Gautam Cherla

Venous mapping using venography and the risk of radiocontrast-induced nephropathy.

Venous mapping using venography has been considered to be the gold standard for identifying veins suitable for arteriovenous fistula (AVF) creation. By utilizing a radiocontrast medium, however, venography introduces the risk of radiocontrast‐induced nephropathy. The risk of this complication in the chronic kidney disease (CKD) population has not been previously studied. Twenty‐five consecutive patients (CKD stage 4 and 5) undergoing venography were enrolled in this study. Patients were advised not to fast for the procedure and were encouraged to take oral fluids. Radiocontrast‐induced nephropathy was defined as a 20% decrease in the estimated glomerular filtration rate (GFR) from the baseline value at 48 hours after contrast administration. Weekly telephone calls were made for a total of 4 weeks to assess the need for dialysis. Venography was performed by interventional nephrology using 10–20 cc of low osmolarity contrast medium. Data were collected prospectively. Median age was 48.9 ± 7.8 years and 52% of the patients had diabetes. Complete sets of pre‐ and postprocedure GFRs were available in 21 patients. At 48 hours, there were no differences between the pre‐ and postprocedure GFRs. At the third week, one patient developed flu‐like symptoms with severe gastroenteritis and was hospitalized for volume depletion. This patient initiated dialysis during the hospital stay. We conclude that at 48 hours, our cohort did not develop radiocontrast‐induced nephropathy. During the 4‐week phone call follow‐up, only one patient needed dialysis. Large‐scale studies with a longer follow‐up using GFR estimation are needed to confirm these preliminary findings.

Role of l-Arginine in the Pathogenesis and Treatment of Renal Disease

L-arginine is a semi essential amino acid and also a substrate for the synthesis of nitric oxide (NO), polyamines, and agmatine. These L-arginine metabolites may participate in the pathogenesis of renal disease and constitute the rationale for manipulating L-arginine metabolism as a strategy to ameliorate kidney disease. Modification of dietary L-arginine intake in experimental models of kidney diseases has been shown to have both beneficial as well as deleterious effects depending on the specific model studied. L-arginine supplementation in animal models of glomerulonephritis has been shown to be detrimental, probably by increasing the production of NO from increased local expression of inducible NO synthase (iNOS). L-arginine supplementation does not modify the course of renal disease in humans with chronic glomerular diseases. However, beneficial effects of L-arginine supplementation have been reported in several models of chronic kidney disease including renal ablation, ureteral obstruction, nephropathy secondary to diabetes, and salt-sensitive hypertension. L-arginine is reduced in preeclampsia and recent experimental studies indicate that L-arginine supplementation may be beneficial in attenuating the symptoms of preeclampsia. Administration of exogenous L-arginine has been shown to be protective in ischemic acute renal failure. In summary, the role of L-arginine in the pathogenesis and treatment of renal disease is not completely understood and remains to be established.

ASDIN Original Investigations: Venous Mapping Using Venography and the Risk of Radiocontrast-Induced Nephropathy

Venous mapping using venography has been considered to be the gold standard for identifying veins suitable for arteriovenous fistula (AVF) creation. By utilizing a radiocontrast medium, however, venography introduces the risk of radiocontrast‐induced nephropathy. The risk of this complication in the chronic kidney disease (CKD) population has not been previously studied. Twenty‐five consecutive patients (CKD stage 4 and 5) undergoing venography were enrolled in this study. Patients were advised not to fast for the procedure and were encouraged to take oral fluids. Radiocontrast‐induced nephropathy was defined as a 20% decrease in the estimated glomerular filtration rate (GFR) from the baseline value at 48 hours after contrast administration. Weekly telephone calls were made for a total of 4 weeks to assess the need for dialysis. Venography was performed by interventional nephrology using 10–20 cc of low osmolarity contrast medium. Data were collected prospectively. Median age was 48.9 ± 7.8 years and 52% of the patients had diabetes. Complete sets of pre‐ and postprocedure GFRs were available in 21 patients. At 48 hours, there were no differences between the pre‐ and postprocedure GFRs. At the third week, one patient developed flu‐like symptoms with severe gastroenteritis and was hospitalized for volume depletion. This patient initiated dialysis during the hospital stay. We conclude that at 48 hours, our cohort did not develop radiocontrast‐induced nephropathy. During the 4‐week phone call follow‐up, only one patient needed dialysis. Large‐scale studies with a longer follow‐up using GFR estimation are needed to confirm these preliminary findings.

Creation of secondary arteriovenous fistulas: maximizing fistulas in prevalent hemodialysis patients.

