Abnormal ankle-brachial index and risk of cardiovascular or all-cause mortality in patients with chronic kidney disease: a meta-analysis.

Prognostic role of ankle-brachial index (ABI) in patients with chronic kidney disease (CKD) is controversial. We aimed to evaluate whether abnormal ABI was an independent predictor of cardiovascular or all-cause mortality in CKD patients with or without hemodialysis by conducting a meta-analysis. We systematically searched Pubmed and Embase databases for prospective observational studies that investigated baseline abnormal ABI and subsequent cardiovascular or all-cause mortality risk in CKD patients with or without hemodialysis. An ABI value of 0.9 to 1.3 was defined as normal. Pooled hazard risk (HR) with 95% confidence interval (CI) was calculated for the abnormal vs. normal ABI category. Six studies enrolling 5820 patients were identified and analyzed. Overall, abnormal ABI was associated with an increased risk of all-cause mortality (HR 2.26; 95% CI 1.60-3.18) and cardiovascular mortality (HR 3.58; 95% CI 2.53-5.06). Subgroup analysis indicated that patients with abnormally low ABI increased by 2.45-fold all-cause mortality and 5.18-fold cardiovascular mortality. Similarly, an abnormally high ABI increased by 1.94-fold all-cause mortality and 4.04-fold cardiovascular mortality. In addition, the effect of abnormal ABI on all-cause mortality was more pronounced among hemodialysis patients (HR 3.06; 95% CI 2.30-4.07) but not in CKD patients (HR 1.42; 95% CI 0.98-2.05). Abnormally low and high ABI are independently associated with cardiovascular or all-cause mortality risk in maintenance hemodialysis patients. This meta-analysis highlighted an U-shaped relationship between ABI and mortality risk in CKD patients undergoing hemodialysis. However, findings of this meta-analysis were undermined by the small number of included studies.

Fibrin sheath formation and intimal thickening after catheter placement in dog model: role of hemodynamic wall shear stress.

PURPOSE: To investigate the role of wall shear stress in aspects of the formation of fibrin sheath and intimal thickening in a dog model. METHODS: Tunneled silicone 14.5-F catheters were inserted into the left internal jugular vein in eight dogs. The dogs were separated into two groups according to catheter indwelling time of 14 and 28 days. All dogs underwent extracorporeal circulation three times a week. Multidetector computed tomography venography (MDCTV) examination was used to examine the catheter tip thrombus. After the animals were sacrificed, histological and immunohistochemistry evaluations were performed to confirm specific cell populations. We used computer modeling to generate wall shear stress profiles for the blood flow through the catheter. RESULTS: Catheter-related sheaths were identified in all catheter specimens, but there was no fibrin sheath around the catheter tip. There were also differences in wall shear stress between the different venous wall sites. Differences in vein wall thickening at different sites have been found at both 14 days (intima to media (I/M) ratio S1 vs S2: p = 0.01, S3 vs S4: p<0.01) and 28 days (I/M ratio S1 vs S2: p<0.01, S3 vs S4: p<0.05). CONCLUSIONS: After catheter placement, fibrin sheath formation partially covered the catheter. Meanwhile, focal areas of intimal thickening were also seen in the venous wall adjacent to the sites of high wall shear stress. These findings indicate an important role of wall shear stress profiles in fibrin sheath formation and intimal thickening.