Renal Artery Thrombosis in a Long-Term Misuser of Anabolic Steroids Treated with AngioJet Rheolytic Thrombectomy

Bilateral renal infarction is an extremely rare condition with only few cases reported in the literature. We present a case of bilateral renal infarction affecting an otherwise healthy 34 year old bodybuilder chronically misusing testosterone and stanozolol. The patient presented with severe flank pain mimicking renal colic and biochemical features of acute kidney injury. Diagnostic workup revealed thrombosis affecting both renal arteries. Subsequently, the patient underwent a percutaneous rheolytic thrombectomy with AngioJet catheter, along with catheter-directed thrombolysis. Right-sided retroperitoneal hematoma developed as an early complication, mandating surgical exploration and nephrectomy due to kidney rupture and the unstable condition of the patient. Intensive care and continuous renal replacement therapy were instigated until a gradual improvement of the patient status and a return of kidney function was achieved. No abnormalities were found in the cardiological and hematological evaluation. We believe this is a first report of bilateral renal infarction associated with anabolic steroid misuse in an otherwise healthy individual, and a first report of AngioJet thrombectomy in bilateral thrombosis of renal arteries. It stresses the importance of a thorough diagnostic workup of colic patients and emphasizes the need for sports medicine to reach out to amateur athletes with education on the harms of doping.

Renal artery stenting with noninvasive duplex ultrasound follow-up: 3-year results from the RENAISSANCE renal stent trial

OBJECTIVE

The multicenter, single-arm RENAISSANCE trial evaluated outcomes in patients with progressive atherosclerotic renal artery stenosis (ARAS) treated with the Express Renal Premounted Stent System (Boston Scientific, Natick, MA).

BACKGROUND

Renal artery stenting may prevent the morbidity and mortality of surgical revascularization and high restenosis rates of percutaneous renal angioplasty (PTRA). Renal artery duplex ultrasonography (DUS) offers an alternative to traditional invasive poststenting angiographic surveillance, though concordance with angiography for in-stent restenosis has yet to be validated independently.

METHODS

RENAISSANCE enrolled 100 patients (117 lesions) with de novo or restenotic ostial atherosclerotic lesions <or=15 mm long in vessels >or=4.0 and <or=7.0 mm diameter with diameter stenosis >or=70%. The primary endpoint, 9-month binary restenosis, was compared to an objective performance criterion (OPC) of 40% for published PTRA results. Follow-up was conducted through 3 years.

RESULTS

Technical and procedural success was both 99%. Follow-up angiography, triggered clinically or by ultrasonography, revealed 21.3% binary restenosis at 9 months, which was superior to the OPC (P < 0.0001). Concordance between ultrasonography and angiography for detection of binary restenosis at 9 months was 87%. Peak systolic velocity and renal-to-aortic ratio were both significantly improved compared to baseline at 9 months and 2 years. The major adverse event (defined as device- or procedure-related death, target lesion revascularization or significant embolic event) rate was 10.5% at 9 months and 20.9% at 3 years.

CONCLUSIONS

RENAISSANCE demonstrates that renal artery stenting is superior to the prespecified OPC at 9 months, and also shows that DUS can accurately identify in-stent restenosis.

Hemobilia due to hepatic artery aneurysm as the presenting sign of fibro-muscular dysplasia

Fibro-muscular dysplasia (FMD) is a rare but well documented disease with multiple arterial aneurysms. The patients, usually women, present with various clinical manifestations according to the specific arteries that are affected. Typical findings are aneurysmatic dilatations of medium-sized arteries. The renal and the internal carotid arteries are most frequently affected, but other anatomical sites might be affected too. The typical angiographic picture is that of a "string of beads". Common histological features are additionally described. Here we present a case of a 47-year-old woman, who was hospitalized due to intractable abdominal pain. A routine work-up revealed a liver mass near the portal vein. Before a definite diagnosis was reached, the patient developed massive upper gastrointestinal bleeding. In order to control the hemorrhage, celiac angiography was performed revealing features of FMD in several arteries, including large aneurysms of the hepatic artery. Active bleeding from one of these aneurysms into the biliary tree indicated selective embolization of the hepatic artery. The immediate results were satisfactory, and the 5 years follow-up revealed absence of any clinical symptoms.

Fibromuscular dysplasia: noninvasive evaluation of unusual case of renal and mesenteric involvement

Fibromuscular dysplasia is the most common cause of renovascular hypertension in young patients. It primarily involves the renal and carotid arteries, and it is less common in the coronary, iliac, and visceral arteries. Digital subtraction angiography is still the best investigation to determine the location, extent, and complications of renal artery involvement. However, currently, other imaging modalities such as ultrasonography, computed tomography, and magnetic resonance imaging can reveal these findings noninvasively. We present the case of a 43-year-old woman who presented with high blood pressure and headache. Imaging revealed fibromuscular dysplasia of the renal arteries and the superior mesentery artery.

