Assessment of Renal Function and Risk Factors for Chronic Kidney Disease in Patients With Peripheral Arterial Disease

The feasibility of low iodine dynamic CT angiography with test bolus for evaluation of lower extremity peripheral artery disease

OBJECTIVE

This study aims to determine if low iodine dynamic computed tomography angiography performed after a fixed delay or test bolus acquisition demonstrates high concordance with clinical computed tomography angiography (using a routine amount of iodinated contrast) to display lower extremity peripheral arterial disease.

METHODS

After informed consent, low iodine dynamic computed tomography angiography examination (using either a fixed delay or test bolus) using 50 ml of iodine contrast media was performed. A subsequent clinical computed tomography angiography using standard iodine dose (115 or 145 ml) served as the reference standard. A vascular radiologist reviewed dynamic and clinical computed tomography angiography images to categorize the lumen into "not opacified", "<50% stenosis", " 50 ̶70% stenosis", ">70% stenosis", and "occluded" for seven arterial segments in each lower extremity. Concordance between low iodine dynamic computed tomography angiography and the routine iodine reference standard was calculated. The clinical utility of 4D volume-rendered images was also evaluated.

RESULTS

Sixty-eight patients (average age 66.1 ± 12.3 years, male; female = 49: 19) were enrolled, with 34 patients each undergoing low iodine dynamic computed tomography angiography using fixed delay and test bolus techniques, respectively. One patient assigned to the test bolus group did not undergo low iodine computed tomography angiography due to unavailable delayed time. The fixed delay was 13 s, with test bolus acquisition resulting in a mean variable delay prior to image acquisition of 19.5 s (range; 8-32 s). Run-off to the ankle was observed using low iodine dynamic computed tomography angiography following fixed delay and test bolus acquisition in 76.4% (26/34) and 100% (33/33) of patients, respectively (p = 0.005). Considering extremities with run-off to the ankle and without severe artifact, the concordance rate between low iodine dynamic computed tomography angiography and the routine iodine reference standard was 86.8% (310/357) using fixed delay and 97.9% (425/434) using test bolus (p < 0.001). 4D volume-rendered images using fixed delay and test bolus demonstrated asymmetric flow in 57.7% (15/26) and 58.1% (18/31) (p = 0.978) of patients, and collateral blood flow in 11.5% (3/26) and 22.6% (7/31) of patients (p = 0.319), respectively.

CONCLUSION

Low iodine dynamic computed tomography angiography with test bolus acquisition has a high concordance with routine peripheral computed tomography angiography performed with standard iodine dose, resulting in improved run-off to the ankle compared to dynamic computed tomography angiography performed after a fixed delay. This method is useful for minimizing iodine dose in patients at risk for contrast-induced nephropathy. 4D volume-rendered computed tomography angiography images provide useful dynamic information.

Dyeless iliac vein stenting

OBJECTIVE

Iliac vein stenting is increasingly being explored for the treatment of chronic venous insufficiency. While venography is considered the gold standard for assessing iliac veins, some have proposed that intravascular ultrasound should be utilized instead due to its greater sensitivity at detecting stenotic lesions. Routinely, our service uses both intravascular ultrasound and venography, but we have noted that some patients cannot tolerate dye due to allergy, renal insufficiency, or deemed high-risk by the interventionalist due to uncontrolled medical co-morbidities. This study aimed to investigate whether forgoing dye had an impact on iliac vein stent thrombosis.

METHODS

From 2012 to 2016, 1482 iliac vein procedures (91 intravascular ultrasound-only and 1391 intravascular ultrasound plus venography) were performed on 992 patients who failed conservative treatment for chronic venous insufficiency. Our mean patient age was 65.8 years (range 21-99; SD ± 14.3) with 347 male and 645 female patients. The clinical presenting symptoms per clinical-etiology-anatomy-pathophysiology classification for the intravascular ultrasound-only cohort were C1:0, C2:3, C3:31, C433, C5:5, C6:20 and for the intravascular ultrasound plus venography cohort were C1:0, C2:24, C3:566, C4:583, C5:30, C6:188. Stent thrombi that developed within or at 30 days of stenting were categorized as early and greater than 30 days as late. Transcutaneous duplex ultrasound classified stent thrombi as either partial or occlusive. Our average follow-up time was 19.4 months (0-42, SD ± 12.5).

RESULTS

A total of 2.2% intravascular ultrasound-only patients versus 2.75% intravascular ultrasound plus venogram patients developed early stent thrombosis, p = 0.35. Early partial stent thrombosis occurred in 1.1% of the intravascular ultrasound-only group versus 2.6% of the intravascular ultrasound plus venogram group, p = 0.38. Early occlusive stent thromboses occurred in 1.1% of intravascular ultrasound-only patients and 0.15% of intravascular ultrasound plus venogram patients, p = 0.06. Late stent thromboses developed in 4% of patients in the intravascular ultrasound-only cohort and 4% in the intravascular ultrasound plus venogram cohort, p = 0.97. Late partial stent thromboses occurred in 2.7% of intravascular ultrasound-only patients versus 2.6% in intravascular ultrasound plus venogram patients, p = 0.99. Late occlusive stent thromboses occurred in 1.3% of intravascular ultrasound-only patients versus 1.4% of intravascular ultrasound plus venogram patients, p = 0.95. Moreover, the formation of any stent was 6.2% in the intravascular ultrasound-only versus 6.75% in the intravascular ultrasound plus venogram group, p = 0.55.

CONCLUSION

Results of our study show no significant difference in stent thrombosis between the intravascular ultrasound-only and intravascular ultrasound plus venogram cohorts. This concludes that using intravascular ultrasound alone is safe for iliac vein stenting.

Does Creatine Supplementation Affect Renal Function in Patients with Peripheral Artery Disease? A Randomized, Double Blind, Placebo-controlled, Clinical Trial

BACKGROUND

Case studies and reviews have shown that creatine supplementation can affect kidney function. The objective of this study is to verify the effects of 8 weeks of creatine supplementation on renal function (creatinine clearance: primary outcome) in patients with symptomatic peripheral arterial disease.

METHODS

Twenty-nine patients, of both genders, were randomized (1:1) in a double-blind manner for administration of Placebo (PLA; n = 15) or creatine monohydrate (Cr; n = 14). The supplementation protocol consisted of 20 g/day for 1 week divided into 4 equal doses (loading phase), followed by single daily doses of 5 g in the subsequent 7 weeks (maintenance phase). Before and after the supplementation period, markers of renal function, serum creatinine, creatinine excretion rate, and creatinine clearance were evaluated. The Generalized Estimation Equation Model was used for comparison between groups. The level of significance was P < 0.05.

RESULTS

No significant differences were found between groups before and after the intervention for serum creatinine (Cr: pre 1.00 ± 0.15 mL/dL vs. post 1.07 ± 0.16 mL/dL; PLA: pre 1.30 ± 0.53 mL/dL vs. post 1.36 ± 0.47 mL/dL, P = 0.590), creatinine excretion rate (Cr: pre 81.73 ± 43.80 mg/dL vs. post 102.92 ± 59.57 mg/dL; PLA: pre 74.37 ± 38.90 mg/dL vs. post 86.22 ± 39.94 mg/dL, P = 0.560), or creatinine clearance (Cr; pre 108 ± 59 mL/min/1.73 m² vs. post 117 ± 52 mL/min/1.73 m²; PLA: pre 88 ± 49 mL/min/1.73 m² vs. post 82 ± 47 mL/min/1.73 m², P = 0.366).

CONCLUSIONS

Eight weeks of creatine supplementation is safe and does not compromise the renal function of patients with peripheral arterial disease.