National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF‐DOQI) guideline 29 suggests that a patient should be evaluated for a secondary arteriovenous fistula (AVF) following each episode of dialysis access failure. Regretfully, it does not appear that this approach is used, even though recent data have emphasized that veins suitable for the creation of a secondary AVF can be identified in dialysis patients who are receiving dialysis via a synthetic arteriovenous graft (AVG) or other type of potentially dysfunctional vascular access. In this study nine patients (five with an AVG and four with an AVF) with vascular access dysfunction undergoing percutaneous interventions were evaluated for secondary AVF creation. All were found to have suitable vascular anatomy and had the AVF created. The secondary fistula was successful in all nine patients with a mean follow‐up of 4.8 ± 1.4 months in post‐AVG cases and 5.6 ± 1.7 months in the post‐AVF patients. In addition, it was possible to continue uninterrupted dialysis without the use of a tunneled dialysis catheter in three of the patients with AVGs. This experience demonstrates the validity and success of this approach to the management of dialysis access dysfunction. In the ongoing effort to optimize vascular health status, we suggest that during percutaneous interventions, patients should routinely have identification of vessels suitable for creation of a secondary AVF.

ASDIN Original Investigations: Creation of Secondary Arteriovenous Fistulas: Maximizing Fistulas in Prevalent Hemodialysis Patients

National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF‐DOQI) guideline 29 suggests that a patient should be evaluated for a secondary arteriovenous fistula (AVF) following each episode of dialysis access failure. Regretfully, it does not appear that this approach is used, even though recent data have emphasized that veins suitable for the creation of a secondary AVF can be identified in dialysis patients who are receiving dialysis via a synthetic arteriovenous graft (AVG) or other type of potentially dysfunctional vascular access. In this study nine patients (five with an AVG and four with an AVF) with vascular access dysfunction undergoing percutaneous interventions were evaluated for secondary AVF creation. All were found to have suitable vascular anatomy and had the AVF created. The secondary fistula was successful in all nine patients with a mean follow‐up of 4.8 ± 1.4 months in post‐AVG cases and 5.6 ± 1.7 months in the post‐AVF patients. In addition, it was possible to continue uninterrupted dialysis without the use of a tunneled dialysis catheter in three of the patients with AVGs. This experience demonstrates the validity and success of this approach to the management of dialysis access dysfunction. In the ongoing effort to optimize vascular health status, we suggest that during percutaneous interventions, patients should routinely have identification of vessels suitable for creation of a secondary AVF.

ASDIN Original Investigations: Venous Mapping Using Venography and the Risk of Radiocontrast-Induced Nephropathy: VENOGRAPHY AND RADIOCONTRAST NEPHROPATHY

Venous mapping using venography has been considered to be the gold standard for identifying veins suitable for arteriovenous fistula (AVF) creation. By utilizing a radiocontrast medium, however, venography introduces the risk of radiocontrast‐induced nephropathy. The risk of this complication in the chronic kidney disease (CKD) population has not been previously studied. Twenty‐five consecutive patients (CKD stage 4 and 5) undergoing venography were enrolled in this study. Patients were advised not to fast for the procedure and were encouraged to take oral fluids. Radiocontrast‐induced nephropathy was defined as a 20% decrease in the estimated glomerular filtration rate (GFR) from the baseline value at 48 hours after contrast administration. Weekly telephone calls were made for a total of 4 weeks to assess the need for dialysis. Venography was performed by interventional nephrology using 10–20 cc of low osmolarity contrast medium. Data were collected prospectively. Median age was 48.9 ± 7.8 years and 52% of the patients had diabetes. Complete sets of pre‐ and postprocedure GFRs were available in 21 patients. At 48 hours, there were no differences between the pre‐ and postprocedure GFRs. At the third week, one patient developed flu‐like symptoms with severe gastroenteritis and was hospitalized for volume depletion. This patient initiated dialysis during the hospital stay. We conclude that at 48 hours, our cohort did not develop radiocontrast‐induced nephropathy. During the 4‐week phone call follow‐up, only one patient needed dialysis. Large‐scale studies with a longer follow‐up using GFR estimation are needed to confirm these preliminary findings.

ASDIN Original Investigations: Creation of Secondary Arteriovenous Fistulas: Maximizing Fistulas in Prevalent Hemodialysis Patients: SECONDARY ARTERIOVENOUS FISTULAS

National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF‐DOQI) guideline 29 suggests that a patient should be evaluated for a secondary arteriovenous fistula (AVF) following each episode of dialysis access failure. Regretfully, it does not appear that this approach is used, even though recent data have emphasized that veins suitable for the creation of a secondary AVF can be identified in dialysis patients who are receiving dialysis via a synthetic arteriovenous graft (AVG) or other type of potentially dysfunctional vascular access. In this study nine patients (five with an AVG and four with an AVF) with vascular access dysfunction undergoing percutaneous interventions were evaluated for secondary AVF creation. All were found to have suitable vascular anatomy and had the AVF created. The secondary fistula was successful in all nine patients with a mean follow‐up of 4.8 ± 1.4 months in post‐AVG cases and 5.6 ± 1.7 months in the post‐AVF patients. In addition, it was possible to continue uninterrupted dialysis without the use of a tunneled dialysis catheter in three of the patients with AVGs. This experience demonstrates the validity and success of this approach to the management of dialysis access dysfunction. In the ongoing effort to optimize vascular health status, we suggest that during percutaneous interventions, patients should routinely have identification of vessels suitable for creation of a secondary AVF.