[Fibromuscular dysplasia]

Fibromuscular dysplasia is an idiopathic, segmental, nonatherosclerotic and noninflammatory disease of the muscle layer of arterial walls that leads to stenosis of small- and medium-sized arteries. Fibromuscular dysplasia preferentially affects young women. Although it can affect every arterial tree, it most often touches the renal and internal carotid arteries. Renal fibromuscular dysplasia can cause hypertension by stenosis of the renal artery, most often seen on angiography as resembling a "pearl necklace". Cerebrovascular fibromuscular dysplasia becomes symptomatic when the arterial stenosis is tight and causes hypoperfusion, embolism, or thrombosis or when arterial dissection or rupture of the associated aneurysm occurs.

Measurement of single kidney function using dynamic contrast-enhanced MRI: Comparison of two models in human subjects

PURPOSE

To compare two methods for assessing the single kidney glomerular filtration rate (SK-GFR) in humans using dynamic contrast-enhanced (DCE)-MRI.

MATERIALS AND METHODS

Images were acquired from 39 separate MR studies of patients with atherosclerotic renovascular disease (ARVD). Data from the kidneys and descending aorta were analyzed using both a Rutland-Patlak plot and a compartmental model. MR estimates of the SK-GFR were compared with standard radioisotope measures in a total of 75 kidneys.

RESULTS

Estimates of renal function using both techniques correlated well with radioisotope-assessed SK-GFR (Spearman's rho=0.81, Rutland-Patlak; rho=0.71, compartmental model). The Rutland-Patlak approach provided a near one-to-one correspondence, while the compartmental method tended to overestimate SK-GFR. However, the compartmental model fits to the experimental data were significantly better than those obtained using the Rutland-Patlak approach.

CONCLUSION

DCE-MRI of the kidneys provides data that correlate well with reference measures of SK-GFR. However, further work, including image registration, is needed to isolate measurement of glomerular filtration to the level of the renal cortex.

Vasoconstriction and blood flow responses in visceral arteries to mental task in humans

The vascular responses to mental task in visceral arteries in humans have not been elucidated. We observed the responses in the renal (RA) and superior mesenteric (SMA) arteries to mental stress, using simultaneous pulsed and echo Doppler ultrasound flowmetry. Nine healthy females performed a computerized colour word conflict test (CWT) for 3 min. The mean blood velocity (MBV) in the right RA and SMA, heart rate (HR) and blood pressure were measured. The mean arterial pressure (MAP) was divided by the flow velocity to assess the vascular resistance (VR). The CWT significantly increased the MAP, HR and VR in both arteries from the first minute. During the CWT, flow in the RA decreased significantly at the third minute relative to baseline, while flow in the SMA showed no significant change from the first to the third minute. The degree of vasoconstriction in the RA bed was greater than that in the SMA bed. These results suggest that the mental task causes vasoconstriction in visceral arteries, and imply that it induces differential blood flow and vascular responses in visceral arteries.

Current management of transplant renal artery stenosis: clinical utility of duplex Doppler ultrasonography

OBJECTIVES

To perform a retrospective study to determine the clinical utility of Doppler ultrasonography (DUS) and to determine its role in the management of transplant renal artery stenosis (TRAS).

METHODS

Patients undergoing DUS between January 1998 and January 2001 for clinical suspicion of TRAS were included in the study. A total of 51 patients were divided into two groups according to the peak systolic velocity. Additional management was based on the clinical and DUS findings and their congruence. Patients were followed up and their outcome was analyzed.

RESULTS

Of the 51 patients who entered the study, 26 were in the low probability group (LPG) and 25 in the high probability group (HPG). Nine patients in the LPG underwent additional investigations; eight underwent magnetic resonance angiography and one angiography. Of these 9 patients, 6 had stenosis, 4 of whom required angiography. In total, 5 patients from the LPG underwent angioplasty, and 4 of them had stenosis (1 with TRAS, 2 with common iliac artery stenosis, and 1 with renal artery ostial stenosis). Three patients underwent angioplasty and 2 of them improved. In the HPG, 20 of 25 patients underwent additional investigations, including magnetic resonance angiography in 12 and angiography in 8, with stenosis in 15 patients. Of the HPG, 13 of 25 patients underwent angiography, with 10 requiring angioplasty--8 for TRAS and 2 for adjacent renal artery stenosis, with improvement in 8 patients. Congruent clinical and DUS findings were highly predictive of significant stenosis more amenable to improvement.

CONCLUSIONS

The results of our study have shown that high-probability DUS and congruent clinical findings are likely to identify a significant stenosis that is amenable to treatment. Low-probability DUS findings do not eliminate the possibility of stenosis, but intervention in this group is less likely to result in improvement.

Contrast-enhanced three-dimensional fast-spoiled gradient magnetic resonance angiography of the renal arteries for potential living renal transplant donors: A comparative study with digital subtraction angiography

Preoperative assessment of the arterial anatomy of prospective renal donors is essential. Various non-invasive techniques are used for such evaluation. We conducted this study using contrast-enhanced 3-D fast-spoiled gradient (CE 3-D FSPGR) magnetic resonance angiography (MRA) on a 1.0 Tesla magnet, for preoperative definition of the renal arteries. Forty-five preoperative living renal donors underwent CE 3-D FSPGR MRA of the renal vessels and the results were compared with conventional digital subtraction angiography (DSA). The renal vascular anatomy, both normal and with variations, was satisfactorily defined in all 45 cases with CE 3-D FSPGR MRA. Fifteen cases showed an accessory or aberrant arterial supply. A small aneurysm was shown in one case. All cases compared well with conventional DSA. Our study revealed that CE 3-D FSPGR MRA on a lower field strength magnet is accurate in defining the renal vascular anatomy and its variations.

Fibromuscular dysplasia

The most common clinical manifestations of fibromuscular dysplasia (FMD) are hypertension due to renal artery involvement and transient ischemic attack or stroke due to carotid or vertebral artery involvement. Patients with renal artery FMD and hypertension should undergo primary angioplasty with the goal of curing the hypertension. If the blood pressure fails to normalize following angioplasty, the physician should institute antihypertensive medications according to the recommendations of the Joint National Committee on the Prevention, Detection, and Treatment of High Blood Pressure VII. In patients with cerebrovascular FMD, antiplatelet agents represent the cornerstone of therapy. Percutaneous angioplasty has emerged as the preferred treatment for symptomatic cerebrovascular FMD.

Comparison of Spatial Resolution in High-Resolution Multislice Computed Tomography and Digital Subtraction Angiography using Renal Specimens

OBJECTIVE

To compare maximum spatial resolution in multislice computed tomography (MS-CT) and digital subtraction angiography (DSA) using an arterial tree model for canine kidney specimens.

METHODS

Twenty-three isolated fox terrier kidneys were catheterized with a 4F catheter and underwent contrast-enhanced MS-CT with a maximum spatial resolution of 0.23-mm isotropic voxel size in an early arterial phase. In addition, a digital subtraction angiogram was performed on all kidneys. The kidneys were segmented semiautomatically, and each parenchymal vessel that was identified in the kidney was marked. The maximum intensity projections of arterial vessels in the CT datasets were evaluated in a comparison with the DSA datasets.

RESULTS

No significant difference in vessel delineation and count was found at any level up to the fourth level of intrarenal branching.

CONCLUSION

MS-CT has the potential of replacing DSA in the diagnosis of intrarenal arteries.

Renal vascular responses to static handgrip: role of muscle mechanoreflex

During exercise, the sympathetic nervous system is activated, which causes vasoconstriction. The autonomic mechanisms responsible for this vasoconstriction vary based on the particular tissue being studied. Attempts to examine reflex control of the human renal circulation have been difficult because of technical limitations. In this report, the Doppler technique was used to examine renal flow velocity during four muscle contraction paradigms in conscious humans. Flow velocity was divided by mean arterial blood pressure to yield an index of renal vascular resistance (RVR). Fatiguing static handgrip (40% of maximal voluntary contraction) increased RVR by 76%. During posthandgrip circulatory arrest, RVR remained above baseline (2.1 +/- 0.2 vs. 2.8 +/- 0.2 arbitrary units; P < 0.017) but was only 40% of the end-grip RVR value. Voluntary biceps contraction increased RVR within 10 s of initiation of contraction. This effect was not associated with an increase in blood pressure. Finally, involuntary biceps contraction also raised RVR. We conclude that muscle contraction evokes renal vasoconstriction in conscious humans. The characteristic of this response is consistent with a primary role for mechanically sensitive afferents. This statement is based on the small posthandgrip circulatory arrest response and the vasoconstriction that was observed with involuntary biceps contraction.

Atherosclerotic renal artery disease

Atherosclerotic renal artery stenosis may present with hypertension, renal failure (ischemic nephropathy), or congestive heart failure. The prevalence of renal artery stenosis is increasing in patients with other manifestations of atherosclerosis. The diagnosis is being made more frequently due to better screening tests such as duplex ultrasound and magnetic resonance angiography. Renal artery stenosis is discovered incidentally during imaging studies performed for other reasons. Revascularization should be performed using angioplasty and stenting in patients who have hypertension that cannot be adequately controlled with medications, in patients with severe bilateral renal artery stenosis or stenosis to a solitary functioning kidney and in patients with congestive heart failure when no other clear cut cause can be found.